Aqueous extract of the calyces of Hibiscus subdariffa Linn.: effects on hepatic cytochrome P450 and subacute toxicity in rats

Abstract

Hibiscus sabdariffa Linn. has been reported to have a broad range of therapeutic effects. Subacute effects of the calyces of H. sabdariffa aqueous extract on the activities of cytochrome P450 (CYP), clinical blood chemistry and hematology were investigated in this study. Thirty male Wistar rats were randomly divided into 3 groups, each group comprised 10 rats. The first group was fed with distilled water 1 ml/kg/day, serving as a control group. The other two groups were fed with H. sabdariffa aqueous extract at dosages of 250 and 1,000 mg/kg/day. After 30 days of treatment period, blood and serum samples were collected for determining hematology and clinical blood chemistry. Microsomes were prepared from livers and being used for determining of total CYP contents as well as the activities of CYP 1A1, 1A2, 2B1/2, 2E1 and 3A. The results showed that H. sabdariffa aqueous extract at both doses did not affect the hepatic total CYP contents and the activities of CYP 1A1, 1A2, 2B1/2, 2E1 and 3A. There were no significant effects of H. sabdariffa aqueous extract on clinical blood chemistry and hematology in rats. These results indicated that H. sabdariffa aqueous extract at both doses used in this study did not modulate the activities of most phase I hepatic CYPs involving in drug metabolism and carcinogenic/mutagenic bioactivation. In addition, this extract at the dose ranging 250-1000 mg/kg/day did not exhibit harmful effects on several important organs/system such as liver, kidney, blood system, electrolytes as well as lipid and carbohydrate metabolism. Further studies on the effects of this extract on human hepatic CYPs, hepatic phase II enzymes and human clinical blood chemistry were suggested.