Resveratrol Extract

Resveratrol extract found in the skin of grapes is available as a dietary supplement. Resveratrol is clasified as polyphenol or polyphenolic phytoalexin which is produced in plants with the help of the enzyme stilbene synthase, which has antifungal properties. It is a stilbenoid, a derivate of stilbene. Besides red grapes it occures in peanuts, blueberries, some pines (Scots pine, eastern white pine) and the roots and stalks of Japanese knotweed (hu zhang in China) and giant knotweed. Resveratrol was first isolated from an extract of the Peruvian legume Cassia quinquangulata in 1974. It is now available as a mass-produced nutritional supplement but not as a therapeutic agent (though it is now registered as an investigational drug). The supplement, first sourced as ground dried red grape skins, has shifted somewhat to include certain of the knotweeds as a raw material.

Resveratrol is often referred to as a nutraceutical, along with other bioactive plant compounds that are being studied for potential clinical applications such as curcumin, EGCG and silibinin, among others.

The amount of resveratrol in food substances varies greatly. Red wine contains approximately 5 mg/L, depending on the grape variety, whilst white wine has much less - the reason being that red wine is fermented with the skins, allowing the wine to absorb the resveratrol, whereas white wine is fermented after the skin has been removed.