Inhibition of adriamycin-promoted microsomal lipid peroxidation by beta-carotene, alpha-tocopherol and retinol at high and low oxygen partial pressures.

Iron-dependent peroxidation of rat liver microsomes, enhanced by adriamycin, was measured in the presence of increasing concentrations of alpha-tocopherol, beta-carotene and retinol at low and high pO2. beta-Carotene and alpha-tocopherol inhibited lipid peroxidation by more than 60% when present at concentrations greater than 50 nmol/mg microsomal protein at both high and low pO2. Retinol inhibited peroxidation by 39% at concentrations greater than 100 nmol/mg microsomal protein. This maximal level of inhibition by retinol was unaltered by pO2. However, beta-carotene was more effective than alpha-tocopherol or retinol at a pO2 of 4 mmHg, whereas alpha-tocopherol was more effective under aerobic conditions. Since adriamycin-dependent lipid peroxidation is maximal at low pO2, beta-carotene may play a role in protecting against this process.