Endocrine Abstracts

Aim: Beneficial effects of Jatropha tanjorensis (J. tanjorensis) extracts in African traditional medicinal practices for the management of type 2 diabetes have been reported. However, mechanisms through which these extracts exert their anti-diabetic actions have not been widely studied.Methods and materialsEffects of various aqueous extracts of root, leaf, and bark J. tanjorensis (0-1000 μg/ml) on insulin-release, cytotoxicity and cell viability were investigated using BRIN-BD11 cells. Effects of leaf extracts (100 μg/ml) on glucose-stimulated insulin secretion and changes in insulinotropic actions in the presence of known modulators as well as the absence of extracellular calcium were also assessed.ResultsJ. tanjorensis extracts stimulated insulin secretion from BRIN-BD11 cells at concentrations ≥0.1 μg/ml for leaf (1.7-fold, P<0.001), 1 μg/ml for bark (2-fold, P<0.05) and 10 μg/ml for root (1.8-fold, P<0.05) extracts. These insulin-releasing effects were not associated with significant release of lactate dehydrogenase at concentrations ≤100 μg/ml for leaf, 100 μg/ml for bark and 100 μg/ml for root extracts. Effects of the leaf extracts were inhibited by diazoxide (51%, P<0.01), verapamil (29%, P0.05) and in the absence of intracellular calcium (41%, P<0.01). However, effects of the extract were enhanced by KCl (2.3-fold, P<0.01. Improved intracellular calcium concentration were observed in cells treated with the leaf extracts of J. tanjorensis (2.4-fold, P0.01).ConclusionThe results confirm insulinotropic actions of J. tanjorensis extracts and suggest that the KATP-dependent pathway may be involved in the mechanism of action.