Inhibition of LDL oxidation by melatonin requires supraphysiologic concentrations

P. Barton Duell, David L. Wheaton, Amy Shultz, Hien Nguyen

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Melatonin has been suggested as a potent antioxidant that may protect against development of atherosclerosis and cancer; however, these effects are unproven and controversial. The antioxidant capacity of melatonin was tested in comparison with α-tocopherol, ascorbic acid, and the melatonin precursors tryptophan and serotonin, by measuring inhibition of metal ion-mediated and human macrophage-mediated oxidation of LDL. Melatonin had weak antioxidant activity that was detectable only at concentrations 10 000- to 100 000-fold higher than physiologic concentrations. These results were comparable with published data showing that the radical scavenging activity of melatonin requires markedly supraphysiologic concentrations. In contrast, α-tocopherol was 50- to 100-fold more potent and was efficacious at physiologic concentrations. Ascorbic acid and tryptophan also were active at physiologic concentrations and were significantly more potent than melatonin. In summary, extremely supraphysiologic concentrations of melatonin had only weak antioxidant activity, which was surpassed by α-tocopherol, ascorbic acid, and tryptophan.

Original languageEnglish (US)
Pages (from-to)1931-1936
Number of pages6
JournalClinical chemistry
Volume44
Issue number9
StatePublished - Sep 12 1998

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, medical

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