Tribal people have gathered their [V 004 / medicines from rainforest plants] for thousands of years and continue to do so today. Around one quarter of all manufactured medicines are derived from plants found in the tropical rainforests. Contraceptive pills, laxatives, antibiotics, tranquilizers and cough medicines all come from rainforest plants. The rainforest plant-based pharmaceutical industry brings annual profits of nearly US$20 billion.
Many rainforest plants contain '[L3 705 / defense chemicals]' in their genetic make-up. Scientists realized that if the plant had developed a chemical substance to fight disease, these chemicals might also be useful for fighting disease in humans.
Two of the most important materials which are extracted from plants and used for making pharmaceutical drugs are [G 03 / alkaloids] and secondary plant metabolites. The rosy periwinkle of the Madagascar rainforests produces the Vinca alkaloids. This substance has been used to manufacture two drugs, vincristine and vinblastine, which help fight leukemia, Hodgkin's disease and many kinds of cancer.
American scientists at the US National Cancer Institute have identified over 1,400 plants from tropical forests which might help fight cancer. Many of these are found in Amazonia. [L3 706 / Both quinine, used for treating malaria, and curare], which helps treat cancer and Parkinson's disease, were discovered in Amazonia. The roots of the Dioscorea vine produce the raw materials for diosgenin which is used in contraceptive pills, cortisone and some other medicines.
Of the 125,000 tropical rainforest plant species which have been identified so far, only about one tenth have been examined by scientists, and only around one hundredth in any great detail. From figures of numbers of plants used for medicines in Java, India and the Philippines, scientists have calculated that approximately five percent of the world's plants have medicinal value. About half of these grow in lowland tropical rainforests. This is huge potential for discovering new drugs to fight various human diseases and even hope for finding a cure for AIDS.
