Bioactivity-guided isolation of antidiabetic principles from the methanolic leaf extract ofBryophyllum pinnatum

Abstract

The antidiabetic principles from methanolic leaf extract of Bryophyllum pinnatum were isolated. The leaf extract was fractionated on silica gel using column chromatography and identified using nuclear magnetic resonance (NMR) spectrometry. The ethylacetate fraction of the partitioned methanolic extract of B. pinnatum lowered blood glucose of alloxan-induced diabetic rats and inhibited α-amylase and α-glucosidase with IC50 137.89 and 110.15 µg/mL, respectively. In addition to lowering blood glucose, fractions A and B inhibited α-amylase with IC50 57.43 and 43.84 µg/mL and α-glucosidase with IC50 11.15 and 25.79 µg/mL, respectively. 1H and 13C NMR showed that fractions A and B are quercetin and kaempeferol, respectively. Molecular docking revealed that kaempferol and quercetin interacted with amino acid residues that bind/hydrolyze substrate molecules These compounds reversed altered lipid profile and oxidative stress biomarkers. Our findings showed that kaempferol and quercetin are responsible for the antidiabetic activity of B. pinnatum. Practical application Bryophyllum pinnatum is an edible vegetable plant in some parts of Nigeria, and its consumption could improve diabetic condition and lower postprandial glucose. Furthermore, extract of the leaves could be developed into food supplements for managing diabetes and its associated complications including dyslipidaemia and oxidative stress.