Comparative Study on the Effect of Hibiscus sabdariffa Calyx Anthocyanins and Ascorbate on 2,4-Dinitrophenylhydrazine-induced Damage in Rabbits

The antioxidant bioactivities of the whole isolated anthocyanins from Hibiscus sabdariffa (HS) calyx were evaluated and compared with the bioactivity of vitamin C as a standard water soluble antioxidant vitamin. They were assessed for antioxidant activity based on their ability to impair 2, 4-dinitrophenylhydrazine (DNPH)-induced oxidative tissue damage in toxicant exposed rabbits. Exposure of rabbits to DNPH (28 mg/kg body weight) caused significant (p<0.05) reduction in packed cell volume (PCV), hemoglobin level and red blood cell (RBC) counts but increased white blood cell (WBC) counts relative to the DNPH-free rabbits. L-alanine aminotransferase (L-ALT) and L-aspartate aminotransferase (L-AST) activities were significantly (p<0.05) increased in the serum of DNPH-exposed rabbits compared to the DNPH-free rabbits. There were corresponding decreases in the liver status of both enzymes. DNPH exposure also caused significant change in malondialdehyde levels in serum and liver relative to DNPH-free controls. However, pre-treatment with 100 mg/kg body weight of the anthocyanin extract and vitamin C separately provided varying degrees of protection against DNPH-induced biochemical and hematological changes. Relative to the controls, HS calyx anthocyanins and vitamin C treatments increased the levels of PCV, hemoglobin and RBC and decreased WBC counts significantly (p<0.05) and so, effectively ameliorated the DNPH-induced hemotoxicity. The same treatments significantly lowered the activities of L-ALT and L-AST in the serum relative to the DNPH-exposed group, while maintaining their levels in the liver. The treatments also significantly (p<0.05) lowered the level of malondialdehyde in the serum and liver. However, when examined separately and compared, the HS calyx anthocyanins appeared to have offered the more effective protection than vitamin C, against the DNPH-induced oxidative damage and so H. sabdariffa calyces possess potent antioxidant principles which are likely to be anthocyanins.