Hypolipidemic and antioxidant effects of ethanolic extract from dried calyx of Hibiscus sabdariffa in alloxan-induced diabetic rats

The present study investigated the hypolipidemic and antioxidant effects of ethanolic extract of Hibiscus sabdariffa L (HSE) in rats treated with alloxan. The results were compared with the standard hypolipidemic drug lovastatin. HSE at doses of 100 and 200 mg/kg elicited dose-dependent effects on the biomarkers evaluated. In alloxan-treated rats, HSE at the dose of 200 mg/kg significantly attenuated the elevated blood glucose concentration by 57%. Lovastatin (10 mg/kg) similarly reduced the glucose level in alloxan-treated rats by 48%. HSE reduced the alloxan-induced increases in cholesterol, very low-density lipoprotein cholesterol (VLDL-C), low-density lipoprotein cholesterol (LDL-C) and atherogenic index by 29%, 36%, 40%, and 32%, respectively while lovastatin decreased the alloxan-induced increases in the parameters by 25%, 23%, 28%, and 31%, respectively. HSE (200 mg/kg) and lovastatin (P < 0.01) decreased the alloxan-induced increases in the lipid profiles both in the liver and the kidneys. HSE at 200 mg/kg attenuated the alloxan-induced decrease in the activities of superoxide dismutase (SOD), catalase (CAT) and the level of glutathione (GSH) by 36%, 44%, and 64% in the liver and by 20%, 43%, and 85% in the kidney of rats. Lovastatin similarly increased SOD, CAT and GSH by 32%, 29%, and 64% in the liver and by 17%, 26%, and 73% in the kidney of alloxan-treated rats. HSE (200 mg/kg) significantly decreased the alloxan-mediated increase in malondialdehyde (MDA) and protein carbonyl (PC) levels in the liver by 44% and 43% and in the kidneys by 45% and 38%, respectively, while lovastatin decreased the alloxan-induced elevation in MDA and PC in the liver by 42% and 41% and in the kidney by 45% and 33%, respectively. While HSE at a dose of 200 mg/kg and lovastatin normalized the activity of phosphatidate phosphohydrolase in the liver, the extract and lovastatin did not elicit significant changes in the kidney enzyme activity in rats treated with alloxan. Overall, our data demonstrate that HSE possesses strong hypolipidemic as well as antioxidant properties in alloxan-induced diabetic rats and as such Hibiscus sabdariffa could be useful in preventing the development of atherosclerosis and possible related cardiovascular pathologies associated with diabetes.