K Aneb

H Oudadesse

H Khireddine

B Lefeuvre

O Merdrignac-Conanec

F Tessier

A Lucas

Study of the effect of ordered porosity and surface silanization on in vitro bioactivity of sol-gel-derived bioactive glasses

Keywords: Bioactive glass, Sol-Gel, Silanization, Mesoporous, Bioactivity, Controlled mineralization

The modification of porosity and surface silanization are efficient methods to improve physicochemical and biological properties of bioactive glass. For sol-gel-derived glasses, the use of surfactant in the synthesis medium allows to pattern porosity and may significantly impact their in vitro bioactivity. Additionally, surface functionalization by silanization may be a key method for grafting drugs or biomolecules to the glass surface. In this work, we realized a comparative study of the effect of porosity modification and surface silanization on in vitro bioactivity of sol-gel-derived bioactive glasses. The materials characterization by FTIR spectroscopy, XRD analysis, ICP-OES spectroscopy, and SEM-EDS, before and after soaking in SBF, showed that the ordered porosity increases significantly the kinetics of hydroxyl-carbonate apatite formation and induces a control of the mineralization at the glass surface. The results show also that the glass remains bioactive after silanization. The present work shows that porosity structuring both improves the in vitro bioactivity of our glass and increases the silanization rate of the glass surface.

Introduction

The first bioactive glass, named 45S5, was synthesized by L. Hench in the early 1970s [START_REF] Hench | Bioceramics: From Concept to Clinic[END_REF][START_REF] Hench | Bioceramics, a clinical success[END_REF][START_REF] Hench | Third-Generation Biomedical Materials[END_REF][START_REF] Hench | The story of Bioglass[END_REF]. Since then, bioactive glass has continued to be of interest to researchers for its use as a biomaterial for hard tissues. Its bioactivity allows the creation of bonds with living bone tissue [START_REF] Hench | Bioceramics[END_REF][START_REF] Hench | Bonding mechanisms at the interface of ceramic prosthetic materials[END_REF][START_REF] Waltimo | Fine-tuning of bioactive glass for root canal disinfection[END_REF][START_REF] Ducheyne | Bioglass coatings and bioglass composites as implant materials[END_REF][START_REF] Kitsugi | Bone-bonding behavior of plasma-sprayed coatings of BioglassR, AW-glass ceramic, and tricalcium phosphate on titanium alloy[END_REF]. Many studies have been carried out to understand the physicochemical and biological behavior of bioactive glasses. Several parameters could influence the reactivity of the glass, including the synthesis method [START_REF] Stöber | Controlled growth of monodisperse silica spheres in the micron size range[END_REF][START_REF] Mezahi | Reactivity kinetics of 52S4 glass in the quaternary system SiO 2 -CaO-Na 2 O-P 2 O 5 : Influence of the synthesis process: Melting versus sol-gel[END_REF][START_REF] Lin | Nanostructure evolution and calcium distribution in sol-gel derived bioactive glass[END_REF][START_REF] Sepulveda | Characterization of melt-derived 45S5 and solgel-derived 58S bioactive glasses[END_REF][START_REF] Migneco | A Guided Walk through the World of Mesoporous Bioactive Glasses (MBGs): Fundamentals, Processing, and Applications[END_REF][START_REF] Mabrouk | Comparative Study of Nanobioactive Glass Quaternary System 46S6[END_REF],textural features such as porosity structure and pore size [START_REF] Migneco | A Guided Walk through the World of Mesoporous Bioactive Glasses (MBGs): Fundamentals, Processing, and Applications[END_REF][START_REF] Mabrouk | Comparative Study of Nanobioactive Glass Quaternary System 46S6[END_REF][START_REF] Letaief | Influence of Synthesis Parameters on the Structure, Pore Morphology and Bioactivity of a New Mesoporous Glass[END_REF][START_REF] Letaïef | Effect of aging temperature on the structure, pore morphology and bioactivity of new sol-gel synthesized bioglass[END_REF][START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF][START_REF] Letaïef | New 92S6 mesoporous glass: Influence of surfactant carbon chain length on the structure, pore morphology and bioactivity[END_REF][START_REF] Rocton | Study of nano bioactive glass for use as bone biomaterial comparison with micro bioactive glass behaviour[END_REF], and the composition by incorporating elements of a physicochemical or biological interest [START_REF] Dietrich | Effects of Mg and Zn on the Surface of Doped Melt-Derived Glass for Biomaterials Applications[END_REF][START_REF] Saravanapavan | Bioactivity of gel-glass powders in the CaO-SiO 2 system: a comparison with ternary (CaO-P 2 O 5 -SiO 2 ) and quaternary glasses (SiO 2 -CaO-P 2 O 5 -Na 2 O)[END_REF][START_REF] Ma | Effect of magnesia on the degradability and bioactivity of sol-gel derived SiO 2 -CaO-MgO-P 2 O 5 system glasses[END_REF][START_REF] Oudadesse | Apatite forming ability and cytocompatibility of pure and Zn-doped bioactive glasses[END_REF][START_REF] Goel | Influence of strontium on structure, sintering and biodegradation behaviour of CaO-MgO-SrO-SiO 2 -P 2 O 5 -CaF 2 glasses[END_REF]. Yan et al. are the first research team that developed mesoporous bioactive glass with ordered porosity [START_REF] Yan | Highly ordered mesoporous bioactive glasses with superior in vitro bone-forming bioactivities[END_REF], this property results in an increased specific surface area and a well-defined porous structure in terms of shape and diameter, this impacts positively the bioactivity of the bioactive glass [START_REF] Alópez-Noriega | Ordered Mesoporous Bioactive Glasses for Bone Tissue Regeneration[END_REF]. Since the bioactive glass is intended to be implanted in a bone site, it may play another role than just a bone filler. Adding therapeutic molecules can confer the glass an additional biological property such as increasing bone regeneration and/or antibacterial activity [START_REF] López-Noriega | Functionalizing mesoporous bioglasses for long-term anti-osteoporotic drug delivery[END_REF][START_REF] Gupta | Effects of transition metal ion dopants (Ag, Cu and Fe) on the structural, mechanical and antibacterial properties of bioactive glass[END_REF]. Surface silanization is one of the most widely used methods that allow the association between glass and different organic molecules [START_REF] Colilla | Ordered Mesoporous Silica Materials[END_REF]. This method consists in grafting to the surface of the glass a silane coupling agent with terminal functional groups [START_REF] Majors | Studies of Siloxane Phases Bonded to Silica Gel for Use in High Performance Liquid Chromatography[END_REF].These groups will allow a chemical bond with one or more well-defined organic molecules. Nevertheless, for this approach to be successful in the purpose of bone implantation, the glass must remain bioactive after surface silanization. In this work, sol-gel derived glasses named92S6 and 92S6 P123 with wt% composition: (84.82% SiO 2 -10.14 % CaO -5.04 % P 2 O 5 ) were synthesized and studied [START_REF] Letaief | Influence of Synthesis Parameters on the Structure, Pore Morphology and Bioactivity of a New Mesoporous Glass[END_REF][START_REF] Letaïef | Effect of aging temperature on the structure, pore morphology and bioactivity of new sol-gel synthesized bioglass[END_REF][START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF][START_REF] Letaïef | New 92S6 mesoporous glass: Influence of surfactant carbon chain length on the structure, pore morphology and bioactivity[END_REF]. In a previous work, a comparative study of the synthesis of bioactive glass with an ionic surfactant (CTAB) and with a non-ionic surfactant (P123) was realized to highlight the effect of the chemical nature of the surfactant on glass physicochemical properties [START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF]. It was showed that, for the tested conditions, the presence of non-ionic surfactant P123 in the glass synthesis medium led to a hexagonal ordered mesoporosity. Conversely, the use of ionic surfactant CTAB did not allow to obtain the ordered mesoporosity [START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF]. Even if the non-ionic surfactant did not allow to order porosity, its presence might influence the textural glass property. In the present work, we synthesized a bioactive glass in presence of the non-ionic surfactant P123 and in strictly the same conditions, except the presence of a surfactant, its unordered counterpart synthesized without any surfactant. We then studied the effect of the ordered porosity induced by the presence in the synthesis medium of the non-ionic surfactant P123 both on porosity and bioactivity features. In addition, we studied the influence of functionalization by silanizationon the bioactivity features for the two glasses.

Materials and methods

Glass synthesis reactants

The different reagents for the glass synthesis are summarized in Table I. The pluronic P123 (Aldrich, France) was used as a surfactant for the synthesis of 92S6 with structured porosity named 92S6 P123 (see section below).

Preparation of bioactive glass samples

The bioactive glasses named 92S6 and 92S6 P123 were synthesized according to a procedure described elsewhere [START_REF] Letaief | Influence of Synthesis Parameters on the Structure, Pore Morphology and Bioactivity of a New Mesoporous Glass[END_REF][START_REF] Letaïef | Effect of aging temperature on the structure, pore morphology and bioactivity of new sol-gel synthesized bioglass[END_REF][START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF][START_REF] Letaïef | New 92S6 mesoporous glass: Influence of surfactant carbon chain length on the structure, pore morphology and bioactivity[END_REF]. The 92S6 P123 is the notation which refers to the 92S6 glass synthesis in presence of the surfactant pluronic P123.

Surface silanization of the bioactive glasses

The two glasses were silanized with 3-aminopropyltriethoxysilane (APTES, 98%, Alfa-Aesar) as follows: glasses were dehydrated by a heat treatment at 200°C under vacuum and then refluxed with 20.10 -3 mol of APTES per gram of glass in dehydrated toluene (20 mL/g of glass) for 24h at 120 °C under Argon. The obtained product was centrifugated and rinsed 3 times with a mixture of diethyl ether and dichloromethane (1:1) and finally dried at 100°C during 12h in air.

The Table II summarizes the four materials to be studied with their notations. J o u r n a l P r e -p r o o f Specific surface areas were derived from the isotherms using the BET method and a set of 10 experimental points of the linear range of the BET plot (0.05P/P 0 0.3).

The ordered porosity in 92S6 P123 was assessed by transmission electronic microscopy using a JEOL JEM 2100 LaB6 microscope operating at 200 KV. The images were obtained in a bright field using a high resolution Gatan US1000 camera, and an Orius 200D camera. The samples 92S6 and 92S6 P123 Sil were also analyzed for comparison.

The silane coupling agent contains an amine group. The nitrogen related to this functional group was quantified to determine the degree of silanization. The analysis was performed using inert gas fusion elemental analysis apparatus LECO TC 600 (LECO, USA). Nitrogen was measured as N 2 by thermal conductivity and oxygen as CO 2 by infrared detection. The apparatus was calibrated using LECO standards. Each analysis was done in triplicate. The mean weight percentage of nitrogen in glass and standard deviation were then calculated.

In vitro bioactivity test

To evaluate the in vitro bioactivity, each glass was soaked in a simulated body fluid (SBF). This solution which presents an ionic composition close to the human plasma (Table III) was synthesized in accordance to Kokubo procedure [START_REF] Kokubo | Solutions able to reproduce in vivo surface-structure changes in bioactive glass-ceramic A-W[END_REF][START_REF] Kokubo | How useful is SBF in predicting in vivo bone bioactivity?[END_REF]. 25 mg of each of the four materials were immersed in 50 mL of SBF. The suspensions (glass in SBF) were placed in an incubator set at 37 °C with a rotation speed of 60 rpm for different soaking times {1, 5, 10 and 15 days}. The procedure was realized in triplicate.

Glass surface characterization before and after soaking in SBF

The glasses surface changes were characterized by FTIR spectroscopy, XRD analysis, and SEM-EDS before and after immersion in SBF. To quantify the ionic exchange between theglasses and SBF over time, the supernatant of SBF was collected and analyzed by ICP-OES after each soaking time.

XRD analysis

X-ray diffraction (XRD) patterns were recorded at room temperature in 10°-60° 2θ range with a step size of 0.0261° and an effective scan time per step of 300 s using a PANalytical X'Pert Pro diffractometer (Cu-L2,L3 radiation, λ = 1.5418 Å, 40 kV,40 mA, PIXcel 1D detector). Data collector and HighScore Plus programs were used, respectively, for recording and

J o u r n a l P r e -p r o o f

analysis of the patterns. The purity of all the prepared powders was systematically checked by XRD.

FTIR spectroscopy

The FTIR spectroscopy was carried out at room temperature on KBr pellets containing the sample using a Alpha Bruker spectrometer between 4000 cm -1 and 400 cm -1 in transmittance mode with a resolution of 1 cm -1 .

SEM-EDS

Scanning electron microscopy coupled to Energy dispersive X-ray spectroscopy (SEM-EDS) was performed by a JEOL JSM 7100 F EDS EBSD (Oxford instrument) to examine the changes of the glasses surface before and after the different soaking times.

ICP-OES

The evolution of the elemental composition (Ca, Si, P) of the SBF after glass soaking was investigated by ICP-OES analysis preformed on SBF supernatant for each soaking time. The analysis was performed by Thermo Scientific iCAP 7000 series ICP-AES spectrometer.

Results and discussion

Porosity features

TEM micrographs and Fourier transform (FT) patterns show for 92S6 (Figure 1A) an unordered porosity and irregular pore distribution. Whereas, for the 92S6 P123 (Figure 1B) the results show an ordered porosity organized in channels gathered in a hexagonal shape. These results are consistent with those obtained by Letaïef et al. [START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF]. For the 92S6 P123 Sil (Figure 1.C), the image and FT patterns reveal that the ordered porosity is preserved after the glass surface silanization. Specific surface area, total pore volume and BJH desorption average pore diameter for the different glasses are presented in Table IV. Results show greater specific surface area and average pore diameter for the glass presenting structured porosity (92S6 P123) than the glass presenting non-structured porosity (92S6). Results indicate also that the silanization decreased the specific surface area, probably because of the smoothing of the surface during the silanization process in solution. The pore diameters are smaller for silanized glasses due to the obstruction created by the carbon chains of the silane coupling agent (APTES) grafted at the pore surface [START_REF] Bauer | Isomerization of nbutene over pre-coked HZSM-5 and HFER[END_REF]. However, the nitrogen adsorption and desorption isotherms (non-presented here) were not modified by the silanization process, which is consistent with an absence of modification of the main porosity features.

J o u r n a l P r e -p r o o f

Nitrogen content analysis

The comparison of glasses nitrogen content is presented in Table V. The increase of nitrogen content after silanization is consistent with the grafting of the silane coupling agent at the glass surface. Results indicate that the glass with structured porosity has a greater degree of silanization than the glass with non-structured porosity. Glass with structured porosity exhibits a lower dispersion in pore diameter than unstructured glass. This allows a regular and easier penetration of the APTES in the glass matrix, and then a greater grafting rate.

XRD analysis

After soaking in SBF, the XRD patterns, for both glasses 92S6 (Figure 2.A) and 92S6 Sil (Figure 2.B), show an appearance of a small peak at 29.4°after 1 day of immersion. This peak is assigned to the calcite formed from day 1 of immersion. The calcite precipitation is related to the high concentration of Ca that was released in SBF solution from the glass matrix in the first hours of immersion. Indeed, the released calcium ions combine with carbonate ions CO 3 2from SBF to form calcite which precipitates on the glass surface [START_REF] Mami | Investigation of the Surface Reactivity of a Sol-Gel Derived Glass in the Ternary System SiO 2 -CaO-P 2 O 5[END_REF]. At day 5 and day 10, no changes were recorded. On day 15 of immersion, we recorded additional peaks that are assigned to (002), ( 211), (310), ( 222) and (004) reflection plans of hydroxyapatite (HA) crystals consistent with the presence of this crystallized phase at the glass surface [START_REF] Ashok | Crystallization of hydroxyapatite at physiological temperature[END_REF][START_REF] Indrani | Phase composition and crystallinity of hydroxyapatite with various heat treatment temperatures[END_REF]. The XRD patterns show, for 92S6 P123(Figure 2.C) and 92S6 P123 Sil (Figure 2.D), after 1 day of immersion, an appearance of peaks assigned to HA similar to those observed for 92S6 after 15 days of soaking in SBF. From day 5 up to day 15, we recorded an increase in the intensities of all recorded peaks for both 92S6 P123 and 92S6 P123 Sil. No peak assigned to calcite was recorded for 92S6 P123 and 92S6 P123 Sil throughout the whole soaking time.

J o u r n a l P r e -p r o o f

FTIR spectroscopy

The FTIR spectra (Figure 3) show, for all glasses, after 1 day of immersion an appearance of a new small band at 878 cm -1 and a large band between 1400 cm -1 and 1500 cm -1 .These bands are assigned to carbonate group (CO 3

2-

) [START_REF] Doat | Synthesis of luminescent bioapatite nanoparticles for utilization as a biological probe[END_REF][START_REF] Koutsopoulos | Synthesis and characterization of hydroxyapatite crystals: A review study on the analytical methods[END_REF]. The bands recorded at 472 cm -1 , 566 cm -1 , 603cm -1 , 964 cm -1 and the large band between 1000 and 1100 cm -1 that covers the regions at 1034 cm -1 and 1093 cm -1 are assigned to tetrahedral phosphate group (PO 4 3-) [START_REF] Fu | In Vitro Study on Different Cell Response to Spherical Hydroxyapatite Nanoparticles[END_REF][START_REF] Li | Investigation of HAP nanoparticles absorbed by hepatoma cells in vitro[END_REF]. The J o u r n a l P r e -p r o o f dual-band at 566 cm -1 and 603 cm -1 , which is a characteristic of crystalline calcium phosphate in hydroxyapatite [START_REF] Hench | Bioceramics: From Concept to Clinic[END_REF][42-44] appears after 1 day of immersion for 92S6 P123 (Figure 3.C) and 92S6 P123 Sil (Figure 3.D) and only after 15 days of immersion for 92S6 (Figure 3.A) and 92S6 Sil (Figure 3.B). The carbonate group bands recorded on the first day of immersion are assigned to carbonate present in calcite for 92S6 and 92S6 Sil, and to carbonate present in hydroxyl-carbonate apatite for 92S6 P123 and 92S6 P123 Sil at this stage of immersion. These results are in good agreement with the recorded XRD patterns (Figure 2). J o u r n a l P r e -p r o o f 10

ICP-OES analysis of SBF

The ICP analysis of SBF solution after immersion of the glass 92S6 (Figure 4.A) shows at first an increase in Ca concentration after 1 day of immersion. From day 1 to day 5 we recorded a decrease in Ca concentration. From day 5 to day 10 Ca concentration remains more or less constant. From day 10 to day 15, Ca concentration decreases. The P concentration remains unchanged up to day 10, after this period up to 15 days of immersion, a decrease is recorded.

For 92S6 P123 (Figure 4.B), a slight decrease in Ca concentration is recorded on day 1. On day 5, the concentration decreases sharply, then the decrease continues slightly up to day 10. After that, the concentration remains practically unchanged up to day 15. The P concentration decreases slightly after day 1 of immersion, then the decrease continues sharply up to day 5, after that the concentration remains practically unchanged.

The Si concentration increases rapidly after the immersion, for both glasses, to reach a practically stationary phase without an important change at this stage. The ICP-OES results for 92S6 versus 92S6-Sil and 92S6 P123 versus 92S6 P123-Sil (Figure 5) show that the evolution of the different ions concentration in SBF is the same for both silanized and non-silanized glass, this result is in a good agreement with the results obtain by FTIR-spectroscopy and XRD analysis which show no difference between the two variants of glass. J o u r n a l P r e -p r o o f

SEM-EDS

The SEM micrographs before immersion for 92S6 (Figure 6.A), 92S6 Sil (Figure 6.D), 92S6 P123 (Figure 6.G) and 92S6 P123 Sil (Figure 6.J) show for all glasses an irregular surface with a granular appearance. The EDS results indicate, for all glasses, a surface very rich in silicon with small amounts of Ca and P, which is in good agreement with the elemental composition of all glasses before immersion in SBF. After 1 day of immersion, no change in surface aspect is recorded for 92S6 (Figure 6.B) and 92S6 Sil (Figure 6.E), whereas, small rods appeared on the surfaces of 92S6 P123 (Figure 6.H) and 92S6 P123 Sil (Figure 6.K). The EDS results show for 92S6 (Figures 6.B) and 92S6 Sil (Figure 6.E) the same results as before immersion. In contrary, for 92S6 P123 (Figure 6.H) and 92S6 P123 Sil (Figure 6.K), the EDS show a layer less rich in silicon and richer in Ca and P. By linking these results to FTIR spectra and XRD patterns, we conclude that the rods correspond to hydroxyl-carbonate apatite (HCA) crystals which was formed after 1 day of immersion on 92S6 P123 whether it's silanized or not. This indicate that no formation of calcium phosphate phase occurred at the glass surface after one day in contact with SBF, on both 92S6 and 92S6 Sil contrary to 92S6 P123 and 92S6 P123 Sil. These results are in accordance with ICP-OES results presented above. After 15 days of immersion, small rods, very similar to those recorded on 92S6 P123 and 92S6 P123 Sil from day 1 of immersion, appear on the surfaces of the 92S6 (Figure 6.C) and 92S6 Sil (Figure 6.F). For 92S6 P123 (Figures 6.I) and 92S6 P123 Sil (Figure 6.L), the same rods were recorded and became more abundant as compared to day 1. J o u r n a l P r e -p r o o f

Effect of ordered porosity on bioactivity

Figure 7 illustrates the different steps of the in vitro reactivity of bioactive glass in SBF described by L. Hench [START_REF] Hench | Bioceramics[END_REF]. The increase in Ca 2+ ion concentration in SBF is due to the cationic exchange between the glass surface and SBF: Ca 2+ ions are released from the glass surface and H 3 O + ions from the SBF solution are uptaken by the glass. This ionic exchange leads to the formation of silanol groups (Si-OH) at the glass surface according to the following reaction:

Si-O ---Ca 2+ ---O-Si + 2 H 3 O +  2 -Si-OH + Ca 2+ + 2H 2 O (Figure 7 -step 1).
The decrease in H 3 O + leads to an alkaline pH which is responsible for the continuous hydrolysis of Si-O-Si and formation of a soluble Si(OH) 4 which explains the increase of Si concentration after immersion (Figure 7 -step 2). The silanol groups at the glass surface condense to form a silica gel layer according to the reaction -Si-OH + HO-Si- -Si-O-Si-+ H 2 O. At this stage, Ca 2+ and PO 4 3-ions precipitate on the silica gel layer surface from the SBF to form the carbonated apatite phase. This mechanism is in good agreement with the simultaneous decrease in SBF concentrations of Ca and P recorded by ICP-OES between day 10 and day 15 for 92S6 (Figure 4.A) and from day 1 for 92S6 P123 (Figure 4.B). These decreases are due to the migration of Ca 2+ and PO 4 3-from the SBF towards the glass surface to form at first an amorphous apatite layer on the silica gel layer (Figure 7 -step 3) which after incorporating OH -and CO 3 2-from SBF crystallizes in hydroxyl-carbonate apatite (HCA) (Figure 7 -step 4) after 1 day of immersion on 92S6 P123 surface and 15 days of immersion on 92S6 surface. This phenomenon explains the characteristic bands and peaks of HCA recorded in both FTIR-spectroscopy and XRD analysis respectively.

J o u r n a l P r e -p r o o f The XRD patterns and FTIR spectra show a faster formation of HCA on 92S6 P123 surface (after 1 day of immersion) in comparison with 92S6 where HCA is formed only after 15 days of immersion. The porosity patterning using pluronic P123 surfactant in the synthesis medium of 92S6 glass induces a regular, organized and well-defined structured porosity [START_REF] Letaïef | Investigation of the surfactant type effect on characteristics and bioactivity of new mesoporous bioactive glass in the ternary system SiO 2 -CaO-P 2 O 5 : Structural, textural and reactivity studies[END_REF] (Figure 1.B), an increase of the specific surface area from 372 m 2 /g to 392 m 2 /g and a greater average pore diameter with a lower dispersion of pores diameter compared to 92S6 synthesized without any surfactant (Figure 1.A). The structured porosity leads to a greater and easier contact with SBF by an easy diffusion and then a higher reactivity of the glass towards SBF [START_REF] Migneco | A Guided Walk through the World of Mesoporous Bioactive Glasses (MBGs): Fundamentals, Processing, and Applications[END_REF]. Consequently, it allows a rapid availability of high concentration of Ca 2+ in the medium which precipitates afterwards with PO 4 3-to form HCA [START_REF] Martínez | Bioactivity of a CaO-SiO 2 Binary Glasses System[END_REF].

The ICP-OES analyses confirm the XRD analysis and FTIR-spectroscopy results and show that the kinetic of ionic exchange and the formation of the hydroxyl-carbonate apatite layer is faster for 92S6 P123 than for 92S6. After one day of soaking, the increase in Ca concentration recorded for 92S6 was not observed for 92S6 P123. This fact is consistent with the absence of formation of apatite layer consecutive to the calcium ions released by the 92S6 glass surface. For 92S6 P123, no significant increase in Ca concentration was recorded one day after soaking: the calcium release was counterbalanced by the calcium uptake for the formation of the calcium phosphate phase: hydroxyl-carbonate apatite (HCA).

J o u r n a l P r e -p r o o f

Additionally to the difference in the formation rate of HCA, related to the difference in porosity features between the two glasses, a significant difference is observed between the 92S6 and 92S6P123 (and their silanized counterparts) about the co-precipitation of calcium carbonate phase, calcite, at the glass surface. As mentioned before, no calcite peak has been recorded for structured glasses 92S6P123 (and 92S6 P123 Sil) despite the fact that it exhibits high reactivity in SBF. In a previous study, it was demonstrated that the formation of calcite on glass surface is related to the continuous release of the Ca 2+ ions which, reaching a given concentration, combine with the CO 3 2-ions present in the SBF and then precipitate as calcite at the glass surface [START_REF] Mami | Investigation of the Surface Reactivity of a Sol-Gel Derived Glass in the Ternary System SiO 2 -CaO-P 2 O 5[END_REF]. Clearly the results found in this study contradict this phenomenon for glasses with ordered porosity. Structured glasses should undergo a priori precipitation of calcite in a more obvious way than for unstructured glass, because of the higher contact surface with SBF. Surprisingly, this is not what the results showed. This lack of precipitation seems to be linked to the structure of the porosity that leads to a confined environment, and a well-determined spatial orientation. It is known that in addition to calcite, calcium carbonates can crystallize in other forms, namely aragonite and vaterite. The thermodynamic stability of these various forms, in the ambient aqueous conditions, is in according to descending order: calcite > aragonite > vaterite [START_REF] Plummer | The solubilities of calcite, aragonite and vaterite in CO 2 -H 2 O solutions between 0 and 90°C, and an evaluation of the aqueous model for the system CaCO 3 -CO 2 -H 2 O[END_REF].

Zeng et al. demonstrated that the crystallization of calcium carbonates in one form or another depends closely on the architecture and volume of the medium in which the phenomenon occurs [START_REF] Zeng | Confinement generates single-crystal aragonite rods at room temperature[END_REF]. The results of their study showed that the more confined the medium, the more the calcium carbonates crystallize as aragonite instead of calcite. The absence of calcite precipitation at the 92S6P123 glass surface is likely due to the fact that the confined medium within the structured glass prevents the precipitation of calcite. The precipitation of the more soluble and less stable aragonite does not occur before the formation of the calcium phosphate phase and the increase in Ca 2+ concentration allows calcium phosphate formation and crystallization of apatite instead of anarchic calcite precipitation in the early stages of immersion. For the 92S6 unstructured glass, we recorded an absence of HCA crystals up to day 15. Calcite precipitate on the first day of immersion and persists throughout the duration of immersion, this is at the origin of the very slow formation of the HCA, which occurs only on the 15th day of immersion.

Effect of silanization on glass bioactivity

Despite a decrease in specific surface area and in average pore diameter for silanized glasses, the porosity patterning of 92S6 P123 is preserved (Figure 1.C). On the other hand, the ICP-OES results, XRD patterns and FTIR spectra showed that the silanization of the glasses surface did not significantly affect the glasses reactivity towards SBF. This can be explained by the fact that the free silanol groups on the glass surface are not part of the interaction with SBF in terms of ionic exchange (Figure 7-step 1). Indeed, in the glass network, it is the network modifiers that initiate the ionic exchange with the SBF; in our case, the network modifier is the calcium ion. On the other hand, the silanization does not lead to an impervious surface and consequently does not affect the SBF infiltration in the glass matrix [START_REF] Chen | Surface Functionalization of Bioglass((R))-Derived Porous Scaffolds[END_REF]. As described above, following the cationic exchange between Ca 2+ and H 3 O + , silanol groups are formed and subsequently condense to form a silica gel layer on which HCA is formed. It is J o u r n a l P r e -p r o o f also, worth mentioning that the absence of any difference in Si evolution in SBF between silanized and non-silanized glass show that the silane coupling agent is strongly fixed to the surface of the glass and this fixation is not altered by the ionic exchanges that occur between the glass and SBF.

The SEM-EDS results are consistent with FTIR-spectra, XRD patterns and ICP-OES results in terms of the faster growth of HCA on 92S6 P123 in comparison to 92S6 and also in the fact that surface silanization does not affect glass reactivity toward SBF.

Conclusion

In this work, we have demonstrated the significant impact of porosity structuring on in vitro bioactivity of 92S6 sol-gel derived glass. Indeed, the ordered shape of the porosity has increased the surface contact between SBF and the glass, which leads to an increase in the ionic exchange kinetics and, consequently, to a faster growth of HCA layer on the bioactive glass surface. We also highlighted the impact of porosity structuring on calcite formation instead of, or in competition with hydroxy-carbonate apatite, the results showed that porosity structuring leads to a confined medium that hinders the ability of calcium carbonate to crystallize as calcite and therefore the Ca 2+ ions released from glass combine rapidly with PO 4

3-to form HCA. The results of this work showed that the porosity structuring of bioactive glass allows the control of crystallization of calcite and consequently the crystallization of HCA, this opens a path toward a deep exploration of this physicochemical phenomenon that allows modulating the reactivity of glass in the SBF, by controlling the crystallization of HCA as a function of textural features of the glass matrix.

On the other hand, we studied the effect of the glass surface silanization on bioactivity feature. We first show that the ordered porosity facilitates the silane grafting. Afterward, we showed that silanization of the glass surface did not impact its reactivity towards the SBF. Indeed, the functional groups on the glass surface involved in the silanization process are not involved in the cationic exchange that occurs after contact with the SBF solution and therefore the bioactivity of the glass remains intact. Results also indicate that the bond between glass and the silane coupling agent is stable despite ionic exchanges and formation of apatite layer. A chemically stable silanized surface will allow the grafting of therapeutic molecules and a very interesting delayed release of the grafted molecules useful in treating cancer and bacterial invasions. The obtained results showed that the surface silanization can only be beneficial to bioactive glass. This surface treatment method allows the bioactive glass to be biologically and/or therapeutically more active, or strengthens one or more of its physicochemical or biological properties without negatively impacting its bioactivity. Our glasses are envisaged as controlled release devices for therapeutic molecules through surface functionalization by silanization.

In conclusion, it should be noted that our sol-gel bioactive glasses 92S6, because of their moldable physicochemical and biological properties, by modulating their porosity and/or surface functionalization, make them good candidates as bioactive implants and drug carriers for bone applications.

J o u r n a l P r e -p r o o f

Figure 1 .

 1 Figure 1. TEM micrographs for 92S6 (A), 92S6 P123 (B) and 92S6 P123 Sil (C) before soaking in SBF.

Figure 2 .

 2 Figure 2. XRD patterns of glass surfaces before and after immersion in SBF solution at different testing times. A: 92S6, B: 92S6 Sil, C: 92S6 P123, D: 92S6 P123 Sil. *Calcium hydroxide phosphate, AR powder (Alfa Aesar, Zeppelinstraße 7, 76185 Karlsruhe, Cat. # 304288, Lot#1386600). **ICDD# 01-086-2340.

Figure 3 .

 3 Figure 3. FTIR spectra of glass surfaces before and after immersion in SBF solution at different testing times. A: 92S6, B: 92S6 Sil, C: 92S6 P123, D: 92S6 P123 Sil. *Calcium hydroxide phosphate, AR powder (Alfa Aesar, Zeppelinstraße 7, 76185 Karlsruhe, Cat. # 304288, Lot#1386600).

Figure 4 .

 4 Figure 4. Evolution of (Ca), (P) and (Si) concentrations in SBF versus time soaking. A: 92S6, B: 92S6 P123.

  r n a l P r e -p r o o f

Figure 5 .

 5 Figure 5. Evolution of (Ca), (P) and (Si) concentrations in SBF versus soaking time for silanized and nonsilanized glasses.

Figure 6 .

 6 Figure 6. SEM micrographs and EDS spectra of 92S6 and 92S6 Sil surfaces before and after 1 day and 15 days of immersion in SBF.

Figure 7 .

 7 Figure 7. Reactions sequence between bioactive glass and SBF.

Table I .

 I Reagents used for glass synthesis.

	Reagent	Tetraethyl	Calcium nitrate	Triethyl	Pluronic P123
		orthosilicate	tetrahydrate	phosphate (TEP)
		(TEOS)	(Ca(NO 3 ) 2 ,
			4H 2 O)
	Supplier	Sigma-Aldrich	Fluka	Sigma-Aldrich	Sigma-Aldrich
	Purity	98%	99%	99.8%	-
		Silica source	Calcium source Phosphorous	Non-ionic
				source	surfactant

J o u r n a l P r e -p r o o f

Table II .

 II The materials studied and their notations.

	Material	Notation
	Non-silanized 92S6	92S6
	Silanized 92S6	92S6 Sil
	Non-silanized 92S6 P123	92S6 P123
	Silanized 92S6 P123	92S6 P123 Sil
	2.3. Glass characterization before and after silanization
	Specific surface area and porosity features were analyzed at 77K using Nitrogen adsorption
	isotherms by a Gemini VII volumetric adsorption analyzer (Micromeritics, USA). Prior to
	measurements, the samples were outgassed during one night at ambient temperature in a
	VacPrep 061 degas system.

Table III .

 III Ionic composition of SBF compared to human blood plasma.

	Ions	Na +	K +	Ca 2+	Mg 2+	HCO 3 -	Cl -	HPO 4 2-
	Plasma (mM)	142	5	2.5	1.5	27	103.8	1
	SBF (mM)	142	5	2.5	1.5	4.2	148	1

Table IV .

 IV Specific surface area (S BET ), total pore volume (V P ) and BJH desorption average pore diameter (D P ) for different glasses

	Glass	S BET (m 2 /g)	V P (cm 3 /g)	D P (Å)
	92S6	372	0.8	65
	92S6 Sil	280	0.6	59
	92S6 P123	392	1.2	119
	92S6 P123 Sil	342	1.3	69

Table V .

 V Nitrogen weight content for the different glasses.

	Glass	Wt N (%) ± SD
	92S6	0.34 ± 0.06
	92S6 Sil	1.25± 0.03
	92S6 P123	0.23 ± 0.06
	92S6 P123 Sil	1.56± 0.11

J o u r n a l P r e -p r o o f

Acknowledgments

The authors of this article would like to acknowledge Vincent Dorcet for the assistance in TEM experiments performed on the THEMIS platform (ScanMAT, UAR2025 University of Rennes 1-CNRS; CPER-FEDER 2007-2014), Loïc Joanny (CMEBA) for SEM-EDS analysis, and François Cheviré (ICSR, Laboratory "Glasses and Ceramics") for XRD analysis at the Université de Rennes 1.

Declaration of interests

☐The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

Graphical abstract:

J o u r n a l P r e -p r o o f


Lynda Golea
email: golea.lynda@gmail.com

Rachid Chebaki

Mohammed Laabassi

Paul Mosset

Synthesis, characterization of some substituted Quinolines derivatives: DFT, computational, in silico ADME, molecular docking and biological activities

Keywords: Alcohols Quinolines, Molecular docking, Antibacterial, Antioxidant, ADME)

scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

1.Rationale

Quinoline and its derivatives are gaining importance in medicinal and organic chemistry. They have displayed a broad spectrum of pharmacological and biological activities such as antimalarial [START_REF] Kumar | Synthesis and bioevaluation of hybrid 4-aminoquinoline triazines as a new class of antimalarial agents[END_REF][START_REF] Xu | Recent advances of pyrazole-containing derivatives as anti-tubercular agents[END_REF], anticancer [START_REF] Afzal | A review on anticancer potential of bioactive heterocycle quinoline[END_REF][START_REF] Jain | Comprehensive review on current developments of quinoline-based anticancer agents[END_REF], antibacterial [START_REF] Sun | Antibacterial activity of N-methylbenzofuro[3,2-b] quinoline and N-methylbenzoindolo[3,2-b]-quinoline derivatives and study of their mode of action[END_REF][START_REF] El Shehry | Quinoline derivatives bearing pyrazole moiety : Synthesis and biological evaluation as possible antibacterial and antifungal agents[END_REF], antifungal [START_REF] Ben Yaakov | The quinoline bromoquinol exhibits broad-spectrum antifungal activity and induces oxidative stress and apoptosis in Aspergillus fumigatus[END_REF][START_REF] Musiol | Antifungal properties of new series of quinoline derivatives[END_REF], antidiabetes [START_REF] Edmont | Synthesis and evaluation of quinoline carboxyguanidines as antidiabetic agents[END_REF], antivirals [START_REF] Mahmoudi | In vitro activities of 25 quinolones and fluoroquinolones against liver and blood stage Plasmodium spp[END_REF], antioxidants [START_REF] Savegnago | Synthesis and antioxidant properties of novel quinoline-chalcogenium compounds[END_REF], anti-inflammatories [START_REF] Yeh | Synthesis and antiinflammatory evaluation of 4-anilinofuro[2,3-b] quinoline and 4-phenoxyfuro[2,3-b] quinoline derivatives. Part 3[END_REF], antiproliferatives [START_REF] Joshi | 4-Phenyl quinoline derivatives as potential serotonin receptor ligands with antiproliferative activity[END_REF], antitubercular [START_REF] Borsoi | Antitubercular Activity of Novel 2-(Quinoline-4-yloxy) acetamides with Improved Drug-Like Properties[END_REF] and corrosion inhibitors [START_REF] Zhong | Identification of benzenesulfonamide quinoline derivatives as potent HIV-1 replication inhibitors targeting[END_REF]. It is known, in the literature that the substituted quinolines, especially in positions C-2 and C-3, present very interesting biological activities such as anti-HIV-1 agents [START_REF] Purvi | Synthesis of C-2 and C-3 substituted quinolines and their evaluation as anti-HIV-1 agents[END_REF], and as inhibitors of SARS-CoV-2 [START_REF] Gautret | Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label nonrandomized clinical trial[END_REF]. In recent years the heterocyclic chemistry of quinolines is well established in the field of biological and pharmacological activities. This system has proved to be a very good scaffold for organic and medicinal chemists. However, quinoline derivatives were extensively studied as bioactive compounds, such as the quinoline alkaloids Quinine (1) that isolated from the bark of the Cinchona tree and has been used for the treatment of malaria [START_REF] Kacprzak | Chemistry and Biology of Cinchona Alkaloids[END_REF]. Camptothecin (2) (Fig. 1), isolated from the Chinese tree Camptotheca acuminata, is the best known and most important quinoline alkaloid from an anticancer perspective [START_REF] Wall | Plant antitumor agents I. The isolation and structure of camptothecin, a novel alkaloidal leukemia and tumor inhabitor from Camptotheca acuminate[END_REF]. Currently, quinoline alkaloids and their derivatives have very broad medical and agricultural applications. In these reports we have designed and synthesized various C-2 and C-3 substituted quinoline derivatives from 2-chloroquinoline-3-carbaldehyde and evaluated their antibacterial, and radical scavenging activities have been investigated by using DPPH method. All the synthesized compounds exhibited moderate antibacterial and antioxidant activities. Due to the therapeutic properties of these derivatives, characterization of structural, geometrical and electronic properties by DFT calculations is fundamental to find out the influence of different substituents on the pharmacological properties of these quinoline rings. In this present work, a simulated molecular docking study of synthesized compounds was studied on the SARS-CoV2 enzyme to determine the types of amino acids responsible for the reaction at the level of the bonds formed with ligand-protien in the three-dimensional structure. Drugs like chloroquine (CQ), hydroxychloroquine (HCQ) are used as promising agents against COVID-19. Additionally, in silico ADME analysis was studied for molecules to check drug ability and toxicity issues. Our hypothesis is to study these synthesized products which contain the quinoline nucleus to determine the binding affinities of these drugs and to identify the main amino acid residues which play a key role in their mechanism of action by utilization of molecular docking which is a very useful strategy for optimizing the best virtual drug assays in the fastest and least expensive manner. According to published works, we have prepared some 2-chloro-3-dimethxymethyl-quinoline derivatives (2a-c). The substitution of chlorine in position C-2 by nucleophilic agent requires the protection of the aldehydic function in the form of acetal to avoid any attack on carbonyl site. The reagent used for this protection is the trimethoxy methane in methanol refluxed during 8 hours. After the protection of the aldehydic function in the first step, we carried out the substitution of chlorine in position C-2. We have reacted allyl alcohol in the presence of the hydride of sodium in the DMF with 2-chloro-3-dimethoxymethyl-quinoline to lead to ethers (3a-c) with good yields. Deprotection of the aldehyde function requires a quantity of paratoluenesulphonic acid and a water/THF mixture to lead to the compounds (4a-c). When we treated derivatives of compound (4a-c) with methyl magnesium iodide in dry THF at room temperature, we obtained products (5a-c) of (80%) yield. The structures of synthesized compounds were confirmed by FT-IR, 1 H NMR and 13 C NMR and theoretical calculations. The general synthetic of title compounds is shown (Scheme.1).

Procedure

Chemistry

All Chemical reagents and solvents were used as received and without any purification. Reactions were examined with TLC using silica gel 60 F254 from Merck. Melting points were measured using Electrothermal capillary fine control apparatus and are uncorrected. The FT-IR spectrum was recorded with JASCO FT/IR-4100 FT-IR spectrometer over the range 400-4000 cm -1 . 1 H and 13 C NMR spectra were recorded in DMSO-d6 solutions on a Fourrier ARX 400 spectrometer at 400 MHz.

Preparation of 2-chloro-3-formyl-quinoline

2-chloro-3-formylquinoline derivatives 1 have been synthesized according to the literature procedures [START_REF] Otto | A versatile new synthesis of quinolines and related fused pyridines, Part 5. The synthesis of 2-chloroquinoline-3-carbaldehydes[END_REF]. Spectroscopic results and physical properties are in full agreement with literature reports [START_REF] Nadaraj | The effective reaction of 2-chloro-3-formylquinoline and acetic acid/sodium acetate under microwave irradiation[END_REF].

Protection of the function aldehyde

General method: A solution of 1 (1g, 0.001 mmol) in 7 ml MeOH and (1 ml, 1.2 equiv.) of CH(OCH3)3 was refluxed during 8h. After cooling, the solution was extracted with CH2Cl2, washed with water, and dried with MgSO4. Evaporation of solvent under reduced pressure gave the products 2, which were purified on silica gel column chromatography using petroleum ether/ethyl acetate: 9/1 as eluent.

-synthesis of 2-chloro-3-dimethoxymethyl-quinoline (2-a) White crystals; yield = 81 %; mp = 61 °C; IR n cm -1 (KBr): 3000-3010 (CH aromatics); 1 H NMR (CDCl3) : 8.42 (s,1H, H-C4), 8.03 (dd,1H, J = 8.5 Hz, J = 1.1 Hz, H-C8), 7.87 (dd, 1H, J = 8.1 Hz, J = 1.4 Hz, H-C5), 7.75 (ddd,1H, J = 8.5 Hz, J = 6.9 Hz, J =1.5 Hz, H-C7), 7.58 (ddd,1H, J = 8.1 Hz, J = 6.9 Hz, J = 1.2 Hz, H-C6), 5.73(d,1H, J = 0.6 Hz, CH(OCH3)2), 3.45 (s, 6H, (OCH3)2); 13 -synthesis of 2-chloro-3-dimethoxymethyl-6-methyl-quinoline (2-b) White crystals; yield = 94 %; mp = 64 °C; IR n cm -1 (KBr): 3008-3001 (CH); 1 H NMR (CDCl3): 8.32 (dd, 1H, J = 1.0 Hz, H-C4), 7.92 (d, 1H, J = 8.6 Hz, H-C8), 7.62-7.60 (m, 1H, H-C5), 7.56 (dd, 1H, J = 8.6 Hz, J = 1.9 Hz, H-C7), 5.73 (broad d, 1H, J = 1.0 Hz, CH(OCH3)2), 3.43 (s, 6H, (OCH3)2), 2.52 (s, 3H, CH3); 13 -synthesis of 2-chloro-3-dimethoxymethyl-7-methoxy-quinoline (2-c) White Crystals; yield = 94 %; mp = 64 °C; IR n cm -1 (KBr): 3008-3001 (CH); 1 H NMR (CDCl3) : 8.32 (dd, 1H, J = 1,0 Hz, H-C4), 7.92 (d, 1H, J = 8.6 Hz, H-C8), 7.62-7.60 (m, 1H, H-C5), 7.56 (dd, 1H, J = 8,6 Hz, J = 1.9 Hz, H -C7), 5.73 (broad d, 1H, J = 1.0 Hz, CH(OCH3)2), 3.43 (s, 6H, (OCH3)2), 2.52 (s, 3H, CH3). 13

Nucleophilic Substitution

General method: A solution of hydride of sodium (0.5 g, 1.5 mmol) in the DMF (3 ml) was added 200 μl (1.2 equiv.) of R-OH at room temperature for 15 min, and then 2-chloro-3-dimethoxymethyl-quinoline 1 (0.5 g, 1.4 mmol) diluted in dry DMF (3 ml). The mixture was stirred for night. The solution was extracted with CH2Cl2, washed with water and dried with Na2SO4. Evaporation of solvent under reduced pressure gave the products 3 and 3', which were purified on silica gel column chromatography using petroleum ether/ethyl acetate: 8/2 as eluent.

-Preparation of 2-allyloxy-3-dimethoxymethyl-quinoline (3-a) Yellow oil; yield = 85%; IR n cm -1 (KBr): 3012 (CH), 1597 (C=C); 1 H NMR (CDCl3):8,25 (dd, 1H, J = 0.9 Hz, H-C4 ), 7.82 (ddd , 1H, J = 8.4 Hz, J = 1.2 Hz, J = 0.6 Hz, H-C8), 7.75 ( ddd, 1H, J = 8.0 Hz, J = 1.5 Hz, J = 0.5 Hz, H-C5), 7.61 (ddd, 1H, J = 8.4 Hz, J = 6.9 Hz, J = 1.5 Hz, H-C7 ), 7.37(ddd, 1H, J = 8.0 Hz, J = 6.9 Hz, J = 1.2 Hz, H-C6), 6.16 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.3 Hz, HC=CH2), 5.70 (d, 1H, J = 0.7 Hz, H-C(OMe)2), 5.46 (ddt, 1H, J = 17.2 Hz, J = 1.7 Hz, J = 1.7 Hz, HC=CH2 ), 5.26 (ddt, 1H, J = 10.5 Hz, J = 1.5 Hz, J = 1.5 Hz, HC=CH2), 5.07 (dt, 2H, J = 5.3 Hz, J = 1.5 Hz, OCH2), 3.42 (s, 6H, CH(OCH3)2); 13 -Preparation of 2-allyloxy-3-dimethoxymethyl-6-methy-quinoline (3-b) Yellow Oil; yield = 88 %; IR n cm -1 (KBr): 3010 (CH), 1587 (C=C); 1 H NMR (CDCl3): 8.14 (broed t, 1H, J = 1.0 Hz, H-C4 ), 7.71 (d, 1H, J = 8.5 Hz, H-C8), 7.53-7.50 ( m,1H , H-C5), 7 .44 (ddd, 1H, J = 8.5 Hz, J = 1.5 Hz, J = 0.6 Hz, H-C7 ), 6.16 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.2 Hz, HC=CH2), 5.69 (d, 1H, J = 0.7 Hz, H-C(OMe)2), 5.45 (ddt, 1H, J = 17.2 Hz, J = 1.6 Hz, J = 1.6 Hz, HC=CH2), 5.25 (ddt, 1H, J = 10.5 Hz, J = 1.5 Hz, J =1.5 Hz, HC=CH2), 5.05 (dt, 2H, J = 5.3 Hz, J = 1.5 Hz, OCH2), 3.42 (s, 6H , CH(OCH3)2), 2.47 (s, 3H, C6-CH3); 13 -Preparation of 2-allyloxy-3-dimethoxymethyl-7-methoxy-quinoline (3-c) Yellow Oil; yield = 74 %; IR n cm -1 (KBr) : 3010 ( CH ), 1518(C = C); 1 H NMR (CDCl3): 8.25 (broad s, H-C4 ), 7.72 (d , 1H, J = 8.9 Hz, H-C5), 7.24 ( d ,1H , J = 2.5 Hz, H-C8) , 7.18 (dd, 1H, J = 8.9 Hz, J = 2.5 Hz, H-C6 ), 6.18 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, CH=CH2), 5.69 (d, 1H, J = 0.5 Hz, H-C(OMe)2), 5.50 (ddt, 1H, J = 17.2 Hz, J = 1.6 Hz, J = 1.6 Hz, HC=CH2), 5.31 (ddt, 1H, J = 10.5 Hz, J = 1.3 Hz, J = 1.3 Hz, HC=CH2), 5.07 (ddt, 2H, J = 5.3Hz, J = 1.6 Hz, J = 1.3 Hz, OCH2), 3.93(s, 3H, C7-OCH3), 3.42 (s, 6H , CH(OCH3)2); 13

Hydrolysis (obtaining aldehyde)

General method: a solution of compounds 3 (1g, 0.36 mmol) in the THF (2.65 ml), (9.25 ml) of water and (62 mg, 0.36 mmol, 0.1 equiv.) of APTH, was refluxed during 2 h. After cooling the solution was extracted with CH2Cl2, washed with water and dried with Na2SO4. Evaporation of the solvent under reduced pressure gave the products 4, which were isolated by column chromatography using petroleum ether/ethyl acetate: 8/2 as eluent.

-Preparation of 2-allyloxy-3-formyl-quinoline (4-a) White crystals; yield = 69 %; mp = 68 °C; IR n cm -1 (KBr) : 3015 (CH), 1696 (C=O), 1607 (C=C); 1 H NMR (CDCl3): 0.52 (s, 1H,CHO), 8.61 (broad s, 1H, H-C4), 7.87-7.83(m, 2H, H-C8, and H-C5), 7.73(ddd, 1H, J = 8.5 Hz, J = 6.9 Hz, J = 1.4 Hz, H-C7 ), 7.43(ddd, 1H, J = 8.0 Hz, J = 6.9 Hz, J = 1.2 Hz, H-C6), 6.20 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, HC=CH2), 5.49 (ddt, 1H, J = 17.2 Hz, J =1.6 Hz, J =1.6 Hz, HC=CH2), 5.33 (ddt, 1H , J = 10.5 Hz, J = 1.6 Hz, J = 1.4 Hz, HC=CH2), 5,13 (dt, 2H, J = 5.5 Hz, J = 1.4 Hz, OCH2). 13 -Preparation of 2-allyloxy-7-methoxy-3-formyl-quinoline (4-c) White crystals; yield = 74 %; mp = 94 °C; IR n cm -1 (KBr): 3008 (CH), 1689 (C=O), 1524 (C=C); 1 H NMR (CDCl3): 10.47 (s, 1H,CHO), 8.61 (broad dd, 1H, J = 0.5 Hz, H-C4), 7.72 (d, 1H, J = 8.9 Hz, H-C5), 7.20 (broad d, 1H, J = 2.5 Hz, H-C8), 7.06 (dd, 1H, J = 8.9 Hz, J = 2.5 Hz, H-C6 ), 6.20 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, H-C=CH2 ), 5.49 (ddt, 1H, J = 17.2 Hz, J = 1.6 Hz, J = 1,6 Hz, HC=CH2), 5.33 (ddt, 1H, J = 10.5 Hz, J = 1.6 Hz, J = 1.3 Hz, HC=CH2), 5.11 (ddd, 2H, J = 5.5 Hz, J = 1.6 Hz, J = 1.4 Hz ,OCH2), 3.97 (s, 3H, OCH3); 13

Alkylation

General method: A solution of 4 (1g, 0.23 mmol) in dry THF (25 ml) was cooled at 0°C, we added CH3MgI (6.5 ml, 2.5 equiv.) dropwise. The reaction mixture was stirred at room temperature for 2 h. HCl (1.3 N) was added slowly at 0 °C. The solution was extracted with CH2Cl2, washed with water, and dried with Na2SO4. Evaporation of the solvent under reduced pressure gave the products 5, which were isolated by column chromatography using petroleum ether/ethyl acetate: 7/3 as eluent.

-Preparation of 1-(2-allyloxy-quinolin-3-yl)-ethanol (5-a) White crystals; yield = 90 %; mp = 74 °C; IR n cm -1 (KBr): 3241 (OH), 3005 (CH); 1639 (C=C); 1 H NMR (CDCl3): 8.03 (t, 1H, J = 0.9 Hz, H-C4), 7.82 (ddd, 1H, J = 8.4 Hz, J = 1.1 Hz, J = 0.6 Hz, H-C8), 7.73 (dd, 1H , J = 8.0 Hz, J = 1.5 Hz, H-C5), 7 .60 (ddd, 1H, J = 8.4 Hz, J = 7.0 Hz, J = 1.5 Hz, H-C7 ), 7.38 (ddd, 1H, J = 8.0 Hz, J = 7.0 Hz, J = 1.2 Hz, H-C6), 6.17 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, HC=CH2), 5.45 (ddt, 1H, J = 17.2 Hz, J = 1.6 Hz, J = 1.6 Hz, HC=CH2), 5.29 (ddt, 1H , J = 10.5 Hz, J = 1.4 Hz, J = 1.4 Hz, HC=CH2), 5.16 (broad q, 1H, J = 6.5 Hz, H-C(CH3)OH), 5.07 (ddd, 2H, J = 5.5 Hz, J = 1.5 Hz, J = 1.5 Hz, OCH2), 2.62 (broad s, 1H, OH), 1.60 (d, 3H, J = 6.5 Hz, HC(OH)-CH3); 13 .43 (dd, 1H, J = 8.4 Hz, J = 1.9 Hz, H-C7 ), 6.16 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, HC=CH2 ), 5.44 (ddt, 1H, J = 17.2 Hz, J = 1.6 Hz, J = 1.6 Hz, HC=CH2), 5.29 (ddt, 1H, J = 10.5 Hz, J = 1.3 Hz, J = 1.3 Hz, HC=CH2), 5,14 (qd, 1H, J = 6.5 Hz, J = 0.7, H-C(CH3)OH), 5.06 (ddd, 2H, J = 5.5 Hz, J = 1.4 Hz, J = 1.4 Hz, OCH2), 2.42 (s, 3H, C6-CH3 ), 1.52 (d, 3H, J = 6.5 HZ, HC(OH)-CH3); 13 -Preparation of 1-(2-allyloxy-7-méthoxy-quinolin-3-yl)-ethanol (5-c) White Crystals; yield = 84 %; mp = 76 °C; IR n cm -1 (KBr): 3271 (OH), 2999-3002 (CH), 1621 (C=C); 1 H NMR (CDCl3): 8.03 (dd, 1H, J = 1.0 Hz, J = 0.9 Hz, H-C4), 7.61 (d , 1H, J = 8.8 Hz, H-C5), 7.20 (d, 1H, J = 2.5 Hz, H-C8), 7.03 (dd, 1H, J = 8.8 Hz, J = 2.5 Hz, H-C6 ), 6.17 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, HC=CH2), 5.45 (ddt, 1H, J = 17.2 Hz, J = 1.6 Hz, J = 1,6 Hz, HC=CH2), 5.30 (ddt, 1H, J = 10.5 Hz, J = 1.3 Hz, J = 1.3 Hz, HC=CH2), 5.14 (qd, 1H, J = 6.5 Hz, J = 0.6 Hz, H-C(CH3)OH), 5.06 (ddd, 2H, J = 5.5 Hz, J = 1.6 Hz, J = 1.3 Hz, OCH2), 3.93 (s, 3H, C7-OCH3), 1.58 (d, 3H, J = 6.5 Hz, HC(OH)-CH3); 13 -c).

Computational methods

The boundary orbitals are known as the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO), and these factors are very valuable for the chemical reactivity of any organic substance. While the HOMO orbital tends to lose electrons, the LUMO tends to receive them. The HOMO energy is related to the ionization potential while the LUMO energy is associated with the electronic activity. In this study, the HOMO-LUMO distributions, their energies in ev units, and their associated quantum chemical descriptors of compounds (5a-c) were investigated. The quantum chemical descriptors of these compounds have been calculated using the DFT/B3LYP method with the basis set 6-311+G (d, p) level of theory included within the Gaussian 09 package [22]. The (HOMO-LUMO energies, band gap energies, ionization potentials, electronic affinities, chemical hardnesses, softnesses and potentials, electronegativities, electrophilicity indices and maximum charge transfer indices) are calculated according to Koopman theorem [START_REF] Tsuneda | On Koopmans' theorem in density functional theory[END_REF] and Pearson and Parr [START_REF] Parr | Absolute Hardness : Companion Parameter to Absolute Electronegativity[END_REF][START_REF] Parr | Electronegativity-The Density Functional Viewpoint[END_REF].

In vitro Antibacterial Activity

The compounds 5a, 5b and 5c were tested against three standard bacterial strains for the determination of their antibacterial activity, the results given in Table 1. All the compounds were screened for their antimicrobial activity against variety of bacterial strain such Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 using dimethyl sulfoxide (DMSO) as solvent and adjusted to a concentration of 250 and 500 μg/ml. The agar well diffusion method was used to determine antimicrobial activity [START_REF] Celikel | Antimicrobial properties of some essential oils against some pathogenic microorganisms[END_REF]. The impregnated disks were placed on the medium suitably spaced apart and the plates were then incubated at 5°C for 1 hour to permit good diffusion and then were transferred to an incubator at 37°C for 24 hours for bacteria, the antibacterial activity was evaluated by measuring the inhibition zone diameter observed. Standard drugs like Ampicillin, Gentamycin were used for comparison purpose. The results were expressed as the mean of three measurements.

In vitro Antioxydant Activity

The radical scavenging activity of the synthesized compounds was evaluated with DPPH 1,1-diphenyl-2picryl hydrazyl. Using the process [START_REF] Carcelli | Antimicrobial and genotoxic activity of 2,6diacetylpyridine bis(acylhydrazones) and their complexes with some first transition series metal ions. Xray crystal structure of a dinuclear copper(II) complex[END_REF], 20 mg/ml solution of DPPH in methanol was prepared daily. The synthesized samples in methanol to prepare six different concentrations (5, 15, 25, 30, 40 and 50 μg/ml), the mixtures were made by adding 1 ml of test sample to 1 ml of DPPH solution to 4 ml of methanol. Ascorbic acid was used for reference standard in similar concentration. The sotution mixtures were kept to stand for 30 min in dark oven at 37°C, and optical density was measured at 517 nm using the spectrophotometer. Percentage inhibition of DPPH radical was determined using the following equation:

Percent (%) inhibition of DPPH activity = 100 × (A' -B) /A'

Where A' = optical density of the blank and B = optical density of the sample

In Silico Molecular Docking evaluation

In December 2019, the Corona virus disease (COVID-19) was identified in the Chinese city of Wuhan for the first time in the world [START_REF] Fengxiang | Emerging 2019 Novel Coronavirus (2019-nCoV)[END_REF]. After that, it began to spread rapidly around the world, costing the lives of millions of people. Chloroquine (CQ) and hydroxychloroquine (HCQ) are drugs used against SARS-CoV-2. These drugs can inhibit the viral protease, called chymotrypsin-like cysteine protease, also known as the Main protease (3CLpro) ; but unfortunately, there is no therapeutic effect against this virus. In this study we focused on the main protease of the virus COVID-19. As a potential target protein for treating the disease. The protiene 6LU7 is the main protease present in the corona virus, which was deposited as a PDB file in 2020 [START_REF] Jin | Structure of M pro from SARS-CoV-2 and discovery of its inhibitors[END_REF]. The mol2 file of active compounds (5a-c) were prepared using ChemBio3D Ultra 14.0. And the PDB formats of these compound were used over their optimized structures with B3LYP/6-311+G (d, p). All preparations for docking were carried out by Discover Studio Visualizer 2.5 software, and for the ligand and protein molecules, they were converted to file format (pdbqt) using AutoDock tools 1.5.6. Three-dimensional structures of the all drug targets were retrieved from the RCSB Protein Data Bank (PDB). Crystallographic structures of the COVID-19 M pro (PDB ID: 6LU7) contsist of 2 chains, A and C, which may be part of interactions with the ligand.

In silico ADME studies

The prediction of the ADME (absorption, distribution, metabolism, excretion) before the experimental studies is one of the most important aspects of drug discovery and development processes. ADME studies play a significant role in helping to optimize the pharmacokinetic properties of new drugs [START_REF] Dincel | Antioxidant activity of novel imidazo[2,1-b] thiazole derivatives: Design, synthesis, biological evaluation, molecular docking study and in silico ADME prediction[END_REF]. The pharmacokinetic and Physicochemical properties of all compounds (5a-c) were determined by using SwissADME server (http://www.swissadme. ch/). The chemical structure of designed compounds is drawn by ChemDraw profssional 17.1 and then converted by SwissADME tool to SMILE name [START_REF] Daina | SwissADME: a free web tool to evaluate pharmacokinetics, druglikeness and medicinal chemistry friendliness of small molecules[END_REF].

Results and discussion

Chemistry

This work has led us to establish a synthesis of new quinoline alcohols which are unknown in the literature, with the aim of leading to new active principles. In this work we proceeded to the synthesis of some derivatives of 2-chloro-3-formylquinoline derivatives (1a-c), one of which is unpublished, according to the method described by O. Meth-Cohn. [START_REF] Otto | A versatile new synthesis of quinolines and related fused pyridines, Part 5. The synthesis of 2-chloroquinoline-3-carbaldehydes[END_REF]. The substitution of the chlorine atom in C-2 position of 2chloro-3-formylquinoline derivatives by a nucleophile can be prevented by a parallel reaction between the nucleophile and the aldehyde function because of the very high reactivity of the latter. Therefore, we proceeded, in a first step, to the protection of the function to lead the compounds (2a-c). After the protection of the aldehyde function in the previous step, we reacted allyl alcohol in the presence of Sodium hydride in DMF with 2-chloro-3-formyl-quinoline derivatives to lead (3a-c). The next step requires the liberation of the aldehyde function in order to proceed to its alkylation, this leads us to deprotect the aldehyde function of the different quinolines, by heating them at reflux in a mixture of THF and distilled water for 1 hour in the presence of a catalytic amount of paratoluenesulfonic acid to lead to the expected ether aldehydes (4a-c). The 1 H NMR spectra allow us to observe the characteristics of the protons ; A weak field singlet signal between 10.47 and 10.50 ppm corresponding to the proton of the carbon carrying the aldehyde function. The last step of this synthesis is to obtain the quinoline alcohols sought for their synthetic interest in organic chemistry. We proceeded to the alkylation of the aldehyde functions obtained in the previous step with methyl magnesium iodide in THF to lead to the expected (5a-c) in very good yields 85%. 1 H/ 13 C NMR spectra of compounds were investigated, and the resulting spectral data were given in the experimental section, In the 1 H NMR spectrum of the compounds (5a-c), the two protons of O-CH2 appear between 5.06-5.08 ppm, however, the chemical shifts of the protons of the double bond Hcis, Htrans of HC=CH2 have almost the same appearance in all cases between 5.40-5.49 ppm, and 5.28-5.30 ppm respetively, while the methoxyl groups resonate, as expected, around 4.00 ppm. But the methyl groups give a strong field singlet signal between 2.35-2.42 ppm. Again, the -CH-proton in the C-3 resonated as quadriplet doublet at δ 5.15 ppm. The doublet observed at δ 1.50 ppm is signal of protons of methyl group. The signals due to quinoline H-4 appeared as singlet between δ 7.94-8.03 for one proton, the signals due to quinoline H-5, H-6, H-7, H-8 appeared in the region δ 7.03-7.83. In the 13 C NMR spectrum of (5a-c), the signals of methyl groups (-CH3) are seen at δ 23.86 ppm. The signal observed at δ 22.50-22.60 ppm is the resonance signal of the -CH-carbon atom in C-3, that was observed between δ 66.00-66.10 ppm, and the signal belonging to the carbon atom (O-CH2) was observed at δ 66.15 ppm. The signals of the aromatic carbon atoms and the carbon atom in the quinoline ring are observed in the range of δ 121.00-142.81 ppm. Spectroscopic data of all synthesized compounds are given in the experimental section. FTIR spectra of all compounds (5a-c) shows characteristic broad band at 3270-3273 cm -1 attributed to ν (-OH) indicating the presence of hydroxyl group. In line with these, the sharp peaks found in the FTIR at 3025 and 2930.9 cm -1 shows very strong asymmetric stretching vibrations of aromatic C-H and aliphatic C-H. The presence of nitrogen in the ring of benzene structure gives rise to C=N stretching vibrations at 1631-1625 cm -1 . The C-C aromatic stretching vibrations give rise to characteristic band in the IR spectra covering the spectral range from 1600-1582 cm -1 .

Frontier molecular orbital (FMO) analyses

The density functional theory is imposed as a relatively fast and efficient way to optimize the electronic and structural properties for all synthesized molecules or natural substances. In this work, we have presented the DFT theory and discussed mainly the essential points related to our project. The global reactivity parameters, associated to each molecule, have been calculated, in this case E Homo and E LUMO, E gap (ΔE), the chemical potential (μ), the electronegativity (χ), the index of electrophilicity (ω), chemical hardness (η) and softness (S) [START_REF] Mckinnon | Towards Quantitative Analysis of Intermolecular Interactions with Hirshfeld Surfaces[END_REF][START_REF] Spackman | Fingerprinting intermolecular interactions in molecular crystals[END_REF]. The aim being to study the relationship and correlation between the structure of the synthesized molecules and the physicochemical and biological properties of these structures. The ground state molecular geometry of the (5a-c) were optimized by density functional theory (DFT/B3LYP) calculations and with the 6-311+G (d, p) basis set as implemented in the Gaussian 6 program package. The optimized geometry of molecules (5a-c) presented in (Fig. 2). In HOMO (highest occupied molecular orbital) of compounds (5a-c), the electron density is strongly localized over quinoline moiety due to the presence of nitrogen and oxygen atoms as there is a presence of lone pair of electrons on them. The rest of the molecule appears to have neutral distribution of charge.

In LUMO (lowest unoccupied molecular orbital) of same compounds the electron density is observed mainly on the C-2 allyloxy radical. The energy gap (ΔE) is observed to be 2.78 and 2.92 eV. The energy gap (ΔE) between the HOMO and LUMO orbitals is a critical parameter for the chemical reactivity and stability of structures. Generally, molecules with small energy gaps (ΔE) have low structural stability and high chemical reactivity. In contrast, molecules with large energy gaps have high structural stability and low chemical reactivity [START_REF] Lamsayah | High liquid -liquid extraction selectivity of Fe (II) and Pb (II) with TD-DFT theoretical calculations of long chain acid pyrazole-and triazole-based ligands[END_REF]. In our study, these parameters were calculated for the most active antioxidant compounds (5a-c). According to DFT calculations, energy bandgap values were found that 3.81, 2.65 and 3.60 eV for 5a, 5b end 5c respectively. From the values found, we can deduce that the compound 5a has much higher structural stability than the others, while the compound 5b has the lowest structural stability than the others. Likewise, we can conclude that the antioxidant activity increases as the energy band gap decrease. The computed values are tabulated in Table 1.

Molecular electrostatic potential analysis

Molecular electrostatic potential (MEP) analysis is very useful for estimating the reactive sites of electrophilically and nucleophilically attacked compounds [START_REF] Politzer | The fundamental nature and role of the electrostatic potential in atoms and molecules[END_REF]. MEP analysis at the B3LYP/6-31G + (d, p) is considered predictive of chemical reactivity since the regions of negative potential are expected to be the sites of protonation and nucleophilic attack, while the regions of positive potential may indicate the electrophilic sites on the entitled molecule. The obtained MEP were indicated as in Fig. 3. In this figure, there are three type colors on the MEP which are blue, green and red. Here blue color indicates the maximum positive which suitable locals for nucleophilic attack points, red represents maximum negative which suitable points for electrophilic attack, and green color indicates zero value in terms of electron density. In all compounds (5a-c) the red regions are localized over nitrogen of the quinoline moiety and oxygen of hydroxy group there by these sites are rich of electron and have affinity towards the electrophiles. The carbon and hydrogen atoms with blue and green colors are poor electron-deficient zones, which could attract nucleophilic moieties.

Antibacterial activity

In this work, an attempt was made to evaluate the newly compounds synthesized for their in vitro antibacterial activities against three bacterial pathogens including S. aureus, E. coli, and P. aeruginosa using paper disk diffusion method. Results demonstrated that the mean inhibition zone of the synthesized compounds varied from 9.33 to 15.1 mm. The mean inhibition zones displayed by the title compounds were different against all of the bacterial strains at 500 μg/ml (Table 2). Compound 5a and 5c showed mean inhibition zones against three of the bacterial strains. At the same concentration, the inhibition zone displayed by compound 5b against P. aeruginosa with a value of 11,667±1,527 mm. These newly synthesized compounds demonstrated moderate antimicrobial profile against all bacterial strains. Ampicillin and Gentamycin were used as standard antibacterial drugs respectively. 19 20 zone of inhibition in mm: < 10: week; > 10: moderate; >16: Significant AMP: Ampicillin GEN: Gentamycin

Antioxydant activity

The data in Fig. 4 reveal that all of the synthetic compounds showed moderate antioxidant activities with IC50 values between 327.67±1.28 and 434.46±1.91 μm, these values were nearly close to standard ascorbic acid with IC50 value 196.46±0.76 μm. The statistical analyze were performed by Microsoft Excel 2010 and all the numerical results were expressed graphically. The DPPH test measures the anti-free radical power of molecules, it measures the ability of an antioxidant to reduce the chemical radical DPPH (2,2-diphenyl-1-picrylhydrazyl) by transfer of hydrogen. The initially purple DPPH turns into pale yellow. This potential activity of these compounds can be explained by the presence of oxygen atoms. But in the compound 5c the presence of an ethoxy group that increases the activity of antioxidants and the degree of solubility of the substance in the aqueous medium and this is the formation of hydrogen bonds, which stabilizes the radicals and improves the antioxidant properties in vitro.

Fig. 4. Antioxydant activity results using DPPH by the synthetic compounds.

In Silico Molecular Docking Evaluation

Molecular docking is a very important way of understanding the binding interactions between a ligand and a protein receptor. This method for drug design is exceptionally reliable, time-saving and costeffective. The (5a-c) compounds containing quinoline cycle, and these types of molecules have profound medicinal and pharmacological importance, so we have undertaken in silico based molecular docking study. Initially, we optimized the ligand molecules with the B3LYP/6-311 G + (d, p) level of theory, and the optimized structures were used for docking analysis. We obtained target main protease (3CL pro ) of SARS-CoV-2 (PDB ID: 6LU7). This target protein structure was taken from the Protein Data Bank [START_REF] Jin | Structure of M pro from SARS-CoV-2 and discovery of its inhibitors[END_REF]. The water molecules and ligands in the target structure were removed. Both ligand and target structures were with AutoDock tools 1.5.6. The best binding pose for each compound was predicted using the discovery studio program, as shown in Fig. 5, Fig. 6 and Fig. 7. The docking score (in kcal/mol) for (5a-c) are -6.18, -5.96 and -6.07 respectively. The binding score suggests that all compounds display similar binding affinity against SARS-CoV-2. The binding energies of all docked conformations for the title compounds (5a-c) and CQ, HCQ are presented in Table 3. Therefore, in the present work, the molecular docking analysis of the synthesized compounds (5a-c) was carried out to investigate their binding pattern with target (3CL pro ) having PDB ID 6LU7 and compare them with standard antimalarial drugs chloroquine (CQ) and its hydroxychloroquine (HCQ) are currently used as drugs for the treatment of COVID-19 [START_REF] Singh | Chloroquine and hydroxychloroquine in the treatment of COVID-19 with or without diabetes: A systematic search and a narrative review with a special reference to India and other developing countries[END_REF]. The synthesized compounds (5a-c) showed similar residual interactions profile with amino acid residues His163, Cys145, Met165 and His41. Compounds 5b and 5c have additional hydrogen bonding interaction with amino acid residue Cys 145.

Lig name

Binding energy (kcal/mol) [37] Gly143, Cys145, His164

His41, Asn142, His163 HCQ -6.58 [37] Phe140, Asn142, Ser144, Glu166

Phe140, Asn142, Cys145, Glu166, His172

In silico ADME

SwissADME webserver was used to measure the bioactivity score of the synthesized compounds (5a-c).

The calculated pharmacokinetics and physicochemical parameters such as cLogP (partition coefficient), compound weight, heavy atoms, hydrogen donors, hydrogen acceptors, rotatable bonds and TPSA values are illustrated in Table 4. From this table, the novel compounds (5a-c) exhibit no Lipinski's violation and having 1 hydrogen bond donors and 3-4 hydrogen bond acceptors. In addition to that, the molecular weight of the synthesized compounds (5a-c) is not more than 500 m/z. As per the above-mentioned parameters, the title compounds have good drug-likeness profile and the compound 5c reveals excellent drug-likeness criteria. The compounds 5a and 5b show 4 rotatable bonds but the compounds 5c exhibit 5 rotatable bonds. This reveals that, the title compounds have excellent ability to interact with the living cells. The bioavailability is the important parameter and the values of bioactivity score greater than zero indicates excellent drug likeness of the molecule [START_REF] Lakshmipraba | Surfactant-copper (II) Schiff base complexes : synthesis, structural investigation, DNA interaction, docking studies, and cytotoxic activity[END_REF]. All the new quinoline derivatives (5a-c) have the bioactivity scores of 0.55 (Fig. 8.A). Pharmacokinetically, all synthesized compounds (5a-c) have high GI absorption, blood brain barrier (BBB) propertie, and medium skin permeation value, and none of the synthesized compounds were predicted as P-glycoprotein substrate. Pharmacokinetically measurements give significant information about the permeation ability of the synthesized compounds (5a-c) which were determined using BOILED-Egg method and the graph is represented in (Fig. 8.B). Points located in the BOILED-Egg's yolk (yellow) signify the molecules predicted to passively permeate through the blood-brain barrier (BBB) whereas The red ones point out to the molecules predicted not to be effluated from the CNS (Central Nervous System-by the P-glycoprotein). However, the ones in the egg white are relative to the molecules predicted to be passively absorbed by the gastrointestinal tract.

Conclusion

In this study, we reported an easily applicable and efficient method for the synthesis of quinoline derivatives (5a-c) by application of Vilsmeier-Haack reaction. Various nucleophiles were introduced into 2-chloroquinoline-3-carbaldehyde using different reaction and conditions to lead C-2 and C-3 substituted quinoline. The structure and purity of all the compounds were indicated by their spectral and physical data. The antibacterial activities of the synthesized compounds were screened by the disc-diffusion method against one Gram-positive and two Gram-negative bacteria. Most of them were found to have moderate activities against the all bacterial strains. In the Gaussian calculations made, the chemical activity of the molecules (5a-c) was highest in the calculations made in the 6-311G (d, p) basis set. The In silico molecular docking study of the synthesized compounds (5a-c) was performed to assess the binding mode of these compounds against the coronavirus-2 (SARS-CoV-2) Protease Inhibitor (PDB ID : 6LU7). The three compounds (5a-c) exhibited good affinity with the coronavirus-2 (SARS-CoV-2). The ADME prediction has been shown a promising result in silico properties which indicate that all the synthesized compounds have an improved pharmacokinetic profile.

Fig. 1 .

 1 Fig. 1. Molecular structures of quinoline alkaloids quinine (1) and Camptothecin (2)

  C NMR (CDCl3): 149.00 (Cquat), 147.48 (Cquat), 137.28(CH), 130.90 (CH), 129.25 (Cquat), 128.25(CH), 128.08 (CH), 127.26 (CH), 126.75 (Cquat), 100.40 (CH (OCH3)2), 53.90(CH (OCH3)2); HRMS m/z [M] +. 273.0556 cald for C12H12NO2Cl, found 237.0545.

  C NMR (CDCl3): 189.27 (CHO), 160.53 (Cquat), 148.91 (Cquat), 139.92 (CH), 132.93 (H-C=CH2), 132.58 (CH), 129.76(CH), 127.30 (CH), 125.09 (CH), 124.43 (Cquat), 119.99 (Cquat), 118.07 (H-C= CH2), 67.08 (OCH2); HRMS m/z [M] +. : 213.0789 cald for C13H11NO2, found 213.0789.-Preparation of 2-allyloxy-6-methyl-3-formyl-quinoline (4-b) Green Crystals; yield = 80 %; mp = 89 °C; IR n cm -1 (KBr) : 3012 (CH), 1694 (C=O), 1565 (C=C); 1 H NMR (CDCl3): 10.51 (s,1H, CHO), 8.52 (broad s, 1H, H-C4), 7.74 (d, 1H, J = 8.5 Hz, H-C8 ), 7,60-7.61 (m, 1H, H-C5), 7.56 (dd, 1H , J = 8.5 Hz, J = 2.0 Hz, H-C7), 6.19 (ddt, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.5 Hz, HC=CH2), 5,49 (ddt, 1H, J = 17.2 Hz, J = 1.5 Hz, J = 1.5 Hz, HC=CH2), 5.32 (ddt, 1H , J = 10.5 Hz, J = 1.4 Hz, J =1.4 Hz, HC=CH2), 5.11 (dt, 2H, J = 5.5 Hz, J = 1,4 Hz, OCH2), 2.50 (s, 3H, C6-CH3);13 C NMR (CDCl3): 189.40 (CHO), 160.18 (Cquat), 147,32 (Cquat), 139.29 (CH), 134.85 (Cquat), 134.80 (H-C=CH2), 133.05 (CH), 128.62 (CH), 126.99 (CH), 124.41 (Cquat), 120.00 (Cquat), 117.93 (H-C= CH2), 66.98 (OCH2 ), 21.24 (C6-CH3); HRMS m/z [M] +. : 227.0946 cald for C14H13NO2, found 227.0955.

  C NMR (CDCl3): 158.89 (Cquat, C2), 145.48 (Cquat), 133.93 (CH), 133.31 (H-C=CH2), 129.20 (CH), 127.49(CH), 126,83 (CH), 125.34 (Cquat), 124.31 (CH), 117.69 (HC=CH2), 66.71 (OCH2). 66.07 (HC(CH3) OH), 22.60 (HC(CH3); MS: (M .+ ): 229.110 cald for C14H15NO2, found 229.1092. -Preparation of 1-(2-allyloxy-6-méthyl-quinolin-3-yl)-ethanol (5-b) Yellow Crystals; yield = 85 %; mp = 76 °C; IR n cm -1 (KBr) : 3278 (OH); 3010 (CH); 1621 (C=C); 1 H NMR (CDCl3): 7.94 (s,1H, H-C4), 7.72(d, 1H, J = 8.5 Hz, H-C8), 7.49-7.50(m, 1H, H-C5), 7

Fig. 2 .

 2 Fig.2. The optimized structure, HOMO and LUMO of compounds (5a-c) obtained from density functional theory

Fig. 3 .

 3 Fig.3. The MEP surfaces of compounds (5a-c).

Fig. 5 .

 5 Fig. 5. (a) 3D and (b) 2D molecular docking results of the compound (5a) + 6LU7.

Fig. 6 .

 6 Fig. 6. (a) 3D and (b) 2D molecular docking results of the compound (5b) + 6LU7.

Fig. 7 .

 7 Fig. 7. (a) 3D and (b) 2D molecular docking results of the compound (5c) + 6LU7.

Fig. 8 .

 8 Fig.8. (A) Bioavailability radar and (B) the BOILED-Egg model of synthesized molecules (5a-c).

  C NMR (CDCl3): 148.42 (C), 146.07(Cquat), 137.28 (Cquat), 136.60 (CH), 133.13 (CH), 129.12 (Cquat), 127.88 (CH), 126.90 (CH), 126.79 (Cquat), 100.51 (CH (OCH3)2), 53.88 (CH (OCH3)2), 21.59 (C6-CH3); HRMS m/z [M] +. 251.1717 cald for C13H14NO2Cl, found 251.0713.

  C NMR (CDCl3): 189.05 (CHO), 163,60 (Cquat), 161.35 (Cquat), 151.31 (Cquat), 139.34 (CH), 132.99 (H-C=CH2), 130.94 (CH), 119.35 (Cquat), 117.93 (H-C=CH2), 117.89 (CH), 117.70 (Cquat), 106.27 (CH), 67.00 (OCH2 ), 55.68(C7,OCH3); HRMS m/z [M] +. : 243.0895 cald for C14H13NO3, found 243.08954.

  C NMR (CDCl3): 160.79 (Cquat), 159.44 (Cquat), 147.00 (Cquat), 133.82 (H-C=CH2), 133.33 (CH), 128.50 (CH), 126.38 (Cquat), 120.02 (Cquat), 117.63 (H-C=CH2), 116.48 (CH), 106.13 (CH), 66.65 (OCH2), 66.00 (HC(CH3)OH), 55.47 (C7-OCH3), 22.59 (HC(CH3)OH); HRMS m/z [M] +. : 259.1208 cald for C15H17NO3, found 259.1203.

	Scheme. 1. Synthesis of compounds (5a

Table 1 .

 1 Calculated E HOMO, ELUMO, energy band gap (ΔE), electronegativity (ω), chemical potential (µ), global hardness (η), global softness (S), (in eV) using B3LYP/6-311+G (d, p).

	Molécules Total Energy	HOMO	LUMO	ΔE	μ		S		ƞ
	5a	-747,790	-6.36	-2.55	3.81	-4.45	4.45 0.26 5.19 1.90
	5b	-787.115	-5.16	-2.51	2.65	-3.83	3.83 0.37 5.53 1.32
	5c	-862,335	-6.14	-2.54	3.60	-4.34	4.34 0.27 5.23 1.80

Table 2 .

 2 Antimicrobial screening data of compounds (5a-c).

	Compounds	Compound 5a	Compound 5b	Compound 5c	AMP	GEN
	Concentration 500 μg/ml	250 μg/ml	500 μg/ml	250 μg/ml	500 μg/ml	250 μg/ml	10 μg/disc	10 μg/disc
	E.coli	10,333±0,577 7,000±2,000	9,333±1,528	6,667±1,155 14,667±0,577 12,000±1,000 28	32
	S.aureus	14,333±1,527 11,333±2,081 10,667±0,577 8,667±1,155 13,667±1,527 10,333±1,527 14	15
	P.aurengenosa 10,667±1,527 10,333±1,527 11,667±1,527 9,000±2,000 15,100±2,000 12,000±1,000

Table 4 .

 4 Calculated in silico ADME parameters of the synthesized quinoline derivatives (

5a-c).

  Number of hydrogen bond acceptor. d Number of hydrogen bond donor.

	Compounds	MW a (≤500)	TPSA b (A˚2)	HBA c (≤10)	HBD d (≤5)	RB e (≤5)	cLogP f (≤5)	Bioavailability Score	Lipinski's Violation
	5a	229.27	42.35	3	1	4	2.62	0.55	0
	5c	243.30	42.35	3	1	4	2.97	0.55	0
	5d	259.30	51.58	4	1	5	2.64	0.55	0
	a Molecular weight.

b Topological polar surface area. c e Number of rotatable bonds. f Consensus of calculated lipophilicity.

Acknoledgments

The synthesis part of this work was carried out at the Laboratory of Chemistry and Chemistry of the Environment (L.C.C.E), Department of Chemistry, Faculty of Materials Sciences, University of Batna-1, Batna. The authors would like to thank all the members of the laboratory (L.C.C.E) for the help provided, either products or materials. And we also thank the Algerian MESRS (Ministère de l'Enseignement Supérieur et de la Recherche Scientifique). And all the people who helped to carry out this work such as biological activities and theoretical studies.

Authors' statement

Lynda Golea : Synthesis, Spectroscopic characterizations, Molecular docking, DFT calculations, Methodology, Visualization, Writing-original draft. Rachid Chebaki : Molecular docking, Visualization, Software. Mohammed Laabassi : Spectroscopic characterizations, Methodology, Investigation. Paul Mosset : Spectroscopic measurements.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.