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A. paniculata is distributed in tropical Asian countries often in isolated patches. It can be found in a variety of habitats viz. plains, hill slopes, waste lands, farms, dry or wet lands, sea shore and even road sides. Native populations of A. paniculata are spread throughout south India and Sri Lanka which perhaps represent the centre of origin and diversity of the species (Hooker, 1885; Bhat and Nanavati, 1978). The herb is also available in northern stations of India, Java, Malaysia, Indonesia, West Indies and elsewhere in Americas where it is probably introduced (Hooker, 1885; Ridley, 1967; Backer and Brink Jr., 1967; Correll and Correll, 1982).
As per personal communication from Krishna Murti (Royal Botanic Gardens, Kew), the species is also available in Hong Kong, Penang, Malacca, Pangkor Island (south of Penang), Malaya, Thailand, West Java, Borneo, Celebes, Brunei, West Indies, Jamaica, Barbados, Bahamas etc. However, precise data are lacking on the introduction and naturalization of the species in these countries.
Unlike other species of the genus, A. paniculata is of common occurrence in most of the places in our country including the plains and hilly areas up to 500 m, which accounts for its wide use. Since time immemorial, village and ethnic communities in India have been using this herb for treating a variety of ailments (Table 1.3).
It is one of the important ingredients in Ayurvedic preparations recommended for fever and liver diseases. These include 'Liv 52' for treating hepatotoxicity (Dwivedi et al., 1987); 'TBR-002' for fever (Subramaniam et al., 1995), 'Kan Jang' for cold, flu and sinusitis (Hancke et al., 1995; Panossian et al., 2000), ‘Tephroli’ for treating viral hepatitis (Dutta and Sukul, 1982); ‘Ayush-57’ effective in treating vitiligo (Rao et al., 1980) and ‘Hepatogard’– an indigenous formulation exhibiting hepatoprotective activity (Saraf et al., 1991). Some industrial units like Natural Remedies India, Bangalore prepare semi-purified leaf extracts containing high concentrations (15-60%) of andrographolide and supply to other drug and fine compound manufacturing companies as the case may be for further value addition. Besides, Natural Remedies India Pvt Ltd (Bangalore), Alpha Omega Labs (USA), Sabinsa Corporation (USA) etc are also preparing extracts and drugs out of this important medicinal plant. Several Web sites deal with ethnobotanical, chemical, pharmaceutical and other aspects of A. paniculata (Table 1.4).
Andrographolide, chief constituent extracted from the leaves of the plant, is a bitter water-soluble lactone exhibiting protective effects in carbon tetrachloride induced hepatopathy in rats. Its LD50 in male mice was 11.46gm/kg, ip (Handa and Sharma, 1990). This bitter principle was isolated in pure form by Gorter (1911). Andrographolide is also attributed with such other activities like liver protection under various experimental conditions of treatment with galactosamine (Saraswat et al, 1995), paracetamol (Visen et al, 1993) etc. The hepatoprotective action of andrographolide is related to activity of certain metabolic enzymes (Choudhury and Poddar, 1984, 1985; Choudhury et al, 1987).
Despite its enormous medicinal and economic importance, attempts to cultivate A. paniculata have seldom been undertaken in any part of the country; hence local vaidyas as well as drug companies depend on wild sources for the supply of raw material. Gupta and Srivastava (1995) have reported a systematic cultivation experiment using different accessions of A. paniculata at NBPGR, New Delhi. Cultivation experiments are also reported by various authors from different parts of SE Asia (Zhou, 1987; Ramesh et al, 1997; Alagesaboopathi and Balu, 1997; Nandi, 1992; Muniramappa et al, 1997). Production of a variant line of A. paniculata by plant tissue culture has been standardised by Roy and Dutta in 1998.
Consequent upon the enforcement of the Convention of Biological Diversity and other patent/IPR regimes, it is imperative that the gene rich third world countries including India work out suitable strategies and mechanisms to evaluate their resources and develop new plant types and plant-specific value added products and processes. Unless these countries develop necessary competence and know-how to prospect their resources, they will be low paid for the unimproved genetic resources they export and may get trampled by the technologically as well as economically rich powerful countries. Against this growing realism and necessity in the developing world, it is of considerable significance to use modern tools and techniques of biotechnology and identify components of biodiversity for conservation and sustainable utilization. Taking A. paniculata as the experimental material, the author has attempted to study the biology of the species to understand its genetic fidelity and the pattern of gene flow and to evaluate the germplasm collected from different phytogeographical regions to identify genotype(s) of greater economic potential. In this process, variability existing in the wild populations of the species purported to have ecological and more importantly genetic basis, has been addressed at morphological, cytological, phytochemical, biochemical and molecular levels. It should be noted that even basic biological data are lacking in A. paniculata as also the case with many other medicinal plants. It is needless to say that in the wilderness of nature, the populations of a sexually reproduced species like A. paniculata are presumably so varied, that selection of high biomass and product yielding genotypes is distinctly possible and holds much promise for upgradation into cultivars.