Neurodegenerative diseases are the leading cause of disability in the
elderly. Growing evidence suggests that oxidative stress, which is associated with
aging, is the basis of most neurodegenerative disorders; and polyphenols, acting as
antioxidant agents, reduce the risk of neurodegenerative diseases. Quercetin is a
flavonoid occurring in many plant foods commonly consumed as part of a regular
diet. It shows a number of biological properties connected to its antioxidant activity.
This review assesses the molecular structure of quercetin, its food sources and
bioavailability. Moreover, the main results obtained from in vitro studies, observing
the mechanisms of action through which quercetin exerts its antioxidant activity, are
reported. However, most of these effects have only been observed in vitro and
clinical studies are lacking.