RESUMO
This study was carried out to determine the effects of tocotrienol-rich fraction [TRF] [200 mg/Kg] on biomarkers of oxidative stress on erythrocyte membranes and leukocyte deoxyribonucleic acid [DNA] damage in streptozotocin [STZ]-induced diabetic rats. Male rats [n = 40] were divided randomly into four groups of 10: a normal group; a normal group with TRF; a diabetic group, and a diabetic group with TRF. Following four weeks of treatment, fasting blood glucose [FBG] levels, oxidative stress markers and the antioxidant status of the erythrocytes were measured. FBG levels for the STZ-induced diabetic rats were significantly increased [P <0.001] when compared to the normal group and erythrocyte malondialdehyde levels were also significantly higher [P <0.0001] in this group. Decreased levels of reduced glutathione and increased levels of oxidised glutathione [P <0.001] were observed in STZ-induced diabetic rats when compared to the control group and diabetic group with TRF. The results of the superoxide dismutase and glutathione peroxidase activities were significantly lower in the STZ-induced diabetic rats than in the normal group [P <0.001]. The levels of DNA damage, measured by the tail length and tail moment of the leukocyte, were significantly higher in STZ-induced diabetic [P <0.0001]. TRF supplementation managed to normalise the level of DNA damage in diabetic rats treated with TRF. Daily supplementation with 200 mg/Kg of TRF for four weeks was found to reduce levels of oxidative stress markers by inhibiting lipid peroxidation and increasing the levels of antioxidant status in a prevention trial for STZ-induced diabetic rats