In vitro insulinotropic actions of various extracts of Moringa oleifera leaves

Abstract

This study investigated the in vitro insulin-releasing and cytotoxic effects of various extracts of Moringa oleifera leaves. Pulverized Moringa oleifera leaves were sequentially extracted with dichloromethane, acetone, ethylacetate and water. Clonal pancreatic beta cells, BRIN-BD11, were grown in an atmosphere of 5% CO₂ and 95% air in RPMI-1640. Insulin and LDH assays were carried out using Krebs Ringers Bicarbonate buffer. Insulin concentration was measured by radioimmunoassay and LDH release was assessed using a commercially available non-radioactive assay kit (Promega, UK). Aqueous extraction produced the best yield (361 mg/20kg powder). Acute incubation of BRIN-BD11 cells with different extracts of M. Oleifera produced a concentration-dependent stimulation of insulin-release at concentrations ≥10 μg/ml. The aqueous extract produced the best insulinotropic effect, with a maximum stimulation of 347% (P<0.001) of basal rate at 100μg/ml and the lowest stimulating concentration of 0.1 μg/ml. Dichloromethane and acetone extracts produced similar stimulatory effects (130% of basal rate, 100μg/ml, P<0.01). Insulin-releasing effects of the four extract were not associated with beta cell cytotoxicity. These results showed that extracts of M. oleifera possess insulinotropic effects and encourage further studies to uncover the physiological mechanism involved.

Keywords: Insulin-releasing; Moringaoleifera; BRIN-BD11 cells; cytotoxicity; anti-diabetic