An α-Sophoradiol Glycoside from the Root Wood of Erythrina senegalensis DC. (Fabaceae) with α-Amylase and α-Glucosidase Inhibitory Potential

Abstract

Phytochemical study of the roots of Erythrina senegalensis led to the isolation of a new α-sophoradiol glycoside, erythrinoside (1), together with four known compounds, lupeol (2), α-sophoradiol (3), isoneorautenol (4) and D-mannitol (5). The structures of the compounds were elucidated using spectroscopic data including 1D and 2D NMR, mass spectrometry and by comparison made with some data reported previously; the samples (extracts and compounds) were also subjected to antidiabetic assay. Erythrinoside and isoneorautenol exhibited good α-amylase inhibitory potential of 54.6% and 53.3%, respectively, compared to acarbose (72.5%) at 400 µg/mL. With α-glucosidase, all samples showed promising inhibition percentages above 50% at 200 µg/mL. In the α-glucosidase assay, the ethyl acetate extract (65.5%), methanol extract (72.1%), erythrinoside (63.3%) and isoneorautenol (66.0%) had percentage inhibitions closer to that of acarbose (69.0%) at 200 µg/mL. The methanol extract (IC50 = 81.2 ± 0.9 µg/mL) was more active than acarbose (IC50 = 94.5 ± 0.7 µg.mL) in the α-glucosidase assay. The inhibition of α-amylase and α-glucosidase indicates that E. senegalensis extracts and compounds could be used to manage diabetic conditions.