April 22 (Bloomberg) -- GlaxoSmithKline Plc, Europe's biggest drugmaker, said it agreed to buy Sirtris Pharmaceuticals Inc. for about $720 million, adding an experimental drug derived from red wine that's thought to slow the effects of aging.

Glaxo will pay $22.50 a share in cash for Sirtris, the London-based drugmaker said today in an e-mailed statement. The offer is 84 percent more than Sirtris' closing price today of $12.23.

Sirtris, based in Cambridge, Massachusetts, focuses on developing drugs that activate sirtuins, a class of enzymes involved in aging. Its most advanced compound is a formulation of resveratrol, a substance found in red wine and plants. The purchase gives Glaxo a foothold in a new area of research and could lead to treatments for diabetes, muscle wasting and neurodegeneration, the company said.

``It's not an inexpensive price, for sure, but this could be a good investment from Glaxo's standpoint,'' said Linda Bannister of Edward Jones & Co. in a telephone interview today. ``Companies like Glaxo are continuing to look for deals whether it's licensing products or making small acquisitions to augment their current pipeline, so this makes sense.''

The price for Sirtris is reasonable compared with the research and development costs Glaxo would have to pay to advance similar compounds itself, Bannister said.

SRT501

``This helps us accelerate our vision,'' said Sirtris Chief Executive Officer Christoph Westphal in a telephone interview today. ``We want to get these drugs to market as soon as possible, and we wouldn't have been able to do it is fast alone.''

The lead drug candidate, SRT501, could come to market as soon as five to seven years from now, Westphal said. He will be staying after the acquisition to continue working with the group.

SRT501 mimics resveratrol, which has been linked to longevity, Sirtris scientists said. The Sirtris molecule is 1,000 times more potent than resveratrol, and could lead to solutions for diseases of aging including cancer and diabetes, according to an article published in the journal Nature.

``Sirtris's core scientific platform is based on enzymes that show interesting results in terms of lifespan extension,'' said Bret Holley, an analyst for Oppenheimer & Co., in a telephone interview today.

SRT501 is being evaluated as a diabetes treatment in the second of three phases of human tests needed for regulatory approval, Holley said. Data from the study is expected later this year, he said.

``Virtually any disease of aging may well be a way to apply this technology,'' Westphal said. ``This is a very hot field. We're a little company several years ahead of anyone else in the field and so that's a wonderful thing for a large pharmaceutical company to want to access.''

The acquisition was approved by the boards of both companies and is expected to be completed in the second quarter.

To contact the reporter on this story: Elizabeth Lopatto at elopatto@bloomberg.net.

Last Updated: April 22, 2008 18:47 EDT