Antioxidant protection against hypochlorous acid in human plasma.

Hypochlorous acid (HOCl) is a powerful oxidizing and chlorinating agent produced by the neutrophil enzyme myeloperoxidase. The antioxidant defenses of freshly prepared human plasma against HOCl/OCl - were explored. Addition of HOCl/OCl - to plasma caused rapid oxidation of ascorbic acid and thiol (-SH) groups but not of uric acid. Plasma -SH groups (which are known to be largely located on albumin) were quantitatively the most important scavenger of HOCl/OCl - , but adding extra ascorbate to plasma caused this molecule to have a more important scavenging role against HOCl/OCL -