Anticancer agents from plants

The initial studies of natural products as potential anticancer agents were made in the 1950s based on compounds from 

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D. G. I. Kingston, Taxol and Other Anticancer Agents from Plants" in J. D. Coombes, Ed., New Drugs from Natural Sources, IBC Technical Services, 1992, pp. 101-108. 

Cordell, G. A., Anticancer agents from plants, in Progress in... 

To continue the enumeration of various reference citations, consider the following partial listing A Dictionary of Natural Products Anticancer Agents from Natural Products Dictionary of Natural Products Phytochemicals Mechanisms of Action Nutrition and Cancer Phytopharmaceuticals in Cancer Chemoprevention Plants That Fight Cancer, etc. It is a sign of changing times and attitudes. The Dictionary of Natural Products has a listing of some 190,000 substances, is available on CD-ROM, and is updated biennially. 

Recent advances in the discovery of novel anticancer agents from higher plants are reported. These compounds are uncovered based on bioassay-directed fractionation and tandem MS analysis to detect analogs of significant lead compounds. The evolution and current status of the screening program of the U.S. National Cancer Institute is reviewed. 

In recent years, however, some of the greatest emphasis has been placed on the search for anticancer and antiviral agents derived from natural products. Success in that area has not heen as great as that achieved in other helds. Since 1960, only seven plant-derived drugs have heen approved by the FDA for use as anticancer agents. Four of those drugs, vinblastine, vincristine, etoposide, and teniposide, were discovered in the 1950s. The last three—Taxol , topotecan, and irinotecan—were discovered and approved much more recently. 

The plant. Podophyllum hexandrum (Podophyllaceae Berberidaceae), produces podophyllotoxin (3) and its glycoside, both of which are effective anticancer agents. Commercial production of podophyllotoxin from... 

One particular example of the early extraction of a chemical from a plant, a small tree found in the rainforests of eastern Queensland, would be that of acronycine 1 [1,2], an alkaloid currently undergoing clinical trials as an anticancer agent. More recently, a group in Perth at Murdoch University succeeded in extracting the alkaloid, swainsonine 2 from a desert shrub which causes poisoning in cattle [3]. Swainsonine has been found to exhibit an interesting spectrum of biological activity [4], especially as a potent, reversible inhibitor of various a-D-mannosidases [5]. 

Historically, plant-based natural products have been a source of useful drugs. The analgesic opiates come from the poppy plant. Digitalis for congestive heart failure was first isolated from the foxglove plant. Various antibiotics (penicillin) and anticancer agents (taxol) are derived from natural product sources. There are numerous other examples. 

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