The company plans to start clinical trials of its resveratrol mimic soon. Sirtris’s value to GlaxoSmithKline is presumably that its sirtuin-activating drugs could be used to treat a spectrum of degenerative diseases, like cancer and Alzheimer’s, if the underlying theory is correct.

Separately from Sirtris’s investigations, a research team led by Tomas A. Prolla and Richard Weindruch, of the University of Wisconsin, reports in the journal PLoS One on Wednesday that resveratrol may be effective in mice and people in much lower doses than previously thought necessary. In earlier studies, like Dr. Auwerx’s of mice on treadmills, the animals were fed such large amounts of resveratrol that to gain equivalent dosages people would have to drink more than 100 bottles of red wine a day.

The Wisconsin scientists used a dose on mice equivalent to just 35 bottles a day. But red wine contains many other resveratrol-like compounds that may also be beneficial. Taking these into account, as well as mice’s higher metabolic rate, a mere four, five-ounce glasses of wine “starts getting close” to the amount of resveratrol they found effective, Dr. Weindruch said.

Resveratrol can also be obtained in the form of capsules marketed by several companies. Those made by one company, Longevinex, include extracts of red wine and of a Chinese plant called giant knotweed. The Wisconsin researchers conclude that resveratrol can mimic many of the effects of a caloric-restricted diet “at doses that can readily be achieved in humans.”

The effectiveness of the low doses was not tested directly, however, but with a DNA chip that measures changes in the activity of genes. The Wisconsin team first defined the pattern of gene activity established in mice on caloric restriction, and then showed that very low doses of resveratrol produced just the same pattern.

Dr. Auwerx, who used doses almost 100 times greater in his treadmill experiments, expressed reservations about the new result. “I would be really cautious, as we never saw significant effects with such low amounts,” he said Tuesday in an e-mail message.

Another researcher in the sirtuin field, Dr. Matthew Kaeberlein of the University of Washington in Seattle, said, “There’s no way of knowing from this data, or from the prior work, if something similar would happen in humans at either low or high doses.”