The Longevity Pill?

Continued from page 1

Still, Burant and others caution that it's too soon to tell how well the drug will work in humans, whose metabolism drastically differs from that of rodents. Sirtris is also testing a resveratrol-like compound in clinical trials for treating diabetes, with initial results expected later this year or early next year.

Both Sinclair and Westphal have high hopes for the drugs, in part because they appear to mimic the effects of caloric restriction, which has been shown to delay or slow the progression of a variety of age-related diseases. So the novel SIRT1 activators might have the potential to treat illnesses ranging from Alzheimer's disease to heart disease to cancer. "The big news here is that maybe all big diseases of aging fall into the same category and can be treated with sirtuin activators," says Leonard Guarente, an MIT biologist whose lab discovered the first sirtuin gene. Guarente recently joined Sirtris's advisory board.

Initial studies suggest that activating SIRT1 can slow neurodegeneration, and tests of the compounds' impact on animal models of different diseases are ongoing.

However, many questions remain to be answered. While Sinclair and Guarente argue that the new findings support the idea that sirtuins lie at the heart of caloric restriction's health and longevity benefits, not everyone agrees. And the issue that has garnered the most media attention--whether or not such compounds will provide a molecular fountain of youth--is still unclear. While the diabetes research is promising, says Burant, "the life-extension part of this story is still incomplete."

In fact, that question may remain open for a few more years. Sinclair's team is testing the compounds' effect on life span, "but we may know if they can treat a disease in humans before we know if mice live longer," he says.