Plant Prospecting

Plant prospecting is the seeking out of plants for the development of new foods, prescription drugs, herbal dietary supplements, flavors and fragrances, cosmetics, industrial materials, pesticides, and other profitable products. Plant prospecting includes the selection and collection of plants from terrestrial, marine, and other aquatic ecosystems by expeditions to diverse areas of the world, such as tropical and temperate rain forests as well as arid and semiarid lands in Latin America, Africa, Australia, and Asia.

Field studies involve collecting plant samples in the wild for identification and labeling the samples for voucher, or reference, specimens . The specimens are deposited in herbaria, which are collections of preserved plants. If searching for plants for drug discovery programs, one kilogram of each plant species is typically gathered for further work in the laboratory. A plant extract is produced for screening for biological activity, followed by chemical isolation and identification of the compounds responsible for activity.

Botanists follow either random or targeted approaches when choosing plants for pharmacological studies and drug discovery. The random prospecting strategy is to gather all of the available vegetation in an area supporting rich biological diversity. The more focused methods are taxonomic, ecological, and ethnobotanical. The taxonomic method emphasizes the collection of close relatives of plants already known to produce useful compounds for medicine or other uses. The ecological approach focuses on plants that offer certain clues promissory of activity, such as plants free from herbivore predation, which imply the presence of chemical defenses. Finally, ethnobotanical prospecting is done by interviewing native healers who have knowledge of the local plant's medicinal properties.

The value of plant prospecting to the pharmaceutical industry is enormous. Some extremely effective treatments in modern medicine are derived from flowering plants in nature. Many prescription drugs contain molecules derived from, or modeled after, naturally occurring molecules in vascular plants. Tropical rain forests, with one-half or 125,000 of the world's flowering plant species, are the source of forty-seven commercial drugs, including vincristine (Oncovin), vinblastine (Velban), codeine, curare, quinine, and pilocarpine. Vincristine is the drug of choice for the treatment of childhood leukemia; vinblastine is used for the treatment of Hodgkin's disease and other neoplasms.

The potential value of the existence of undiscovered plants for use as drugs for modern medicine and other plant products of economic interest provide an incentive to conserve species-rich ecosystems throughout the world. A fear shared by many is that plant species, as well as tribal healing and conservation knowledge, will vanish before they are studied and recorded.

Because developing countries are rich in plant biodiversity but technology-poor, while developed countries are biodiversity-poor but technology-rich, arrangements should be made to compensate the holders of plant resources when these are used to make patentable and economic products. Efforts are underway to establish property rights of plant biodiversity, as yet-undiscovered drugs will become another powerful financial incentive to conserve tropical forests and other ecosystems. The 1992 Convention on Biological Diversity established for the first time international protocols for protecting and sharing national plant and other biological resources and specifically addressed issues of traditional knowledge.

see also Herbaria.

Barbara N. Timmermann

Bibliography

Artuso, Anthony. Drugs of Natural Origin. New York: Haworth Press, 1997.

Grifo, Francesca, and Joshua Rosenthal, eds. Biodiversity and Human Health. Washington, DC: Island Press, 1997.

Rouhi, A. Maureen. "Seeking Drugs in Natural Products." Chemical and Engineering News 75, no. 14 (1997): 14-29.

Ten Kate, Kerry, and Sarah A. Laird. The Commercial Use of Biodiversity. London:Earthscan Publications Ltd., 1999.