Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a phytoalexin produced naturally by several plants when under attack by pathogens such as bacteria or fungi, significantly extends the lifespan of the yeast Saccharomyces cerevisiae, Caenorhabditis elegans and the fruit fly Drosophila melanogaster. Resveratrol is currently a topic of numerous animal and human studies into its effects. The effects of resveratrol on the lifespan of many model organisms remain controversial. Anti-cancer, anti-inflammatory, blood-sugar-lowering, and other beneficial cardiovascular effects of resveratrol have been reported in experiments with mouse and rat model systems. However, most of these results have yet to be replicated in humans. Resveratrol is found in the skin of red grapes and is a constituent of red wine. Resveratrol has also been produced by chemical synthesis or by biotechnological synthesis and is sold as a nutritional supplement derived primarily from Japanese knotweed.