Grape catechins - natural antioxidants.

摘要

Grape skins contain catechin monomers and procyanidin dimers, which are natural antioxidants. Concn. of the catechin monomers (+)-catetechin and (-)-epicatechin and the procyanidin dimers B1, B2, B3 and B4 were determined by HPLC in grape skin extracts of 10 winemaking grape cv. grown in the Dalmatian region of Croatia (Plavac mall, Trnjak, Vranac, Merlot, Cabernet sauvignon, Plavina, Game bojadiser, Kajundzusa, Okatica bijela and Rkaciteli). Catechin monomers were present in almost all grape skin extracts from the 1990-1992 vintages. The main catechin monomer was (+)-catechin, except in 1992 Cabernet sauvignon samples. The (+)-catechin concn. ranged from 0 to 45 mg/kg; (-)-epicatechin concn. ranged from 0 to 84 mg/kg. Most samples except those from the cv. Okatica bijela contained procyanidin dimers; the predominant fraction was procyanidin dimer B1. Ranges of values for concn. of the procyanidin dimers were (mg/kg): B1, 0-64; B2, 0-42; B3, 0-27; and B4, 0-42. It is concluded that concn.of catechin monomers and procyanidin dimers in grape skins are not sufficiently high for them to be considered a rich source of these natural antioxidants.