Metabolic effects of resveratrol in mammals--a link between improved insulin action and aging.

Resveratrol, a polyphenol found in several vegetal sources, has been shown to possess lifespan-promoting properties in yeast and metazoans, including small mammals. While in yeast and low metazoans resveratrol acts mainly by activating the histone deacetylase Sir2, in mammals it appears to target - besides the Sir2 homolog SIRT1 - several crucial pathways for the control of metabolism, including the AMPK and the insulin-IGF1 receptors axis. The action of resveratrol on these pathways has been linked to its capability to i) prolong lifespan following chronic administration to mice and ii) protect from the development of diet-induced obesity and obesity-dependent metabolic disorders. Here we summarise the current understanding on how resveratrol displays its remarkable properties by acting on the control of insulin secretion and by modulation of insulin action in pheripheral insulin-responsive tissues. Since resveratrol has the potential for pharmacological exploitation to prevent the establishment of insulin-resistance and thus postpone - or even prevent - the onset of type 2 diabetes, toxicologic and pharmacodynamics studies in humans have been initiated. These studies show that resveratrol is non-toxic and easily absorbed by humans. As a drawback, its bioavailability is very limited due to the fast metabolic alterations to which it is subjected in the plasma. Therefore, we also review here the efforts that have been made - in the drug discovery field - to identify new molecules endowed with resveratrol-like pharmacological properties but with better bioavailability, which could prove to possess therapeutic potential.