In vitro effects of aspirin on malondialdehyde formation and on activity of antioxidant and some metal-containing enzymes.

The in vitro effects of aspirin in different concentrations on malondialdehyde formation and on the activity of antioxidant and some metal-containing enzymes in rat liver homogenate and erythrocytes were studied. Aspirin showed a biphasic dependence on concentration: low concentrations (to 1.0 mM) stimulated the spontaneously formed malondialdehyde in the liver homogenate and the high concentration (5.0 mM) inhibited it; all aspirin concentrations tested had no effect on the liposomes; 5.0 mM aspirin inhibited the Fe(2+)-induced lipid peroxidation in the liver homogenate but had an opposite effect on the liposomes. Aspirin dose-dependently inhibited nitro-blue tetrazolium reduction and decreased deoxyribose degradation. The higher aspirin concentrations inhibited the activity of antioxidant and some metal-containing enzymes. It is suggested that these aspirin effects are determined by the aspirin-metal complexes formed rather than by aspirin itself.