Antioxidant Actions of Dried Flower Extracts of Hibiscus sabdariffa L. On Sodium Arsenite - Induced Oxidative Stress in Rats

The antioxidant actions of 80% ethanolic extract of dried flowers of Hibiscus sabdariffa L. (HSE) on lipid peroxidation (LPO), reduced glutathione (GSH), glutathione-s-transferase (GST), catalase (CAT), superoxide dismutase (SOD) and vitamin C (VITC), were examined using a model of sodium arsenite (SA) induced oxidative stress in rats. The oral administration of the extracts (200 and 300mg/kg body weight) significantly (P<0.05) decreased by 37% SA induced malondialdehyde (MDA) formation in liver, suggesting the role of the extract in protection against pro-oxidant induced membrane damage. Pretreatment with the extracts prior to the intra-peritoneal administration of 10mg/kg body weight of SA reduced significantly (by 86%) and induced non-significantly (by 37%) the level of GSH depletion and GST activity respectively in a dose dependent manner. The extract also attenuated SA induced reduction in the serum level of VITC as evidenced by a significant (P<0.05) dose dependent increase (by 60%) in serum VITC level. Pretreatment with the extracts showed a significant (P<0.05) increase in liver and decrease in whole blood activities of SOD (by 369% and 85%) and CAT (by 829% and 58%) respectively, hence revealing the hepatoprotective and antioxidant effectiveness of the extracts. Furthermore, the extracts, evaluated (in vitro) by their capacity of quenching 1, 1-diphenyl 2-picrylhydraxyl (DPPH) free radical, showed strong scavenging effects on DPPH free radical at concentration of 0.20mg/ml (1C50 = 0.20mg/ml). The extracts at low and high concentrations showed no inhibitory effect on nitric oxide radical. These findings are suggestive of the possible chemopreventive and antioxidative role played by dried flower extract of Hibiscus sabdariffa L.