Keywords

Herbal leafy vegetables, Biodiversity, Chemotaxonomic database.

INTRODUCTION

Indian civilization possesses a rich ancient heritage of plant based health care system which was reflected in prehistoric literatures like Vedas (mentioned 129 medicinal plants), Kalpasutras (mentioned 519 medicinal plants of contemporary society) [1], Charakasamhita and Sushrutasamhita etc. Being a biodiversity rich country India makes the home for 45000 different plant species out of which 3500 are medicinal while 1100 species are used in ISM and 650- 700 species are used in herbal industries; yet only 150 species are used commercially [2]. Due to the recent upsurge of use of herbal formulations in the developed world for primary health care needs, the worldwide business volume of Phyto-pharmaceutical industries is poised nearly 70 billion USD as compared to 16.50 billion USD during late 90's with an annual growth rate of about 15- 20% of European and 25-30% for North American market [3]. The global market for herbal plants would be 5 trillion USD by the end of 2050 [4] which would become a potential money spinner for the biodiversity rich developing countries. Being a gene rich country, India harbors about 320 species of wild relatives of cultivated plants contributing a large section of the species gene pool. Indian herbal flora belongs to 2200 genera under 386 plant families [5] are largely trees (33%) followed by herbs (32%) [6]. Till date majority of medicinal plant species are collected from their natural habitat leading to depletion in the population causing a disturbance in the ecological balance. The problem is more acute where the roots are the economic plant part [7]. Nearly 80% of herbal raw materials worldwide are wild crafted and 20% from cultivated source chiefly from South American countries, the African Union, India, China and Pakistan [3]. Gangopadhyay (2007) [8] reported that out of 422000 species of flowering plants throughout the world, 52885 are medicinal in nature and 4160 species out of them are presently in threatened condition. Leafy vegetables are naturally available important constituent of Nutraceuticals, rich in several minerals, vitamins, crude fiber, antioxidants and active principles. Such vegetables, which are having miraculous healing properties of human ailments are considered as herbal leafy vegetables. The nutrient, minerals and vitamin content of some herbal leafy vegetables are presented in table -1 [9-12].

Table 1: Nutritional value of some common herbal leafy vegetables

Northern part of West Bengal, comprising of six northern districts of the state namely-Maldah, Uttar Dinajpur, Dakshin Dinajpur, Darjeeling, Jalpaiguri and Coochbehar, popularly known as North Bengal possesses three distinct agro-climatic conditions explicitly Hill agro-climatic zone, Terai agro-climatic zone and Old Alluvial agro-climatic zone has the unique positional advantage of being in the juncture of three major phyto-geographical regions, namely the north east, the eastern peninsula and the eastern Himalaya with thick natural forest. Continuity and mixing of these three zones have created unique ethnobotanical diversity of cultivated and wild members of herbal species that are prevalent in these three regions. Owing to the natural location at the International boundary between the three different countries this region is in a high risk position for biopiracy-a significant menace for the natural wealth of India. Due to massive habitat destruction, overexploitation and environmental pollution in India, a number of species are subjected to threat on a regular basis, this region being no exception. The Terai Agro-climatic zone of the North Bengal region is endowed with fabulous biodiversity-a considerable portion of which is consumed by the inhabitants as leafy vegetables, which are uncommon to the southern counterpart of the state, some of which possess medicinal values also. Documentation of the indigenous knowledge through ethno-botanical study is important for the conservation and utilization of biological resources [13]. Hence, it is very urgent to conserve, evaluate and characterize this valuable natural wealth of this region up to the ultimate extent. The Chemotaxonomic approach of classification of such biodiversity offers an additional advantage over the traditional binomial classification as the nature of secondary metabolites which have no apparent function in plants primary metabolism would be well versed which have immense potential to the herbal drug industries or herbal drug developers to generate new herbal formulations. The recent advances in plant genetic resources and intellectual property right (IPR) changes the outlook towards the unexplored herbal species, making the nation as the custodian as well as a major beneficiary of any development generated out of those species. However, the diversity and potential of herbal leafy vegetables of this region still becomes untapped and not thoroughly investigated for rational utilization. Considering the potential of leafy vegetables, sample village level survey was conducted to explore the diversity and traditional use of herbal leafy vegetables in this region. After collection of field level observations the data were processed further for documentation of herbal properties and secondary metabolites present in them. The diversity of secondary metabolites was observed through intensive literature survey. The present study was aimed with an eye to develop an exhaustive chemotaxonomic database of the prevalent biodiversity of herbal leafy vegetables in the Terai region of West Bengal.

MATERIALS AND METHODS

The study was formulated to develop an exhaustive chemotaxonomic database of the existing biodiversity of herbal leafy vegetables in the Terai region of West Bengal, India. To understand the diversity of herbal leafy vegetables, sample village level survey was conducted in Cooch Behar [88o47′44′′ - 89o54′35′′ East longitude and 25o57′47′′ - 26o36′2′′ North latitude (https://coochbehar.nic.in/HTMfiles/CoB_in WB.html)] and Jalpaiguri [88°4' - 89°53' East longitude and 26o16′ - 27°0' North latitude (https://www.jalpaiguri. gov.in/html /disprof.html)] districts during 2011 and 2012. The villages included - Dhalaguri, Haripur, Khagribari, Pundibari, Jatrapur, Raserkuthi, Dhangdhinguri, Konamalli, Satmile, Bararangras, Madhupur, Atialiguri, Kholta, Baneswar, Sakunibala, Okhrabari, Nishiganj, Barbisha, Kunjanagar, Jateshwar, Kamakhyaguri, Bhutnir Ghat, Salbari etc. Information was collected through participatory field observation and related taxonomic identification. More emphasis was given to the native people who were familiar with different herbal leafy vegetables. Initially the vernacular name and herbal properties of the prevalent leafy vegetables were collected. Afterwards the taxonomic positions, medicinal properties and the active principles of the observed herbal leafy vegetables of this region were tabulated through consultation with published and unpublished documents. The chemotaxonomic database of the observed herbal biodiversity was prepared through extensive literature survey.

RESULTS AND DISCUSSION

Through participatory discussion and field observation forty six (46) different species of leafy vegetables, belonging to 42 genera distributed in 28 families were identified in the Terai agro-ecological zone of North Bengal which were having potential medicinal properties. The vernacular name, plant family, habitat, season of use and medicinal properties of those species were collected and presented in table-2. All the leafy vegetables have traditional medicinal use. The native people rely on the herbal plants for the treatment of various ailments and disorders. The preferential use of herbal leafy species in remedial preparations may be due to their easy availability, inherent practice and quicker result. Use of Amaranthus, Brassica, Centella and Chenopodium as ethnomedicinal plants was observed among the inhabitants of Shivalik Hills of Himachal Pradesh, India [14]. Allium cepa, Azadirachta indica and Corchorus sp. were also successfully utilized as ethnomedicinal plants by the Idoma people of Nigeria [15]. However, the knowledge is restricted to the older people and most of the young people are indifferent about the medicinal and healing properties of the herbal leafy vegetables. This could be due to easy accessibility of medical facilities in nearby hospitals. The valuable indigenous traditional knowledge of herbal healing is going into oblivion very fast. Efforts are required to conserve the traditional knowledge for the future generations through inculcating awareness, publicity and documentation. The scientific basis of health benefit with herbal leafy vegetables can be well understood if the active principles or the bioactive compounds present in the plants are identified. In the present work, the different active principles of the selected herbal leafy vegetables were collected and presented in Table- 3. Most of the herbal leafy vegetables contain multiple phytochemicals having a potential for the health benefit of the human body. Most of green herbal leafy vegetables have been identified to exhibit antioxidant activities. They have different antioxidants such as vitamin C, vitamin E, carotenes, lycopenes, polyphenols and other phytochemicals [16]. In recent years, renewed awareness has been generated among the consumer regarding the relationship between diet and health. Credible scientific research indicates potential health benefit and disease-risk reduction attributes of the phytochemicals present in the herbal leafy vegetables [17-20]. It has increased the demand for information on beneficial components of different active principles present in the plant. However the vast potential of the active principles of different leafy vegetables cannot be achieved without understanding the mechanisms of action to ensure the safety and efficacy of the chemicals. Additional research in this direction will be of immense helpful for wider use of these traditional natural resources for cheaper and effective plant remedies for human ailments.

Table 2: Identified herbal leafy vegetables in the Terai agro-ecological zone of West Bengal

Table 3: Active principles of the observed herbal leafy vegetables

CONCLUSION

Terai agro-ecological zone is endowed with favorable climatic condition for the growth of diverse herbal leafy vegetables. Chemotaxonomic classification of those biodiversity now-a-days offers an additional advantage as the chemical nature of secondary metabolites is also expressed which is having immense significance to the herbal drug develops. Traditionally the inhabitants use those for both as vegetable and home herbal remedy. 46 major species of the existing flora of herbal leafy vegetables of the Terai region of West Bengal used by the villagers have been documented with their main chemical constituents through literature survey. This information would become valuable to the researchers and herbal drug industry.

ACKNOWLEDGEMENT

The authors express their sincere thanks to all the respondents for sharing information and extending co-operation during the course of the investigation. The technical and financial support from Uttar Banga Krishi Vishwavidyalaya is duly acknowledged.

REFERENCES

1. Kaushik P, Dhiman AK. Medicinal Plants and Raw Drugs of India. Publ. Bishen Singh Mahendra Pal Singh, Dehra Dun, India. 2000.
2. Tyagi CS, Yadav OP, Verma PK. Conservation of biodiversity of medicinal and aromatic plants. In: Course compendium- Winter school on Advances in Medicinal, Aromatic and Under-Utilized Plants Research, edited by C S Tyagi, P K Verma, J S Hooda, O P Yadav & R K Goyal, 29th September – 19th October, 2005, CCSHAU, Hisar, Haryana, India. 2005; pp. 8-11.
3. Chatterjee SK. Status of medicinal plants in global perspective: biodiversity destruction and conservation. In: Proceedings of Botanicals in Integrated Health Care Convention, 26-28 December, 2010, The Agri Hort. Society of India, Kolkata, India. 2010; pp. 32-36.
4. Kalia AN. Worldwide trade scenario of medicinal and aromatic plants. In: Course compendium-Winter school on Advances in Medicinal, Aromatic and Under-Utilized Plants Research, 29th September-19thOctober, 2005,edited by C S Tyagi, P K Verma, J S Hooda, O P Yadav & R K Goyal, CCSHAU, Hisar , Haryana, India. 2005; pp. 271-273.
5. Maitra S, Satya P. Ethnomedicinal plants of India. In: Dynamics of medicinal and aromatic plants, edited by H P Singh, S T Pandey & B Singh, Indus Valley Publication, Jaipur, India. 2009; pp. 74-99.
6. Tiwari DN. Medicinal plants for health care. Yojana. 1999; pp. 8-17.
7. Singh BM. Collection and conservation of endangered medicinal and aromatic plants. In: Course compendium-Winter school on Advances in Medicinal, Aromatic and Under-Utilized Plants Research, edited by C S Tyagi, P K Verma, J S Hooda, O P Yadav & R K Goyal, 29th September – 19thOctober, 2005, CCSHAU, Hisar , Haryana, India. 2005; pp.1-7.
8. Gangopadhyay A. Medicinal plants on biodiversity. In: Plant biodiversity. Ed. Gangopadhyay, A., Gene-Tech Books, New Delhi, India. 2007; pp. 95-120.
9. Thamburaj S, Singh N. Textbook of Vegetables, tuber crops and spices. First edition. ICAR Publication. New Delhi. 2001; pp. 1-451.
10. Watson RR. Vegetable, fruits and herbs in health promotion. CRC Press, London, New York, Washington DC. 2001.
11. Nath P, Gaddagimath, Dutta OP. Food security and vegetables: A global perspective. Dr. Prem Nath Agricultural Science Foundation, Bangalore, India. 2004; pp. 1-412.
12. Vincent ER, Yamaguchi M. World Vegetables: Principles, Production and Nutritive Values. Springer publication.1997.
13. Kumar SS, Samydurai P, Nagarajan N. Indigenous knowledge on some medicinal pteridophytic plant species among the Malasar Tribe’s in Valparai Hills, Western Ghats of Tamilnadu. American Journal of Ethnomedicine. 2014; 1(3):164-173.
14. Devi U, Sharma P, Rana JC. Assessment of ethnomedicinal plants in Shivalik Hills of Northwest Himalaya, India. American Journal of Ethnomedicine. 2014; 1(4):186- 205.
15. Idu MD, Erhabor JO, Uvo OO. Ethnomedicinal plants used by the Idoma people- Benue State, Nigeria. American Journal of Ethnomedicine. 2014; 1(1): 072- 088.
16. Prior RL, Cao G. Antioxidant phytochemicals in fruits and vegetables - diet and health implications. Hort. Science. 2000; 35(4): 588–592.
17. Gupta S, Lakshmi JA, Manjunath MN, Prakash J. Analysis of nutrient and antinutrient content of underutilized green leafy vegetables. Lebensmittel-Wissenschaft und Technologie (LWT). 2005; 38: 339– 345.
18. Latif SS, El-Aal ABDHA. Mineral Profile- Shelf Life Extension and Nutritive Value of Fresh Green leafy vegetables Consumed in Egypt. In: Proceedings of African Crop Science Conference. 2007; pp. 1817-1826.
19. Gupta S, Prakash J. Studies on Indian green leafy vegetables for their antioxidant activity. Plant foods and Human Nutrition. 2009; 64 (1): 39-45.
20. Gohil KJ, Shende VM, Hamdulay NM. Pharmacological potential of Trichosanthes dioica: Current prospects. Int. J of Advances in Pharmacy, Biology and Chemistry. 2012; 1(2):192-198.