Bacchus Knows Best: Cancer Drug in Grapes?

A battery of lab tests has indicated that a chemical found in grapes and other fruits and vegetables is a potential antitumor agent. But experts caution that the compound, described in a Report in tomorrow's issue of Science, is at least 2 years away from testing in humans, and the early results don't justify more trips to the wine rack.

Medicinal chemist John Pezzuto and colleagues at the University of Illinois, Chicago, weren't expecting to enhance the image of red wine when they began their study. His team was one of several that a few years ago began testing some 1000 plant extracts from around the world for the presence of potential antitumor agents. Their main assay pinpointed extracts that inhibit an enzyme called cyclooxygenase-1, a cog in the body's inflammatory response. Explains Pezzuto, "Anti-inflammatory agents tend to be good antitumor compounds."

> The team whittled these 1000 extracts down to three that seemed especially promising. The most potent came from the roots of Peru's Cassia quinquangulata tree, extracts of which are used in folk medicine to treat fever. Further experiments homed in on a constituent of the extract called resveratrol, a compound produced in some plants when they are under stress or attack from a pathogen. The compound did well in antitumor tests. Besides inhibiting cyclooxygenase, it impeded DNA mutations in Salmonella bacteria, increased activity of a mouse liver enzyme that detoxifies carcinogens, inhibited precancer lesions in mouse mammary cells, and thwarted growth of skin tumors on mice exposed to a potent skin carcinogen.

Resveratrol is particularly attractive as a candidate anticancer drug because it's easily obtained: The chemical is abundant in grape skin and has been found in at least 70 other plant species, including peanuts and mulberries. But experts caution that the compound has a long road ahead before a pharmacy debut. "This is a good lead, but it's early on," says Peter Greenwald, director of the National Cancer Institute's Cancer Prevention and Control division. Greenwald adds that resveratrol faces at least 2 years of further animal tests and safety tests before it's considered for a human cancer prevention trial: "We're certainly far from saying 'Drink a lot of red wine.' "