Antioxidant polyphenols from tart cherries (Prunus cerasus)

Montmorency and Balaton tart cherries were lyophilized and sequentially ext racted with hexane, ethyl acetate, and methanol. Methanolic extracts of dri ed Balaton and Montmorency tart cherries (Prunus cerasus) inhibited lipid p eroxidation induced by Fe2+ at 25 ppm concentrations. Further partitioning of this methanol extract with EtOAc yielded a fraction that inhibited lipid peroxidation by 76% at 25 ppm. Purification of this EtOAc fraction afforde d eight polyphenolic compounds, 5,7,4'-trihydroxyflavanone (1), 5,7,4'-trih ydroxyisoflavone (2), chlorogenic acid (3), 5,7,3',4'-tetrahydroxy-flavonol -3-rhamnoside (4), 5,7,4'-trihydroxyflavonol 3-rutinoside (5), 5,7,4'-trihy droxy-3'methoxyflavonol-3-rutinoside (6), 5,7,4'-trihydroxyisoflavone-7-glu coside (7), and 6,7-dimethoxy-5,8,4'-trihydroxyflavone (8), as characterize d by H-1 and C-13 NMR experiments. The antioxidant assays revealed that 7-d imethoxy-5,8,4'-trihydroxyflavone (8) is the most active, followed by querc etin 3-rhamnoside, genistein, chlorogenic acid, naringenin, and genistin, a t 10 mu M concentrations.