a tree found in India is the world's richest source of camptothecin (cpt), a drug used to treat cancers of the ovaries and the colon. In an effort to ensure sustainable availability of cpt, researchers from Bangalore have carried out a survey of Nothapodytes nimmoniana trees in the Western Ghats. They found that some individual trees had cpt content almost twice of what had been reported earlier.
The researchers were drawn from the University of Agricultural Sciences, gkvk Campus, Ashoka Trust for Research in Ecology and the Environment, College of Forestry, Sirsi and Jawaharlal Nehru Centre for Advanced Scientific Research in Jakkur.
As part of the survey, samples of stem wood, bark, root and mature leaves were collected from three sites -- Sirsi, Joida and Ulvi in the Uttara Kannada district of Karnataka. Among the various tissues analysed, the root bark yielded the highest cpt content. The researchers also found that the mean cpt content in root bark was significantly greater for trees in Ulvi than that for the trees in Sirsi and Joida. The researchers feel that the differences in the levels of cpt are related to both the genetic and environmental backgrounds of the population.
The researchers hope that once the high-yielding varieties have been identified, the trees could be used to prepare clones or cell lines, which could provide the chemical. Individuals with high cpt content could be a used to raise plantations of high cpt yielding trees as a part of agro forestry systems. Several captive plantations of the tree have already been initiated in the states of Karnataka and Tamil Nadu.
Though other plants also yield this chemical, N nimmoniana, commonly called the "stinking tree" is being overexploited. As a result, there has been an estimated 20 per cent decline in its natural population over the last decade in India. The tree is found in southern India, the Himalayan foothills and Assam. It also grows in Sri Lanka, Myanmar and Thailand.