Antioxidant properties of raisins (Vitis vinifera L.).

Currants and sultanas (Vitis vinifera L., Family Vitaceae) are dried vine products produced in Greece and used widely in the Mediterranean diet. We investigated the polar methanol extracts from the raisins for the antiradical activity, polyphenol content, cytotoxicity in peripheral blood mononuclear cells, total glutathione (GSH) levels, oxidized glutathione (GSSG) levels, and inhibition of low-density lipoprotein (LDL) oxidation. Extracts exhibited 1,1-diphenyl-2-picrylhydrazyl scavenging activity and inhibited tert-butylhydroperoxide (tBHP)-induced cytotoxicity, GSH decrease, and LDL oxidation. Fluorescence microscopy revealed the characteristic apoptotic patterns with tBHP and inhibition with the extracts. Elevated levels of total GSH and unaltered levels of GSSG with extract treatment demonstrated the induction of gamma-glutamylcysteine synthetase. The antioxidant activity was correlated to the polyphenolic content. Greek currants and sultanas are suggested as antioxidant components of the Mediterranean basin.