The drugs are synthetic versions of resveratrol, found in red wine, an organic chemical believed to have an anti-ageing effect, by boosting activity of a protein called SIRT1.
GSK, the pharmaceutical firm, is testing them on people with particular medical conditions, namely Type II diabetes and psoriasis, a serious skin condition.
David Sinclair, professor of genetics at Harvard University, said ageing might not actually be an "irreversible affliction".
He said: “Now we are looking at whether there are benefits for those who are already healthy.
"Things there are also looking promising. We're finding that ageing isn't the irreversible affliction that we thought it was.
"Some of us could live to 150, but we won't get there without more research."
He explained that increasing SIRT1 activity improved how well our cells operated, making them less sluggish. In previous experiments, mice, bees and flies given the SIRT1-boosting compounds lived longer.
Writing in the journal Science, Prof Sinclair claimed to have performed experiments which showed these resveratrol-based compounds were having a direct effect on health. Some scientists have argued that the effect was not real, but experimental artifice.
Despite the controversy, there have already been promising results in some trials with implications for cancer, cardiovascular disease and heart failure, Type II diabetes, Alzheimer's, Parkinson's, fatty liver disease, cataracts, osteoporosis, muscle wasting, sleep disorders and inflammatory diseases such as psoriasis, arthritis and colitis.
Current trials look at how the compounds might help treat these age-related disease.
But Prof Sinclair believed that in time they would also be examined for their preventative effect. Just as statins are used today to prevent heart disease and strokes, so these compounds could be used to slow a wide-range of diseases.
Prof Sinclair is a consultant and inventor on patents licensed to Sirtris, the GSK company running the trials.