Protection against peroxynitrite by cocoa polyphenol oligomers

Flavonoids, natural plant constituents, protect against peroxynitrite and c an thereby play a role in defense against this mediator of inflammation. Pr ocyanidin oligomers of different size (monomer through nonamer), isolated f rom the seeds of Theobroma cacao, were examined for their ability to protec t against peroxynitrite-dependent oxidation of dihydrorhodamine 123 and nit ration of tyrosine, By molarity, oligomers were more effective than the mon omeric epicatechin; the tetramer was particularly efficient at protecting a gainst oxidation and nitration reactions. These results suggest that epicat echin oligomers found in cocoa powder and chocolate may be a potent dietary source for defense against peroxynitrite, (C) 1999 Federation of European Biochemical Societies.