Ascorbate-dependent capacity of dialysed rat liver cytosol to prevent nonenzymatic lipid peroxidation

The capacity of rat liver cytosol to decrease Fe/ADP ascorbate-induced lipid peroxidation in microsomes was evaluated using the chemiluminescence technique and measuring the formation of thiobarbituric acid-reactive substances (TBARS). The inhibiting effect of dialysed cytosol depended on the ascorbate concentration and was highest in the range of 1.0mM. Precipitation of cytosolic proteins with ammonium sulfate at 53% saturation yielded an active antioxidative fraction. Gel-filtration on Sephadex G-200 led to the separation of at least two cytosolic compounds of approximate molecular masses of 60 kDa and > 400 kDa. Both factors were active at 1.0mM ascorbate in the presence of freshly prepared microsomes. No inhibition of lipid peroxidation was observed using microsomes stored for one month at -70 degrees C.