Ethnobotanical Survey of Three Species of Desmodium genus (Desmodium ramosissimum, Desmodium gangeticum and Desmodium adscendens) Used in Traditional Medicine, Benin

In Africa, conventional medicines are not within the reach of everybody. High costs of classic treatment lead 82% of the patients to traditional remedies. The study was aimed at identifying and documenting these plants used in the traditional medicine of Benin. Between December 2017 and March 2018, an ethnobotanical study was conducted in the markets of Cotonou, Abomey – Calavi, Porto-Novo and Pobè using a semi-structured questionnaire. A total of 100 respondents which included 91% of females and 9% of males were interviewed. These three species are involved in the treatment of 19 categories of diseases. The respondents are mostly females. It appears from this survey that the Desmodium ramosissimum is the most represented species in Benin (85%). The parts of the plant used are the stem with leaves (98%) and roots (2%). The recipes are prepared mainly by a decoction and administered orally. The price of samples sold varies from 200F cfa to 1000F cfa. The herb teas are cooked with one herb or a combination of several herbs. In terms of knowledge, information on plants was handed down from one generation to another orally through the word of mouth or without any published records. The ethnobotany survey revealed that no prohibitions or side effects are linked to the use of these plants. The three species of Desmodium occupy an important place in the therapeutic arsenal of Benin. These results constitute an essential tool for the experimental evaluation of the potentialities of these plants in order to make available for the Beninese population, new improved traditional medicines.


Introduction
Consumption of fruits and vegetables is considered by many authorities as a public health stake and is the subject of many nutritional recommendations at the global level by FAO and WHO (INRA, 2007). For You  year before their fifth birthday and the causes of these deaths are multiple. Benin, likewise all developing countries, has a high prevalence rates of malnutrition. The main determinant of the high prevalence of chronic malnutrition is the persistence of inadequate feeding practices of young children and poorly supplemented feeding. Nowadays, the treatment of diseases remains a crucial problem of humanity, especially in developing countries with insufficient resources following weak economic systems (Mangambu, 2013). In Africa, conventional medicines are not available to everybody; its high costs of treatment lead 82% of the patients to traditional remedies (WHO, 2011). Patients often combine ethno-medical and pharmaceutical treatments to hope for a quick cure (Mangambu et al., 2012, Singh & Singh, 2012. The use of plants for medicinal and food purposes dates back to prehistory and this tradition has been passed on from generation to generation (Soh et al., 2007). Africa abounds with a multitude of food and therapeutic plants. They improve the nutritional quality of diets because of their chemical composition and medicinal properties (Tchiegang andKitikil 2004, Dansi et al.,2008). In fact, out of 300 000 plant species recorded on the planet, more than 200 000 species are found in the tropical countries of Africa and have medicinal properties (Souad et al., 2010). In Benin, out of the 3000 species of plants listed in the forest ecosystems (MEHU, 2002) In Benin, herbal medicine occupies an important place. But the use of plants is empirical and abusive, often resulting in a panoply of side effects, even the disappearance of the species. The work on the inventory of medicinal plants sold in local markets is scarce in sub-Saharan Africa (Maiga et al., 2005). Thus in Benin scientific data concerning the three species of Desmodium genus are almost non-existent, while these plants are the subject of several therapeutic uses in Benin (Akoègninou et al., 2006). Desmodium leaf sap instilled in the eyes would relieve headaches and seizures, while ingestion of watery macerate from leafy stems calms pain, treats ulcers, eases delivery, etc. Recently, some nutritional studies have been initiated on plants to extract foliar proteins. Indeed, Desmodium is very rich in nutrients (vitamins, minerals and proteins). Further studies on the itinerary of these extracts have been carried out at the medicinal and sanitary levels for the purpose of their more rational use. Some authors have reported that the powder obtained from dry leaves of Desmodium has a higher nutrient concentration than fresh leaves. It is therefore used more and more as a food supplement by rural populations.
It is then essential for scientists to carry out ethnobotanical studies to find out how Beninese people are using these plants. it's also compulsory to create a synergy between traditional medicine and conventional medicine.; especially now that we are witnessing a decline of some species including the three kinds of Desmodium considered as more important according to the indigenous knowledge of local populations due to the strong human pressure.
We therefore propose in this present work to carry out an ethnobotanical study in the communes of Abomey-calavi, Cotonou, Porto-Novo and Pobè; in order to identify the different usages of these three species for sustainable management and safe use in Benin.

2-1 Material
The three plants were previously identified at the National Herbarium of Abomey-Calavi University using Benin's analytical flora (Akoègninou et al., 2006). To carry out this ethnobotanical study certain elements were used: an audio device for recording interviews; a digital camera and plastic bags.

2-2 Method 2-2-The Study Area
The surveys were carried out in four (4) communes (Abomey-Calavi, Cotonou, Porto-Novo and Pobè) located at the south of Benin (Figure 1) in the departments of Atlantic, Coastline, Ouémé, Plateau respectively. These communes are inhabited by people of different ethnic groups for whom the use and marketing of plants are ancestral activities. Our study area is located at the level of the Guinea Gulf. It lies between 110 0 0' and 140 0 0 'W, 60°0 'S and 80°0'N.
Rainfall is binomial (from April to June and September to November) with an annual average of 1200 mm. The average temperature varies from 25 °C to 29 °C and the relative humidity is 69% The Atlantic Department has equatorial climate with an alternation of two rainy seasons and two dry seasons. The average rainfall is 1200 mm per year, with an average daily temperature ranging from 25 °C to 29 °C and relative humidity ranging from 69% to 97% (Sinsin et al., 2004). The soil is reddish with tree vegetation. There is also the presence of clear forests.
The coastal department is located in the coastal sector. This sector extends over a length of 120 km and a variable width between 3 km to the west (towards Grand -Popo) and 10 km to the east (south of Porto-Novo) with an altitude less than 50 metres (Akoègninou et al., 2006). Recent and old barrier beaches are distinguished along the sea, interspersed by the lagoons and fluvial-lacustrine complex of Ouémé, Nokoué's Lake, Couffo, Lake Ahémé and Mono (Akoègninou et al., 2006). We meet various types of non-sandy substrates or rarely flooded, periodically flooded sands, clays prolonged flooding, submerged freshwater substrates and substrates inundated with brackish water. (Akoègninou et al., 2006). The climate is Guinean with a rainfall gradient from western (Grand-Popo) east (Porto-Novo), respectively 900 mm per year (Grand-Popo) and 1300 mm per year (Porto-Novo). The average annual temperature is 26.6 ° C. This sector is marked by a mosaic of plant formations and plant groups, whose floristic composition varies according to the type of substrate and the degree of flooding.
The department of Ouémé is especially characterized by a reddish soil, ferruginous, clay, alluvial and coalluvial with vegetation formed of forest relics, expanses of grass, raphias and some mangroves.
In the Department of plateau climate is Sudano-Guinean type with a shrubby savannah vegetation dominated by Daniellia oliveri. There are ferruginous and clay soils. We also note the presence of some relics forests (INSAE, 2004).

2-2-2. Exploratory investigation
After the documentation phase, a preliminary study was realized on the Geographic's distribution of the three species of Desmodium concerned by our study. A prospective study was also made. The aim was the meeting of resources' people that are able to give us reliable information about the three plants. This study also allowed us to refute our questionnaires, identify target groups concerned by this study. The methodology used in this prospective study was based on the ethno-ecological approach (relational study of the society with its natural environment) described by Bilaso (2008). After this exploratory survey, 12 markets were identified to conduct this work.  Table (1).

Table 1: Communes and markets involved in the investigation Communes Market
Abomey The registration of herbals' practitioner was previously done in order to obtain their consent to participate to our studies. Their selection resided essentially in the wealth of their display. The interview was based on a dialogue in the local language (Fon, Yoruba, Mina and Goun). Information collected from them include; the profile of the resource person (age, sex, level of study) and ethno-pharmacological data such as the vernacular name, uses of the plants, method of preparation and also administration, prohibitions and side effects related to each recipe. The data were collected using a survey sheet designed to assess the knowledge's level of herbal's practitioners on the different plants involved.

2-2-5. Data processing:
The collected data were coded and inserted in excel 2016 databases and then analysed by the software Minitab 17.0 and Graph pad 2017. The frequency of quotation (Fc) of each plant was determined by the formula:

Results and discussion Strengths and weaknesses of the survey method used
In this study, ethnobotany data were collected in the field through a retrospective method based on an ethno-ecological approach. But this retrospective method requesting the memory of respondents could induce biases related to personal appreciation of the respondent (Lykke et al., 2004). The importance given to the general use of Desmodium species is given by individuals who, in the first place, implicitly take into account a personal appreciation; which often refers to their preference or experience. Despite these few biases, this method is widely used in Ethnobotanical study by many authors (

Sociodemographic
Characteristics of the Respondents Table 2 presents characteristics relating to age, sex and levels of schooling. In average, 91% of the surveyed herbalists are female compared to 9% of males. The same observation had been made by Fah et al. (2013) and ADIKO et al. (2013) who pointed out in their studies that the number of women herbalists was higher than the number of men. This observation is explained by the fact that the surveys were carried out in the markets. In addition, it confirms the sociological reality of some African countries, where selling in the market is an activity reserved mainly to women.
The age range of the respondents is between 30 and 95 years old with an average age of 55 years. Subjects with at least sixty (60) years old represent more than the third of the study population. These results are explained by the fact that in Benin, the sale of medicinal plants is reserved to people of advanced age.    (Table 3). These species are the most sold by herbalists for traditional treatments. The frequency's quote of each species varies according to their locations. Nevertheless D. ramosissimum is the most cited specie in all markets (Table 3) Table 4). The most cited diseases have been: Hepatitis (30%); delivery complications (14%); Gestational Diabetes (11%) and cancer (10%). On the other hand, the least cited diseases have been snakebites (2%), dysmenorrhoea (1%) and osteo pathy's traumatism (1%). The study revealed that the treatment of certain diseases involves several plant species while hepatitis, cancer, childbirth complications are only processed by the plant species alone.  adscendens, local production is low, most of the plant marketed in the study area is imported from Nigeria. This observation is due to the soil conditions of the study area which would not be favourable to the cultivation of this species.
Although the production of D. ramosissimum and D. gangeticum is low, 98% of the herbalists get their supplies from Pobè.
The average purchase and selling prices of each plant recorded during the study period as well as the gains varied significantly depending on the level of involvement of the actors. In general, the gains range from 3000 FCFA to 4000 CFA per 50 kg bag, depending on the sector actors ( Table 5). The producers are the main beneficiaries of the products in the study area and can realize the benefits of 1000f to 3000 f a day on a 50 kg bag. For others (wholesalers, semi-wholesalers and retailers) involved in detail selling, prices vary between 100f and 200f. They get a bigger profit. Finally, although the species is the least profitable for certain importers in the sale, Desmodium ramosissimum remains the bestselling species in terms of quantity. This economic potential must be considered for the development of herbal genetic resources in Benin.

CONCLUSION
This study highlighted the essential role of traditional healers in the treatment of diseases in South Benin. It appears that the three species of the Desmodium genus play a major role in Benin's therapeutic arsenal. Frequently cited diseases have been: hepatitis; complications of childbirth; Gestational diabetes and cancer. The data revealed that Desmodium ramosissimum is the most common species in the four communes (Abomey-Calavi, Cotonou, Porto Novo and Pobè). Such information requires the implementation of a laboratory photochemical screening, to isolate the bioactive compounds in these plants, which could be responsible for biological activities. This will enable the production of improved traditional medicines at a lower cost in Benin.