Introduction To Medicinal Plants

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About 250,000 higher plant species on earth, more than 80,000 species are reported to have at least some medicinal value and around 5000 species have specific therapeutic value.Herbs are staging a comeback and herbal 'renaissance' is happening all over the globe. The herbal products today symbolize safety in compare to the synthetics that are considered as unsafe to human and environment. Even though herbs had been priced for their medicinal, flavoring and aromatic qualities for centuries, the synthetic products of the modern age surpassed their importance, for a while.

However, the blind dependence on synthetics is over and people are returning to the herbals with hope of safety and security. Over three-quarters of the world population relies mainly on plants and plant extracts for health care. More than 30% of the entire plant species were used for medicinal purposes. (Joy, P.P., 2001)

Herbals in world market:

It is estimated that world market for plant derived drugs may account for about Rs.2, 00,000 crores. Presently, Indian contribution is less than Rs.2000 crores. The annual production of medicinal and aromatic plant's raw material is worth about Rs.200 crores.

This is likely to reach US $5 trillion by 2050. It has been estimated that in developed countries such as United States, plant drugs constitute as much as 25% of the total drugs, while in fast developing countries such as China and India, the contribution is as much as 80%. Thus, the economic importance of medicinal plants is much more to countries such as India than to rest of the world. (Joy, P.P., 2001)

Biodiversity of herbals in India:

India is one of the world's 12 biodiversity centers with the presence of over 45000 different plant species. India's diversity is UN compared due to the presence of 16 different agro-climatic zones, 10 vegetation zones, 25 biotic provinces and 426 biomes (habitats of specific species). Among these, about 15000-20000 plants have good medicinal value. However, only 7000-7500 species are used for their medicinal values by traditional communities.In India, drugs of plant origin have been used in traditional systems of medicines such as Unani and Ayurveda since ancient times. The Ayurveda system of medicine uses about 700 species, Unani 700, Siddha 600, Amchi 600 and modern medicine around 30 species.

About 8,000 herbal remedies have been included in Ayurveda. The Rig-Veda (5000 BC) has recorded 67 medicinal plants, Yajurveda 81 species, Atharvaveda (4500-2500 BC) 290 species, Charak Samhita (700 BC) and Sushrut Samhita (200 BC) had described properties and uses of 1100 and 1270 species respectively, in compounding of drugs and these are still used in the classical formulations, in the Ayurvedic system of medicine. (Joy, P.P., 2001)

Sources of medicinal drugs:

The drugs are derived either from the whole plant or from different organs, like leaves, stem, bark, root, flower, seed, etc. Some drugs are prepared from excretory plant product such as gum, resins and latex. Plants, especially used in Ayurveda can provide biologically active molecules and lead structures for the development of modified derivatives with enhanced activity and /or reduced toxicity. Some important chemical intermediates needed for manufacturing the modern drugs are also obtained from plants (Eg. β-ionone).The forest in India is the principal(diosgenin, solasodine) repository of large number of medicinal and aromatic plants, which are largely collected as raw materials for manufacture of drugs and perfumery products.

The small fraction of flowering plants that have so far been investigated have yielded about 120 therapeutic agents of known structure from about 90 species of plants. Some of the useful plant drugs include vinblastine, vincristine, taxol, podophyllotoxin, camptothecin, digitoxigenin, gitoxigenin, digoxigenin, tubocurarine, morphine, codeine, aspirin, atropine, pilocarpine, capscicine, allicin, curcumin, artemisinin and ephedrine among others. (Joy, P.P., 2001)

History of herbal medicine:

Ayurveda, Siddha, Unani and Folk (tribal) medicines are the major systems of indigenous medicines. Among these systems, Ayurveda is most developed and widely practiced in India. Ayurveda dating back to 1500-800 BC has been an integral part of Indian culture. The term comes from the Sanskrit root Au (life) and Veda (knowledge).

As the name implies it is not only the science of treatment of the ill but covers the whole gamut of happy human life involving the physical, metaphysical and the spiritual aspects. Ayurveda is gaining prominence as the natural system of health care all over the world. Today this system of medicine is being practiced in countries like Nepal, Bhutan, Sri Lanka, Bangladesh and Pakistan, while the traditional system of medicine in the other countries like Tibet, Mongolia and Thailand appear to be derived from Ayurveda.

Phytomedicines are also being used increasingly in Western Europe. Recently the US Government has established the "Office of Alternative Medicine" at the National Institute of Health at Bethesda and its support to alternative medicine includes basic and applied research in traditional systems of medicines such as Chinese, Ayurvedic. (Joy, P.P., 2001)

Disadvantages:

A major lacuna in Ayurveda is the lack of drug standardization, information and quality control. Most of the Ayurvedic medicines are in the form of crude extracts which are a mixture of several ingredients and the active principles when isolated individually fail to give desired activity. This implies that the activity of the extract is the synergistic effect of its various components. About 121 (45 tropical and 76 subtropical) major plant drugs have been identified for which no synthetic one is currently available.The scientific study of traditional medicines, derivation of drugs through bio prospecting and systematic conservation of the concerned medicinal plants is of great importance.Unfortunately, much of the ancient knowledge and many valuable plants are being lost at an alarming rate.

Red Data Book of India has 427 entries of endangered species of which 28 are considered extinct, 124 endangered, 81 vulnerable, 100 rare and 34 insufficiently known species (Thomas, 1997).There are basically two scientific techniques of conservation of genetic diversity of these plants. They are the in situ and ex situ method of conservation. (Joy, P.P., 2001)

In Situ conservation of medicinal plants:

It is only in nature that plant diversity at the genetic, species and eco-system level can be conserved on long-term basis. (www.ggssc.net)It is necessary to conserve in distinct, representative bio geographic zones inter and intra specific genetic variation.

Ex situ conservation of medicinal plants:

A. Ethno-medicinal plant gardens:

Creation of a network of regional and sub-regional ethno-medicinal plant gardens which should contain accessions of all the medicinal plants known to the various ethnic communities in different regions of India. This chain of gardens will act as regional repositories of our cultural and ethno medicinal history and embody the living traditions of our society's knowledge of medicinal plants. (www.ggssc.net)

Current status:

There are estimated to be around 50 such gardens in the country ranging from acre to 40 acres some of them were set up by an All India Health Network (AHN). More recently a network of 15 such gardens has been set up in 3 states of South India with the initiative of FRLHT. One of the gardens is located in TBGRI, (Tropical botanical garden research institute) Palode at Thiruvananthapuram.

B. Gene banks:

In India there is a large number of medicinal plant species are under various degrees of threat. The precautionary principles would suggest that an immediate and country-wide exercise be taken up to deposit seeds of wild medicinal plants with a first priority to known Red listed species and endemic species.

Current status:

The department of bio-technology, Government of India has recently taken the initiative to establish 3 gene banks in the country. One is with ICAR at the NBPGR (National Bureau of plant genetic Resources) Campus, the second is with CIMAPs, (Central Institute of Medicinal and Aromatic plants) Luck now and the third with TBFRI in Thiruvananthapuram.

C. Nursery network:

The most urgent and primary task in order to ensure immediate availability of plants and planting materials to various user groups is to promote a nationwide network of medicinal plant nurseries, which will multiply all the regional specific plants that are used in the current practice of traditional medicine. These nurseries should become the primary sources of supply of plants and seed material that can be subsequently multiplied by the various users.

Current status:

Planting material for 40 odd species of medicinal and aromatic plants is reportedly available in the ICAR and CSIR (CIMAP) network. In South India FRLHT (Foundation for Rural Revitalization of Local Health Tradition) has recently set up a network of 55 supply nurseries.

D. Cultivation of medicinal plants:

Figures projecting demand and trade in medicinal plant species globally indicate a step upward trend in the near future.One estimate puts the figure of world trade in medicinal plants and related products at US $ 5 trillion by A.D. 2050 (world bank report , 1996).The demand so far has been met mainly from wild sources. This can't go on for much longer; policy intervention is urgently needed to encourage and facilitate investments into commercial cultivation of medicinal plants. (Joy, P.P., 2001)Cultivation of medicinal plants is inversely linked to prevalence of easy and cheap collection from the wild, lack of regulation in trade, cornering of the profits from wild collection by a vast network of traders and middlemen and absence of industry's interest in providing buy-back guarantees to growers.

Current status:

In the Govt. sector agro-technology of 40 odd species has been developed by ICAR - Agricultural University System and CSIR (CIMAOs & RRL, Jammu and Jorhat). In recent years industries like Dabur, Zandu, Indian Herbs, Arya Vaidya Shala, and Arya Vaidya Pharmacy and others have made some symbolic efforts to initiate cultivation. Since1984 NABARD (National Bank of Agricultural and Rural Development) has formulated schemes for financing cultivation and processing of medicinal plants.

E. Community based enterprises:

The income generated by the traditional medicine industry benefits small section of the society. A strong case exists for promotion of community level enterprises for value addition to medicinal plants through simple, on site techniques like drying, cleaning, crushing, powdering, grading, packaging etc. This will also increase the stake of rural communities in conservation and change the skewed nature of income distribution of the industry.

Current status:

Three community based enterprises are known in south India, one in Gandhi gram

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