Stilbene synthase catalyses the conversion of p-Cumaroyl-CoA to resveratrol.

Resveratrol (3,5,4-trihydroxy-trans-stilbene) belongs to the flavonoid group of compounds and is classed among the phytoalexins.Phytoalexins are a class of antibiotic polyphenol compounds that form part of the plant defence system.  Resveratrol was first identified and isolated from Japanese knotweed plants, but it is also present in grapevine (Vitis vinifera), pine, linseed, sesame seed and peanuts. In grapevine the highest concentration of resveratrol (between 50 and 100 μg/g) is found in the grape skins.

Resveratrol is a metabolite produced by the plant in response to stress, for instance, when subjected to high levels of ozone or ultra violet irradiation, or when under attack by fungi or insects. Beneficial effects on the human immune system have also been attributed to resveratrol. This is based mainly on its antioxidant properties. Resveratrol is primarily a scavenger of peroxy radicals. It reduces lipoprotein lipid (LDL) peroxidation and protects cell membranes against the damaging effects of oxidated LDL. Resveratrol is also thought to have anticarcinogenic and cancer-inhibiting properties.