Lipophilized Grape Seed Proanthocyanidin Derivatives as Novel Antioxidants

Grape seed proanthocyanidin (GSP) is a natural food antioxidant. Natural proanthocyanidins (PC) in grape seed are usually polyhydroxy derivatives which exhibit hydrophilic character. GSP was modified structurally to improve its lipophilicity, expand its application in lipophilic media, and enhance its cellular absorption in vivo. Esterification of the water-soluble GSP was prepared by immobilized lipase Lipozyme TL IM with lauric acid, and their enhanced lipophilicity was confirmed by the 1-octanol/water partition coefficient. The presence of mono-, di-, and trilauroylated derivatives in GSP derivatives was confirmed by HPLC-MS-MS, and four lauroylated derivatives were identified as 3',5'-2-O-lauroyl epigallocatechin, 3'-O-lauroyl catechin, 3'-O-lauroyl epicatechin, and 3',3″,5″-3-O-lauroyl epicatechin gallate by NMR. GSP derivatives exhibited the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀ of 41 μg/mL) compared to that of GSP, hydroxytoluene (BHT), and tert-butyl hydroquinone (TBHQ). The results suggest that GSP derivatives may be used as potential lipophilic antioxidants in the food industry.