Naturally occurring resveratrol Rapid release capsules Food supplement Grapeseed Extract is derived from the seeds of red wine grapes and contains oligomeric proanthocyanidins (OPC's) and other polyphenolic compounds. Proanthocyanidins are naturally occurring bioflavonoids. Naturally occurring resveratrol Rapid release capsules Food supplement Grapeseed Extract is derived from the seeds of red wine grapes and contains oligomeric proanthocyanidins (OPC's) and other polyphenolic compounds. Proanthocyanidins are naturally occurring bioflavonoids.