Soon-Lim Chong

Arshia Hematpoor

Hazrina Hazni

Mohd Sofian-Azirun

Marc Litaudon

Unang Supratman

Michio Murata

Khalijah Awang
email: khalijah@um.edu.my

Chong Soon-Lim

Pascal Richomme

Jamil Ahmad-Shilpi

Yoshinori Asakawa

Mosquito larvicidal limonoids from the fruits of Chisocheton erythrocarpus Hiern

Keywords: Chisocheton erythrocarpus Hiern, Meliaceae, limonoid, erythrocarpines F-H, mosquito larvicidal activity Taxonomy Biological Activity of Plant Product, Phytochemicals Chisocheton erythrocarpus Hiern, Meliaceae, limonoid, erythrocarpines F-H, mosquito larvicidal activity

come   L'archive ouverte pluridisciplinaire

 Four new limonoids were isolated  Limonoids with rare 1,29-oxymethylene bridge and 3β,8β-ether linkage were isolated  Limonoids exhibited toxicity against larvae of several types of mosquitoes

Introduction

Over the years, various scientific studies have established the Meliaceae family as a rich source of limonoids. By definition, limonoids are tetranortriterpenoids characterized by the formation of a furan ring after the excision of four terminal carbons from the side chain of apotirucallane or apoeuphane [START_REF] Tan | Meliaceous limonoids: Chemistry and biological activities[END_REF]. Extensive skeletal rearrangements that entails, such as ring opening and closure, oxidation, and epoxidation, result in high diversification of the carbon skeleton. Limonoids are produced abundantly in families like Meliaceae and Rutaceae, and to a lesser extent in Cneoraceae and Simaroubaceae.

Structural-wise, meliaceous limonoids are far more complex and diverse than the chemical equivalent of its botanical counterparts [START_REF] Roy | Limonoids: Overview of Significant Bioactive Triterpenes Distributed in Plants Kingdom[END_REF]. In continuation of our efforts to isolate new bioactive compounds from family Meliaceae [START_REF] Nagoor | Correction: Regulation of Apoptotic Effects by Erythrocarpine E, a Cytotoxic Limonoid from Chisocheton erythrocarpus in HSC-4 Human Oral Cancer Cells[END_REF][START_REF] Najmuldeen | Chisomicines A-C, Limonoids from Chisocheton ceramicus[END_REF], we have carried out a phytochemical investigation on the fruits of Chisocheton erythrocarpus Hiern. The genus Chisocheton comprises of approximately 50 species that are distributed in tropic and subtropic region of Asia. Chisocheton erythrocarpus Hiern is a species found mainly in Peninsular Malaysia, Borneo, and Philippines. From the dichloromethane extract of its fruits, four new limonoids designated as erythrocarpine F (1), erythrocarpine G (2), erythrocarpine H (3) and 14-deoxy-Δ 14,15 -xyloccensin K (4), along with seven known compounds, 14-deoxyxyloccensin K (5) (A. [START_REF] Najmuldeen | 14-Deoxyxyloccensin K from Chisocheton ceramicus (Meliaceae)[END_REF], khayasin B (6) (K. [START_REF] Adesogan | Extractives from Khaya senegalensis(Desr.) A. Juss[END_REF], erythrocarpine A (7) [START_REF] Awang | Erythrocarpines A-E, new cytotoxic limonoids from Chisocheton erythrocarpus[END_REF], erythrocarpine B (8) [START_REF] Awang | Erythrocarpines A-E, new cytotoxic limonoids from Chisocheton erythrocarpus[END_REF], 7-deacetoxy-7-oxogedunin (9) [START_REF] Ambrozin | Limonoids from andiroba oil and Cedrela fissilis and their insecticidal activity[END_REF], dammaradienone (10) [START_REF] Phongmaykin | A new sesquiterpene and other terpenoid constituents of Chisocheton penduliflorus[END_REF] and moronic acid (11) [START_REF] Inada | Phytochemical Studies on Meliaceous Plants. VIII. Structures and Inhibitory Effects on Epstein-Barr Virus Activation of Triterpenoids from Leaves of Chisocheton macrophyllus KING[END_REF] were isolated and characterized. Mosquito larvicidal activity revealed that 4 and 5 were toxic to third instar larvae of Aedes aegypti, Aedes albopictus and Culex Quinquefasciatus.

Results and discussion

Erythrocarpine F (1) was afforded as white amorphous powder. The HRESIMS showed a quasi-molecular ion peak [M+H] + at m/z 589.2445 (calcd. for C 34 H 37 O 9 , 589.2438), establishing a molecular formula of C 34 H 36 O 9 with 17 elements of unsaturation. The IR spectrum showed the presence of hydroxyl and carbonyl groups at 3480 and 1718 cm -1 , respectively. Careful inspection of NMR spectra suggested signals ascribable to three tertiary methyl groups (δ H 0.68, 1.04 and 1.13; δ C 14.3, 14.7 and 21.8), a β-substituted furan (δ H 6. 44, 7.40 and 7.46; δ C 110.2, 120.3, 141.3 and 143.0), a methyl ester (δ H 3.67; δ C 52.0 and 173.6) and a δ-lactone (δ H 5.04; δ C 79.7 and 165.1). Altogether, these individual substructure units were indicative of a phragmalin skeleton. In addition, a pair of double bonds were revealed by the olefinic proton signals at δ H 5.78 and δ H 6.25. The former signal was assigned as H-15 based on the HMBC cross peak of H-15/C-16, while the latter signal had to be H-30 due to its involvement in an AMX spin system with H-2 (δ H 3.19), which in turn coupled to H-3 (δ H 5.15) in the COSY experiment. In the HMBC spectrum, the H-3 (δ H 5.15) was correlated to C-1' (δ C 166.0) of the benzoyl group, therefore established a benzoate group at C-3 position. The formation of 1,29-oxymethylene bridge in phragmalin skeleton was a rarity [START_REF] Chen | Absolute configurations of new limonoids from a Krishna mangrove, Xylocarpus granatum[END_REF], and its presence was evident from the oxymethylene H 2 -29 signals (δ H 3.52, pro S and 3.99, pro R) that gave HMBC cross peaks to C-1 (δ C 96.4), C-3 (δ C 76.3), C-4 (δ C 36.4) and C-5 (δ C 33.6). In effect, the incorporation of an oxygen atom in the ring A converts a norbornane substructure in normal phragmalin to a norcineole structural unit as in 1. Therefore 1 was elucidated as an 1,29-oxymethylenebridged phragmalin possessing a conjugated diene lactone and a benzoate ester. In the NOESY experiment, cross peaks of H-5/H 3 -28 and H-5/H-12β indicated that H-5 assumed a β-orientation. On the other hand, H-9 was confirmed as α-oriented based on cross peaks of H-9/H 3 -18 and H-9/H 3 -19. In addition, cross peaks of H-3/H-2 and H-3/H-29 pro S implied that H-2 and H-3 were α-oriented. The 1 H and 13 C NMR assignments of 1 were shown in Table 1 and Table 2, respectively, whereas the chemical structure was shown in Fig. 1.

Erythrocarpine G (2) was isolated as white amorphous powder. It has a molecular formula of C 34 H 38 O 9 , assigned on the basis of quasi-molecular ion peak [M+H] + at m/z 591.2598 (calcd. for C 34 H 39 O 9 , 591.2594) in the HRESIMS spectrum. The 1D NMR spectral patterns showed evidences that it possessed an altered phragmalin skeleton similar to that of 1, such as three methyl groups (δ H 0.65, 0.91 and 1.11; δ C 14.2, 15.9 and 16.7), a βsubstituted furan (δ H 6.42, 7.47 and 7.56; δ C 110.0, 121.0, 141.4 and 142.7) and a methyl ester (δH 3.71; δ C 52.0 and 174.3). In addition to that, the existence of rare 1,29oxymethylene bridge was demonstrated by the HMBC correlations of H 2 -29 (δ H 3.50 and 3.93) to C-1 (δ C 97.3), C-3 (δ C 77.6), C-4 (δ C 36.2) and C-5 (δ C 34.4). The information obtained from 13 C and DEPT NMR spectra showed that 2 differed from 1 only in the substitution pattern of the main ring, of which 2 possessed a tetrasubstituted double bond, Δ 8,14 (δ C 129.4 and 129.5) whereas 1 had two trisubstituted double bonds, Δ 8,30 and Δ 14,15 .

Erythrocarpine H (3) showed a molecular formula of C 36 H 40 O 9 as determined by the quasi-molecular ion peak [M+H] + at 617.2752 (calcd. for C 36 H 41 O 9 , 617.2751) in the HRESIMS. Comparison of 1 H and 13 C NMR spectra between 3 and 2 revealed that they differed only in the nature of the substituent at C-3 position. Whereas 2 possessed a benzoate group, it can be shown that 3 had a cinnamoyl moiety. This was discernible on the basis of AA'BB'C-type spin system of aromatic ring in the 1 H NMR spectrum of 3 that was consistent with the presence of cinnamoyl moiety instead of a benzoyl group. Further evidence was provided by both olefinic proton signals of H-2ʹ (δ H 6.41) and H-3ʹ (δ H 7.87) that gave HMBC correlations to C-1ʹ (δ C 166.7) and C-4ʹ (δ C 133.7).

14-Deoxy-Δ 14,15 -xyloccensin K (4), obtained as white amorphous powder, was assigned a molecular formula of C 27 H 32 O 7 based on the quasi-molecular ion peak at m/z 469.2221 (calcd. for C 27 H 33 O 7 , 469.2226) in the HRESIMS. The IR spectrum gave an intense band at 1721 cm-1 corresponding to various carbonyl stretches. The 1 H and 13 C NMR spectra contained signals ascribable to four methyl groups (δ H 0.67, 0.93, 1.08 and 1.15), a βsubstituted furan ring (δ H 6.46, 7.43 and 7.50). That 4 accommodated a methyl ester was indicated primarily by the methoxy singlet at δ H 3.68. All these typical signals suggested 4 to possess a mexicanolide skeleton. In addition, 4 was postulated to form a rare 3β,8β -oxygen bridge. This could be deduced from the H-3 signal that was observed as a doublet (J = 5.6 Hz) at δ H 4.23, along with C-3 and C-8 signals that were detected at δ C 88.8 and δ C 80.0, respectively. Further proof of this oxygen bridge was derived from HMBC cross peak of H-3/C-8. Comparison of 1D NMR data between 4 and two structurally similar compounds, xyloccensin K [START_REF] Kokpol | A limonoid from Xylocarpus granatum[END_REF] and andirolide N [START_REF] Tanaka | Andirolides H-P from the flower of andiroba (Carapa guianensis, Meliaceae)[END_REF], also gave a good agreement. As for the relative configuration of 4, NOESY cross peaks of H-3/H-2, H-2/H 3 -29α and H-3/H 3 -29α indicated that H-2 and H-3 were α-oriented. Likewise, H-9 was αoriented as can be deduced from the cross peaks of H-9/H-11α, H-9/H-12α, H-9/H 3 -18α and H-9/H 3 -19α. On the other hand, H-5 and H-17 were confirmed to be β-oriented from the cross peaks of H-5/H 3 -28β and H-17/H-12β. The establishment of 3β,8β-ether linkage was likely to be due to severe steric hindrance on the β-surface [START_REF] Veitch | Four New Tetranortriterpenoids from Cedrela odorata Associated with Leaf Rejection by Exopthalmus jekelianus[END_REF]. Overall, the NMR assignments resulted in a structure as depicted in Fig. 2 (A &B).

Limonoids that were isolated in substantial quantity were tested for mosquito larvicidal activity. Of all the tested limonoids, only 14-deoxy-Δ 14,15 -xyloccensin K (4) and 14deoxyxyloccensin K (5) displayed significant toxicity to late third instar larvae of Aedes aegypti, Aedes albopictus and Culex Quinquefasciatus. 14-Deoxyxyloccensin K (5) was the most potent larvicide and showed lethal concentrations comparable to rotenone, a wellknown botanical insecticide. In addition, 4 also exhibited very high larvicidal activity but its toxicity was significantly lower than rotenone and 5. Details were shown in Table 3.

Experimental

General experimental procedures

All NMR spectra were obtained from a 400 MHz ( 1 H) Jeol ECA NMR machine, using deuterated chloroform as solvent. The chemical shifts were recorded in ppm relative to TMS.

The NMR solvent peaks were referenced to δ 7.26 ppm ( 1 H) and 77.2 ppm ( 13 C). The highresolution mass spectra were obtained from an Agilent 6530 Accurate-Mass Q-TOF LC/MS, using SPD-M20A diode array detector coupled to an IT-TOF mass spectrometer. The UV spectra were recorded on a Shimadzu UV-2600 spectrometer, with spectroscopic grade acetonitrile and methanol as solvent. The IR spectra were measured on a Perkin Elmer Spectrum FTIR Spectrometer RX1. Silica gel (Merck silica gel, 70-230 mesh) was used for column chromatography, with binary solvent systems; hexane-ethyl acetate and dichloromethane-ethyl acetate, used as mobile phase. Preparative TLC separations were performed on Merck silica gel 60 F 254 (20x20cm). The final purification of compounds was achieved with a Waters HPLC system equipped with photodiode array detector (PDA). The Supelco C18 column (15cm x 10mm, 5 µm) was used as stationary phase whereas methanol-water or acetonitrile-water binary solvent systems were used as mobile phase.

Plant materials

The fruits of Chisocheton erythrocarpus Hiern were collected from Hutan Simpan Terenas, Kedah, which is a northwestern state of the Peninsular Malaysia. The identification of the plant species was done by botanist Mr. Teo Eng-Leong whereas the dried plant material for extraction work was prepared by Mr. Din Mat Nor. Voucher specimens were deposited at the Herbarium of Department of Chemistry, Faculty of Science, University of Malaya.

Extraction and isolation

The extraction of dried fruits (0.7 kg) was carried out using simple maceration method.

The pulverized dried fruits were first defatted with hexane, and then soaked in dichloromethane for 48 hours. Periodical stirring (by hand) was applied throughout the duration to enhance the extraction yield. Upon 48 hours, the liquid extract was separated from the fruit mass by straining with filter paper. It was then dried under reduced pressure using rotary evaporator. To maximize the extraction yield, the fruit mass was subjected to the same extraction procedure for two more times, each time with fresh dichloromethane.

The combined crude dichloromethane extract (14 g) was first subjected to column chromatography with hexane-ethyl acetate as mobile phase to yield 24 fractions. Fractions 12-18 were subjected to preparative HPLC using acetonitrile-water (80:20) as mobile phase to obtain compounds 1 (8.9 mg), 2 (12.6 mg), and 3 (8.4 mg). Compound 4 (58 mg) was obtained from fractions 8-11 through preparative TLC, with hexane-ethyl acetate (85:15) as solvent system. Fractions 19-24 were subjected to repeated microcolumn separation and preparative TLC using hexane-ethyl acetate binary solvent system to obtain 5 (187 mg), 6 (23.2 mg), 7 (4.6 mg), 8 (3.2 mg) and 9 (8.5 mg). Compounds 10 and 11 were obtained from fractions 3-7 by repeated microcolumn separation using hexane-ethyl acetate solvent system.

Erythrocarpine F (1)

White amorphous powder; [α] D 25 +63 (c 0.2, MeOH); IR (KBr) 3480, 1718 cm -1 ; 1 H NMR (400 MHz, CDCl 3 ) and 13 C NMR (100 MHz, CDCl 3 ), see Table 1 and2

Erythrocarpine G (2)

White amorphous powder; [α] D 25 -89 (c 0.24, MeOH); IR (KBr) 3420, 1721 cm -1 ; 1 H NMR (400 MHz, CDCl 3 ) and 13 C NMR (100 MHz, CDCl 3 ), see Table 1 and2

Erythrocarpine H (3)

White amorphous powder; [α] D 25 -113 (c 0.2, MeOH); IR (KBr) 3426, 1716 cm -1 ; 1 H NMR (400 MHz, CDCl 3 ) and 13 C NMR (100 MHz, CDCl 3 ), see Table 1 and2

14-Deoxy-Δ 14,15 -xyloccensin K (4)

White amorphous powder; [α] D 25 +15 (c 0.2, MeOH); IR (KBr) 1721 cm -1 ; 1 H NMR (400 MHz, CDCl 3 ) and 13 C NMR (100 MHz, CDCl 3 ), see Table 1 and2

Mosquito larvicidal assays

  ; HR ESI-MS m/z found 589.2445 ([M+H] + ) (calcd. for C 34 H 37 O 9 [M+H] + , 589.2438).

  ; HR ESI-MS m/z found 591.2598 ([M+H] + ) (calcd. for C 34 H 39 O 9 [M+H] + , 591.2594).

  ; HR ESI-MS m/z found 617.2752 ([M+H] + ) (calcd. for C 36 H 41 O 9 [M+H] + , 617.2751).

  ; HR ESI-MS m/z found 469.2221 ([M+H] + ) (calcd. for C 27 H 33 O 7 [M+H] + , 469.2226).

  Mosquito larvicidal assays follow standard procedures recommended by World Health Organization (1981). The mosquitoes Aedes aegypti, Aedes albopictus and Culex quinquefasciatus were obtained from the lab strains in Institute of Biological Department of University Malaya. Mosquitoes were cultured at laboratory condition (25°C±2°C and R.H: 75 to 80%). Rotenone (from Derris elliptica) was used as standard for larvicidal activity comparison. Six milligrams of a standard w/v concentrate and each limonoid were dissolved in 10ml acetone made as stock solution. Serial dilution was established using 250ml dechlorinated tap water to achieve different concentrations. Twenty five late third or early fourth instar larvae of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus (vectors of dengue fever and lymphatic filariasis) were introduced separately in varying doses to each compound. Experiments were performed at laboratory condition 25°C±2°C and the relative

Fig. 1 :Fig

 1 Fig. 1: Chemical Structures of Limonoids 1-4

Table 1

 1

	. 1 H NMR Data for 1-4 (CDCl 3 , 400 MHz)
			δ H in ppm (J in Hz)
	Position 1	2	3	4
	2	3.19 dd (6.3, 10.1)	2.64 ddd (2.3, 5.5,	2.62 m	3.13 pseudo t (5.6)
			10.5)
	3	5.15 d (10.1)	5.22 d (10.5)	5.17 d (10.5)	4.23 d (5.6)
	5	2.90 br d (11.0)	3.18 br d (11.2)	3.03 br d (10.4)	2.94 dd (2.3, 11.1)
	6a	2.36 m	2.42 dd (1.7, 16.5)	2.39 m	2.08-2.22 m
	6b	2.43 dd (11.0, 17.4)	2.53 dd (11.2, 16.5)	2.46 m	2.08-2.22 m
	9	2.33 m	2.40 m	2.42 m	1.66 m
	11α	1.74 m	1.77 m	1.71 m	1.41 m
	11β	1.33 m	1.63 m	1.63 m	1.93 m
	12α	1.36 m	1.04 m	1.09 m	1.68 m
	12β	1.84 m	1.69 m	1.70 m	1.95 m
	14
	15α	5.78 s	2.97 br s	3.30 d (20.8)	6.34 s
	15β			3.67 d (20.8)
	17	5.04 s	5.40 s	5.51 s	5.19 s
	18	1.04 s	0.94 s	1.01 s	1.08 s
	19	1.13 s	1.13 s	1.12 s	0.93 s
	21	7.46 br s	7.59 s	7.56 s	7.50 s
	22	6.44 t (0.9)	6.44 d (1.4)	6.44 d (1.5)	6.46 s
	23	7.40 br s	7.50 s	7.50 br s	7.43 br s
	28	0.68 s	0.67 s	0.62 s	1.15 s
	29 pro-R 29 pro-S 30α	3.99 d (9.6) 3.52 dd (1.6, 9.6) 6.25 d (6.3)	3.95 d (9.8) 3.53 dd (1.7, 9.8) 2.20 m	3.92 d (9.6) 3.50 dd (2.2, 9.6) 2.19 m	0.67 s 2.13 d (12.0)
	30 β		2.26 dd (2.3, 15.2)	2.37 br d (15.4)	2.49 dd (6.0, 12.0)
	OCH 3 2'	3.67 s	3.73 s	3.72 s 6.41 d (16.0)	3.68 s
	3'	8.08 br d (7.4)	8.13 d (7.1)	7.87 d (16.0)
	4'	7.48 br t (7.8)	7.48 m
	5'	7.60 br t (7.5)	7.59 m	7.58 m
	6'	7.48 br t (7.8)	7.48 m	7.34 m
	7'	8.08 br d (7.4)	8.13 d (7.1)	7.34 m
	8'			7.34 m
	9'			7.58 m

Table 3 .

 3 LC values of 4, 5 and rotenone (standard/control) against third instar larvae of Aedes aegypti, Aedes albopictus and Culex Quinquefasciatus with 95% confidence index

	Tested Insects

a LC 50 and LC 95 values followed by a common letter were not significantly different (P ʹ 0.05) as based on nonoverlap of the 95% CL.

humidity (R.H) was 75 to 80%, 14:10 light and dark photo period. Each treatment was replicated four times. Mortality was observed after 24 hours.

Acknowledgments

This research was carried out in the framework of the International French-Malaysian Natural Products Laboratory (IFM-NatPro-Lab) established between CNRS, ICSN, the French Embassy in Malaysia, and the University of Malaya. In addition to that, this research was financially supported by the Postgraduate Research Funds of the University of Malaya (PV040-2011B) and (PV085/2011A), and University of Malaya High Impact Research Grant (UM.C/625/1/HIR/MOHE/SC/37).

Conflict of Interest

The authors declare no conflict of interest.


Carole Berthod
email: carole.berthod@uca.fr

Etienne Médard

Patrick Bachèlery

Lucia Gurioli

Andrea Di Muro

Aline Peltier

Jean-Christophe Komorowski

Mhammed Benbakkar

Jean- Luc Devidal

Jessica Langlade

Pascale Besson

Georges Boudon

Estelle Rose-Koga

Christine Deplus

Anne Le Friant

Manon Bickert

Sophie Nowak

Isabelle Thinon

Pierre Burckel

Samia Hidalgo

Melanie Kaliwoda

Stephan J Jorry

Yves Fouquet

Nathalie Feuillet

The 2018-ongoing Mayotte submarine eruption: magma migration imaged by petrological monitoring

Keywords: Mayotte, submarine eruption, dredges, petrological model, mantle reservoirs, multiple storage zone

Highlights

-Lavas erupted offshore Mayotte since May 2018 are evolved basanites (~5 wt% MgO).

-The eruption is fed by a deep (> 37 km) mantle reservoir.

-Primitive magma has undergone at least 50% of crystallization in a ≥ 10 km 3 mantle reservoir.

-Magma transfer rate show that the eruption is steadily supplied from the deep mantle reservoir.

-After May 2019, ascending magma intersected a more evolved and shallower magma reservoir.

INTRODUCTION

The discovery in May 2019 of an active volcanic submarine edifice of exceptional size 50 km east of Mayotte island (Comoros Archipelago, Mozambique Channel, Fig. 1a) caused an immediate mobilization of the French scientific community [START_REF] Feuillet | MAYOBS cruises, RV Marion Dufresne[END_REF], and the creation of the Mayotte Volcanological and Seismological Monitoring Network (ReVoSiMa, 2021). The eruptive site is located on the distal part of a 60 km long WNW-ESE volcanic ridge that runs off the eastern flank of Mayotte, the subaerial expression of which is Petite Terre Island (Fig. 1b). As of October 2020, this volcano had risen 820 m above the 3300 m deep seafloor with an erupted lava volume of ~ 6.5 km 3 (ReVoSiMa, 2021). This volume implies exceptionally high time-averaged magma discharge rates ranging from 150 -200 m 3 /s (first year), decreasing through 70 -80 m 3 /s (May-July 2019) to less than 35 -45 m 3 /s since August 2019 (ReVoSiMa, 2021). As such, it represents by far the largest monitored submarine eruption [START_REF] Carey | The largest deep-ocean silicic volcanic eruption of the past century[END_REF][START_REF] Chadwick | A recent volcanic eruption discovered on the central Mariana back-arc spreading center[END_REF][START_REF] Chadwick | Voluminous eruption from a zoned magma body after an increase in supply rate at Axial Seamount[END_REF][START_REF] Clague | Volcanic morphology of West Mata Volcano, NE Lau Basin, based on high-resolution bathymetry and depth changes[END_REF][START_REF] Perfit | Magmatism at mid-ocean ridges: Constraints from volcanological and geochemical investigations[END_REF][START_REF] Resing | Active submarine eruption of boninite in the northeastern Lau Basin[END_REF][START_REF] Rubin | Volcanic eruptions in the deep sea[END_REF] and the third largest mafic eruption of the last two millennia after Eldgjá in 939 [START_REF] Oppenheimer | The Eldgjá eruption: timing, long-range impacts and influence on the Christianisation of Iceland[END_REF] and Laki in 1783-1784 [START_REF] Thordarson | The Laki (Skaftár Fires) and Grímsvötn eruptions in 1783-1785[END_REF], both in Iceland.

The seismo-volcanic crisis began in May 2018 with a series of strong tectonic earthquakes, including 32 events with MW³5, located between 12 and 42 km depth, ~35 km east of Mayotte [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF]. On land, surface deformation (subsidence and eastern motion) have been continuously observed since July 2018, and Very Long Period (VLP) seismic events related to fluid migration and possible magmatic activity have been occurring at least since mid-June 2018 [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF], suggesting that the eruptive activity has been ongoing for more than two years. On-going subsidence and seismicity have been linked to the eruption-related withdrawal of magma from its storage zone [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Feuillet | Birth of a large volcanic edifice through lithosphere-scale diking offshore Mayotte (Indian Ocean)[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF].

Three oceanographic cruises (MAYOBS 1, Feuillet, (2019), MAYOBS 2, Jorry, (2019), MAYOBS 4, [START_REF] Fouquet | MAYOBS4 cruise, RV Marion Dufresne[END_REF], Fig. 1c,d) between May and July 2019 provide an exceptional time-series of bathymetric, textural, petrological, and geochemical data for the 2018-2019 eruptive period (Table 1). Since most mafic submarine eruptions are short-lived and have only been sampled after the end of the eruption, their study provides little information on their temporal evolution [START_REF] Chadwick | A recent volcanic eruption discovered on the central Mariana back-arc spreading center[END_REF][START_REF] Clague | Chemical variations in the 1998, 2011, and 2015 lava flows from Axial Seamount, Juan de Fuca Ridge: Cooling during ascent, lateral transport, and flow[END_REF][START_REF] Rubin | Volcanic eruptions in the deep sea[END_REF]. The geographically and temporally well-characterized sampling performed during the MAYOBS cruises thus brings an invaluable opportunity to better constrain the evolution of magma storage and transfer during a long-lived submarine eruption. In this paper, we present a detailed petrological, textural, and geochemical study of the submarine samples, to provide insights into the temporal and spatial evolution of a large volume of gas-rich magma rapidly intruding the lithosphere and reactivating multiple levels of magma storage. This is the first time that this methodology, developed for subaerial eruption at monitored volcanoes (Di [START_REF] Muro | The shallow plumbing system of Piton de la Fournaise Volcano (La Reunion Island, Indian Ocean) revealed by the major 2007 caldera-forming eruption[END_REF][START_REF] Edmonds | Magma storage, transport and degassing during the 2008-10 summit eruption at Kīlauea Volcano, Hawai 'i[END_REF][START_REF] Gansecki | The tangled tale of Kīlauea's 2018 eruption as told by geochemical monitoring[END_REF][START_REF] Gurioli | Integrating field, textural, and geochemical monitoring to track eruption triggers and dynamics: a case study from Piton de la Fournaise[END_REF], and combining a large range of petrological and geochemical approaches on a temporal series of lava samples, is applied to a submarine eruption.

GEOLOGICAL SETTING

The Comoros Archipelago is located in the Mozambique Channel between the northern tip of Madagascar and the eastern coast of Mozambique (Fig. 1a). The four islands which compose the archipelago, Grande Comore, Moheli, Anjouan and Mayotte, are aligned on a NW-SE trend [START_REF] Tzevahirtzian | Submarine morphology of the Comoros volcanic archipelago[END_REF]. This trend is superimposed on a zone of active seismicity connecting the northern extremity of Madagascar on the east, to the African coast to the west, and several authors suggest the presence of a boundary between the Lwandle microplate and the Somalia plate [START_REF] Famin | The Comoros archipelago: a right-lateral transform boundary between the Somalia and Lwandle plates[END_REF][START_REF] Saria | Present-day kinematics of the East African Rift[END_REF][START_REF] Stamps | A Geodetic Strain Rate Model for the East African Rift System[END_REF]. By combining a structural study with stress inversion of earthquake focal mechanisms, [START_REF] Famin | The Comoros archipelago: a right-lateral transform boundary between the Somalia and Lwandle plates[END_REF] propose that this Lwandle and Somalian plate boundary is related to a complex E-W zone of immature right-lateral wrenching of the lithosphere.

Despite numerous studies, the origin of the volcanism in this geodynamic context remains a matter of debate [START_REF] Bachèlery | Geochemical and Petrological Aspects of Karthala Volcano[END_REF][START_REF] Class | The process of plume-lithosphere interactions in the ocean basins-the case of Grande Comore[END_REF][START_REF] Bourdon | Ra-Th-Sr isotope systematics in Grande Comore Island: a case study of plume-lithosphere interaction[END_REF][START_REF] Coltorti | Carbonatite metasomatism of the oceanic upper mantle: evidence from clinopyroxenes and glasses in ultramafic xenoliths of Grande Comore, Indian Ocean[END_REF][START_REF] Deniel | Geochemical and isotopic (Sr, Nd, Pb) evidence for plume-lithosphere interactions in the genesis of Grande Comore magmas (Indian Ocean)[END_REF][START_REF] Flower | Evolution of basaltic and differentiated lavas from Anjouan, Comores Archipelago[END_REF][START_REF] Michon | The volcanism of the Comoros archipelago integrated at a regional scale[END_REF][START_REF] Nougier | The Comores archipelago in the western Indian Ocean: volcanology, geochronology and geodynamic setting[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF][START_REF] Strong | Petrology of the island of Moheli, western Indian Ocean[END_REF][START_REF] Thompson | One-atmosphere melting and crystallization relations of lavas from Anjouan, Comores Archipelago, Western Indian Ocean[END_REF]). Many hypotheses have been formulated including the interaction of a mantle plume with oceanic lithosphere [START_REF] Class | The process of plume-lithosphere interactions in the ocean basins-the case of Grande Comore[END_REF][START_REF] Class | Grand Comore Island: A well-constrained "low 3He/4He" mantle plume[END_REF][START_REF] Class | Osmium isotopes in Grande Comore lavas: a new extreme among a spectrum of EM-type mantle endmembers[END_REF][START_REF] Bourdon | Ra-Th-Sr isotope systematics in Grande Comore Island: a case study of plume-lithosphere interaction[END_REF][START_REF] Emerick | Age progressive volcanism in the Comores Archipelago, western Indian Ocean and implications for Somali plate tectonics[END_REF][START_REF] Hajash | Paleomagnetic and radiometric evidence for the age of the Comores Islands, west central Indian Ocean[END_REF] and the reactivation of lithospheric structures possibly in relation with the East African Rift System [START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF][START_REF] Michon | The volcanism of the Comoros archipelago integrated at a regional scale[END_REF][START_REF] Nougier | The Comores archipelago in the western Indian Ocean: volcanology, geochronology and geodynamic setting[END_REF].

Trace elements and EM1 -HIMU isotopic signatures of volcanic rocks in the Comoros

Archipelago would support the interaction of a mantle plume with amphibole/phlogopitebearing oceanic metasomatized lithosphere [START_REF] Bachèlery | Geochemical and Petrological Aspects of Karthala Volcano[END_REF][START_REF] Class | The process of plume-lithosphere interactions in the ocean basins-the case of Grande Comore[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF][START_REF] Späth | The geochemistry of lavas from the Comores Archipelago, Western Indian Ocean: petrogenesis and mantle source region characteristics[END_REF]. However, the mantle plume hypothesis is considered incompatible with the migration of the African Plate towards the NNE and with the structural features of the region [START_REF] Famin | The Comoros archipelago: a right-lateral transform boundary between the Somalia and Lwandle plates[END_REF]. Finally, since the youngest volcanic activity occurs both in Grande Comore (0.13 ± 0.02 Ma to present; [START_REF] Hajash | Paleomagnetic and radiometric evidence for the age of the Comores Islands, west central Indian Ocean[END_REF][START_REF] Emerick | Age progressive volcanism in the Comores Archipelago, western Indian Ocean and implications for Somali plate tectonics[END_REF] with the active Karthala volcano (Bachèlery et al., 2016) and in Mayotte [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Feuillet | Birth of a large volcanic edifice through lithosphere-scale diking offshore Mayotte (Indian Ocean)[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF][START_REF] Zinke | Postglacial flooding history of Mayotte lagoon (Comoro archipelago, southwest Indian Ocean)[END_REF], the age progression of volcanism is not consistent with formation of the archipelago by the migration of the Somali plate over a fixed hotspot. Several lines of evidence suggest that the volcanism of the Comoros archipelago is associated with lithospheric deformation rather than the result of a deep mantle plume [START_REF] Famin | The Comoros archipelago: a right-lateral transform boundary between the Somalia and Lwandle plates[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF][START_REF] Michon | The volcanism of the Comoros archipelago integrated at a regional scale[END_REF].

Mayotte, the easternmost island of the archipelago, southwestward of Anjouan (Fig. 1a), is the oldest island with a maximum age of 20 Ma for the onset of subaqueous volcanic activity [START_REF] Debeuf | Étude de l'évolution volcano-structurale et magmatique de Mayotte (archipel des Comores, océan Indien[END_REF][START_REF] Emerick | Age progressive volcanism in the Comores Archipelago, western Indian Ocean and implications for Somali plate tectonics[END_REF][START_REF] Hajash | Paleomagnetic and radiometric evidence for the age of the Comores Islands, west central Indian Ocean[END_REF][START_REF] Michon | The volcanism of the Comoros archipelago integrated at a regional scale[END_REF][START_REF] Nougier | The Comores archipelago in the western Indian Ocean: volcanology, geochronology and geodynamic setting[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF]. It is composed of two main volcanic islands, Grande Terre and Petite Terre, the latter located 4 km east of Grande Terre. Mayotte subaerial activity is subdivided into multiple phases beginning in the southern part of Grande Terre (10.6 -1.9 Ma) and then migrating towards the north (5 -0.75 Ma) and the northeast (0.75 -Present) separated by periods of quiescence [START_REF] Debeuf | Étude de l'évolution volcano-structurale et magmatique de Mayotte (archipel des Comores, océan Indien[END_REF][START_REF] Nehlig | Notice de la carte géologique de Mayotte[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF].

The current volcanic activity takes place 50 km off Mayotte, on a WNW-ESE submarine volcanic ridge on the east flank of the island, Fig. 1b, [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Feuillet | Birth of a large volcanic edifice through lithosphere-scale diking offshore Mayotte (Indian Ocean)[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF].

METHODS

Sampling

We first performed a high-resolution bathymetric survey of the eruptive site [START_REF] Feuillet | MAYOBS1 cruise, RV Marion Dufresne[END_REF](Feuillet et al., , 2021) ) to identify strategic dredging sites. Erupted lavas were dredged on five sites, each dredge running for about 100 -600 m and returning a weight of approximately 300 -900 kg (Fig. 1c). During three oceanographic campaigns (MAYOBS 1, Feuillet, (2019), MAYOBS 2, Jorry, (2019), MAYOBS 4, [START_REF] Fouquet | MAYOBS4 cruise, RV Marion Dufresne[END_REF]), three dredges sampled the main volcanic cone and the radiating ridges built before May 2019 (phase 1: DR01, DR10, DR12, Table 1 and Fig. 1c,d), and two dredges on the S and SE flanks collected lava flows emitted during a second phase in June 2019 (DR08) and July 2019 (DR11). We selected fresh samples with representative morphologies and textures, including quenched pillow rims, pillow cores, sediments, samples containing xenoliths and phenocrysts. For this paper, we focused our study on glassy pillow rims that preserved the pre-quench textures, as well as xenoliths and phenocryst-rich fragments.

Analytical techniques

Bulk rock compositions were obtained on a set of 10 samples from 5 dredges (DR0101, DR0105, DR0801-ALF, DR080102, DR100511, DR11, DR1107(1), DR1107(2), DR110704b and DR120202, Suppl. material Table 1). Major elements were analyzed on a HORIBA-Jobin-Yvon ULTIMA C ICP-AES at Laboratoire Magmas et Volcans (LMV, Clermont-Ferrand, France). Trace elements were analyzed on an Agilent 7900 ICP-MS at Institut de Physique du Globe de Paris (IPGP, Paris, France). In situ chemical analyses of minerals and glasses were performed using the CAMECA SXFive Tactis electron microprobe at LMV. Raman spectra were acquired on melt inclusions in olivine and magnetite, and on matrix glasses at the Ludwig Maximilian University (LMU -Laboratory of crystallography) using an XPlora One spectrometer (Jobin Yvon) coupled with an Olympus microscope at 100x magnification. Details of the analytical procedures are presented in Supplementary Material "Methods".

Physical properties and textures

Density measurements were performed on 27 lava samples using a Micromeritics Geopyc 1360 envelope density analyzer, following the procedure detailed by [START_REF] Thivet | Basaltic dyke eruptions at Piton de La Fournaise: characterization of the eruptive products with implications for reservoir conditions, conduit processes and eruptive dynamics[END_REF]. The instrument measures the volume of particles with different sizes and shapes. These density measurements lead to reproducible data with a maximum standard deviation of ± 30 kg.m -3 (1σ) on five repeated measurements. The porosity of the samples was then calculated using vesicle-free rock density values [START_REF] Houghton | A vesicularity index for pyroclastic deposits[END_REF]) calculated from the partial molar volumes of oxide components [START_REF] Bottinga | Densities of liquid silicate systems calculated from partial molar volumes of oxide components[END_REF]. Petrographic observations and microtexture analysis were performed using optical microscope and scan. Vesicle and crystal size distribution (VSD and CSD), vesicle and crystal number density (NV and NC), and vesicle to melt ratio (VG/VL) were measured following the procedures in [START_REF] Shea | Textural studies of vesicles in volcanic rocks: an integrated methodology[END_REF] and assuming a spherical shape for both vesicles and crystals (mostly olivine).

Fractional crystallization model

Back-crystallization models were performed to reconstruct a potential mantle-derived parental melt. Equilibrium olivine and clinopyroxene were added in 1 wt % increments to the bulk composition of sample DR0101 until the melt was in equilibrium with a Fo90 mantle olivine. For each step, the composition of the equilibrium olivine was calculated from the magma composition of the previous step assuming a Kd of 0.30 (Kd = (FeO/MgO)olivine / (FeO/MgO)melt, [START_REF] Roeder | Olivine-liquid equilibrium[END_REF]) and a partition coefficient DNi = (Ni olivine / Ni melt = 124 / MgO -0.9, [START_REF] Hart | Nickel partitioning between olivine and silicate melt[END_REF]). The composition of the equilibrium clinopyroxene was calculated assuming a Kd of 0.28 [START_REF] Putirka | Thermometers and Barometers for Volcanic Systems[END_REF], oxides vs Mg# trends derived from a series of unpublished clinopyroxene analyses in basanite samples from Mayotte [START_REF] Ali | Etude pétrochimique du volcanisme récent de Mayotte[END_REF], and DNi = 2. The proportions of olivine and clinopyroxene were adjusted to fit the trend provided by a compilation of published bulk rock analyses from the Comoros Archipelago.

Diffusion modelling

Preliminary residence times were estimated using diffusion in zoned olivine crystals, modelled with the DIPRA software [START_REF] Girona | DIPRA: A user-friendly program to model multi-element diffusion in olivine with applications to timescales of magmatic processes[END_REF]. Reversely zoned olivine crystals were oriented using an EBSD detector attached to a Zeiss Supra 55 VP field-emission scanning electron microscope housed at ISTeP (Paris, France). Electron microprobe analyses were acquired along carefully selected profiles: we chose olivine crystals most likely to be cut close to their center (large homogeneous core), and the shortest possible profiles, perpendicular to euhedral faces and far from other faces, to avoid artificial lengthening of the profiles (e.g., [START_REF] Costa | Time scales of magmatic processes from modeling the zoning patterns of crystals[END_REF][START_REF] Couperthwaite | Reducing epistemic and model uncertainty in ionic inter-diffusion chronology: A 3D observation and dynamic modeling approach using olivine from Piton de la Fournaise, La Réunion[END_REF]. Fo profiles (Fo = atomic Mg/(Mg+Fe+Mn+Ca+Ni)*100) were modelled using an average temperature of 1095 ± 20 °C, an oxygen fugacity on the NNO buffer, and an arbitrary pressure of 200 MPa. Influence of pressure on diffusion times is within uncertainty.

RESULTS

Petrological and geochemical features

Bulk rock compositions of the lavas from the eruptive site fall within the compositional range of the moderately to slightly alkaline series of the Comoros archipelago, the "Karthala trend" [START_REF] Bachèlery | Geochemical and Petrological Aspects of Karthala Volcano[END_REF][START_REF] Class | The process of plume-lithosphere interactions in the ocean basins-the case of Grande Comore[END_REF][START_REF] Bourdon | Ra-Th-Sr isotope systematics in Grande Comore Island: a case study of plume-lithosphere interaction[END_REF][START_REF] Coltorti | Carbonatite metasomatism of the oceanic upper mantle: evidence from clinopyroxenes and glasses in ultramafic xenoliths of Grande Comore, Indian Ocean[END_REF][START_REF] Deniel | Geochemical and isotopic (Sr, Nd, Pb) evidence for plume-lithosphere interactions in the genesis of Grande Comore magmas (Indian Ocean)[END_REF][START_REF] Flower | Evolution of basaltic and differentiated lavas from Anjouan, Comores Archipelago[END_REF][START_REF] Nougier | The Comores archipelago in the western Indian Ocean: volcanology, geochronology and geodynamic setting[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF][START_REF] Strong | Petrology of the island of Moheli, western Indian Ocean[END_REF][START_REF] Thompson | One-atmosphere melting and crystallization relations of lavas from Anjouan, Comores Archipelago, Western Indian Ocean[END_REF]. They are silica-poor (46 < SiO2 wt.% < 48, Fig. 2a and Suppl. material Table 1), and plot in the tephrite / basanite field of the TAS classification diagram.

Since their normative olivine content is > 10 % they will be referred to as basanites in this study, although they are significantly evolved (4.4 < MgO wt.% < 5.3), and different from mantlederived primitive basanites. Phase 2 lavas (DR08, DR11) are slightly more evolved than the earliest erupted ones with MgO content spanning a narrow range from 4.4 -4.6 wt.%. All lavas analyzed are enriched in REE and other incompatible elements and display a steep chondritenormalized REE pattern, close to the upper range found in the older subaerial Mayotte lavas (Fig. 2c).

Quenched samples are glassy, crystal-poor (4-6% crystals, Figs 3,4,and Suppl. material Tables 2 and3), and contain significant amounts of vesicle-trapped volatiles ("popping rocks").

The average vesicularity of lavas is high, 35%, with a maximum of 43%, for phase 1 products (DR01-DR10-DR12) collected on the ridges radiating from the main edifice. Phase 2 lavas, collected on lava flows, are denser (average vesicularity of 31% for DR08, down to 18% for DR11). Except for DR11, these values are much higher than vesicularities of typical MORB popping rocks [START_REF] Chavrit | Mapping modern CO2 fluxes and mantle carbon content all along the mid-ocean ridge system[END_REF][START_REF] Chavrit | Influence of magma ascent rate on carbon dioxide degassing at oceanic ridges: Message in a bubble[END_REF], but comparable with the few values measured for submarine alkali basalts. The average vesicularity for all investigated samples is 27 %. Using this average value, the 6.5 km 3 of the new volcano are equivalent to 4.8 km 3 of dense rock. Two binary images of lava fragments from the two textural endmembers (the most and the least vesicular lava) are shown in Fig. 3. DR0103a1 (Fig. 3b) from phase 1, is highly vesicular (43%) and characterized by a homogeneous population of rounded vesicles with a mean size of 0.4 mm. The sample has a relatively high number of vesicles per unit of liquid (Nv, 17 mm -3 ). In contrast, DR110704b (Fig. 3a) is characterized by a lower vesicularity than DR01, with big, coalesced vesicles, up to 3 mm in diameter and a mean value of 0.8 mm and a drastic decrease in small vesicles, that translate in a low Nv (0.1 mm -3 ). A general decrease in number of vesicles is evident between the lava samples from phase 1 (DR01-DR10-DR12) and those from phase 2 (DR08-DR11), with DR11 samples being the lowest in terms of vesicularity and hence inferred pre-eruptive gas content (Fig. 3c).

Crystals in all samples include coeval Fe-rich olivine (50 -790 µm, Fo69-73.5), Timagnetite (50 -100 µm), and apatite (< 20 µm, Fig. 4a,b). Rounded FeS droplets either included in olivine and magnetite crystals or directly in the glass indicate the presence of an immiscible sulphide liquid in some of the samples. Most crystals are euhedral, but skeletal crystals of olivine and titanomagnetite (Fig. 4b) are present in all samples, providing evidence for fast growth, likely linked to fast ascent rates. The small population of olivine phenocrysts, > 0.4 mm (for phase 1 samples) and > 1 mm (for phase 2 samples), represents a very low fraction of the total crystal population (0.3 -1% of all olivine crystals). In samples from phase 2 (June 2019 -July 2019, samples DR08 and DR11), some of the olivine phenocrysts are reversely zoned (Fo53 in the cores to Fo70 in the rims, Fig. 4c). Their rim composition is similar to that of olivine microlites (Fig. 4a,b).

The June 2019 lava flow (sample DR080205) contains small mantle xenoliths (Fig. 4d,e). The largest one (DR080205-x4) is ~5 mm in diameter, and composed of ~1 mm long crystals of Fo90 olivine and orthopyroxene with a Mg# (atomic (Mg/(Mg+Fe))*100) of ~90 (Fig. 4d). Some of the orthopyroxene crystals contain clinopyroxene exsolutions. This xenolith also contains veins of SiO2-and K2O-rich silicate melts, typical of the melts produced by low-degree melting of phlogopite-bearing mantle [START_REF] Condamine | Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism[END_REF]. These melt veins are associated with small (< 100 µm) clinopyroxene crystals with Mg# between 92 and 94. A second and smaller xenolith (DR080205-x1), 2.5 mm long (Fig. 4e), is mostly composed of a single clinopyroxene crystal with orthopyroxene exsolutions, and small included crystals of olivine and orthopyroxene. Mineral compositions are similar to those in the first xenolith. A third investigated xenolith (DR080205-x3), only 2 mm in diameter, is similar to the first one, with mostly olivine and orthopyroxene crystals, and clinopyroxene exsolutions in the orthopyroxene. All xenoliths reacted with the surrounding melts: pyroxene crystals react to form a fine-grained corona of clinopyroxene, olivine, and Ti-magnetite, while olivine crystals are overgrown by an Fo72 olivine rim (Fig. 4d,e). Sample DR080205 also contains a few clinopyroxene megacrysts (Fig. 4f). These megacrysts have a magmatic origin and show an inner, normally zoned core (Mg# 68-61), surrounded by a more magnesian rim (Mg# 68 -78). This magnesian rim shows evidence of dissolution and is in turn surrounded by an outer rim made of dendritic clinopyroxene crystals with interstitial glass (Fig. 4f).

Quantification of dissolved water has been performed by micro-Raman spectroscopy in melt inclusions hosted by olivine and titanomagnetite crystals. The pre-eruptive water content is constrained to a minimum of 2.3 wt. % for DR01 and 1.2 wt. % for DR08 (Fig. 5). Our preliminary data suggest that open embayments can retain high water contents comparable to those of the closed melt inclusions, suggesting the occurrence of disequilibrium water degassing during magma ascent. Disequilibrium water degassing typically results from fast magma ascent.

It can be favored by the low crystal content, and in turn can delay melt crystallization and bubble nucleation [START_REF] Ferguson | Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments[END_REF][START_REF] Lloyd | NanoSIMS results from olivine-hosted melt embayments: magma ascent rate during explosive basaltic eruptions[END_REF].

Thermobarometry

Pre-eruptive temperatures for the main erupted magmas were calculated using the olivine-melt equilibrium and the equations of [START_REF] Beattie | Olivine-melt and orthopyroxene-melt equilibria[END_REF] and [START_REF] Ford | Olivine-liquid equilibria: temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn[END_REF]. Equilibrium olivine-glass pairs were selected based on a Fe/Mg Kd of 0.30 ± 0.05, assuming a Fe 3+ /Fetotal ratio of 0.15, and the temperatures were averaged on 3 -14 couples per sample. For thermometry calculations, the pressure was arbitrarily set at 200 MPa, however, the influence of pressure is limited to a few degrees per 100 MPa. Results from the model of [START_REF] Beattie | Olivine-melt and orthopyroxene-melt equilibria[END_REF], and from the Tsum equation of [START_REF] Ford | Olivine-liquid equilibria: temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn[END_REF] are within 2 -8 °C of each other. Anhydrous calculated temperatures were corrected for the effect of H2O using average H2O concentration determined by micro-Raman spectrometry and the olivine liquidus depression model of [START_REF] Médard | The effect of H2O on the olivine liquidus of basaltic melts: experiments and thermodynamic models[END_REF]. Uncorrected pre-eruptive temperatures are 1151 ± 20 °C for phase 1 (DR01-DR10-DR12) and 1136 ± 20 °C for phase 2 (DR08-DR11). Corrected temperatures are within error for all samples, at 1095 ± 20 °C. Note that if melt inclusion provides a minimum preeruptive water content, this calculation provides a maximum pre-eruptive temperature.

Pre-eruptive temperature and oxygen fugacity for the magma batch parent to the Fo55 olivine cores were calculated from an ilmenite-titanomagnetite intergrowth included in Fo55 olivine, which constrains magmatic conditions of this evolved batch to 1024 ± 50 °C and an oxygen fugacity (fO2) close to that of the nickel-nickel oxide buffer [START_REF] Sauerzapf | The Titanomagnetite -Ilmenite Equilibrium : New Experimental Data and Thermo-oxybarometric Application to the Crystallization of Basic to Intermediate Rocks[END_REF].

Thermometry of melt inclusions in Fo52 olivine gives similar anhydrous temperatures of about 1046 ± 20 °C [START_REF] Beattie | Olivine-melt and orthopyroxene-melt equilibria[END_REF].

We analyzed a series of clinopyroxene-orthopyroxene pairs in the mantle xenoliths (Fig. We made an estimation of the magma storage depth by applying a clinopyroxene-only geobarometer (Equation 32b with water content of 2.3 wt.%, [START_REF] Putirka | Thermometers and Barometers for Volcanic Systems[END_REF] to a zoned clinopyroxene megacryst in sample DR080502-x2 (Fig. 4f). The core of the crystal returns a depth range of 37 to 48 (P = 1.01 -1.34 GPa). A second cluster with values ranging from 24 to 34 (P = 0.62 -0.92 GPa) is associated with the inner rim. A few low-pressure values (0.14 -0.38 GPa) were obtained on the outer dendritic rim and could indicate crystallization in the conduit during magma ascent (Fig. 6d). Uncertainties associated with these calculations are 10 km (0.28 GPa, [START_REF] Putirka | Thermometers and Barometers for Volcanic Systems[END_REF]. A second analyzed zoned clinopyroxene megacryst generates similar clusters. Phenocrysts in equilibrium with the bulk rock are expected to have Mg# of 75 (olivine) and 78 (clinopyroxene), indicating that the most magnesian olivine cores and the clinopyroxene inner rims are in equilibrium with the magma. The more Fe-rich clinopyroxene cores should thus be interpreted as an antecrystic crystal cargo.

Olivine diffusion and residence times

Five different reversely zoned olivine crystals in DR0801-ALF, DR110704 and DR110401 samples were investigated (Fig. 7a,b), assuming an initial step function with an olivine core between Fo53-60 depending on the crystal, surrounded by an overgrowth rim Fo69-70 (Fig. 7b).

Two zoned olivine crystals at the edge of an harzburgite xenolith (DR080502x4) were also modelled, using a step function with a Fo90 olivine core and a Fo72 olivine overgrowth (Fig. 7c,d) but without EBSD orientation.

The five diffusion profiles in reversely zoned olivine crystals can be modelled with diffusion times of 29 ± 9, 24 ± 8, 19 ± 7, 38 ± 12 and 40 ± 11 days (supplementary material Table 6, errors are given at the two sigma level). Since no EBSD data was acquired in the two normally zoned olivine crystals from xenolith DR080205x4, we can only provide a time bracket using maximum and minimum diffusion coefficient. Thus, these profiles can be modelled with diffusion times between 12 and 69 and between 8 and 47 days. Fits assuming instantaneous growth of the outer rims followed by pure diffusion are excellent with the reversely zoned crystals (supplementary material Table 6), and very good for the xenolith. The assumption of instantaneous crystal growth is supported by the orders of magnitude of difference between crystal growth rates and elemental diffusion rates (e.g., [START_REF] Petrone | Pre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics[END_REF]. These preliminary diffusion times can be interpreted as residence times for the olivine crystals and the xenolith, between injection of the incoming magma in the shallow magma pocket and its eruption at the surface.

DISCUSSION

Source

The magmas erupted during the ongoing Mayotte eruption are evolved basanite that likely derive from more primitive (unerupted) basanitic mantle melts. The low HREE concentrations and the strongly fractionated REE patterns ((Tb/Yb)N = 2.9 -3.2, Fig. 2c) indicate the presence of residual garnet in the mantle source. Moreover, Sm/Yb and La/Sm ratios for the erupted lavas indicate a spinel/garnet lherzolitic source (Fig. 2d). This is consistent with previous studies on subaerial Comoros lavas which suggest that primary magmas are produced by small degrees of partial melting at the depth of the spinel to garnet lherzolite transition, 80 -100 km [START_REF] Bachèlery | Geochemical and Petrological Aspects of Karthala Volcano[END_REF][START_REF] Class | The process of plume-lithosphere interactions in the ocean basins-the case of Grande Comore[END_REF]. Furthermore, olivine melilitites in Mayotte volcanic products and evidence of metasomatizing carbonatitic fluids on Grande Comore suggest a CO2-rich mantle source [START_REF] Coltorti | Carbonatite metasomatism of the oceanic upper mantle: evidence from clinopyroxenes and glasses in ultramafic xenoliths of Grande Comore, Indian Ocean[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF]. The P2O5 enrichment of the new volcano samples, together with the high Sr and Ba contents, and high Nb/Yb ratio, are consistent with an apatite contribution in the genesis of these lavas. Presence of a mm-sized apatite xenocryst in one of our lava samples suggests a possible assimilation of apatite-bearing veins during the ascent of primary melts formed at a greater depth, as indicated by [START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF]. Homogeneous P2O5 enrichment compared to other Comoros lavas is observed in all of our samples (1. 6 -2.0 wt.%, Suppl. material Table 1), which precludes a late assimilation and argues for a mantle source origin of the inferred apatite-bearing veins.

Deep magma reservoir in the lithospheric mantle

The evolved nature (low Mg#, 43 -47) of the erupted magmas shows that they are not primary products of mantle melting since the expected Mg# of primary mantle melts in equilibrium with Fo90 olivine is ~73, assuming an olivine/melt Kd of 0.30 [START_REF] Roeder | Olivine-liquid equilibrium[END_REF]. Extensive cooling and crystallization must thus have occurred in a lithospheric magma reservoir (Fig. 8). A back-crystallization model consistent with the general trend of Comoros lavas [START_REF] Bachèlery | Geochemical and Petrological Aspects of Karthala Volcano[END_REF][START_REF] Class | The process of plume-lithosphere interactions in the ocean basins-the case of Grande Comore[END_REF][START_REF] Bourdon | Ra-Th-Sr isotope systematics in Grande Comore Island: a case study of plume-lithosphere interaction[END_REF][START_REF] Coltorti | Carbonatite metasomatism of the oceanic upper mantle: evidence from clinopyroxenes and glasses in ultramafic xenoliths of Grande Comore, Indian Ocean[END_REF][START_REF] Deniel | Geochemical and isotopic (Sr, Nd, Pb) evidence for plume-lithosphere interactions in the genesis of Grande Comore magmas (Indian Ocean)[END_REF][START_REF] Flower | Evolution of basaltic and differentiated lavas from Anjouan, Comores Archipelago[END_REF][START_REF] Nougier | The Comores archipelago in the western Indian Ocean: volcanology, geochronology and geodynamic setting[END_REF][START_REF] Pelleter | Melilite-bearing lavas in Mayotte (France): An insight into the mantle source below the Comores[END_REF][START_REF] Strong | Petrology of the island of Moheli, western Indian Ocean[END_REF][START_REF] Thompson | One-atmosphere melting and crystallization relations of lavas from Anjouan, Comores Archipelago, Western Indian Ocean[END_REF] requires approximately 50% crystallization of an olivineclinopyroxene assemblage (80% clinopyroxene Mg#91-76 and 20% olivine Fo90-75) to reproduce the erupted magma compositions (Fig. 2b). This implies that the reservoir, where mantlederived magma is ponding and differentiating, has a volume of at least ~10 km 3 (~5 km 3 of erupted magma and the same amount of crystals) and is zoned, with ~ 5 km 3 of residual dense cumulates. This is a minimum reservoir size, since the estimation relies on the unlikely hypothesis that melt and cumulates were perfectly segregated, and does not take into account any interstitial melt within the cumulates and the contribution of deep CO2 exsolution. The occurrence of a large reservoir is also supported by ratios of intrusive to extrusive volumes commonly estimated at ~5:1 for oceanic mid-ocean ridges [START_REF] Crisp | Rates of magma emplacement and volcanic output[END_REF][START_REF] White | Long-term volumetric eruption rates and magma budgets[END_REF].

Since the erupted magma was a true homogeneous liquid, and the few crystals of the main conebuilding phase 1 are unzoned, this suggests the system was not disturbed by new primary magma replenishment and was able to evolve to yield a single well-stratified reservoir. In sample DR080205-x2, clinopyroxene megacryst cores were equilibrated at pressures of 1.01 -1.34 GPa (from Putirka, 2008, equation 32b, i.e. 37 -48 km, Figs 6d and 8). This provides the depth for the main reservoir feeding the current eruption, which is thus located in the lithospheric mantle, in agreement with seismological and geodetic models [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF]. The slowly waning effusion rate is also characteristic of an eruption fed by a deep reservoir [START_REF] Wadge | The variation of magma discharge during basaltic eruptions[END_REF].

Magma ascending from lithospheric mantle storage entrained mantle xenoliths from a shallower depth, near the Moho, at an average depth of 17 ± 6 km. The time between entrainment of the mantle xenoliths and eruption is estimated less than 70 days. Given that the xenoliths were picked up en route to the surface, this is a preliminary estimation of the transfer time between the deep magma reservoir and the eruption site. It is consistent with the 6 weeks of precursory unrest estimated from seismological data [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF].

Differentiated shallower magma batch

Phase 1 products are crystal-poor lavas with high density of vesicles (Fig. 3b), skeletal crystals (Fig. 4a,b) and high dissolved water content (Fig. 5). Thus, we suggest that during the first year, eruption is fed by direct ascent of magma from the deep reservoir to the surface. The shape and the size of microlites indicate that most micro-crystallization occurred in the shallow part of the ascending dyke. The degree of magmatic evolution increases from phase 1 to phase 2 lavas (Fig. 1d). This increase is mirrored by a decrease in vesicularity, vesicle number density (Fig. 3) and dissolved water content (Fig. 5), indicating that late erupted lavas were increasingly outgassed. Reverse zoning in olivine phenocrysts from phase 2 lavas (Fig. 4c) records the interaction between the hot basanitic magma, ascending from the ≥ 37 km deep storage zone, and a second cooler magma batch (Fig. 8). Since transfer times estimated from diffusion in those crystals (~ 1 month) are similar to transfer times estimated from the mantle xenoliths, the zoned olivine crystals probably came from a similar or shallower depth than the xenoliths.

Pyroxenes in the mantle xenoliths record a depth of 17 ± 6 km, interpreted to represent the maximum depth of this shallower reservoir (Fig. 6). The inner rim in clinopyroxene megacryst (DR080205-x4, Fig. 4f), equilibrated at pressures of 0.8 ± 0.28 GPa (28 ± 10 km), may indicate the location of a third magma storage zone.

Because no seismicity at this shallow depth was detected (ReVoSiMa, 2021), the differentiated magma batch is unlikely to occupy a large dynamic reservoir but rather perhaps magma ponding at the base of the Moho. Analysis of diffusion profiles in reversely zoned olivine from phase 2 lava flows constrain the time between the start of Fo70 olivine crystallization and eruption. We obtain minimum estimations of ~ 1 month for the time between mixing with the shallower magma batch and eruption of the hybrid magma (Fig. 7, Suppl. material Table 6). Magma mixing and transfer of hybrid magma thus occurred during the eruption and were not related to long-term precursor activity detected by the permanent landbased monitoring networks.

Eruption trigger

The erupted products are evolved alkaline mafic magmas and have a minimum dissolved water content of ca. 2 wt. % (Fig. 5). Available thermodynamic models permit us to crudely estimate the pre-eruptive dissolved CO2 content as being in the range 0.6 -1.2 wt % [START_REF] Allison | H2O-CO2 solubility in alkali-rich mafic magmas: new experiments at mid-crustal pressures[END_REF][START_REF] Papale | The compositional dependence of the saturation surface of H2O+ CO2 fluids in silicate melts[END_REF]. This is compatible with the possible presence of an exsolved CO2-rich fluid phase in the plumbing system. Under these conditions, the magma chamber will be pressurized, but stable. Because of the deep location and the associated pressure, volume changes due to crystallization or volatile exsolution should not be sufficient to act as an eruption trigger. Moreover, we found no evidence of primitive magma in the erupted products. Therefore, we suggest that fault movement or earthquakes rather than a deep reservoir recharge event was responsible for the sudden initial decompression and fast ascent of a large volume of volatile-rich melt stored in the mantle.

The eruption site belongs to a WNW-ESE volcano-tectonic ridge, parallel to regional trends, suggesting relation to a pre-existing tectonic structure. Deep seismicity recorded during the seismo-volcanic crisis [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF]ReVoSiMa, 2021) implies that these structures are deeply rooted in the lithosphere (up to 50 km depth). The sequence of strong tectonic earthquakes recorded at the beginning of the eruption (volcano-tectonic events located at 34 -41 km depth, 35 km east of Mayotte [START_REF] Cesca | Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation[END_REF][START_REF] Lemoine | The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption[END_REF] might thus be related to the movement along the lithospheric faults.

Syn-eruptive magma path change

Since the melt was volatile-saturated (CO2+H2O) in the deep reservoir, magma ascent towards the surface would have resulted in continuous exsolution of CO2 first and then CO2+H2O up to the eruption site. Full exsolution of pre-eruptive dissolved volatiles at the vent would produce a fluid with a molar volume of ca. 320 cm 3 /mol and vesicularity in the range 54 -71 vol%, values much higher than those measured in our samples (Suppl. material Tables 2 and3). Vesicularity would be even higher if there were additional exsolved CO2 in the reservoir.

Incomplete disequilibrium degassing because of the fast ascent rate and rapid quenching on the seafloor can explain the difference between the expected and measured vesicularities. We also suggest that rapid decompression-induced crystallization [START_REF] Hammer | Degassing and microlite crystallization during pre-climactic events of the 1991 eruption of Mt. Pinatubo, Philippines[END_REF] in the shallow conduit may be responsible for the skeletal shape of olivine and Ti-magnetite crystals [START_REF] Faure | A developmental model of olivine morphology as a function of the cooling rate and the degree of undercooling[END_REF]. The absence of reversely zoned olivine crystals in phase 1 products suggests that basanitic melts ascended from the deep reservoir directly to the surface during the first year of eruption (Fig. 8).

In contrast, the presence of reversely zoned olivine with Fo53 cores in phase 2 lava flows (Fig. 4c) indicates that, after May 2019 magma ascending from the deep reservoir intersected a more evolved magma batch, at a depth near the Moho on its way to the surface (Fig. 8). Using a simple mass balance model, we estimate that only 6% of the evolved magma (represented by melt inclusions in Fo53 olivine in sample DR11) was assimilated in the erupted lavas, indicating that the intersected volume of this shallower reservoir is much smaller than the deeper one. Less abundant (low Nv) and larger vesicles (Fig. 3) are consistent with a slower ascent and lower volatile content during phase 2. The residual magmatic liquid in the shallower magma batch could have been produced by fractional crystallization from an older magma intrusion, as observed during Kilauea's 2018 eruption [START_REF] Gansecki | The tangled tale of Kīlauea's 2018 eruption as told by geochemical monitoring[END_REF]. Due to the time required for magmatic differentiation (decades, [START_REF] Gansecki | The tangled tale of Kīlauea's 2018 eruption as told by geochemical monitoring[END_REF], this observation implies magma intrusion and possible recent volcanic activity in the offshore part of the volcanic ridge prior to the current eruption. The emission of the more evolved magma in phase 2 could have resulted either from a change in the dyke pathway (as suggested by the presence of mantle xenoliths) and/or a decrease in magma discharge rate allowing the input from the second shallower magma source.

Zoned olivine phenocrysts took ~ 1 month to be transferred from the ~ 17 km shallow reservoir to the seafloor. Thus, we obtain a minimum ascent rate of 0.005 m.s -1 from the shallow reservoir to the surface for the slower pathway (Fig. 8).

CONCLUSIONS

The large and long-lasting effusive eruption offshore from Mayotte is fed by a deep (> 37 km) and large (≥ 10 km 3 ) pre-existing mantle reservoir of evolved, alkaline magma that experienced extensive crystallization. This has important volcanic hazard implications, because it demonstrates that this large, volatile-rich deep reservoir could quickly be tapped in a tectonically active region to feed a voluminous and long-lasting effusive eruption. During the eruption, magma ascent slowed and switched to a pathway that sampled a small more chemically evolved shallower magma batch at the base of the crust. Our petrological study provides important constraints on the entire deep magmatic system from the source to the surface. These results bring valuable and critical information complementary to geophysical datasets, showing that we can use the petrology of erupted products for long-term monitoring of extreme events even when they occur in poorly accessible environments. These data helped to determine the geometry and the dynamics of magmatic plumbing systems, and provided critical constraints for the interpretation of geophysical datasets in terms of processes and patterns. 1) with that of subaerial lavas from the Comoros archipelago. Blue and green arrows show the moderately silica-undersaturated ("Karthalatrend") and the highly silica-undersaturated ("La Grille-trend") trends identified in Comoros lavas, respectively. b) Fractional crystallization models for Comoros and Mayotte lavas plotted in Ni (ppm) vs Mg# space. Melts in equilibrium with the mantle have a Mg# ~70 (the melting grid with mantle melting temperature and melt fractions has been computed following [START_REF] Späth | The geochemistry of lavas from the Comores Archipelago, Western Indian Ocean: petrogenesis and mantle source region characteristics[END_REF]). Back calculation models start from DR0101 composition by adding in small increments of equilibrium olivine and clinopyroxene compositions appropriate to match the composition of subaerial Comoros lavas and consistent with the Ni concentration for a primary mantle melt (300-500 ppm, [START_REF] Späth | The geochemistry of lavas from the Comores Archipelago, Western Indian Ocean: petrogenesis and mantle source region characteristics[END_REF]). Olivine-only fractionation fails to reproduce the Comoros trend. c) Chondrite-normalized REE patterns of the submarine lavas of the new edifice compared to Mayotte subaerial lavas. d) La/Sm vs Sm/Yb diagram annotated with partial melting curves for garnet and spinel lherzolite mantle sources [START_REF] Pouclet | The Cenozoic volcanism in the Kivu rift: Assessment of the tectonic setting, geochemistry, and geochronology of the volcanic activity in the South-Kivu and Virunga regions[END_REF]. 3.6 wt% of dissolved water (Etna glass). Bands in the 100-1200 cm -1 region are related to vibrations of the glass network, while the band at 3570 cm -1 is produced by stretching of OH bonds and its intensity linearly correlates with the concentration in total dissolved water (Di [START_REF] Muro | Quantification of water content and speciation in natural silicic glasses (phonolite, dacite, rhyolite) by confocal microRaman spectrometry[END_REF]. additional clusters of pressures of 1.01 -1.34 GPa and 0.62 -0.92 GPa with a second set of geobarometry estimations using zoned clinopyroxene megacrysts (Fig. 4f). Moho is shown by a black dotted line [START_REF] Dofal | Crustal structure variation across the southwestern Indian Ocean from receiver functions determined at Ocean-Bottom Seismometers[END_REF]. 6).

Figure captions

The diffusion rate for P in olivine is extremely slow so this immobile element marks the initial boundaries between zones that crystallized at different times. In the reversely-zoned phenocryst of b), the initial profile was a step between a Fo53 core and a Fo70 rim, then Ca and Mg/Fe diffused away from this initial step. In the normally zoned xenolith of d), the initial profile was a step between a Fo90 core and a Fo72 rim, then Ca and Mg/Fe diffused away from this initial step. in the shallow part of the ascending dyke. A shallower and smaller differentiated magma reservoir located close to the Moho (< 17 ± 6 km) was sampled en route during the second year of the eruption. It is important to note that this magma batch and the shallow conduit were not imaged by on-land seismometers because they are located too far from the eruption site to allow identification of small, shallow earthquakes. Moho: grey dotted line [START_REF] Dofal | Crustal structure variation across the southwestern Indian Ocean from receiver functions determined at Ocean-Bottom Seismometers[END_REF]. Tt:

Transfer time, Tr: Transfer rate = distance / transfer time, V: volume.

Table captions

Tab. 1: Location of dredges performed during MAYOBS 1 (DR01), MAYOBS 2 (DR08) and MAYOBS 4 (DR10, DR11 and DR12) oceanographic campaigns. No dredges were performed during MAYOBS 3.

Latitude

  4d, e) to obtain pressure and temperature constraints. In xenolith DR080205-x4, we analyzed clinopyroxene-orthopyroxene pairs associated with the high-SiO2 high-K2O veins, as well as exsolutions of clinopyroxene in orthopyroxene. In the other two xenoliths, we only analyzed exsolutions, either of orthopyroxene in clinopyroxene (DR080205-x1), or of clinopyroxene in orthopyroxene (DR080205-x3). Temperatures were calculated using equation (36) of[START_REF] Putirka | Thermometers and Barometers for Volcanic Systems[END_REF] with reported uncertainties of 45 °C. For pressure, both equations (38) and (39) were tested against experiments performed at 1.00 GPa by[START_REF] Condamine | Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism[END_REF] on pyroxene in equilibrium with high-SiO2 high-K2O veins. Since equation (38) returned an average pressure of 1.02 GPa, whereas equation (39) returned an average pressure of 0.88, Equation (38) was preferred for the calculation. It reproduces the experimental data with an average error (SEE) of 0.19 GPa. Equilibration pressures for the xenoliths are 0.43 GPa at a temperature of 926 °C for DR080205-x1 (Fig.6a-c, Suppl. material Table5), 0.41 GPa at a temperature of 890 °C for DR080205-x3 and 0.46 GPa at a temperature of 913 °C for DR080205-x4. Assuming an average density of 2890 kg m -3 for an oceanic crust and 3300 kg m -3 for the upper mantle, these xenoliths were equilibrated at an average depth below the sea level of 17 ± 6 km (0.45 ± 0.19 GPa).

Fig. 1 :

 1 Fig. 1: Location of the eruptive site. a) Comoros volcanic archipelago is located in the northern

Fig. 2 :

 2 Fig. 2: Bulk rock geochemistry of the dredged evolved basanite lavas emitted during the 2018-

Fig. 3 :

 3 Fig. 3: Textural characteristics of the studied lava samples. Binary images of two lava

Fig. 4 .

 4 Fig. 4. Petrographic features of the dredged lavas. a) All lavas have very low crystallinity: BSE

Fig. 5

 5 Fig. 5 Raman spectra of an olivine-hosted melt inclusion from sample DR0103 and a spinel-

Fig. 6 :

 6 Fig. 6: Histograms showing depth obtained using geobarometry on clinopyroxene-

Fig. 7 :

 7 Fig. 7: Core-rim diffusion profiles in zoned olivines. Red arrows show the trace of the profiles

Fig. 8 .

 8 Fig. 8. Magma plumbing system feeding the 2018-2020 Mayotte eruption interpreted on the

  Table shows H2O content (wt%) in melt inclusions and embayment in DR0103 and DR0801 samples.

Acknowledgements

MAYOBS 1 campaign was funded by the CNRS-INSU TELLUS MAYOTTE program (SISMAYOTTE project). MAYOBS 1, 2 and 4 campaigns were conducted by several French research institutions and laboratories (IPGP/CNRS/BRGM/IFREMER/IPGS). We want to thank the crew of R/V Marion Dufresne (TAAF/IFREMER/LDA). Analyses were funded by the Service National d'Observation en Volcanologie (SNOV, INSU) and the Réseau de Surveillance Volcanologique et Sismologique de Mayotte (REVOSIMA), a partnership between the Institut de Physique du Globe de Paris (IPGP), the Bureau de Recherches Géologiques et Minières (BRGM), and the Observatoire Volcanologique du Piton de la Fournaise (OVPF-IPGP), the Centre National de la Recherche Scientifique (CNRS), and the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER). The authors would like to thank Andrew Harris for reviewing and English improvement before submission, IFREMER for their welcome during the sampling and E. Humler for his support and national funding coordination (CNRS, REVOSIMA). Raman data were acquired by ADM as a side project during his fellowship at the Center for Advanced Studies of the Ludwig-Maximilians-Universität München (CAS LMU) in collaboration with the CAS Research Group on "Magma to Tephra: Ash in the Earth System" (Resp. Prof. Donald Dingwell). We thank Ivonne Cocca (Université de Paris) for assistance in sample preparation. Finally, we are also grateful for the helpful reviews provided by William Chadwick, an anonymous reviewer, and editorial handling by Chiara Petrone. This is a Labex ClerVolc contribution number 466.


Van Cuong Pham
email: phamvc@imbc.vast.vn

Thi Mai Doan

Le Huong

Nguyen Tran

Luu Vu

Anh The

Thi Nguyen

Nhiem Cuc

Nguyen

Huu Bui

Phan Van Tai

Marc Kiem

Litaudon

Tran Dang

Minh Thach

Hyun Chau

Tran Minh Kim

Tuyen Ngoc

Nguyen Van

Cuc

Xuan Nguyen

Nhiem

Tran Litaudon

Chau Van Dang Thach

Pham Minh

Van Cuong

Huong

Tran Le

Nguyen Vu

Luu The

Anh B Nguyen

Thi Cuc

Tai

Phan Van Kiem

Marc Litaudon

Tran Dang Thach

Chau Van Minh

Prof Pham Van Cuong

Cytotoxic prenylated flavonoids from the leaves of Macaranga

Keywords: Macaranga indica, macarindicin D, macarindicin E, macarindicin F, cytotoxic Taxonomy Molecular Structure, Natural Product Biochemistry Macaranga indica, macarindicin D, macarindicin E, macarindicin F, cytotoxic

), (-)-woonenoside XI (10), and (+)lyoniresinol 4-O-β-D-glucopyranoside (11) were isolated from the leaves of Macaranga indica Wight. Their structures were determined on the basis of extensive spectroscopic methods, including 1D-, 2D-NMR and MS data. All the isolated compounds were tested for their cytotoxic activities against KB, MCF-7, HepG-2, and LU human cancer cell lines. As results, compound 2 showed significant cytotoxic activity on all human cancer cell lines with IC50 values ranging from 11.0 to 17.0 μM. Compound 3-5, exhibited moderate cytotoxic activity against four cancer cell lines with an IC50 values ranging from 15.0 to 38.2 μM.

Graphical abstract

Cytotoxic prenylated flavonoids from the leaves of Macaranga indica

Introduction

Prenylated flavonoids play important roles in the plant's defensive strategy. Recently, the research on prenylated flavonoids have received the attention from the scientists due to their promising and diverse bioactivities on multitarget tissues. Prenylated flavonoids showed potential cytotoxic activity against tumor and cancer cell lines (Chen et al. 2014).

The genus Macaranga (Euphorbiaceae) comprises of about 300 species which are mainly distributed in tropics of Africa, Asia, Australia, and the Pacific regions. The Macaranga genus have been used in traditional medicine for the treatments of cuts, swellings, boils, bruises, and sores. Phytochemical investigation of this genus confirmed the presence of stilbenes, flavonoids, coumarins, terpenoids, and tannins (Magadula 2014). The extracts and those compounds showed a wide spectrum of pharmacological activities including anti-cancer, anti-inflammatory, anti-oxidant, anti-microbial, and anti-plasmodial activities. Previous phytochemical investigations of M. indica led to the isolation and identification of flavonoids and prenylated derivatives (Yang et al. 2015a). As part of our research on anticancer drug candidates from 2,500 Vietnamese medicinal plants, the ethyl acetate extract of M. indica was found to inhibit 69% the growth of KB human cancer cell line at the concentration of 1.0 μg/ml. Herein, we report the isolation and structure elucidation of three new prenylated flavonoids together with eight known compounds from M. indica and evaluation of their cytotoxic effects. one aromatic proton of A ring at δ H 6.50 (1H, s) suggested the presence of flavonol moiety; one olefinic proton at δ H 5.19 (1H, t, J = 7.0 Hz) and two methyl groups at δ H 1.63 (3H, s) and 1.73 (3H, s) suggested the presence of a prenyl group; and one aldehydic proton at δ H 10.35 (1H, s).

Results and discussion

The [START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR and HSQC spectra ( 17.6 and 25.4). Analysis of the 1 H-and [START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR data of 1 suggested the structure 1 was a prenylated flavone, similar to those of glyasperin A (5) (Nomura et al. 1992), except for the disappearance of isoprenyl group at C-3′ of B ring. This could be oxidation of prenyl group to form aldehydic group. The positions of the functional groups were confirmed by analysis of the HSQC and HMBC spectra (Figure 2). The HMBC correlations between H-5′ (δ H 7.18) and C- at δ H 6.30 (1H, s) assigned the presence of flavonol moiety; three olefinic protons δ H 5.17 (1H, t, J = 6.5 Hz), 5.85 (1H, t, J = 10.0 Hz), and 6.46 (1H, t, J = 10.0 Hz); four methyl groups at δ H 1.62 (3H, s), 1.74 (3H, s), 1.42 (6H, s) suggested the appearance of two prenyl groups. The [START_REF]C-NMR spectrum of compound 3[END_REF]

1′ (δ C 122.3)/C-3′ (δ C 122.

Experimental

General experimental procedures

All NMR spectra were recorded on a Bruker 500 MHz. HR-ESI-MS spectra were obtained using an AGILENT 6550 iFunnel Q-TOF LC/MS system. Column chromatography (CC) was performed on silica-gel (Kieselgel 60, 70-230 mesh and 230-400 mesh, Merck) or RP-18 resins (30 -50 μm, Fuji Silysia Chemical Ltd.). For thin layer chromatography (TLC), pre-coated silica-gel 60 F254 (0.25 mm, Merck) and RP-18 F254S (0.25 mm, Merck) plates were used.

Plant material

The leaves of Macaranga indica Wight were collected at Huong Hoa, Quangtri, Vietnam in August 2010 and identified by Dr. Nguyen The Cuong, Institute of Ecology and Biological Resources, VAST. A voucher specimen (MI1008) was deposited at the Institute of Marine Biochemistry, VAST.

Extraction and isolation

The dried leaves of M. indica (1.92 kg) were sonicated with hot MeOH three times (3×6 L) to yield 155 g extract after evaporation of the solvent. This extract was suspended in H 2 O and successively partitioned with CH 2 Cl 2 and EtOAc to obtain the CH 2 Cl 2 (MI1, 88.0 g), EtOAc (MI2, 16.0 g), and H 2 O (MI3) extracts after removal of the solvents in vacuo.

The MI1 fraction was chromatographed on a silica gel column eluting with a gradient solvent of CH 2 Cl 2 /MeOH (100:0→2.5/1, v/v) to give five fractions, MI1A-MI1E. MI1B was chromatographed on an RP-18 column eluting with acetone/water (2.5/1, v/v) to give four fractions, MI1B1-MI1B4. MI1B1 was chromatographed on a silica gel column eluting with nhexane/EtOAc (5/1, v/v) to give two fractions, MI1B1A-MI1B1B. Compounds 3 (7.0 mg) and 3 (35.0 mg) were obtained from MI1B1B on a silica gel column eluting with n-hexane/acetone (3/1, v/v). MI1B2 was chromatographed on a silica gel column eluting with CH 2 Cl 2 /MeOH (60/1, v/v) to give three smaller fractions, MI1B2A-MI1B2C. Compound 1 (12.0 mg) was obtained from MI1B2B on a silica gel column, using n-hexane/EtOAc (3/1, v/v) as eluent solvents. MI1B2C was chromatographed on a silica gel column eluting with n-hexane/EtOAc

Macarindicin A (1)

Yellow amorphous powder. HR-ESI-MS m/z: 383.1125 [M + H] + (Calcd. for [C 21 H 19 O 7 ] + , 383.1131). 1 H-NMR (DMSO-d 6 , 500 MHz) and [START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR (DMSO-d 6 , 125 MHz): see Table 1.

Macarindicin B (2)

Yellow amorphous powder. HR-ESI-MS m/z: 421.1642 [M + H] + (Calcd. for [C 25 H 25 O 6 ] + , 421.1651). 1 H-NMR (DMSO-d 6 , 500 MHz) and [START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR (DMSO-d 6 , 125 MHz): see Table 1.

Macarindicin C (3)

Yellow amorphous powder. HR-ESI-MS m/z: 421.1642 [M + H] + (Calcd. for [C 25 H 25 O 6 ] + , 421.1651). 1 H-NMR (DMSO-d 6 , 500 MHz) and [START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR (DMSO-d 6 , 125 MHz): see Table 1 The concentration that inhibits 50% of cell growth was calculated (IC 50 ). Compounds were tested at a maximum concentration of 100 μM. Data are means of three experiments.

OH R 2 H 3 CO R 2 O OH OH OCH 3 OH R 1 R 2 6 H H 7 H OH 8 Glc O H R 1 R 1 R 1 R 2 9 H H 10
b) Mitoxantrone (MX), an anticancer agent, was used as reference compound.

HR-ESI-MS

  Thi Mai Huong, Le Tran Nguyen Vu, Luu The Anh, Nguyen Thi Cuc, Nguyen Xuan Nhiem, Bui Huu Tai, Phan Van Kiem, Marc Litaudon, Tran Dang Thach, Chau Van Minh, and Pham M) 15.0±1.7 18.1±1.9 17.9±1.5 20.3±2.0 KB MCF7 HepG2 Lu IC 50 (M) 11.0±1.0 15.5±1.2 11.9±1.3 17.0±1.3

Compound 1

 1 was obtained as a yellow amorphous powder. Its molecular formula was defined as C 21 H 18 O 7 by HR-ESI-MS at m/z 383.1125 [M+H] + (Calcd. for [C 21 H 19 O 7 ] + , 383.1131). The 1 H-NMR spectrum of 1 showed the signals of three aromatic protons with ABX system of B ring at δ H 7.18 (1H, d, J = 9.0 Hz), 8.29 (1H, dd, J = 2.0, 9.0 Hz), and 8.50 (1H, d, J = 2.0 Hz);

  3); between H-6′ (δ H 8.29) and C-2′ (δ C 128.3)/C-4′ (δ C 161.8)/C-2 (δ C 145.0); between aldehydic proton (δ H 10.35) and C-2′ (δ C 128.3)/C-3′ (δ C 122.3)/C-4′ (δ C 161.8) suggested the positions of hydroxy group at C-4′ and the aldehydic group at C-3′. The HMBC correlations between H-8 (δ H 6.50) and C-6 (δ C 110.3)/C-7 (δ C 161.7)/C-9 (δ C 154.0)/C-10 (δ C 102.8); between H-1′′ (δ H 3.24) and C-5 (δ C 157.4)/C-6 (δ C 110.3)/C-7 (δ C 161.7) suggested the position of prenyl group at C-6 and the hydroxy groups at C-5 and C-7. Thus, the structure of 1 was determined and named macarindicin D. Macarindicin E (2) possessed a molecular formula of C 25 H 24 O 6 as deduced from HR-ESI-MS at m/z 421.1642 [M+H] + (Calcd. for [C 25 H 25 O 6 ] + , 421.1651). The 1 H-NMR spectrum of 2 showed the following signals: three ABX aromatic protons of B ring at δ H 6.92 (1H, d, J = 9.0 Hz), 7.85 (1H, d, J = 2.5 Hz), and 7.93 (1H, dd, J = 2.5, 9.0 Hz); one aromatic proton of A ring

  C-NMR and HSQC spectra of 2 showed the signals of 25 carbons, including one carbonyl, twelve non-protonateds, seven methines, one methylene, and four methyl carbons. The anaylsis of 1 Hand[START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR data indicated the strucuture of 2 was similar to those of macadenathin B (4) (Yang et al. 2015b), excepted for the change of prenyl group at A ring. The HMBC correlations between H-6 (δ H 6.30) and C-5 (δ C 158.2)/C-7 (δ C 161.2)/C-8 (δ C 105.6)/C-10 (δ C 103.0); between H-1′′ (δ H 3.43) and C-7 (δ C 161.2)/C-8 (δ C 105.6)/C-9 (δ C 153.4) suggested the position of prenyl group at C-8. The HMBC correlations between H-5′ (δ H 6.92) and C-1′ (δ C 123.7)/C-3′ (δ C 120.6); between H-6′ (δ H 7.93) and C-2 (δ C 146.0)/C-2′ (δ C 125.6)/C-4′ (δ C 153.9); between H-6′′ (δ H 6.46) and C-2′ (δ C 125.6)/C-3′ (δ C 120.6) C-4′ (δ C 153.9)/C-8′′ (δ C 77.0) suggested the position second prenyl group at C-3′. The cyclization of prenyl group with B ring of flavonol via oxy-bridge at C-4′ and C-8′′ was confirmed by the shift to low field of C-8′′ (δ C 77.0) as well as HR-ESI-MS. Based on the above evidence, the structure of 2 was determined and named macarindicin E. Compounds 3 was also obtained as yellow amorphous powders. HR-ESI-MS experiments resulted in the same molecular formula as that of 2 (see Experimental). The 1 H-and 13 C-NMR data were almost the same to those of macarindicin E (2), suggesting the possibilities exchange of pyran ring and prenyl positions. The HMBC correlations between H-8 (δ H 6.51) and C-6 (δ C 103.9)/C-7 (δ C 158.3)/ C-9 (δ C 155.1)/C-10 (δ C 103.9); H-4′′ (δ H 1.43)/ H-5′′ (δ H 1.43) and C-2′′ (δ C 128.8)/C-3′′ (δ C 77.8); and between H-1′′ (δ H 6.61) and C-5 (δ C 154.6)/C-6 (δ C 103.9)/C-7 (δ C 158.3) suggested the cyclization of prenyl group with flavonol (pyran ring) at C-7 and C-3′′. In addition, the presnce of prenyl at C-3′ was confirmed by HMBC correlations from H-9′′ (δ H 1.70)/H-10′′ (δ H 1.70) to C-7′′ (δ C 122.3)/C-8′′ (δ C 131.7); from H-6′′ (δ H 3.28) to C-2′ (δ C 129.2)/C-3′ (δ C 127.7)/C-4′ (δ C 157.0). Consequently, the structure of 3 was determined and named macarindicin F. The known compounds, macadenathin B (4) (Yang et al. 2015b), glyasperin A (5) (Nomura et al. 1992), kaempferol (6), quercetin (7), quercitrin (8) (Nhiem et al. 2011), (+)-isolariciresinol (9) (Jutiviboonsuk et al. 2005), (-)-woonenoside XI (10) (Niwa et al. 2004), and (+)lyoniresinol 4-O-β-D-glucopyranoside (11) (Buske et al. 2001) were identified by comparison of their NMR data with those reported in the literature. Compounds 1-11 were evaluated for cytotoxic activity against KB, MCF-7, HepG-2, and LU human cancer cell lines (Table 2). As results, compound 2 showed significant cytotoxic activity on all human cancer cell lines with IC 50 values ranging from 11.0 to 17.0 μM, compared to those of positive control, mitoxantrol. Compound 3-5, exhibited moderate cytotoxic activity against four cancer cell lines with IC 50 values ranging from 15.0 to 38.2 M. Compounds 6-11 did not show cytotoxic activity (IC 50 >100 M). In the structure-activity relationship, prenylated flavonoids with pyran ring at A or B ring of flavonol (2-4) of showed stronger cytotoxic activity than prenylated derivatives (1 and 5) as well as remaining flavonoids (6-8). Recent reports have shown significant cytotoxic effects of prenylated flavonoids (Chen et al. 2014). Flavonoids have the potential of modulating many biological events in cancer such as apoptosis, vascularization, cell differentiation, cell proliferation, etc (Lopez-Lazaro 2002). These results suggest that discovery of prenylated flavonoids may increase the possibility of finding new anticancer agents. The mechanism of action of the 2 from this plant or other sources need to be further studied.

( 3 /

 3 1, v/v) to yield compound 2 (10.0 mg). MI1B4 was chromatographed on a silica gel column eluting with CH 2 Cl 2 /EtOAc (20/1, v/v) to give two fractions, MI1B4A-MI1B4B. MI1B4A was chromatographed on a sephadex LH-20 column eluting with MeOH/water (1/1, v/v) to yield compound 5 (70.0 mg). The MI1D was chromatographed on silica gel column eluting with n-hexane/acetone (2/1, v/v) to give four fractions, MI1D1-MI1D4. MI1D3 was chromatographed on a silica gel column eluting with n-hexane/EtOAc (1/1, v/v) to give two smaller fractions, MI1D3A-MI1D3B. MI1D3A was chromatographed on a Sephadex LH-20 column eluting with MeOH/water (1/1, v/v) to yield compound 9 (6.0 mg). MI1E was chromatographed on a RP-18 column eluting with acetone/water (2/1, v/v) to give three fractions, MI1E1-MI1E3. MI1E2 was chromatographed on a silica gel column eluting with CH 2 Cl 2 /MeOH (5/1, v/v) to give two fractions, MI1E2A-MI1E2B. MI1E2A was chromatographed on a sephadex LH-20 column eluting with MeOH/water (1/1, v/v) to yield compound 8 (9.0 mg). The MI2 fraction was chromatographed on a silica gel column eluting with a gradient of CH 2 Cl 2 / MeOH (40/1→1/1, v/v) to give four fractions, MI2A-MI2D. MI2A was chromatographed on a RP-18 column eluting with MeOH/water (1.5/1, v/v) to give two smaller fractions, MI2A1-MI2A2. MI2A1 was chromatographed on a sephadex LH-20 column eluting with MeOH/water (1/1, v/v) to yield compound 7 (40.0 mg). Compound 6 (35.0 mg) was obtained from MI2A2 on a silica gel column using CH 2 Cl 2 /MeOH (10/1, v/v) as eluent solvents. The MI3 was chromatographed on a Diaion HP-20 column first eluting with water to remove sugar components, then increasing concentration of MeOH in water (25, 50, 75, and 100 % of MeOH) to obtain four fractions, MI3A-MI3D. The MI3B fractions were chromatographed on a silica gel column eluting with a gradient of CH 2 Cl 2 /MeOH (10/1→0/1) to give four fractions, MI3B1-MI3B4. MI3B1 was chromatographed on a RP-18 column eluting with MeOH/water (1/2, v/v) to give three fractions, MI3B1A-MI3B1C. MI3B1A was chromatographed on a silica gel column eluting with CH 2 Cl 2 /MeOH (5/1, v/v) to yield compounds 10 (8.0 mg) and 11 (12.0 mg).

  .

3. 4 .Figure 1 .

 41 Figure 1. Chemical structures of compounds 111.

Figure 2 .

 2 Figure 2. The key HMBC correlations of compounds 13.

6 .

 6 Counts vs. Mass-to-Charge (m/z) 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260 265 270 275 280 285 290 295 300 305 310 315 320 325 330 335 340 345 350 355 360 365 370 375 380 385 390 395 400 405 410 415 420 425 430 435 440 445 450 455 460 465 470 2. 1 H-NMR spectrum of compound 1 HR-ESI-MS of compound 2

  Counts vs. Mass-to-Charge (m/z) 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 7. 1 H-NMR spectrum of compound 2 10. HMBC spectrum of compound 2 11. HR-ESI-MS of compound 3

Table

  1) of 1 showed the signals of 21 carbons, including

	one carbonyl carbon (δ C 175.9), one aldehydic carbon (δ C 190.5), eleven non-protonateds (δ C
	102.8, 110.3, 122.3 ×2, 130.6, 136.2, 145.0, 154.0, 157.4, 161.7, and 161.8), five methines (δ C
	92.7, 117.7, 122.1, 128.3, and 134.9) one methylene (δ C 20.9), and two methyl carbons at (δ C

Table 1 .

 1 1 H-and[START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR spectroscopic data for compounds 1 -3 in DMSO-d 6 .

	C	1	2	3
	δ C

δ H (mult., J in Hz) δ C δ H (mult., J in Hz) δ C δ H (mult., J in Hz)

	2 145.0 -	146.0 -	147.5 -
	3 136.2 -	135.9 -	135.7 -
	4 175.9 -	176.1 -	175.9 -
	5 157.4 -	158.2 -	154.6 -
	6 110.3 -	97.8 6.30 (s)	103.9 -
	7 161.7 -	161.2 -	158.3 -
	8	92.7 6.50 (s)	105.6 -	94.5 6.51 (s)
	9 154.0 -	153.4 -	155.1 -
	10 102.8 -	103.0 -	103.9 -
	1′ 122.3 -	123.7 -	121.4 -
	2′ 128.3 8.50 (d, 2.0)	125.6 7.85 (d, 2.5)	129.2 7.93 (d, 2.0)
	3′ 122.3 -	120.6 -	127.7 -
	4′ 161.8 -	153.9 -	157.0 -
	5′ 117.7 7.18 (d, 9.0)	116.0 6.92 (d, 9.0)	114.8 6.94 (d, 8.5)
	6′ 134.9 8.29 (dd, 2.0, 9.0)	128.8 7.93 (dd, 2.5, 9.0)	128.8 7.88 (dd, 2.0, 8.5)
	1″	20.9 3.24 (d, 7.0)	21.1 3.43 (d, 6.5)	114.5 6.61 (d, 10.0)
	2″ 122.1 5.19 (t, 7.0)	122.5 5.17 (t, 6.5)	128.8 5.79 (d, 10.0)
	3″ 130.6 -	130.9 -	77.8 -
	4″	25.4 1.63 (s)	25.3 1.62 (s)	27.8 1.43 (s)
	5″	17.6 1.73 (s)	17.8 1.74 (s)	27.8 1.43 (s)
	6″ 190.5 10.35 (s)	121.2 6.46 (d, 10.0)	28.1 3.28 (d, 7.5)
	7″		131.8 5.85 (d, 10.0)	122.3 5.30 (t, 7.5)
	8″		77.0 -	131.7 -
	9″		27.8 1.42 (s)	25.4 1.70 (s)
	10″		27.8 1.42 (s)	17.6 1.70 (s)

Table 2 .

 2 Cytotoxic effects of compounds 1-11

	Compounds			IC 50 (M) a)
		KB	MCF7	HepG2	LU
	1	47.4±2.4	>100	53.1±3.7	>100
	2	11.0±1.0	15.5±1.2	11.9±1.3	17.0±1.3
	3	15.0±1.7	18.1±1.9	17.9±1.5	20.3±2.0
	4	32.9±2.1	33.1±3.2	33.1±1.5	35.0±1.7
	5	38.2±2.4	34.4±3.1	30.1±4.0	34.6±3.7
	6	>100	>100	>100	>100
	7	>100	>100	>100	>100
	8	>100	>100	>100	>100
	9	>100	>100	>100	>100
	10	>100	>100	>100	>100
	11	>100	>100	>100	>100
	MX b)	7.8±0.7	10.3±1.1	8.2±0.6	7.7±0.4
	a)

[START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR spectrum of compound 1

[START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR spectrum of compound 2

HSQC spectrum of compound 2

1 H-NMR spectrum of compound 3

[START_REF]C-NMR spectrum of compound 3[END_REF] C-NMR spectrum of compound 3

Acknowledgment

The Centre National de la Recherche Scientifique (CNRS, France) is gratefully acknowledged for the Franco-Vietnamese Cooperation Program and The Ministry of Science and Technology of Vietnam for financial support [Grant number ĐTĐLCN.14/16].

Appendix A. Supplementary data

Supplementary material associated with this article can be found, in the online version, at sciencedirect.com.

SUPPLEMENTARY MATERIAL

Cytotoxic prenylated flavonoids from the leaves of Macaranga indica

Doan Thi Mai Huong a,c) , Le Tran Nguyen Vu a,c) , Luu The Anh b) , Nguyen Thi Cuc a,c) , Nguyen Xuan Nhiem a,c) , Bui Huu Tai a,c) , Phan Van Kiem a,c) , Marc Litaudon