Ethnobotanical survey of folklore plants used in treatment of snakebite in Paschim Medinipur district, West Bengal

Abstract

1. Introduction

Traditional human populations have a broad natural pharmacopoeia consisting of wild plants and animal species. Ingredients sourced from plants and animals are not only used in traditional medicines, but also increasingly valued as raw materials in the preparation of modern medicines and herbal preparations. The World Health Organization defines traditional medicines as practices, knowledge, and belief system which uses minerals, plants and animal based remedies, spiritual therapies and exercises to prevent, treat and maintain well being[1]. A great number of the natural products have come to us from the scientific study of remedies traditionally employed by various cultures. Traditional ecological knowledge is of significance from a conservation perspective and an attribute of societies with a continuity in resource use practice.

Snake bite is a neglected health hazard worldwide[2]. Snakebite data based on diverse methodologies show that global incidence of snakebite is around 5 400 000 bites per year leading to over 2 500 000 envenoming and around 125 000 fatal cases annually[3]. Agricultural and tropical regions report more snake bites than anywhere else. In India alone more than 200 000 cases are reported and it is estimated 35 000 to 50 000 people die each year. Antiserum is the only therapeutic agent available throughout the world. Antiserum contains purified, enzyme-refined and concentrated heterologous immunoglobins. In India, particularly in the rural areas snake bite victims turn to traditional medicine men and healers, due to lack of availability of antiserum. A review of past literature on ethnobotany indicates that ample research work has been done in various parts of the world on herbal antagonists of snake venom[4]–[9]. In India, medicinal plants have been used to cure specific ailments since ancient times. Plants are primarily used due to their safety, effectiveness, cultural preferences, inexpensiveness and abundant availability. Plants are used either single or in combination, as antidotes for snake envenomation by rural populations in India and in many parts of the world[10]. Several medicinal plants with accepted therapeutic values in snake bite treatment are now attracting attention. Recently due to unplanned developmental programs, increasing modern healthcare facilities and impact of modern civilization, natural resources as well as traditional knowledge and tribal cultures are depleting rapidly at an alarming rate. Therefore, it is imperative to explore and document this unique and indigenous, traditional knowledge of the tribal community, before it diminishes with the knowledgeable persons.

Paschim Medinipur is one of the eleven districts of West Bengal (Figure 1).

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Figure 1.

Map of West Bengal.

Geographically located in 21°36′N to 22°57′N and 86°33′E to 88°11′E, it covers an area of 9 345 square kilometres (Figure 2). North and Northwest of this district is a part of Chotanagpur plateau. The area has a gentle slope from east to west. The flora of this region is constituted predominantly with sal of coppice origin and covers 60% of the average area. The usual associates of sal in this region are Pterocarpus marsupium, Terminalia arjuna, Madhuca latifolia, Bombax ceiba, Terminalia belerica. Plantation mainly includes Eucalyptus, Akashmoni, Bamboo and Kaju. The tribal communities residing in this region are the Santhals, Mundas, Lodhas, Bhumijs, Oraon and Kherias. This region is characterized by sandy loam or loamy soil of reddish or reddish brown colour. The maximum temperature recorded in April is 45-46 °C and minimum temperature in winter is 6 °C. The average annual rainfall is about 1 500 mm. The present work makes an attempt to provide a comprehensive account of some of the Indian medicinal plants used in the treatment of snake bite in Paschim Medinipur district of West Bengal by the tribal communities and traditional healers.

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Figure 2.

Paschim Medinipur district.

2. Materials and methods

Field investigations were conducted during April 2012 to March 2013 in 8 different villages of Paschim Medinipur district, West Bengal. Ethnobotanical data was collected through individual and Focus Group Discussion interviews using semistructured open-ended questionnaires as proposed in standard literature[11]. Subjects were selected on the basis of their knowledge pertaining to the use of medicinal plants in tradition. A total of 88 individuals (30-70 years) were interviewed during the survey including medicine men (ojha), elder villagers, plant collectors and forest dwellers belonging to four different communities-Santhal, Munda, Lodha and Oraon. Interview based field study and guided field work was done, in which the taxonomic diversity, distribution, local names, parts of plants used in treatment of snake bite, preparatory methods and mode of administration of these plants were recorded[12]. Group discussion were made with the healers and local people to know their perception about the use of traditional folk medicines, awareness about the conservation of phytodiversity and indigenous knowledge. Plant collection was carried out by standard method[13]. Herbaria were prepared according to conventional herbaria technique[14]. All the voucher specimens were identified using relevant floras and standard literature[15] and deposited in the herbarium of the Department of Botany and Forestry, Vidyasagar University, Paschim Medinipur, West Bengal. The collected plants were crosschecked by neighbouring herbalists and traditional medicinal healers. For each species the proportion of informants who independently reported its use in snake bite was assessed following[16]. Each medicinal practice was cross checked with at least 3 to 4 informants.

3. Results

The present study reports 20 ethnomedicinal plants belonging to 16 families traditionally used for treatment of snakebite by the tribal population of Paschim Medinipur district, West Bengal (Table 1). The plants have been enumerated alphabetically according to their scientific name, habit, local name, family, parts used, mode of preparation and medicinal uses. A high degree of informant consensus for each species was observed.

4. Discussion

The focus of the present study is to provide a comprehensive picture of the medicinal plants with anti snake venom activity that are used by the tribal population of Paschim Medinipur district, West Bengal. Paschim Medinipur is a repository of floral and faunal resources. It is inhabited by a number of tribal communities like Santhals, Mundas, Lodhas, Bhumijs, Oraon and Kherias. The use of medicinal plants was a chosen practice in this district throughout history, the knowledge of which was gathered through the experience of many generations. The present study documents 20 species of ethnomedicinal plants from 16 families used by the tribal healers and practioners of the district. Among the plants reported, there are 4 species of trees, 8 species of shrubs, 7 species of herbs and one species of climber. The reported plants are used by more than one ethnic group. The local tribes mainly use leaf, root, bark, rhizome, stem, fruit, seed and latex of these plants as antidote against snakebite. The reported plants are mostly administered as decoction, extracts, paste, juice and poultice. Some of these plants like Emblica officinalis Linn[17], Azadirachta indica A. Juss[18], Rauvolfia serpentina (L.) Benth. ex Kurz have been earlier reported to have anti snake venom activity in various ethnomedicinal studies[19]. In Indian tradition, some plants are supplemented with pepper and garlic for snakebite treatment[20]. Thus the reported data validates the claims of traditional healers and tribal communities of Paschim Medinipur district regarding the herbal antagonists of snakebite. The consensus among users indicates that plants have protective activity when administered for snake bite. Particularly plants like Rauvolfia serpentina (L.) Benth. ex Kurz, Emblica officinalis Linn and Moringa oleifera Lam have a high consensus agreement regarding their use in snakebite. Thus the present investigation can provide leads for specific venom inhibitory compounds from the reported medicinal plants that could be used in combined therapy with antiserum in the near future.

Snakebite till date remains a public health hazard in tropical countries especially in India. The first antivenom was developed by Albert Calmette, a French scientist of Pasteur Institute in 1895. Due to lack of availability, cost and hypersensitivity, alternative therapy for snakebite has received much attention. Snake bite remedies are of interest since they may have recognizable therapeutic or toxic effects and are steeped in cultural beliefs that invariably conflict with formal health care practices. Envenomations due to snakebites are commonly treated by parenteral administration of horse or sheep-derived polyclonal antivenoms aimed at neutralization of toxins. However, despite the widespread success of this therapy, it is still important to search for different venom inhibitors, either synthetic or natural, that could complement or substitute for the action of antivenoms. The present study investigates the ethnomedicinal resources of Paschim Medinipur district of West Bengal to identify the therapeutic potential of some herbal remedies against snake bite. The high degree of consensus among the informants suggests that the current use and knowledge about the plants used in snakebite treatment are still strong. Thus studies exploring pharmacopoeia of unrelated cultures for plants treating specific medical conditions (like snake bites in this study) present one way of validating anecdotal field reports, corroborating and selecting promising lead plants and conservation of potentially threatened species.

Acknowledgments

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