The National Cancer Institute (NCI) has several ongoing collabrative programs which screen plants for the possiblility of new drugs and active plant chemicals for cancer and AIDS/HIV.

Because well over 50 percent of the estimated 250,000 plant species found on earth come from tropical forests, NCI concentrates on these regions. Plants have been collected from the African countries of Cameroon, the Central African Republic, Gabon, Ghana, Madagascar, and Tanzania. Collections are now concentrated in Madagascar (one of the most rapidly dissappearing rainforest regions in the world), and collaborative programs have been established in South Africa and Zimbabwe.

In Central and South America, samples have been collected from Belize, Bolivia, Colombia, the Dominican Republic, Ecuador, Guatemala, Guyana, Honduras, Martinique, Paraguay, Peru, and Puerto Rico. The NCI has established collaborative programs in Brazil, Costa Rica, Mexico, and Panama. Southeast Asian collections have been performed in Bangladesh, Indonesia, Laos, Malaysia, Nepal, Pakistan, Papua New Guinea, the Philippines, Taiwan, Thailand, and Vietnam. Collaborative programs have been established in Bangladesh, China, Korea, and Pakistan. In each country, NCI contractors work in close collaboration with local botanical institutions.

These collabrative programs include the following:

• The South American Organization for Anticancer Drug Development (SOAD) in Porto Alegre, Fundacao Oswaldo Cruz-FIOCRUZ in Rio de Janeiro, and the University Paulista in Sao Paulo investigate plants from Brazil.
• The Institute of Biological Diversity (INBio) in Costa Rica studies insects and plants.
• The Institute of Chemistry, National University of Mexico, studies medicinal plants.
• The Kunming Institute of Botany in China studies Chinese medicinal plants.
• The Korean Research Institute of Chemical Technology examines Korean medicinal plants.
• The H.E.J. Institute of Chemistry, University of Karachi, studies Pakistani plants.
• The University of Dhaka in Bangladesh studies plants and microbes.
• University of Panama studies Panamanian medicinal plants.
• Brigham Young University (Dr. Paul Cox) studies Polynesian medicinal plants.
• Tel Aviv University (Dr. Yoel Kashman) studies Red Sea marine invertebrates.
• The New Zealand National Institute of Water and Atmospheric Research studies marine organisms.
• The Cancer Research Center at the Russian Academy of Medical Sciences in Moscow studies Russian medicinal plants.
• The Zimbabwe National Traditional Healers Association and the University of Zimbabwe study Zimbabwean medicinal plants.
• The South African Council for Scientific and Industrial Research studies South African plants.

Thus far seven plant-derived anticancer drugs have received Food and Drug Administration (FDA) approval for commercial production:

• Taxol / Paclitaxel
  A chemical discovered in the Pacific Yew tree (Taxus brevifolia) is now the first drug of choice in several tumorous cancers including Breast Cancer.

• Vinblastine
  A chemical discovered in the Madagascar Periwinkle in the 1950s. Vinblastine is the first drug of choice in many forms of leukemia and since the 1950's it has increased the survival rate of childhood leukemias by 80%

• Vincristine
  Another antileukemic drug discovered in the Madagascar periwinkle.

• Topotecan
  Has been approved by the FDA for the treatment of ovarian and small cell lung cancers. It is currently in clinical trials, either alone or in combination with other anticancer drugs, for several types of cancer. Topotecan is a analog (a synthesized chemical) of a plant alkaloid discovered in the Chinese tree species, Camptotheca acuminata

• Irinotecan
  Another chemical analog which has been developed from yet another plant alkaloid discovered in the same tree Camptotheca acuminata. It has been approved by the FDA for the treatment of metastatic colorectal cancer. It is currently in clinical trials for a variety of other cancers.

• Etoposide
  A semisynthetic derivative of a plant chemical epipodophyllotoxin discovered in the Mayapple plant family (Podophyllum peltatum)

• Teniposide
  Another semisynthetic derivative of a plant chemical discovered in the Mayapple plant family (Podophyllum peltatum).

Since 1986, over 40,000 plant samples have been screened, but thus far only five chemicals showing significant activity against AIDS have been isolated. Three are currently in preclinical development. Before being considered for clinical trials in humans, these agents must show tolerable levels of toxicity in several animal models. For AIDS, three agents are presently in preclinical or early clinical development. The following are plants and chemicals which are still under research for cancer and AIDS/HIV:

• (+)-Calanolide A and (-)-Calanolide B (costatolide) are isolated from Calophyllum lanigerum and Calophyllum teysmanii, respectively, trees found in Sarawak, Malaysia. Both these agents are licensed to Medichem, Inc., Chicago, which is developing them in collaboration with the Sarawak State Government through a joint company, Sarawak Medichem Pharmaceuticals, Inc. (+)-Calanolide A is currently in early clinical trials in the United States.
• Conocurovone, isolated from the shrub species, Conospermum incurvum (saltbush), found in Western Australia, has been licensed for development to AMRAD, a company based in Victoria, Australia.
• Michellamine B, from the leaves of Ancistrocladus korupensis, a vine found in the Korup rainforest region of southwest Cameroon, has undergone extensive preclinical study, but is considered too toxic for advancement to clinical trials.
• Prostratin, isolated from the wood of Homolanthus nutans, a tree found in Western Samoa, has been placed on low priority, largely due to its association with a class of compounds shown to be tumor promoters.
• A tree native to China--Camptotheca acuminata--is the source of four promising anticancer drugs, two of which have been approved by the FDA and are described above. The other two chemicals still under research include:
• 9AC (9-aminocamptothecin): Currently in clinical trials for several types of cancer, including ovarian and stomach cancers and T-cell lymphoma.
  
• Camptothecin: While no clinical trials are being performed in the United States, trials are ongoing in China.
• Homoharringtonine from the Chinese tree, Cephalotaxus harringtonia are in early clinical trials.
• Perillyl alcohol, and flavopiridol, a totally synthetic compound based on a flavone isolated from Dysoxylum binectiferum are in early clinical trials.
  
  
  

Need more on this subject? Try theses resources:


(Easy) This 2017 article updates the plant tables above: Plant-derived-anticancer-agents
(Hard) Discovery and resupply of pharmacologically active plant-derived natural products: A review
(Easy) For more on this subject, also see Chapter 2 of The Healing Power of Rainforest Herbs, by Leslie Taylor
(Easy) Why do plants have medicinal properties
(Easy) History of medical botany

The above text has been authored by Leslie Taylor, Milam County, Texas 77857 and copyrighted © 2000 to present. All rights reserved. Please refer to the Copyright Statement on permitted uses of this document.