I n vitro inhibitory effects of cranberry bean ( P haseolus vulgaris L .) extracts on aldose reductase, α‐glucosidase and α‐amylase

Summary The in vitro inhibitory activities of different seed extracts prepared from cranberry bean mutant SA‐05 and its wild‐type variety Hwachia against aldose reductase, α‐glucosidase and α‐amylase were examined. The results indicated that the polyphenolics‐rich extracts obtained using 800 g kg−1 methanol and 500 g kg−1 ethanol demonstrated inhibitory activities against aldose reductase (IC50 of 0.36–0.46 mg mL−1) and α‐glucosidase (IC50 of 1.32–1.94 mg mL−1). The 500 g kg−1 ethanol extracts also showed α‐amylase inhibitory activities (IC50 of 70.11–80.22 μg mL−1). Subsequent extracts, prepared further with NaCl and H2O from precipitates of 800 g kg−1 methanol or 500 g kg−1 ethanol extracts, exhibited potent α‐amylase inhibitory activities (IC50 of 17.68–38.68 μg mL−1). A combination of 500 g kg−1 ethanol extraction plus a subsequent H2O extraction produced highest polyphenolics and α‐amylase inhibitors. The SA‐05 α‐amylase inhibitor extracts showed greater inhibitory activities than that of Hwachia. Thus, cranberry bean mutant SA‐05 is an advantageous choice for producing anti‐hyperglycaemic compounds.