The antioxidant action of N-acetylcysteine: its reaction with hydrogen peroxide, hydroxyl radical, superoxide, and hypochlorous acid

Free Radic Biol Med. 1989;6(6):593-7. doi: 10.1016/0891-5849(89)90066-x.


N-acetylcysteine has been widely used as an antioxidant in vivo and in vitro. Its reaction with four oxidant species has therefore been examined. N-acetylcysteine is a powerful scavenger of hypochlorous acid (H--OCl); low concentrations are able to protect alpha 1-antiproteinase against inactivation by HOCl. N-acetylcysteine also reacts with hydroxyl radical with a rate constant of 1.36 X 10(10) M-1s-1, as determined by pulse radiolysis. It also reacts slowly with H2O2, but no reaction of N-acetylcysteine with superoxide (O2-) could be detected within the limits of our assay procedures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine*
  • Antioxidants*
  • Blood Proteins / metabolism
  • Free Radicals
  • Hydrogen Peroxide*
  • Hydroxides*
  • Hydroxyl Radical
  • Hypochlorous Acid* / pharmacology
  • Kinetics
  • Pancreatic Elastase / antagonists & inhibitors
  • Protease Inhibitors / metabolism
  • Superoxides*
  • alpha 1-Antitrypsin


  • Antioxidants
  • Blood Proteins
  • Free Radicals
  • Hydroxides
  • Protease Inhibitors
  • alpha 1-Antitrypsin
  • Superoxides
  • Hydroxyl Radical
  • Hypochlorous Acid
  • Hydrogen Peroxide
  • Pancreatic Elastase
  • Acetylcysteine