Source Naturals - Grape Seed Extract 200mg 60 caps. Source Naturals Grape Seed Extract is a rich source of procyanidins - water-soluble antioxidant flavonoids that are excellent free radical scavengers and have been shown to support the capillaries and circulatory health. Grape Seed Extract also has b... - Source Naturals - Grape Seed Extract 200mg 60 caps.