GC-MS analysis, phytochemical screening and In vitro alpha amylase and alpha glucosidase inhibitory activities of Vernonia amygdalina root extract and fractions

Abstract

The aim of this study was to evaluate the in vitro inhibitory activity of Vernonia amygdalina root methanol extract and fractions on Porcine alpha amylase and Baker’s yeast alpha glucosidase at varying concentrations and to analyse the most potent of the methanol extract and its fractions through phytochemical screening and Gas Chromatography-Mass Spectroscopy analysis (GC-MS). Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycemia in which there is an elevated glucose level in the blood. Inhibitors of alpha amylase and alpha glucosidase are used to achieve good control over hyperglycemia in type 2 diabetes mellitus. The present study intends to screen novel alpha amylase and alpha glucosidase inhibitors from a natural source (plant) so as to reduce the toxicity and side effects of the synthetic inhibitors currently used to control hyperglycemia. The alpha amylase inhibition assay showed that the methanol crude extract of Vernonia amygdalina root (18.17mg/ml), the n-hexane fraction (71.41 mg/ml), the dichloromethane fraction (95.06mg/ml) and the aqueous fraction (165.51mg/ml) exhibited 50% alpha amylase inhibition activity at the mentioned concentrations. The alpha glucosidase IC50 for Vernonia amygdalina root methanol crude extract, n-hexane fraction, dichloromethane fraction and aqueous fraction was found to be 12.17mg/ml, 13.59mg/ml, 59.83 mg/ml and 12.93mg/ml respectively. The phytochemical screening and GC-MS analysis of the methanol crude extract (the most potent in both the alpha amylase and alpha glucosidase inhibition assays) revealed the presence of bioactive agents reported to have anti-diabetic activities. The results of this study therefore clearly support the traditional use of Vernonia amygdalina root extract to manage hyperglycemia.