ANTIOXIDATIVE ACTIVITY OF 4-OXY-NITROXIDES AND 4-HYDROXY-NITROXIDES IN TISSUES AND ERYTHROCYTES FROM RATS

AIM: To compare the activities of antioxidation of 4-oxy- and 4-hydrox y-nitroxides in tissues and RBC from rats. METHODS: The homogenates of liver, heart, and kidneys of rats were used to determine malondialdeh yde (MDA) formation using TBA colorimetric method. H2O2-caused hemolys is was measured spectrometrically. Superoxide anion from zymosan-stimu lated neutrophils of rats was assayed by NBT reduction method. RESULTS : Nitroxide free radicals OTMPO and HTMPO inhibited MDA generation cau sed by . OH generation system (MIC 10.5 and 21 mu mol . L(-1), respect ively), antagonized hemolysis induced by H2O2 (MIC: 338 and 168 mu mol . L(-1), respectively), but did not affect O-2(-) formation from acti vated neutrophils. 1-Hydroxyl compounds OTMPOH and HTMPOH possessed si milarly potent antilipoperoxidative activities. But nonfree radical OT MP and HTMP had no effect on peroxidation of tissues. CONCLUSION: Nitr oxides exert their antilipoperoxidative effect by specifically scaveng ing . OH free radicals in biological system. Trapping of OH . free rad icals by nitroxides is not by reduction of NO . group in nitroxides. B oth NO . group and NOH group are essential active groups.