Xuan Minh Nguyen

Ai

Sok-Siya Bun
email: sok-siya.bun@univ-amu.fr

Evelyne Ollivier
email: evelyne.ollivier@univ-amu.fr

Dang Thi

Phuong Thao

Thi Dang

Phuong

ETHNOBOTANICAL STUDY OF MEDICINAL PLANTS USED BY K'HO-CIL PEOPLE FOR TREATMENT OF DIARRHEA IN LAM DONG PROVINCE, VIETNAM

Keywords: Ethnobotany, medicinal plants, diarrhea, fidelity level, knowledge transmission, K'Ho people

Background: Many medicinal plants have been used in Vietnam but most of them have not been studied and documented. In this study, the traditional plants used by K'Ho-Cil people living in BiDoup-Nui Ba National Park, Vietnam for treatment of diarrhea and identified potential medicinal plants were documented.

Methods: Information of the medicinal plants used was collected through field surveys and semi-structured interviews with key informants. Plants used for anti-diarrhea were selected for further analysis in structured questionnaires. The potential medicinal plants were identified through quantitative tools: fidelity level (FL) and choice value (CV). The relationship between traditional knowledge and gender, age and geological site was also evaluated using statistical analysis.

Results:

Of the 133 taxa reported by 12 key informants, 34 anti-diarrheal plants were confirmed by 127 non-specialist informants. Interestingly, these plants were also used for 35 other health problems. Among the medicinal plants, Asteraceae was the most predominant family. Elephantopus mollis and Chromolaena odorata belonging to this family with the highest CV were the most preferred ones in diarrheal treatment (1.23 and 1.04, respectively). Moreover, in regard to FL and literature review, several potential plants for further studies were identified, for example Hedyotis capitellata var pubescens and Syzygium ripicola (FL = 100%), or Clitoria mariana and Dacrycarpus imbricatus (FL = 80%).

3 Conclusion: In Vietnam, folk medicine has been widely used by many people without documentation for preservation and scientific study. This study contributes a database of anti-diarrhea plants used by K'Ho-Cil people living in BiDoup-Nui Ba National Park, Vietnam.

Introduction

The widespread use of common folk medicine is an important widely used in most countries around the world. In some Asian and African countries, about 80% of the population relies predominantly on plants and plant preparation for primary health care [START_REF] Who | Diarrhoeal disease[END_REF]. In Vietnam and China traditional plant-based medicines are being integrated into the national mainstream healthcare system [START_REF] Royal | State of the world's plants[END_REF][START_REF] Ngo | Đại cương về dược liệu (Overview of pharmacognosy)[END_REF]. Recently, the trend of using herbal medicines alongside pharmaceutical drugs has become popular in some Western countries [START_REF] Royal | State of the world's plants[END_REF]. In addition, medicinal plants also offer significant economic benefits. Sales of plant-based drugs in the United States amounted to 15.5 billion dollars. The precise value of global markets for products derived from plants is difficult to estimate, but it is clear that the industry is growing rapidly by over 4% per annum [START_REF] Royal | State of the world's plants[END_REF][START_REF] Saroya | Herbalism, phytochemistry and ethnopharmacology[END_REF].

Vietnam is the easternmost country on the Indochina Peninsula in Southeast Asia with its own long traditional medicine history. For several thousand years, Vietnamese Traditional Medicine (VTM) has evolved under the shadows of Chinese Traditional Medicine, culture, and rule but medical texts and instruments found in Northern Vietnam suggested that Vietnamese people already had a developed system of medicine. In addition, among Chinese medical texts from the 4th century B.C., references were given to the "Yue Prescriptions", indicating that "Thuoc Nam" (Southern Medicine or Vietnamese Traditional Medicine) was an established discipline, discriminated from "Thuoc Bac" (Northern Medicine or Traditional Chinese Medicine). However, traditional Vietnamese and Chinese Medicine continued to evolve closely for the next millennium as a consequence of Chinese's conquest [START_REF] Thai | Traditional Vietnamese medicine: Historical perspective and current usage. Ethnomed[END_REF]. It can be said that VTM has developed from its early beginnings and gradually developed into an essential part of the present-day Vietnamese medical system like Oriental traditional medicine, VTM was built based on the philosophy of ancient dialectical materialism presented in works such as I Ching, Confucius and Laotzu and discriminated from the logical foundation of modern medicine [START_REF] Woerdenbag | Vietnamese traditional medicine from a pharmacist's perspective[END_REF]. In recent years, traditional medicine particularly from medicinal plants, has drawn much attention from Vietnamese government, institutes and researchers, demonstrated through the increased number of publications over time. However, it is regretted that most of them are written in Vietnamese or just presented within national conferences. Moreover, previous and present studies mainly focus on chemical properties and pharmacological activities while medicinal plants and indigenous knowledge still have other interesting issues that are not thoroughly studied [START_REF] Nguyen | Thực vật dân tộc học: Cây thuốc của đồng bào dân tộc Thái Con Cuông, Nghệ An (Ethnobotany: Medicinal plants of Thai Con Cuong people, Nghe An Province)[END_REF]. According to the nonexhaustive survey of the Institute of Medicine (Ministry of Health), at the end of 2005, there were 3,948 species of plants and mushrooms used as medicinal drugs in Vietnam. In regard to their origin and distribution, over 85% of these species are found in forest habitats and mostly used as folk medicine (Project Support specialized non-timber forest products in Vietnam -stage II, 2007) [START_REF] Luu | Cây cỏ được sử dụng làm thuốc trong cộng đồng ở Khu bảo tồn thiên nhiên Takóu (Medicinal plants are used by local communites in Takou Nature Reserve)[END_REF]. Only about 20-30% of total species have been assessed for their therapeutic activity and mechanism of action, which implies that many species may have not yet been discovered.

It is estimated that nearly 25% of modern medicines are derived from nature, many of which were derived from traditional uses [START_REF] De Luca | Mining the biodiversity of plants: A revolution in the making[END_REF] and the recent document of Kew Royal Botanic Garden reported at least 28.187 plant species are currently recorded as being of medicinal use [START_REF] Royal | State of the world's plants[END_REF]. However, traditional medicinal plants and indigenous knowledge now fade because most of home remedies are mainly verbally transmitted from generation to generation. In addition to the changes in the economy, culture and society such as the neglect of the younger generation to inherit this precious knowledge from their family, the overexploitation of the environment seriously threatens medicinal plant resources [START_REF] Kim | Ethnobotany[END_REF][START_REF] Simbo | An ethnobotanical survey of medicinal plants in Babungo, Northwest Region, Cameroon[END_REF]. These reasons above motivated us to carry out a comprehensive ethnobotanical study of medicinal plants used by K'Ho-Cil people, one of ethnic minorities in Vietnam. The local people reside in the area of BiDoup-Nui Ba National Park, Lam Dong Province for a long time and have a close relationship with the forests but their traditional medicinal plants have been poorly studied. Only some studies have been conducted on biodiversity or non-timber products. In ethnobotanical studies, apart from documents which extensively report knowledge of plants held by native groups, there are also some works designed to quantify the local knowledge using popular indices of relative or cultural importance. It has become increasingly common among ethnobotanists to apply rigorous scientific methodologies in analyzing diversified ethnobotanical data over the last fifty years. According to [START_REF] Phillips | The useful plants of Tambopata, Peru: II. Additional hypothesis testing in quantitative ethnobotany[END_REF], the quantitative approaches for analyzing informant knowledge can be grouped into three categories: informant consensus, subjective allocation and total uses [START_REF] Phillips | The useful plants of Tambopata, Peru: II. Additional hypothesis testing in quantitative ethnobotany[END_REF]. In the two latter approaches, the relative importance of each plant used is subjectively assigned by the researcher whereas it is obtained directly from the informant's responses in the informant consensus method. One of its applications is the classification of potential medicinal plants according to their rank-order priority or fidelity level before performing experimental evaluations [START_REF] Friedman | A preliminary classification of the healing potential of medicinal plants, based on a rational analysis of an ethnopharmacological field survey among Bedouins in the Negev Desert, Israrel[END_REF]. Therefore, the aim of the present study is to document systematically plants used by local people for treatment of diarrhea. In addition, potential healing plants are also identified based on fidelity level, a quantitative tool in order to provide further information for phytochemical and pharmacological studies in future.

Material and Methods

Study area

BiDoup-Nui Ba National Park (BNNP) (12°00' to 12°52'N, 108°17' to 108°42'E), one of four centers of biodiversity in Vietnam, which is entirely located within Lac Duong District and a small portion of Dam Rong District, Lam Dong Province, Central Highland of Vietnam (Figure 1), covers an area of about 70,038 hectares.

Although BNNP is situated in the tropical monsoon region, the high elevation contributes to its cool climate, leading to its rich diversity of vegetation. The annual average temperature is about 18 0 C with high humidity (over 80%) and the average rainfall is about 1,800 mm. However, in areas with elevation above 1,900 m such as Bidoup, Hòn Giao,and Gia Rích, the rainfall can reach 2,800-3,000 mm per year [START_REF] Nguyen | Đa dạng sinh học và đặc trưng sinh thái VQG Bidoup-Núi Bà (Biodiversity and ecological characteristic in BiDoup-Nui Ba National Park). NXB. Khoa học tự nhiên và Công nghệ[END_REF].

K'Ho is one of fifty-four ethnic minorities in Vietnam, using the Môn-Khmer language. They embrace five minor groups: Sre, Lạch, Mạ, Cil and M'Nông who reside in different parts of Southern Central Highland area and Lam Đong Province, Vietnam. According to national demographics in 2004, the K'Ho's population was approximately 14,585,000 and they mainly settled in Lam Dong Province [START_REF] Niê K'dam | Văn hóa dân gian truyền thống của tộc người K'Ho (Traditional culture of K'Ho people)[END_REF] . K'Ho-Cil community follows matriarchy system in which descent and relationship pass through the female line. They have a nomadic farming lifestyle but at present the local people develop settled agriculture. Their major income is derived from the sales of coffee (one crop per year). Moreover, farming, hunting and gathering non-timber forest products like firewood, mushrooms, bamboo shoots and orchid flowers and handicrafts also supplement the household income, especially in the period after harvest time.

Nowadays, owing to the government's investment in infrastructure (roads, hospitals, schools, …), the living condition of K'Ho-Cil people has been much improved. However, they still retain their close connection with natural resources, especially medicinal plants for daily health care. 6

Collecting ethnobotanical information

Three villages of K'Ho-Cil people, namely K'Long K'Lanh (K), Đưng K'Si (DS) and Đưng K'Nớ (DN), were the subjects of an ethnobotanical study from 2013-2015. In order to have an overview of traditional medicine from local people, K and DN villages were chosen because they were located not only near the forests (core zone) but also on two different sides of BNNP with different vegetation covers.

In addition, DS village, adjacent to K village, was also chosen for an ethnobotanical hypothesis test (Figure 1).

Prior to the survey, preliminary meetings with local authorities, leaders and representatives of villages were organized with the assistance of BNNP's officials in order to explain the aims of the study and to obtain their verbal agreements in documenting the traditional knowledge of medicinal plants.

The collection of information was carried out in two progressive stages:  First stage (May 2013 -March 2014): A total of 12 key informants knowledgeable in using medicinal plants were contacted according to advice from local authorities and habitants as well as BNNP's officials. Researchers accompanied key informants on field trips to collect all medicinal plants that they encountered along the routes. The information of 133 traditional plants obtained through semi-structured interviews was recorded following Martin's method (1995) [START_REF] Martin | Ethnobotany: A methods manual[END_REF].

From which, 37 plants mainly used for the treatment of diarrhea, one of the most prevalent health problems in the study area, were compiled into an illustrated book with the photos of each plant in its natural habitat in order to facilitate an extensive interview later.

 Second stage (July-August 2015): About 10% of total households in each village were randomly chosen for the extensive ethnobotanical study. A total of 127 non-specialist informants participating in structured interviews were independently asked about the 37 plants present in the illustrated book which was prepared during the first stage. They were interviewed using the same set of questions (questionnaire), such as do you know this plant? If so, have you ever used it for any medicinal purposes and which plant parts do you use in the treatment of health problems? and others.… (Appendix A). For each household, the interviews were conducted in the presence of the head of the family, usually the husband and/or wife and their children over the age of 12. Most of the informants were familiar with the Vietnamese official language (Kinh) so that they were able to understand and reply in Kinh. But whenever necessary, translation was done by the head of the village or key informants accompanying the researchers.

Botanical identification

All plants mentioned by key informants were collected two-fold, coded, and dry-pressed in the field.

One set of voucher specimens was deposited at the Herbarium of University of Science, Vietnam National University, Ho Chi Minh City (HCMUS) and the second one was preserved at BNNP. The taxonomic identification was carried out by PhD. student, a botanist, Nguyen Xuan Minh Ai with the help of standard literatures [START_REF] Lecomte | Flore générale de L'Indo-Chine[END_REF][START_REF] Pham | Cây cỏ Việt Nam (An illustrated flora of Vietnam)[END_REF]. The nomenclature of identified plants followed The Plant List (The Plant List, 2013) while the taxonomy system referred to Tropicos (Tropicos, 2017).

Data analysis

Fidelity level (FL)

The FL was firstly introduced by [START_REF] Friedman | A preliminary classification of the healing potential of medicinal plants, based on a rational analysis of an ethnopharmacological field survey among Bedouins in the Negev Desert, Israrel[END_REF] to quantify the importance of a species for a given purpose [START_REF] Friedman | A preliminary classification of the healing potential of medicinal plants, based on a rational analysis of an ethnopharmacological field survey among Bedouins in the Negev Desert, Israrel[END_REF].

The fidelity level of each plant was determined as follows:

FL = I p I u x 100
in which: I p is the number of informants who suggested the use of the species for the same major purpose, here being anti-diarrhea/dysentery. I u is the total number of informants who mentioned the plant for any medicinal use.

It is assumed that medicinal plants which are more frequently cited by respondents for the same category are more likely to be biologically active plants [START_REF] Giday | Medicinal plants of the Meinit ethnic group of Ethiopia: An ethnobotanical study[END_REF][START_REF] Tariq | Ethnomedicinal evaluation of medicinal plants used against gastrointestinal complaints[END_REF].

2.4.2 Choice value (CV) [START_REF] Kremen | An interdisciplinary tool for monitoring conservation impacts in Madagascar[END_REF] suggested the choice value (CV) to determine the most preferred species in each use category [START_REF] Kremen | An interdisciplinary tool for monitoring conservation impacts in Madagascar[END_REF]. In the present study CV was used to measure relative preference for treatment of diarrhea.

CV = P cs S c in which: P cs is percent of informants who cited certain species for diarrheal treatment S c is total number of species mentioned for treatment of diarrhea by all informants CV ranges from 0 to 100, in which a species with higher value reflected greater preference and/or few alternatives.

Status of plants

The status of each medicinal plant according to the Vietnam Red Data Book (flora section) (2007)

Results and discussion

Demographic characteristics of local informants

The social demography of 127 non-specialist informants participating in the ethnobotanical interviews is detailed in Table 1. There were 47 people from K; 41 from DS and 39 from DN with an age range of 12 to 70 years (mean = 34.9  2.2); 12 to 63 (mean = 33.6  1.7) and 12 to 84 (mean = 45.9  2.8), respectively (Figure 2). The average age of males and females was 39.3  2.1 and 36.6  1.8, respectively. There was no significant difference (independent-samples t-test, p = 0.35) in informants' ages between genders (Figure 2).

Most local people mainly depended on agricultural practices as a means of income (94.5%) but with old fashioned cultivation techniques. Some families also raised cattle with funding from local authorities.

It was also noted that no one was a traditional practitioner or an herbalist, even the 12 key informants.

Overview of K'Ho pharmacopoeia

From the field surveys with the 12 key informants, 133 taxa used for all medicinal purposes were recorded. Of which, 37 species were mainly used for diarrhea, one of the most prelevant ailments in the study area and were, therefore, selected for an extensive ethnobotanical survey with 127 non-specialist informants. The criterion for consensus was that medicinal plants cited by less than three individual reports would be excluded from any further discussion [START_REF] Johns | Herbal remedies of the Luo of Siaya District, Kenya: Establishing quantitative criteria for consensus[END_REF]. As a result, there were 34 plants mentioned by at least three local people not only for the treatment of diarrhea but also for a variety of health problems (35 disorders) (Table 2). This result showed the effectiveness of using extensive interviews with non-specialist informants for cross-checking and adding further information which had previously been gathered from key informants (Grosvenor et al., 1995a).

The majority of the 34 K'Ho medicinal plants were used individually (73.5% of total plants), known as single-ingredient remedies. Only 9 species (33 citations, 3.6% of total reported) were prescribed in combination with others for treatments, but the combination was quite simple using 2-3 plants only or the medicinal plants were used with other elements (salt, honey, eggs). For example, Mimosa pudica was combined with Zingiber officinale and Cymbopogon spp. to treat malaria, while Paederia microcephala was mixed with fresh eggs and the mixture was either used directly or cooked for the treatment of diarrhea. The popularity of simple herbal recipes of K'Ho people was obviously different from the practice which was found with Bunong people (Cambodia) who utilized up to 68% of the total of plants collected in multi-ingredient remedies [START_REF] Chassagne | Natural remedies used by Bunong people in Mondulkiri province (Northeast Cambodia) with special reference to the treatment of 11 most common ailments[END_REF]. [START_REF] Teklehaymanot | Ethnobotanical study of medicinal plants used by people in Zegie Peninsula, Northwestern Ethiopia[END_REF] reported that healers tend to use multiple prescriptions more than non-healers [START_REF] Teklehaymanot | Ethnobotanical study of medicinal plants used by people in Zegie Peninsula, Northwestern Ethiopia[END_REF]. This was also found to be true in the present study where the use of the combination of medicinal plants was usually reported by key informants who were knowledgeable about the plants.

Diversity of medicinal plants

Regarding the distribution of medicinal plants in the taxonomy system, 34 taxa belonged to 20 genera, 21 families, 16 orders, 2 subclasses. Of these, Asteraceae was the most predominant family with 7 species cited (20.5% of the total plants), followed by Fabaceae (4 species, 11.8%). The remaining 19 families contained one to two species (Figure 3A). The fact that Asteraceae was one of the most common medicinal families was also reported in previous studies [START_REF] Aati | Traditional use of ethnomedicinal native plants in the Kingdom of Saudi Arabia[END_REF][START_REF] Bahmani | Ethnobotanic study of medicinal plants in Urmia city: Identification and traditional using of antiparasites plants[END_REF][START_REF] Luziatelli | Asháninka medicinal plants: A case study from the native community of Bajo Quimiriki, Junín, Peru[END_REF]. This is probably due to its widespread growth and large number of species.

Growth forms and habitats

Of the 34 medicinal plants, herbs and trees were dominant with 11 species for each group (32.4%), followed by vines/ lianas/ climbers with 6 species (17.6%) while shrubs, geophytes and hydrophytes contributed only 2 taxa of the medicinal flora (5.9% each) (Figure 3B). The common growth form of the first two groups was also found in a study by Luziatelli et al [START_REF] Luziatelli | Asháninka medicinal plants: A case study from the native community of Bajo Quimiriki, Junín, Peru[END_REF][START_REF] Umair | Ethnomedicinal uses of the local flora in Chenab riverine area, Punjab province Pakistan[END_REF].

Up to 85.5% of medicinal plants were wild and were found around the residential area, in the forest or along the riverbank. Only 3 species (8.3%) were cultivated in home gardens/ farm plots and 2 species (5.9%) were found in both wild and private areas (Figure 3C). There is no special protection or care given to wild plants. The fact that medicinal plants derived from the natural environment occupied a high proportion of K'Ho pharmacopoeia suggested that they still played an important role in health care among indigenous people.

Plant parts used

Regarding the plant parts used in the treatment of diarrhea and of other health problems, leaves were the main part used in both groups, making up 45.5% and 51.5% of the total citations, respectively. The second choice were roots/ tuberous roots making up 28.2% (diarrhea) and 21.3% (other medicinal uses).

The remaining plant parts, such as sprouts, bark, stems/ rhizomes or the whole plant, were also utilized but they occupied a relatively small proportion of plant choice. While sprouts and bark were preferred for the treatment of diarrhea, they seemed to be used less for other ailments. In addition, flowers and latex were only seen in several remedies for certain diseases, but not diarrhea (Figure 4B).

In previous studies, leaves were also prefered in traditional recipes [START_REF] Kidane | Ethnobotanical study of medicinal plants in Ganta Afeshum District, Eastern Zone of Tigray, Northern Ethiopia[END_REF][START_REF] Umair | Ethnomedicinal uses of the local flora in Chenab riverine area, Punjab province Pakistan[END_REF]. [START_REF] Bhattarai | Ethnomedicinal plants used by the people of Manang district, central Nepal[END_REF] suggested that leaves and roots were selected more than other parts because they were physically more vulnerable than fruits, seeds or stem bark, so they would potentially produce more chemically defensive compounds [START_REF] Bhattarai | Ethnomedicinal plants used by the people of Manang district, central Nepal[END_REF].

Mode of preparation and administration

The K'Ho people preferred fresh material for preparing home remedies rather than dried (96.2% versus 3.8% of total reported) (Figure 4A). It could be due to the urgency of certain health issues. The thirty-four plants mentioned here were mainly used for diarrhea/ dysentery, followed by external injuries such as wounds or boils. These acute ailments need to be treated immediately with a minimum of preparation. Often in emergencies, the material was first used fresh (starting dose) and thereafter more carefully prepared (e.g. infusion, decoction) with fresh or dried material to continue the treatment more efficiently (maintenance dose). This result was higher than that of Bussmann'study (2010), in which the authors reported more than 60% of medicinal plants were prepared from fresh material for reproductive problems and female health in Northern Peru [START_REF] Bussmann | Medicinal plants used in Northern Peru for reproductive problems and female health[END_REF].

The mode of preparation of herbal drugs was illustrated in Figure 4D. Although leaves were the most preferred plant parts used for both groups, diarrhea only and other ailments, each group also had their own preferred method of preparation, in which decoction was the first choice for diarrhea (57,7% of total citations), followed by "without preparation" where the plants were eaten directly or chewed in one's mouth (27.6%). For the "other ailments" group, simple methods of preparation were firstly chosen, including rub (29.9%) and crush (18.1%) in which the plant parts were impacted by hands or pestles. The decoction was in second place in that group (23.9%).

Regarding the route of administration, oral route was more largely predominant than topical one (98.0% versus 2.0% of total citations) for diarrheal treatments. In the "other ailments" group, herbal drugs were prescribed in more diverse ways. Among them, topical application was the most preferred method (56.7%), followed by oral (34.1%), bath/ steam bath (8.1%) and inhalation (1.0%). The popularity of a certain administration partially depends on the type of ailment, i.e. internal administration was normally used to treat internal conditions and vice versa, which is also true in the present study. However, there were some special instances which did not follow the general trend. For example, to treat diarrhea, besides the decoction taken orally, leaves of Melicope pteleifolia were also rubbed and applied on the abdomen or the whole plant of Polygala paniculata was used in steam baths for people who had high temperature. It was interesting that both medicinal species contained essential oils which can partially be attributed to pain relief and cooling effects [START_REF] Pizzolatti | Analysis of volatile compounds released from flowers and roots of Polygala cyparissias and Polygala paniculata by Headspace/SPME[END_REF][START_REF] Thang | Composition of essential oils from ????[END_REF]. In such cases, external application should be effective for internal diseases [START_REF] Chassagne | Natural remedies used by Bunong people in Mondulkiri province (Northeast Cambodia) with special reference to the treatment of 11 most common ailments[END_REF]Grosvenor et al., 1995a).

In the study area, the recommended dosage varied among informants for treating the same health problems. Hence, the measurements used to determine the dosages were not standardized and depended on the age and physical appearance of each individual. Usually they estimated through various ways, including fist size, bowls with a diameter of about 12-15 cm or small glasses with a volume of around 80 mL (similar to a shot glass). In general, children are usually given less than adults. For example, they are given one fourth of a coffee cup (2-5 ml) whereas adults take one glass (approximately 250 ml). As a result, traditional medicinal knowledge is often considered as having a lack of precision and standardization.

Traditional knowledge and geographical, social factors

Verma (2010) suggested that health status of different communities, particularly the tribal groups was influenced by their way of life including their social and economic conditions, age, socio-religious beliefs and superstitions, etc. [START_REF] Verma | Traditional medicine of the Nicobarese[END_REF]. Therefore, a hypothesis is set whether there is a relationship between the knowledge of medicinal plants which is represented by the number of medicinal plants reported by informants and social factors, including gender, age and geographical features.

In terms of informant's gender, no difference in the number of medicinal plants reported was found between men and women (independent-samples t-test, p > 0.05). Although K'Ho society follows a matriarchy system in which descent and relationship are reckoned through the female line, even so the role of men in families is now becoming more recognized. They can now also learn and share knowledge of traditional medicine with other members, which had previously occurred only among females. This is contrary to Hoang's results (2008), who studied traditional medicinal plants in Bến En National Park (Vietnam), where women were reported to be mainly responsible for health care and collecting herbal medicines and also had a better knowledge of traditions than men at almost every age level [START_REF] Hoang | Traditional medicinal plants in Ben En National Park, Vietnam[END_REF].

There seems to be a positive correlation between knowledge of medicinal plants and age of informants (r = 0.254, p < 0.05). However, the ANOVA (Analysis of Variance) test showed no significant difference in the number of cited plants among age groups. This might be because plant knowledge was also influenced by other factors.

It was expected that people living in areas further away from town center (DN village) more frequently resorted to medicinal plants for daily health care needs than those living close to town center (K and DS villages). However, the number of plants reported by people living in K village was equal to those of DN village (7 plants) whereas the number of plants used in DS was the least (4 plants) (one-way ANOVA test, p = 0.005). This again showed that plant knowledge was simultaneously influenced by many variables.

In regard to ethnic group, most informants were K'Ho (96.8%). Included among the "other groups"

(3.2%) were Kinh (2 people), ChuRu (1) and Mường (1) (Table 1), who came from other areas and settled there after marrying K'Ho women. It became clear that the number of medicinal plants they used was significantly less than those who were born in the village.

Fidelity level (FL) -Proposed potential healing plants

The World Health Organization (2013) reported that diarrhea is the second leading cause of death in children under five years old and is responsible for killing around 760,000 children every year. Globally, there are nearly 1.7 billion cases of diarrheal disease every year [START_REF] Who | Diarrhoeal disease[END_REF]. Although the disease is usually not severe and patients can recover eventually by themselves, some acute cases are considered as a leading cause of death, especially in developing countries. In fact, diarrhea is not itself a disease, but can be a symptom of several ones and it's the most common clinical sign of gastrointestinal problems [START_REF] Sarin | Herbal Antidiarrhoeals: A review[END_REF]. The causes can be bacterial, viral or parasite organisms which infect the intestine and easily spread through contaminated food, drinking water or from person-to-person as a result of poor hygiene.

According to our records, the studied people mostly use water from rivers and springs for daily activities like cooking or washing. Nevertheless, natural water sources are not always safe to use, especially when local people spray herbicides for their rice or corn crops, which are normally established near water resources for convenience. Only a few well-to-do families were able to contribute money to dig a well. Therefore, a quantitative ethnobotanical tool, fidelity level was used to quantify the relative importance of a species for anti-diarrhea activity.

Out of 34 species, there were 11 plants (32.3%) which scored FL values over 50% (Table 2, Additional file 2). It could be suggested that these plants had potential for further investigation, such as phytochemistry or bioactivity tests. In addition, the present study also followed another method suggested by Frieman (1986) to identify popular plants which were cited more frequently than others. Based on the number of informants reporting on a certain plant for any medicinal purpose and the number of different uses of that plant, Friedman established a co-ordinate system to classify plant popularity as popular and unpopular groups [START_REF] Friedman | A preliminary classification of the healing potential of medicinal plants, based on a rational analysis of an ethnopharmacological field survey among Bedouins in the Negev Desert, Israrel[END_REF]. As can be seen in Figure 5, there seems to be a positive correlation between the number of informants reporting the plant and the number of plant's uses. It was true for the plants belonging to the unpopular group. However, for popular plants, for example the plants numbered 9, 30 and 34, even if the number of informants citing any sort of plant use notably increased, the number of uses per plant remained consistent, indicated by the horizontal line. This implied that all the information concerning the plant was already fully reported. The intersection created by the linear line with the horizontal line marks the zone between popular and unpopular plants (Figure 5). It could be assumed that six plants belonging to the "popular" group were also potential for a certain activity due to their popularity in K'Ho traditional medicine.

In attempting to corroborate the anti-diarrheal effectivity in plants scoring high FL value (over 50%) (Table 2), the authors extended i/ cross-cultural comparison and ii/ literature review on bioassay tests. The bibliography review was carried out based on the valid nomenclature of species and its synonyms. The results were represented in Table 3.

The anti-diarrheal activity of medicinal plants probably relates to their antibacterial, antiviral and/ or astringent effects. These properties are normally considered to be involved with the presence of high tannin content in plant parts [START_REF] Djipa | Antimicrobial activity of bark extracts of Syzygium jambos (L.) Alston (Myrtaceae)[END_REF][START_REF] Jaradat | Ethnopharmacological survey about medicinal plants utilized by herbalists and traditional practitioner healers for treatments of diarrhea in the West Bank/Palestine[END_REF][START_REF] Mukherjee | Screening of antidiarrheal profile of some plant extracts of a specific region of West Bengal[END_REF][START_REF] Murugan | Antimicrobial activity of Syzygium jambos against selected human pathogens[END_REF]. Indeed, from the literature survey on the eleven highest-fidelity-level plants, similarities in traditional uses which had been reported by other ethnic minorities as well as scientific evidence validated the bioactivity of four plants, particularly for anti-diarrheal activity. For example, [START_REF] Shah | Antidiarrhoeal and spasmolytic activities of the methanolic crude extract of Alstonia scholaris L. are mediated through calcium channel blockade[END_REF] studied the anti-diarrheal and spasmolytic activities in vitro and in vivo of Alstonia scholaris whose methanol extract of the aerial part significantly inhibited the frequency of defecation in castor oil-induced diarrheal mice. The extract also showed an intestinal smooth muscle relaxant (spasmolytic) activity in isolated rabbit jejunum [START_REF] Shah | Antidiarrhoeal and spasmolytic activities of the methanolic crude extract of Alstonia scholaris L. are mediated through calcium channel blockade[END_REF]. Furthermore, the later study of [START_REF] Qin | Indole alkaloids with antibacterial activity from aqueous fraction of Alstonia scholaris[END_REF] confirmed the antibacterial activity of two new indole alkaloids Alstoniascholarine F and J against Pseudomonas aeruginosa which was considered as a cause of infectious diarrhea [START_REF] Qin | Indole alkaloids with antibacterial activity from aqueous fraction of Alstonia scholaris[END_REF]. Another highfidelity-level plant, Careya arborea was also verified for its traditional use as an anti-diarrheal plant through in vivo test [START_REF] Rahman | Antidiarrhoeal activity of the bark extract of Careya arborea Roxb[END_REF]. Consequently, the remaining plants deserve to be studied further in order to validate their traditional uses which have previously existed in local communities. [START_REF] Johns | Herbal remedies of the Luo of Siaya District, Kenya: Establishing quantitative criteria for consensus[END_REF] admitted that the first impression that they obtained from their ethnobotanical data was its inconsistency and high degree of randomness, in which nearly 50% of the remedies were reported only once [START_REF] Johns | Herbal remedies of the Luo of Siaya District, Kenya: Establishing quantitative criteria for consensus[END_REF]. Similar results were seen in Friedman's study (1986) [START_REF] Friedman | A preliminary classification of the healing potential of medicinal plants, based on a rational analysis of an ethnopharmacological field survey among Bedouins in the Negev Desert, Israrel[END_REF]. Although there were only three plants in the present study excluded from further discussion according to the criteria of consensus, most of the remaining ones had certain uses which were known by one or two local people (out of total of 127 informants). It pointed out that there is an urgent need to conduct more ethnobotanical studies before traditional knowledge completely disappears. At the same time, randomness in the ethnobotany data should not be equated with unreliability, which was demonstrated through the authors recent study on the species Medinilla septentrionalis reported for its medicinal uses for the first time [START_REF] Nhut | Anti-diarrheal evaluation of Medinilla septentrionalis[END_REF]. In fact, its relatively low FL and CV value (22.2 and 0.05, respectively) indicated that the plant was not widely known and used in the community. However, the results showed that the ethanol extract obtained from the aerial part of M. septentrionalis expressed strong antibacterial activity, particularly against diarrhea-related bacteria such as Salmonella spp., Shigella spp. Vibrio spp. and E. coli. In addition, the extract also effectively prevented enteropooling and reduced either time of charcoal transit in small intestine or defecation in castor oil-induced mice [START_REF] Nhut | Anti-diarrheal evaluation of Medinilla septentrionalis[END_REF].

The reasons why one species is known by few people is probably because its remedy is either a family secret remedy or gradually lost over time due to verbal transmittance handed down from generation to generation. Another probability suggested by [START_REF] Johns | Herbal remedies of the Luo of Siaya District, Kenya: Establishing quantitative criteria for consensus[END_REF] is that if the plant was considered ineffective by certain people than it could be replaced by other ones that were available in their environment [START_REF] Johns | Herbal remedies of the Luo of Siaya District, Kenya: Establishing quantitative criteria for consensus[END_REF].

Together with FL, CV was also calculated for each species (Table 3.

4). Elephantopus mollis and

Chromolaena odorata with the highest CV values (1.23 and 1.04, respectively) were the most preferred plants in treatment of diarrhea in this area. Both plants also displayed among the highest FL group (56.4 and 60.6, respectively). However, it was not always true that a species with high CV also exhibited high FL value. For example, although Streptocaulon juventas ranked as the third highest CV plant (0.42), its FL scored less than 50%. Indeed, this plant was also used for 8 other health problems along with diarrhea. As a result, the informant's consensus represented by FL value considerably decreased. Therefore, CV is also additional index for selecting potential plants for further phytochemical and pharmacological studies.

Pattern resort for health problems

Local people try employing different means when encountering health problems, especially for minor ailments such as colds, fever, coughing, diarrhea or wounds. Normally, they choose simple methods like using medicinal plants (home remedies) or western drugs which they can buy from general stores without prescriptions during the first stage of a treatment. If health condition does not improve, a more modern treatment can be adapted as an alternative and at that time, they would have to go to hospitals/ health facilities which are usually quite far away from where they live (about 60 km). Thus health-seeking behaviors were studied to learn about how medicinal plants are important in their lives.

Among the 124 respondents, 98 people took the choice of medicinal plants at least once during their treatment (79.0% of total reported) for the following reasons: availability, accessibility and more effectiveness. This implied that traditional herbs still play an important role in the daily health care in rural areas which usually lack modern medical services.

There was a difference in health-seeking behavior of the respondents living in the three different villages (Figure 6). Specifically, in the first stage of treatment, the selection of health care method was significantly different between K and the others (DS and DN) (Pearson Chi-square test, p < 0.05).

Generally, when encountering health problems, the people from K village tended to use medicinal plants primarily, which was greater than those living in DS and DN who preferred western medicine first (40.4%

versus 24.4% and 25.0%, respectively). If they did not feel better, alternatives would be sought out in the second stage.

In the second stage, although there was a slight decrease in the consumption of medicinal plants in K village (40.4% decreased to 34.1%), the choice of home remedies was still higher than that of DS (24.2%). It should be noted that there was a tendency of often switching from modern health facilities to home remedies among DN (increased from 25.0% to 59.4%). At the third stage, the choice of health treatment was equally shared between both medicinal plants and western medicine.

While the choice between medicinal plants and western medicine fluctuated during the stages of health care (increased in a certain stage and decreased in following stages), the choice of hospitals/ health facilities always decreased over time for all three villages. This might be because it was the most timeconsuming and expensive method for local people.

Transmission of traditional knowledge in the study area

Unlike other minorities in Vietnam, especially in the northern regions and elsewhere, K'Ho people in the three villages studied did not have their own traditional healers, herbalists or apothecaries who could earn a living by prescribing or collecting herbs [START_REF] Jaradat | Ethnopharmacological survey about medicinal plants utilized by herbalists and traditional practitioner healers for treatments of diarrhea in the West Bank/Palestine[END_REF][START_REF] Shale | Screening of medicinal plants used in Lesotho for antibacterial and anti-inflammatory activity[END_REF] Instead they sought the advice of knowledgeable people who were experienced in medicinal plants who often used these plants for solving their own health problems or for their families and neighbors. Knowledge of medicinal plants in this area is transmitted verbally from ancestors to descendants.

According to [START_REF] Eyssartier | Cultural transmission of traditional knowledge in two populations of North-western Patagonia[END_REF], cultural transmission is a process of social dissemination in which behavioral patterns, cosmological beliefs and a culture's technological knowledge were communicated and acquired [START_REF] Eyssartier | Cultural transmission of traditional knowledge in two populations of North-western Patagonia[END_REF]. There are two main types of transmission, one occurring between individuals of different generations but within the genealogy, called 'Vertical transmission', as is the case from parents to children. The other consists in the transmission between individuals from the same generation, irrespective of their relationship, called 'Horizontal or contagious transmission'.

In this study, vertical transmission is more common than the horizontal. About 70.6% of the informants said that they learned traditional knowledge through family experiences. The remaining (29.4%) achieved knowledge from their neighbors, spouses, siblings, or from books, communication or the media (Table 4). Similar results were also found in the previous study [START_REF] Jaradat | Ethnopharmacological survey about medicinal plants utilized by herbalists and traditional practitioner healers for treatments of diarrhea in the West Bank/Palestine[END_REF].

In the vertical transmission group, parents (25.0%) were mentioned as the most important transmitters who passed on the traditional knowledge to their family members, followed by grandparents (19.4%). The role of the father and mother in such cases seemed to be equal because most informants confirmed that both their father and mother had taught them how to use the plants. This correlated with the results mentioned above which showed that men and women had equal knowledge of medicinal plants. Although K'Ho society is matriarchal, nowadays the role of husbands/fathers in the family has increased. They have become the breadwinners as well as decision-makers in their family.

The transmission of traditional knowledge related to the uses of medicinal plants begins in the early life stages. Locals start studying when they were about 12 years old. People probably think that such an age is too young for a child to acquire medicinal plant knowledge, but it is the case that exists in the study area where the children have to help their parents to do chores and work in the fields after school.

Therefore, the transmission of medicinal skills might take place on these occasions. For example, parents

show their children certain medicinal plants that they accidentally encounter on the road on their way to the fields or the children can study how to use herbs when they themselves are being treated by their parents.

Currently, there are fewer opportunities, especially for children and teenagers, to spend time learning traditional knowledge from their parents and others who are proficient with medicinal plants due to the socio-cultural changes, such as the introduction of schooling in the family life and the neglect of younger generations or the availability of Western medicine. Another great concern is that the transfer of valuable knowledge from generation to generation mainly practiced by word of mouth, might be lost forever due to the lack of a proper written system. Indeed, while some medicinal plants were frequently cited, a lot of herbal species were used for medicinal purposes by only a quite limited number of people within the communities, such as Calamus palustris (4 reported), Engelhardtia serrata (5 reported). Although local people are aware of this vertical transmission, it is still declining quickly and they have no idea about how to resolve this inextricable problem. Therefore, it is crucial that the results of this project will provide them with feedback in various ways (documents and talks for example), as a thankful return for their participation in the study, and to allow the spread and sustainability of those skills and traditions in the community as well as in the whole population and eventually at an international level (publications, databases).

Conservation of medicinal plants: an important issue

All medicinal plants are checked for their presence in the Vietnam Red Data Book (Plant section) any plants cited in the endangered or vulnerable group does not mean that there is no cause for concern.

For example, although not mentioned as an endangered species, Dacrycarpus imbricatus has been decreasing in population according to IUCN and is even listed as a protected species in the Vietnam Red Data Book. Local people confirmed that it was hard to find big trees in the surrounding areas.

Additionally, most of the medicinal plants (85.5% of total) were collected from natural vegetation.

However, there is no special protection or care given to these plants. Therefore, medicinal plants might be too damaged to satisfy the demands of local people who do not much pay attention to conservation issues.

In fact, the interrelationship between society and nature is close and has only recently become widely acknowledged. Human health cannot be considered in isolation but depends highly on the quality of the environment in which people live [START_REF] De Albuquerque | Quantitative ethnobotany or quantification in ethnobotany? Ethnobot[END_REF]. Damage which can be included as biodiversity loss equals a reduction of the supplies of raw materials for industries, drug discovery as well as the decline of food production, water quality and the spread of human diseases. It is also quite clear that the practice of traditional medicine is not immune to the current environmental crisis facing our planet [START_REF] Alves | Biodiversity, traditional medicine and public health: where do they meet?[END_REF]. Degradation of forests affects the erosion of the sole health care option for the poor living in remote rural areas.

Conclusion

The present study recorded 34 traditional medicinal plants used by K'Ho-Cil people. These results help to preserve the plant lore and contribute basic data for phytochemical and pharmacological studies on potential medicinal plants as well as provide precious information for the Vietnamese pharmacopeia.

For example, the information on the number of medicinal plant species distributed in the families in the present study along with data on phytochemical active compounds obtainined from literature surveys could serve as a signpost for future drug development with the Asteraceae and Fabaceae families containing the most medicinal plants.

Among the medicinal plants cited, several species are widely used for the treatment of various health problems by not only local people but also other minorities elsewhere. For example, Ageratum conyzoides for wound healing, diarrhea or flu, common cold; Chromolaena odorata for wound healing and diarrhea and Eurycoma longifolia for diarrhea or malaria [START_REF] Agyare | An ethnopharmacological survey and in vitro confirmation of ethnopharmacological use of medicinal plants used for wound healing in Bosomtwi-Atwima-Kwanwoma area, Ghana[END_REF][START_REF] Ahmed | Relative importance of indigenous medicinal plants from Layyah District, Punjab Province, Pakistan[END_REF][START_REF] Chassagne | Natural remedies used by Bunong people in Mondulkiri province (Northeast Cambodia) with special reference to the treatment of 11 most common ailments[END_REF][START_REF] Inta | Analysis of traditional knowledge in medicinal plants used by Yuan in Thailand[END_REF][START_REF] Nguyen-Pouplin | Antimalarial and cytotoxic activities of ethnopharmacologically selected medicinal plants from South Vietnam[END_REF][START_REF] Ong | Malay ethno-medico botany in Machang, Kelantan, Malaysia[END_REF][START_REF] Sharma | Ethnomedicinal plants used to treat skin diseases by Tharu community of district Udham Singh Nagar, Uttarakhand, India[END_REF][START_REF] Silalahi | The local knowledge of medicinal plants trader and diversity of medicinal plants in the Kabanjahe traditional market, North Sumatra, Indonesia[END_REF][START_REF] Waruruai | An ethnobotanical survey of medicinal plants used in the Siwai and Buin districts of the Autonomous Region of Bougainville[END_REF]. In addition, it is worth noting that there are still some potential anti-diarrheal plants whose high FL values have been recorded for the first time, including Clitoria mariana, Paederia microcephala and Syzygium ripicola. For this reason, further studies on their phytochemistry and in vitro, in vivo tests are essential for the validation of ethnomedicinal plants.

Although medicinal plants still have an important role in the daily health care of local people, it seems that the dissemination of valuable traditional knowledge is not fully appreciated. Wild herbs are facing overexploitation, misuse or environmental degradation, which may lead to the extinction of more than 29

List of figures

The number in rectangle refers to the plant code in Table 2. The numbers in columns represent the number of people who gave the choice for that case. -Antibacterial activity (broad spectrum) [START_REF] Khan | Antibacterial activity of Alstonia scholaris and Leea tetramera[END_REF][START_REF] Liu | Antibacterial monoterpenoid indole alkaloids from Alstonia scholaris cultivated in temperate zone[END_REF][START_REF] Qin | Indole alkaloids with antibacterial activity from aqueous fraction of Alstonia scholaris[END_REF] -Anti-diarrheal activity [START_REF] Shah | Antidiarrhoeal and spasmolytic activities of the methanolic crude extract of Alstonia scholaris L. are mediated through calcium channel blockade[END_REF] Careya arborea 100.0 Diarrhea/ Dysentery -Astringent and tonic [START_REF] Mandal | A triterpenoid saponin possessing antileishmanial activity from the leaves of Careya arborea[END_REF] -Diarrhea/ dysentery [START_REF] Bhandary | Medical ethnobotany of the Siddis of Uttara Kannada District, Karnataka, India[END_REF][START_REF] Chassagne | Natural remedies used by Bunong people in Mondulkiri province (Northeast Cambodia) with special reference to the treatment of 11 most common ailments[END_REF][START_REF] Rajakumar | Ethno-medicinal application of plants in the eastern region of Shimoga District, Karnataka, India[END_REF][START_REF] Swain | In vitro antibacterial efficacy of plants used by an Indian aboriginal tribe against pathogenic bacteria isolated from clinical samples[END_REF] -Sore in intestine [START_REF] Bhat | Ethnomedicinal plants to cure skin diseases-An account of the traditional knowledge in the coastal parts of Central Western Ghats, Karnataka, India[END_REF][START_REF] Swain | In vitro antibacterial efficacy of plants used by an Indian aboriginal tribe against pathogenic bacteria isolated from clinical samples[END_REF] -Ulcer [START_REF] Chandrashekara | 210 Po and 210 Pb in medicinal plants in the region of Karnataka, Southern India[END_REF].

-Anti-diarrheal activity [START_REF] Rahman | Antidiarrhoeal activity of the bark extract of Careya arborea Roxb[END_REF] (Grosvenor et al., 1995b) -postpartum and kidney problem [START_REF] Lajis | Phytochemical studies and pharmacological activities of plants in genus Hedyotis[END_REF][START_REF] Ong | Malay ethno-medico botany in Machang, Kelantan, Malaysia[END_REF] -wound [START_REF] Wiart | Antimicrobial screening of plants used for traditional medicine in the state of Perak, Peninsular Malaysia[END_REF] Hedyotis capitellata Wall. ex G.Don was found to have antibacterial activity against: Staphylococcus aureus and Proteus vulgaris (Grosvenor et al., 1995b;[START_REF] Nakanishi | Phytochemical survey of malaysian plants preliminary chemical and pharmacological screening[END_REF], Bacillus cereus [START_REF] Wiart | Antimicrobial screening of plants used for traditional medicine in the state of Perak, Peninsular Malaysia[END_REF].

Syzygium ripicola 100.0 Diarrhea/ Dysentery No reference No reference was found for S. ripicola but several species from the same genus Syzygium were reported to have activity against diarrhea. For example, S. cumini (synonym Eugenia jambolana Lam.) [START_REF] Mukherjee | Screening of antidiarrheal profile of some plant extracts of a specific region of West Bengal[END_REF], S. samarangense [START_REF] Ghayur | Presence of calcium antagonist activity explains the use of Syzygium samarangense in diarrhoea[END_REF].

Moreover, antimicrobial activity was also found with S. jambos [START_REF] Djipa | Antimicrobial activity of bark extracts of Syzygium jambos (L.) Alston (Myrtaceae)[END_REF][START_REF] Murugan | Antimicrobial activity of Syzygium jambos against selected human pathogens[END_REF] Clitoria mariana 80.0 Diarrhea, stomachache, constipation

No reference was found for C. mariana but a lot of information for the common herb C. ternatea: various therapeutic effects, including constipation [START_REF] Mukherjee | The Ayurvedic medicine Clitoria ternatea-From traditional use to scientific assessment[END_REF], snake bite, indigestion, tumour [START_REF] Rahmatullah | A survey of medicinal plants used by Kavirajes of Chalna area, Khulna district, Bangladesh[END_REF], diarrhea [START_REF] Upwar | Evaluation of antidiarrhoeal activity of the root of Clitoria ternatea Linn[END_REF].

No reference was found for C. mariana but anti-diarrheal activity of C. ternatea Linn. was investigated [START_REF] Sini | Anti-diarrheal activity of the leaves of Clitoria ternatea[END_REF][START_REF] Upwar | Evaluation of antidiarrhoeal activity of the root of Clitoria ternatea Linn[END_REF] -Diarrhea [START_REF] Chassagne | Natural remedies used by Bunong people in Mondulkiri province (Northeast Cambodia) with special reference to the treatment of 11 most common ailments[END_REF] -Rashes [START_REF] Inta | Analysis of traditional knowledge in medicinal plants used by Yuan in Thailand[END_REF] -Stop bleeding [START_REF] Ong | Malay ethno-medico botany in Machang, Kelantan, Malaysia[END_REF], wound Antibacterial (against Pseudomonas aeruginosa and Streptococcus faecalis) [START_REF] Irobi | Activities of Chromolaena odorata (Compositae) leaf extract against Pseudomonas aeruginosa and Streptococcus faecalis[END_REF] and anti-diarrheal bacteria strains (Klebsiella oxytoca, Salmonella enterica, Shigella sonnei and Vibrio cholera) (Atindehou et al., healing [START_REF] Agyare | An ethnopharmacological survey and in vitro confirmation of ethnopharmacological use of medicinal plants used for wound healing in Bosomtwi-Atwima-Kwanwoma area, Ghana[END_REF][START_REF] Inta | Analysis of traditional knowledge in medicinal plants used by Yuan in Thailand[END_REF] 2013).

Elephantopus mollis 56.4

Diarrhea, stop bleeding, wound healing, cough -Asthenic fever [START_REF] Breitbach | Amazonian Brazilian medicinal plants described by C.F.P. von Martius in the 19th century[END_REF] -Cough, anemia, dysentery, hepatitis, diabetic, wound healing and diseases related to free radical-mediated [START_REF] Ooi | Cytotoxic, apoptotic and anti-alphaglucosidase activities of 3,4-di-O-caffeoyl quinic acid, an antioxidant isolated from the polyphenolicrich extract of Elephantopus mollis Kunth[END_REF] -Fracture healing, abdominal pain, cancer, snake bites [START_REF] Ngueguim | Evaluation of Cameroonian plants towards experimental bone regeneration[END_REF] Cytotoxic, apoptotic and anti--glucosidase [START_REF] Ooi | Cytotoxic, apoptotic and anti-alphaglucosidase activities of 3,4-di-O-caffeoyl quinic acid, an antioxidant isolated from the polyphenolicrich extract of Elephantopus mollis Kunth[END_REF] Erigeron canadensis (syn. Conyza canadensis)

54.5

Diarrhea/ dysentery, stop bleeding, wound healing, headaches Various health problems, including diarrhea, dysentry, styptic, injuries, etc. [START_REF] Gairola | A cross-cultural analysis of Jammu, Kashmir and Ladakh (India) medicinal plant use[END_REF][START_REF] Shinwari | Folk use of medicinal herbs of Margalla Hills National Park, Islamabad[END_REF][START_REF] Thakur | Observations on traditional usage of ethnomedicinal plants in humans and animals of Kangra and Chamba districts of Himachal Pradesh in North-Western Himalaya, India[END_REF][START_REF] Zheng | Ethnobotanical study on medicinal plants around Mt.Yinggeling, Hainan Island, China[END_REF] Antibacterial and antifungal activities [START_REF] Shakirullah | Antimicrobial activities of Conyzolide and Conyzoflavone from Conyza canadensis[END_REF] * Medicinal uses reported in both present study and other bibliographic data were written in bold letters.

(

  2007) (Vietnam Academy of Science and Technology, 2007) and the Red List of IUCN (2016) (International Union for Conservation of Nature and Natural Resources, 2016). Despite there not being

Fig 1 .

 1 Fig 1. Map of BiDoup-Nui Ba National Park. The map shows the location of the three K'Ho villages participating in the ethnobotanical survey (red circles).

Fig 2 .

 2 Fig 2. Age of informants by village and gender.

Fig 6 .

 6 Fig 6. Health-seeking behavior of local people.

Table 2

 2 List of the medicinal plants used for the treatment of diarrhea (arranged alphabetically according to family) and their FL, CV values. Bold letters found in "medicinal uses" column indicate that this is the most important medicinal use for the plant mentioned. If not, it means that the plant is mainly used for the treatment of diarrhea.

	Plant code	Scientific name/ Vietnamese name/ Voucher specimen	Family	Anti-diarrheal treatment Mode of Plant parts preparation and used administration	FL ()	CV	Other medicinal uses	Non-medicinal purposes
	1	Acorus calamus L./ Thuỷ	Acoraceae	Rhizomes	Eaten raw.	3.0	0.02	* Stop bleeding	Condiment
		xương bồ/ PHH0004869						(wound or
								menstruation
								problems), cough,
								fever, parturition
								stimulant
	2	Acorus calamus var.	Acoraceae	Rhizomes	Boil with water. The	11.5	0.05	Cough, stop	Handicraft
		angustatus Besser/			decoction is used			bleeding, wound
		Bồ bồ núi/ PHH0004870			orally.			healing, fever,
								typhoid,
								stomachache,
								kidney stone
	3	Streptocaulon juventas	Asclepiadaceae	-Leaves or	-Boil with water.	35.3	0.42	Stop bleeding,	Tea
		(Lour.) Merr./		sprouts or	The decoction is			wound healing,	Shampoo
		Hà thủ ô/		whole plant	used orally.			cough, aches and	(helps hairs
		PHH0004871		-Roots	-Eaten raw or boil			pains, insect bites,	black and
					with water.			toothache,	silk)
								insomnia,
								parturition
								stimulant
	4	Alstonia scholaris (L.)	Apocynaceae	Leaves	Boil with water. The	100.0	0.05		Construction
		R. Br./			decoction is used				material
		Hoa sữa/ PHH0004872			orally.
	5	Calamus palustris Griff/	Arecaceae	Pith of young	Roasted piths are	50.0	0.05	Malaria	Food
		Mây tàu/		stem	eaten raw.				Handicraft
		PHH0004873							Construction
									material
	6	Erigeron canadensis L./	Asteraceae	-Leaves	-Eaten raw or cook	54.5	0.28	Stop bleeding,	Edible
		Thượng lão/			with meat or fish as			wound healing,	vegetable
		PHH0004874			daily meal.			headache	Tobacco
				-Leaves/	-Cut into small
				Aerial parts	pieces, air-dry and
					boil with water. The

*

Table 3

 3 Literature review on anti-diarrheal plants with FL over 50%.

	Plant	FL (%)	Medicinal uses in the present study	Cross-cultural comparison	Bioassay tests
	Alstonia scholaris	100.0	Diarrhea/ Dysentery *	-Diarrhea (Pardo de
				Tavera, 2008; WHO, 2009;
				Wiart, 2006).
				-Malaria (Pardo de Tavera,
				2008; WHO, 2009; Wiart,
				2006)
				-Other health problems:
				fever, diabetes, beriberi, …
				(WHO, 2009; Wiart, 2006)

  2010)

	Dacrycarpus	80.0	Diarrhea, cough,	Diarrhea (Sujarwo et al.,	Anti-proliferative activity
	imbricatus		itching	2015)	(against A549-human lung
	(syn. Podocarpus				adenocarcinoma epithelial
	imbricatus)				and NCI-H292-human lung
					mucoepidermoid carcinoma
					cell lines) (Han et al., 2014)
	Paederia	80.0	Diarrhea, stop	No reference	No reference was found for P.
	microcephala		bleeding, nosebleed,		microcephala but the species
			flu, eye sore		in same genus P. foetida
					possessed anti-diarrheal
					(Afroz et al., 2006) and
					antibacterial activities (Uddin
					et al., 2007)
	Piper sarmentosum	71.4	Diarrhea, toothache,	-(Malarial) fever (Ong and	-Anti-microbial activity
	(syn. P. lolot)		hypertension	Nordiana, 1999; Zakaria et	against: Bacillus subtilis and
				al., 2010)	Escherichia coli) (Masuda et
				-Postpartum dizziness,	al., 1991), E. coli and
				headaches (De Boer et al.,	Fusobacterium nucleatum
				2012; Zakaria et al., 2010)	(Teanpaisan et al., 2016)
				-Stone kidney (De Boer et	-Anti-nociceptive and anti-
				al., 2012)	inflammatory activities
				-Toothache (De Boer et al.,	(Zakaria et al., 2010)
				2012)	-Hypoglycemic effect
				-Other health problems:	(Peungvicha et al., 1998)
				beriberi, …. (De Boer et al.,
				2012; Zakaria et al., 2010)
	Chromolaena odorata	60.6	Diarrhea/ dysentery,	This is a very common plant
	(syn. Eupatorium		typhoid, fever, stop	used by other ethnic groups
	odoratum)		bleeding, itching,	elsewhere.
			sinusitis

Table 4

 4 Main transmitters in medicinal knowledge in K'Ho communities.

		Main transmitters	Number of reports (% of total reported)
	Vertical transmission	Parents	40 (25.0)
		Grandparents	31 (19.4)
		Father	22 (13.7)
		Mother	17 (10.6)
		Mother/ Father-in-law	3 (1.9)
	Horizontal transmission	Community	35 (21.9)
		Husband/ Wife	6 (3.7)
		Newspaper/ Book/ Television	3 (1.9)
		Siblings	3 (1.9)
		Total	151 (100.0)

15.000 plant species (Aati et al., 2019). It is necessary therefore to establish projects with the aim of improving awareness of social, cultural and political dimensions on the ecosystem and valuable knowledge before traditional plants and their associated knowledge completely disappear. Moreover, agro-techniques should be applied for potential domesticated medicinal plants to enhance their yield and quality. A seed bank would also be helpful for the preservation of genetic diversity of medicinal plants.

Once the local people's income is improved, negative impacts caused by them on biodiversity may be reduced.

Funding

This study was funded by the Vietnam National University Ho Chi Minh City (VNU-HCM) under grant number B2014-18-04.

Ethics approval and consent to participate

Before conducting interviews, prior informed consent was obtained from all participants. No further ethics approval was required.

Consent for publication

This manuscript does not contain any individual person's data and further consent for publication is not required.

Conflicts of interests

The authors declare that they have no competing interest.

Appendices

Appendix A: Questionnaire used in extensive ethnobotanical interviews.

Appendix B: Photographs of 11 plants with high fidelity level value.

Acknowledgements

The authors would like to acknowledge to BiDoup-Nui Ba National Park for supporting sampling and to local people who participated in the ethnobotanical survey and freely gave their valuable knowledge.