Increase of stress resistance and lifespan of Caenorhabditis elegans by quercetin.

The health beneficial effects of a diet rich in fruits and vegetables are, at least in part, attributed to polyphenols that are present in many herbal edibles. Although many in vitro studies revealed a striking variety of biochemical and pharmacological properties data about the beneficial effects of polyphenols in whole organisms, especially with respect to ageing, are quite limited. We used the well established model organism Caenorhabditis elegans to elucidate the protective effects of quercetin, the main representative of the flavonol class of polyphenols, in vivo. Quercetin is taken up by the worms, enhanced the resistance to oxidative stress and prolonged the mean lifespan of C. elegans by 15%. Quercetin was shown to be a strong radical scavenger possibly explaining the observed down-regulation of mitochondrial manganese superoxide dismutase by a reduced need for this antioxidant enzyme for maintenance of cellular redox homeostasis. Quercetin treatment also led to a translocation of the C. elegans FoxO transcription factor DAF-16 into the nucleus, a state often correlated with stress response and longevity. According to our results we suggest that the protective and life prolonging action of quercetin is not only due to its strong antioxidant capacity but may also be mediated by modulation of signalling pathways.