Peroxynitrite (ONOO(-)) is a powerful oxidant produced by neutrophils, macrophages, and lymphocytes as a signaling and cytotoxic molecule from their primary production of nitric oxide (NO) and superoxide anion (O(2)(-)). In the vascular space, ONOO(-) will likely oxidize lipoproteins and promote atherogenesis. Pure wine flavonoids (catechin, epicatechin, myricetin), hydroxycinnamates (caffeic acid, ferulic acid, chlorogenic acid), and plain Argentine red wines were assayed as ONOO(-) scavengers in two assays: (a) ONOO(-)-initiated chemiluminescence and (b) ONOO(-)-dependent oxidation. The assayed polyphenols as well as the red wines were effective inhibitors of the ONOO(-)-driven oxidation reactions. Fifty percent of the pure substances were observed in the range of 30-300 microM and in the case of red wines with the equivalent of 80-120 microM of flavonoids. The amphipatic nature of wine polyphenols will lead to their accumulation at the lipoprotein surface, according to the Gibbs adsorption equation, where they are likely to prevent ONOO(-)-induced tyrosine nitration and LDL modification.