Evaluation of the anti-diabetic and toxicological profile of the leaves of Stachytarpheta jamaicensis (L.) Vahl (Verbenaceae) on alloxan-induced diabetic rats

Abstract

This study is aimed at ascertaining the scientific basis for the ethnomedicinal uses of Stachytarpheta jamaicensis (SJ) leaf extracts in diabetes mellitus, determining the phytoconstituents present in the plant and the safety (beneficial/toxicity) of the plant. The methanol extract of S. jamaicensis (MESJ) was fractionated into n-hexane (HFSJ), ethyl acetate (EFSJ), n-butanol (BFSJ) and water fractions (WFSJ). The MESJ and fractions were screened for anti-diabetic activities using oral glucose tolerance test, normoglycemic and hyperglycemic models. Other parameters e.g. blood, liver, renal and lipid profiles were determined in normal and alloxan induced diabetic rats after oral administration of MESJ for 28 days. Histopathological changes in normal and diabetic rat organs (pancreas, liver and kidney) were also observed after MESJ treatment. The LD50 of MESJ was >5000 mg/kg. The phytochemical analysis showed the presence of flavonoids, resins, alkaloids, glycosides, steroids, terpenoids, reducing sugars and saponins. Preliminary anti-diabetic study revealed a non-dose dependent reduction in the blood glucose level of alloxan-induced diabetic rats. MESJ showed significant (P< 0.01) hypoglycemic/anti-hyperglycemic effects (25.40 and 55.80%) against glibenclamide (12.60 and 51.40%) in normal rats for acute and chronic studies respectively and (22.00 and 86.90%) against glibenclamide (19.37 and 85.50%) in diabetic rats for acute and chronic studies respectively. It also improved body weight, blood parameters, kidney, liver functions and hyperlipidaemia in alloxan-induced diabetic animals. MESJ also showed improvement in blood parameters and non significant increases in liver, kidney and lipid profile of normoglycemic rats. Furthermore, MESJ also had a favorable effect on the histopathological changes of the pancreas, liver and kidney in alloxan-induced diabetes. Histopathological pictures of the pancreas, liver and kidney of normoglycemic rats were normal. Stachytarpheta jamaicensis thus posses anti-diabetic property and is also not toxic to body organs on long term administration.