Inhibition of low density lipoprotein oxidation by melatonin

The antioxidant activity of the lipophilic hormone melatonin, “an ideal inhibitor of free radicals,” is studied in models of cellular (peritoneal mouse macrophages) and copper-induced oxidation of low density lipoproteins. Oxidative modification of low density lipoproteins is assessed by accumulation of thiobarbituric acid reactive substances and degradation of¹²⁵I-labeled lipoproteins in a fresh culture of macrophages. Melatonin inhibits in a dose-dependent manner cellular and copper-induced oxidation of lipoproteins and production of the superoxide anion radical by macrophages, the mean concentrations of 50% inhibition being 300, 1230, and 900 μM, respectively. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 10, pp. 399–402, October, 1996