ANTIOXIDANT EFFECTS OF DIETARY POLYMERIC GRAPE SEED TANNINS IN TISSUES OF RATS FED A HIGH CHOLESTEROL VITAMIN-E-DEFICIENT DIET

Effects of dietary monomeric and polymeric grape seed tannins on the a ctivity of antioxidant enzymes, total glutathione and level of lipid p eroxidation in various tissues were investigated in rats fed a high ch olesterol diet poor in vitamin E. They were compared with those in rat s receiving a high cholesterol-vitamin E-sufficient diet without addit ion of tannins. Four groups of rats were studied for 10 weeks: Group 1 , sufficient vitamin E diet; Group 2, deficient vitamin E diet; Group 3, deficient vitamin E diet + monomeric tannins (71 mg/kg); Group 4, d eficient vitamin E diet + polymeric tannins (71 mg/kg). Compared with a normal vitamin E diet (Group 1), aortic, cardiac, hepatic, intestina l, muscular and renal catalase, glutathione peroxidase and superoxide dismutase activities were significantly lower in rats receiving the de ficient vitamin E diet (Group 2); polymeric tannins (Group 4), but not monomeric tannins, were able to restore all these enzymic activities. In all tissues and in blood, total glutathione concentration, which w as significantly lowered by vitamin E deficiency, was brought to the n ormal level only with polymeric tannins. Furthermore, the lipid peroxi dation in plasma and tissues was significantly reduced in the presence of supplemented polymeric tannins as much as in the presence of vitam in E. It is therefore likely that polymeric grape seed tannins functio n as antioxidants in vivo, negating the effects of the oxidative stres s induced by both vitamin E deficiency and atherogenic diet. (C) 1997 Elsevier Science Ltd. All rights reserved.