In vitro and in vivo studies on the alpha-glucosidase inhibitory effects of the leaf extract of Carica papaya Linn

The search for novel alpha-glucosidase inhibitory agents is currently an important scientific endeavour to the biopharmaceutical companies due to their potentials to reduce postprandial hyperglycaemia in type 2 diabetic patients. The present research attempted to investigate the alpha-glucosidase inhibitory effects of the leaf extract of Carica papaya. Aqueous, methanol, ethyl acetate and n-hexane extracts of C. papaya leaf were subjected to in vitro alpha-glucosidase inhibitory studies, and methanol extract was the most potent (IC₅₀ = 171.83 ± 26.89 μg/mL). Consequently, the methanol extract was further fractionated by column chromatography which yielded six pooled fractions (A–F) and fraction A (FA) showed the lowest IC₅₀ (78.62 ± 25.23 μg/mL). Subsequently, the FA was subjected to in vivo oral maltose and sucrose tolerance tests which revealed that FA had potent inhibitory effects on maltose and sucrose tolerance in rats. The computed area under the curves (AUC_(0–120)) further indicates that FA (200 mg/kg bw) have better inhibitory activity on maltase than sucrase. The GC-MS analysis of FA indicates the presence of phenolics, various fatty acids and their derivatives. This research suggests that the leaf extract of C. papaya possesses alpha-glucosidase inhibitory effects and might be exploited in retarding postprandial hyperglycaemia.