Ethnomedicine of Santal tribe living around Susunia hill of Bankura district , West Bengal , India : The quantitative approach

Article history: Received on: 27/10/2014 Revised on: 22/11/2014 Accepted on: 04/01/2015 Available online: 27/02/2015 The present paper deals with the observations on ethnomedicinal uses of wild plants by the Santal tribal people of villages surrounding the Susunia hill of Bankura district, West Bengal. Data were collected by interviewing Santal medicine men and knowledgeable persons with the help of semi-structured and open-ended questionnaire. The data have been analyzed employing suitable statistical tools like Informant Consensus value for Plant Part (CPP), Consensus Factor (Fic), Fidelity Level (FL%), Preference ranking exercise, Importance value (IVs) and Pearson Correlation Coefficient (PCC). Altogether 25 plants have been recorded which are used by the Santal people in formulation of 40 ethnomedicinal preparations for curing 27 types of diseases. Leaves secured the highest CPP value (0.33). Circulatory system disorder, Nervous System disorder and Birth/Puerperium disorder secured the highest Fic value (1). Abrus precatorius L., Ampelocissus latifolia (Roxb.) Planch., etc. secured the highest FL value(100%). Curcuma longa L. has been identified as most preferred species by preference ranking exercise. The highest score of IVs observed in Borassus flabellifer L., Cajanus cajan (L.) Millsp.,etc. The PCC between IVs and FL was 0.679 showing moderate positive significant association. Bioassay of these ethnomedicinal remedies has to be carried out further for their scientific validation.


INTRODUCTION
Ethnomedicine has been playing very important role in human health care since time immemorial.This practice of health care is based on belief and experience of the ethnic people, which is a part of their tradition and culture.There has been an increased demand of herbal drug in international trade because herbal medicines are cheap, more effective, easily available and supposed to have no side effects.This branch of ethnobotany is now getting more importance in the field of pharmacognosy for its basic information regarding medicinal plants, their various traditional uses, way of preparations, doses, and mode of administration of crude drugs.In our national agenda, documentation, conservation, preparation of database of medicinal plants and their cultivation are now priority issues.Number of medicinal plants is steadily being increased in the traditional pharmacopoeias of our country through extensive research work in the field of ethnobotany.The information about prescription, pharmacology, attitude towards diseases, diagnosis, etc. of the age-old tribal medicine system are still lying unclaimed in different parts of the district Bankura.A perusal of literature shows that documentation of ethnobotanical works from this district has been made by different workers (Acharya and Mukherjee, 2010a, b;Banerjee et al., 2013;Basu, 2003;Choudhuri et al., 1982;Ghosh et al., 1996;Ghosh, 1999Ghosh, , 2002Ghosh, , 2003aGhosh, , b, 2006Ghosh, , 2008;;Kar, 1999;Mallick and Mallick, 2012;Mallick et al., 2012;Mondal and Biswas, 2012;Mukherjee and Namhata, 1988;Namhata and Mukherjee, 1988, 1989, 1992;Namhata and Ghosh, 1993;Pal et al.,1989;Paul, 2004;Paul and Verma, 2004;Sinhababu and Banerjee, 2013).No ethnobotanical work including its quantitative analysis has been carried out from the Susunia hill of Bankura district.In this context, present study has been designed to document and conserve the traditional herbal knowledge of Santal tribe living around Susunia hill.Bankura is one of the seven districts of Burdwan Division in the Indian state of West Bengal.It lies between N 22 °46′ and N 23 °38′ and between E 86 °36′ and E 87 °46′.The district has an area of 6881.24sq km and total forest area of 1404 sq km.It is a very small hill and runs for a length of about 3 km.Like other forest areas in the district, forest of the Susunia hill is also tropical dry deciduous type dominated by Sal tree (Shorea robusta Gaertn.f.).The hill is very rich in its plant resources including medicinal plants.The district Bankura is inhabited by many tribal communities such as Santals, Oraons, Koras, Bhumij, Mech, Mahali, Bedia and Mundas.Santals represent the largest indigenous tribal community in the district and the villages surrounding the Susunia hill are dominated by this tribe.The tribal villages selected for this study are located within 10 km radius around the hill.

Data collection
Ethnomedicinal data were collected between March 2011-February 2013 following the standard methods (Jain, 1987;Jain and Mudgal, 1999) from 14 tribal villages that were selected with the help of aged persons in the villages on basis of the .availability of traditional healers (Figure -1).The villages were visited in different seasons (summer, monsoon and winter) to avail most of the plant resources in their flowering condition.Twenty Santal key medicine men and five knowledgeable persons were selected as informants using purposive sampling method (Dolores and Tongco, 2007) (Table -1 and Figure-2).Most of the informants belong to an age between 50 and 80 years.The key informants selected from each sampled villages were the most knowledgeable ones as suggested by the tribal elders of respective villages.Before interview, Prior Informed Consent (PIC) was taken from each informant.The data have been collected by interviewing the informants through semi-structured and open-ended questionnaire.The Santal name of the plant, parts used, preparation and mode of administration of the crude drug, disease cured, etc. were recorded in detail.Interviews were conducted in the local languages i.e.Santali and Bengali.The plant specimens were collected and identified with the help of different Floras (Prain, 1903;Sanyal, 1994;Saxena and Brahmam, 1994;Varma, 1981).Correct and Valid scientific names for the recorded plant species have been used here following The International Plant Names Index (IPNI).Collected plant specimens have been preserved as herbarium specimen following conventional techniques (Jain and Rao, 1977) and kept in Visva-Bharati Herbarium, Department of Botany, Visva-Bharati, Santiniketan for future references.

Quantitative ethnomedicinal data analysis
Here in this study, different quantitative tools like Consensus value for Plant Part [CPP] (Monteiro et al., 2006) Consensus value for Plant Part (CPP) measures the degree of agreement among informants concerning the plant part used and is calculated as CPP = P x / P t , where P x = number of times a given plant part was cited; P t = total number of citation of all parts.
F ic has been determined to identify the most potential medicinal plant species used in the culture of Santal people of the study area.It is expressed by a formula: F ic = N ur -N t / N ur -1, where N ur is the number of use reports from informants for a particular disease category, N t is the number of taxa that are used for that disease category.F ic value ranges between 0-1, where a high value indicates the greater informant consensus and a lower value signifies disagreement among the informants.
The Fidelity Level (FL%) is used to quantify the percentage of informants claiming the use of a certain plant for the same major purpose and is calculated as : FL= N p / N x 100, where N p = number of informants who cited the species for a particular disease ; N = total number of informants that cited the species to treat any given disease.
Preference ranking exercise (Martin, 1995) was conducted by six key medicine men on five medicinal plants used to treat boil in the study area.Boil was the disease against which highest number of medicinal plants was prescribed by the informants.The informants were given the plants and asked them to arrange plants based on their personal experience regarding efficacy of the plants.Medicinal plant that believed to be the most effective was given the highest value i.e. 5 and the one with least effectiveness was given a value of 1. Finally, rank was determined based on the total score of each species.
The Importance Value (IVs) measures the proportion of informants who regard a species as most important and is calculated as follows: IVs = n is / n, where n is = number of informants who consider the species s most important; n= total number of informants.
Pearson product-moment correlation coefficient is a good measure to numerically quantify the nature of the linear relationship between two variables , giving a value between +1 and -1 inclusive, where 1 is total positive correlation, 0 is no correlation, and -1 is total negative correlation.The strength of the relationship is indicated by the correlation coefficient (r) but is actually measured by the coefficient of determination (r 2 ).The significance of relationship is expressed in probability levels p (0.05).In our case, the two variables of interest are IVs and FL.Pearson product-moment correlation coefficient is done with the help of Statistics software [version 1.1.23-r7] ( Wessa, 2014).

RESULTS AND DISCUSSION
The result has been presented in tabular form.The species are arranged in alphabetical order of their scientific names with family name and voucher number, followed by the Santal name, plant parts used, mode of administration, diseases cured FL% and IV s (Table -2).

Medicinal plants reported
Altogether 25 ethnomedicinal plants have been recorded from the district.These 25 recorded taxa spread over 22 species, 22 genera, 14 families of dicotyledons and 3 species, 3 genera, 3 families of monocotyledons.
The family Fabaceae was represented by the highest number of species (4 species, 16%) followed by Asteraceae (3 species, 12%), Euphorbiaceae, Solanaceae and Vitaceae (2 species each, 8%).Remaining 12 families had single species representation (Figure -3).Dominance of medicinal plant species from families Fabaceae and Asteraceae could be attributed to their wide distribution and abundance in the flora of this area.
Habitually the investigated taxa fall under 4 groups like Trees, Shrubs, Herbs and Climbers.The numbers of species in each group and their respective percentage have been defined as Trees-8 (32%), Shrubs-4 (16%), Herbs-10 (40%) and Climbers-3 (12%) (Figure -4).The most dominant life form of the species used by the tribal people in the district includes herbs (40%) which indicate that they are easily accessible and commonly grown around the tribal villages in the district.

Diseases treated
The recorded 25 plant species are used in formulation of 40 types of ethnomedicinal preparations that cure 27 types of diseases.The diseases which occur most frequently in the area are boil, scorpion sting, stomachache, elephantiasis, intestinal worm, etc.These 27 types of diseases were grouped into 11 major categories like dermatological disorder, muscular-skeletal system disorder, digestive system disorder, infections, genitio-urinary system disorder, etc.It has been observed that against boil, a medicinal condition under the category of dermatological disorder, a large number of medicinal plants (6species) were prescribed.For scorpion sting, the number of prescribed species is 4, followed by 3 species in case of stomachache, 2 species in case of external cut, elephantiasis, intestinal worm, jaundice, etc.

Plant parts used
The leaf part of the plants (CPP value 0.33) was used by the tribal people very frequently in formulation of the remedies as compared to other plant parts.Flower, fruit and seed secured the CPP value of 0.29 followed by root and rhizome (0.24), stem bark (0.07), latex and gum (0.05) and whole plant (0.02) (Figure -5).Medicine men here in the study area prefer leaves most in preparation of their remedies because this part of plant is easily accessible than other parts, more efficacious and it is known to us that leaves are the sites for synthesis of bioactive secondary metabolites .Collection of plant parts specially leaves by the tribal people would support the sustainable method of harvest because in most of the cases at least a number of leaves are left unplucked which allow the parent plant to survive normally.Harvesting root , rhizome and seed poses more threat to survival of plants than collecting other parts such as leaves ,bark and flower.

Use of drugs in various forms
It has been observed that Santal medicine men in the study area follow various ways of remedy preparation which depend on type of disease treated.The major modes of remedy preparations were paste (50%), ointment (12.5%), powder (7.5%), cooking, juice, pill (5%), burning ash, decoction, gum, latex, mouthwash and plaster (2.5%)(Figure -6).Along with herbal ingredients, different additives like coconut oil, molasses, black salt and termite mound's soil were often used in preparation of remedies.Plant ingredients were collected by the medicine men from wild habitat in the study area and other ingredients like coconut oil, molasses, black salt were procured from the commercial sources.The soil of termite's mound was collected from its mounds which are very common in forest floor of the district.
The majority (72.5%) of the remedies were prepared from fresh materials only.Some remedies were prepared from dried materials (15%) exclusively and few were prepared from dried or fresh materials depending upon their availability in the area (12.5%).The fact that both fresh and dried forms are used in the preparation of remedies create a better opportunity for the Santal people here to have access to the materials used in medicinal formulation across different seasons of the year.It is the opinion of the informants regarding their use of fresh ingredients in remedy preparation that in fresh form the efficacy potential of the ingredients remain intact , which they thought, could be lost on drying.

Routes of administration and doses
More than half (57.5%) of the remedies were applied externally on affected part of the skin directly, and 42.5% of the preparations were applied internally in the form of oral application.Results show that there was no agreement in measurement or unit used among informants.Informants generally used measuring units such as teaspoon, cup, fingers, etc. but still differed in the doses they administered.

Statistical analysis
Finally, the data were analyzed by employing the quantitative tools like F ic , FL%, preference ranking exercise, IVs and Pearson product-moment correlation coefficient to get more objectivity in this study.Our study reveals that there is a high level of consensus among the informants regarding disease cure and medicinal plant use.The F ic value for different disease categories ranges from 0.909 to 1.00 which indicates greater agreement among the informants regarding phyto-therapeutic uses of medicinal plants (Table-3).Circulatory system disorder, nervous system disorder and birth/puerperium disorder secured the highest F ic value (1) which indicates the remedies against these disease categories are very efficacious and those remedies are actively practising among the Santal healers in the study area.The species used in remedies for the disease categories with high F ic values are considered as high consensus species which have established as very prospective one in many natural product studies.It has been established by many workers that high consensus species are the prospective candidates for investigation of their phytochemistry and pharmacology (Heinrich, 2000;Trotter and Logan, 1986).One earlier study found that the good consensus of Kenyah healers in Borneo on antimalarial plants was indicative of high activity in laboratory antiplasmodium assays (Leaman et al., 1995).Like wise the plant species which have been identified as highest scorer in respect of their F ic value can be considered useful in development of evidence-based phytomedicine for the tribal people of the study area.
Fidelity Level (FL%) value of the recorded 25 plant species ranges from 28% -100% (Table -2).Highest fidelity level value (100%) has been recorded for ten plants such as Ampelocissus latifolia (Roxb.)Planch.and Lannea coromandelica (Houtt.)Merr.against elephantiasis, Cajanus cajan (L.) Millsp.and Diospyros melanoxylon Roxb.against jaundice, Calotropis gigantea (L.) W.T. Aiton against scorpion sting, Abrus precatorius L. against sprain, Blumea lacera (Roxb.)DC and Borassus flabellifer L. against external cut, Centratherum anthelminticum (L.) Gamble for good digestion, Cissus adnata Roxb.against bone fracture, etc.The highest FL% value could be considered as an indicator for the high healing potential of those plants used against the corresponding diseases.Plants with highest fidelity level value could also be targeted for further phytochemical investigation to identify the bioactive compounds that are responsible for their high healing potential.These ten plant species are till commonly growing in natural habitats in the study area with no adverse effect of collection pressure upon them, but in future there may be a chance of declining the population of them due to their high use pressure in long term.Preference ranking exercise conducted on six medicinal plants which are used to treat boil reveals that Curcuma longa L. is the most preferred medicinal plant followed by Andrographis paniculata Nees, Ricinus communis L. .The fact that Curcuma longa L. is the most frequently used plant for treatment of boil in the area which highlights its highest efficacy potential among the six plant species cited by the informants.Here IV s of the plants ranges from 0.2 -1.The highest Importance Value (IV s ) calculated here is 1 which has been recorded for the plants like Borassus flabellifer L. against external cut, Cajanus cajan (L.) Millsp.against jaundice, Centratherum anthelminticum (L.) Gamble for digestion, Cissus adnata Roxb.against bone fracture, Moringa oleifera Lam.against pox and high blood pressure, Solanum surattense Burm.f.against toothache (Table -2).The highest score for Importance Value of these plants also highlights that these plants are therapeutically very important and tribal healers in the area rely mostly upon them for effective treatment.Here the Pearson correlation coefficient has been determined between IVs and FL% and its value is 0.679 (Table-5) which showed a moderate positive correlation between the proportion of informants who regard a species as most important and percentage of informants claiming the use of a certain plant for the same major purpose.The IVs and FL% are moderately correlated which means that their use patterns across the species moderately match.The degree to which IVs and FL% varies across the species is measured numerically by r 2 which states that around 46 percent variation in IVs can be explained by that of FL.These findings have further supported by a scattered plot which reflects a moderate positive correlation (Figure -7).

Fig. 1 :
Fig. 1: map of Bankura district showing the study sites.

Fig. 2 :
Fig. 2: A. An interview with Rabindranath Hembrame (a key medicine man); B. Rasamoy Murmu showing his medicinal collection; C. Kartik Murmu giving medicine to a patient; D. Mohan Hansda performing some rituals as part of his ethnomedicinal practice and patients waiting for him.

Fig. 3 :
Fig. 3: Number of plant species in their respective family.

Fig. 5 :
Fig. 5: CPP values of plant parts used in herbal preparations.
as A to F; where, A = Kankaram Tudu; B = Syamapada Besra; C = Panchu Hembrame; D = Mohan Hansda; E = Kartik Murmu; F = Rabindranath Hembrame The Biharinath and Susunia are two remarkable hills of this district.Susunia hill (around N 23.39693 °and E 86.98527 °) is situated in the north-west of Bankura district, in the Chhotanagpur gneissic plateau of West Bengal and rises to 439.5 m above sea level (Figure-1).

Table - 2
: Medicinal plants used by the Santal tribal people of surrounding villages of the Susunia hill

Table . 4
: Preference ranking of six medicinal plants reported for treating boil

Table . 5
: Summary statistics for Pearson Product-Moment Correlation.