Antioxidant protection against hypochlorous acid in human plasma

Miao Lin Hu, Samuel Louie, Carroll E Cross, Paul Motchnik, Barry Halliwell

Research output: Contribution to journalArticlepeer-review

263 Scopus citations


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 add 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-. Added HOCl/OCl- produced no detectable lipid peroxidation in plasma or depletion of lipid-soluble antioxidants (α-tocopherol or ubiquinol10). No evidence of oxidative damage to protein amino acid residues (other than -SH) was detected by the carbonyl assay. It seems that -SH groups are a major target of attack by HOCl/OCl- in vivo, and plasma albumin may be an important protective antioxidant. Ascorbic acid might also play a protective role, especially in individuals supplemented with this vitamin. Ascorbate might also be important in extracellular fluids with low albumin concentrations such as synovial, respiratory tract lining, and cerebrospinal fluids.

Original languageEnglish (US)
Pages (from-to)257-262
Number of pages6
JournalThe Journal of Laboratory and Clinical Medicine
Issue number2
StatePublished - 1993

ASJC Scopus subject areas

  • Medicine(all)
  • Pathology and Forensic Medicine


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