These redox-active catechin oligomers (procyanidin B-2; FW = 575.50 g/mol; procyanidin B-3; FW = 575.50 g/mol) exhibit potent antioxidant activity. After lignin, they are among the most abundant natural phenolics. Fourteen dimeric, eleven trimeric, and one tetrameric procyanidins alreadyt identified within grape seeds. Target(s): 1-alkylglycerophosphocholine Oacetyltransferase, inhibited by procyanidin B-2 3,3'-di-O-gallate and procyanidin B-5 3,3'-di-O-gallate; 5-lipoxygenase, or arachidonate 5- lipoxygenase, inhibited by di- and trimeric procyanidins; 12- lipoxygenase, or arachidonate 12-lipoxygenase, inhibited most by decameric procyanidins; 15-lipoxygenase, or arachidonate 15- lipoxygenase, inhibited most by decameric procyanidins; myosin-lightchain kinase; peptidyl-dipeptidase A, or angiotensin I-converting enzyme; protein kinase A; protein kinase C, inhibited by procyanidin B-2 and procyanidin C-1; squalene monooxygenase, or squalene epoxidase, inhibited by procyanidin B-2 3,3'-di-O-gallate and procyanidin B-5 3,3'-di-O-gallate; tyrosinase, or monophenol monooxygenase, weakly inhibited.
