Effect of rosella (Hibiscus sabdariffa L) extract on glutathione-S-transferase activity in rats

Purpose: To determine the effect of rosella (Hibiscus sabdariffa L) extract on glutathione-S-trasferase (GST) activity and its hepatoprotective effect. Methods: A total of 25 rats were divided randomly into 5 groups (5 rats per group). Group I served as the baseline, group II was the negative control group, while groups III, IV and V were treated with rosella extract at doses of 10, 50 and 100 mg /kg /day, respectively for 35 days. On day 36, the animals were given a single dose of dimethyl benz(a) anthracene (DMBA) orally. After one week, blood was taken from the sinus orbitalis for measurement of serum glutamate pyruvate transaminase (SGPT) and serum glutamate oxaloacetate transaminase (SGOT) activities by a kinetic method with DIasys (R) kit. The activity of GST was measured in liver homogenate using 1-choloro-2, 4-dinitrobenzene (CDNB) method, while the expression of GST gene was determined by reverse transcriptase polymerase chain reaction (RT-PCR). Results: Treatment with rosella extract at 10, 50 and 100 mg /kg for 35 days led to significant increases in GST activity relative to the control group. In addition, serum SGPT and SGOT activities were significantly decreased. There were significant increases in the expression of GST gene as evidenced by increased GST band intensity. Conclusion: These results indicate that rosella possesses significant hepatoprotective effect against hepatic injury caused by DMBA treatment. Thus, rosella may be useful for the prevention of oxidative stress caused by free radicals produced from pollutants and foods.