Anti-diabetic and antioxidant activities of <i>Entandrophragma cylindricum</i> and <i>Triclisia subcordata</i>

Abstract

The study evaluated the stem bark of Entandrophragma cylindricum and Triclisia subcordata leaf for their anti-diabetic and antioxidant activities and determined possible contribution of antioxidant properties to their anti-diabetic effects. Anti-diabetic activities of the methanol extracts of the plants were tested in vivo in normal, glucose and alloxan-induced hyperglycaemic rats while the antihyperglycaemic activities of the partition and column fractions of E. cylindricum were carried out in glucose-loaded rats. The antioxidant properties of the extracts and their fractions were studied using 1,1-diphenyl-2-picylhydrazyl (DPPH) and total antioxidant capacity (TAC) methods. The extracts of E. cylindricum and T. subcordata at 100, 200 and 400 mg/kg elicited significantly lower hypoglycaemic activity in normal rats than glibenclamide (5 mg/kg). In glucose-induced hyperglycaemic rats, only E. cylindricum gave a comparable activity to glibenclamide (5 mg/kg) both at 200 and 400 mg/kg while its 400 mg/kg was significantly more active than glibenclamide in the sub chronic alloxan-induced diabetic model. Similarly, it also exhibited a significantly better antioxidant activity than T. subcordata in the DPPH and TAC assays. The ethylacetate fraction (B3) of E. cylindricum extract was the most active anti hyperglycaemic and antioxidant fraction while column fraction C3 with the highest antihyperglycaemic activity gave the best antioxidant activity in TAC and second best in DPPH assays. This study justified the ethnomedicinal use of E. cylindricum and T. subcordata in the management of diabetes, and established contribution of antioxidant properties to the antidiabetic effects of E. cylindricum.

Keywords: Diabetes mellitus, Entandrophragma cylindricum, Triclisia subcordata, Anti-diabetic and antioxidant activities