Protection against peroxynitrite-dependent tyrosine nitration and alpha(1)-antiproteinase inactivation by oxidized and reduced lipoic acid

Peroxynitrite, formed by combination of superoxide radical with nitric oxide, is a reactive tissue-damaging species apparently involved in the pathology of several human diseases. Peroxynitrite nitrates tyrosine residues and inactivates alpha(1)-antiproteinase, We show that both lipoic acid and dihydrolipoic acid efficiently protect against damage by peroxynitrite, By contrast, other disulphides tested did not, The biological antioxidant effects of lipoate/dihydrolipoate may involve scavenging of reactive nitrogen species as well as reactive oxygen species.