Effect of Inhibitors of Oxidation on Lipid Peroxidation in Mice

Objective: To evaluate dietary-agent protection from oxidative damage in mouse tissues using malondialdehyde (MDA), a marker of lipid peroxidation products, as an endpoint. Methods: The effects of several antioxidant-containing diets on MDA levels were measured in different organs of male CD-2 mice previously treated with these diets. The assay used the thiobarbituric acid (TBA) reactive substances assay, which involves adding TBA to a 9000 × g tissue extract (S-9 fraction), acidifying, centrifuging, and heating the supernatant. Fluorescence of the product was determined using 510 nm excitation and 553 nm emission. MDA standard solutions were used to construct a calibration curve. MDA was then added to tissue extracts to show MDA could be accurately measured in an S-9 fraction, and linearity with increasing amounts of liver S-9 fraction was observed. Results: Statistically significant differences were observed between MDA levels in liver and lung S-9 fractions of control group and the groups receiving the different inhibitors. The antioxidant inhibitors included: 1) vitamins C + E, 2) N-acetylcysteine, 3) amifostine (a free radical scavenger) and 4) calorie restriction. Another group received 1,2-dithiole-3-thione, (a possible inducer of protective enzymes) and was not different from controls. The average of MDA amount in pmol /mg protein in liver S-9 of the control group was 37.3 ± 1.The following are the average values for the other groups; vitamin C and E (4.4 ±1), N-acetylcysteine (21.3 ±1), amifostine (12.6 ±1), calorie restriction (24.5 ±1), and 1,2-dithiole-3-thione (39.9±1). Similar results were obtained in lung S-9. As dietary agents may have both systemic and topical effects in the oral cavity, the effects of the inhibitors will also be tested in oral tissues from the treated mice. Conclusion: Certain dietary agents as well calorie restriction can inhibit lipid peroxidation and may be effective in reducing oxidative damage-related health effects.