Alpha-Glucosidase Inhibitory Activity of Compounds from Bauhinia strychnifolia

This study has investigated the α-glucosidase inhibitory activity of Thai medicinal plant (Bauhinia strychnifolia). The colorimetric method and chromatographic technique were carried out for bioassay and phytochemistry. The ethanol extract of B. strychnifolia exhibited good inhibitory activity against α-glucosidase activity with an IC50 value of 160 μg/mL which was higher than the value of positive control, acarbose, (α-glucosidase drug, IC50=189 μg/mL). From bioassay-guided isolation, the water fraction was observed to separate into two compounds namely; 3,5,7-Trihydroxychromone-3-O-α-L-rhamnopyranoside (1) and 3,5,7,3’,5’-pentahydroxy-flavanonol-3-O-α-L-rhamnopyranoside (2). Among the tested samples, 3,5,7-Trihydroxychromone-3-O-α-L-rhamnopyranoside (1) showed the highest activity against α-glucosidase with an IC50 value of 540 μg/mL similar to that of the positive control, acarbose (α-glucosidase drug, IC50=550 μg/mL). This was followed by 3,5,7,3’,5’-pentahydroxy-flavanonol-3-O-α-L-rhamnopyranoside (2) which gave an IC50 value of 980 μg/mL. From the present study, the findings would be the first report on the anti α-glucosidase activity of compounds from Bauhinia strychnifolia.