Melatonin: a peroxyl radical scavenger more effective than vitamin E

Life Sci. 1994;55(15):PL271-6. doi: 10.1016/0024-3205(94)00666-0.


We have compared the peroxyl radical scavenger ability to melatonin with that of vitamin E, vitamin C and reduced glutathione (GSH). In the assay system, beta-phycoerythrin (beta-PE) was used as fluorescent indicator protein, 2-2'-azo-bis(2-amidinopropane)dihydrochloride as a peroxyl radical generator and the water soluble vitamin E analogue. Trolox, as reference standard. Results are expressed as oxygen radical absorbing capacity (ORAC(perox)) units, where 1 ORAC unit equals the net protection produced by 1 microM Trolox. A linear correlation of ORAC values with concentration (0.5-4 microM) of all the substances tested has been observed. However, on molar basis, the relative ORAC(perox) of Trolox, vitamin C, GSH and melatonin was 1:1.12:0:68:2.04, respectively. Thus, melatonin, which is a lipid-soluble compound, was twice more active than vitamin E, believed to be the most effective lipophilic antioxidant.

Publication types

  • Comparative Study

MeSH terms

  • Amidines
  • Ascorbic Acid / pharmacology
  • Free Radical Scavengers*
  • Glutathione / pharmacology
  • Melatonin / pharmacology*
  • Peroxides / pharmacology*
  • Phycoerythrin
  • Time Factors
  • Vitamin E / pharmacology*


  • Amidines
  • Free Radical Scavengers
  • Peroxides
  • Phycoerythrin
  • Vitamin E
  • perhydroxyl radical
  • 2,2'-azobis(2-amidinopropane)
  • Glutathione
  • Melatonin
  • Ascorbic Acid