Isolation and comparative characterization of α-amylase inhibitor from white kidney bean (Phaseolus Vulgaris): A serious in vitro assessment of the commercial product

Plant α-amylase inhibitors (αAIs) show great potential as tools to manipulate resistance of crop plants against pests. They can be also considered as drug-design target for treatment of diabetes and digestion disorder. In this study, an amylase inhibitor-rich fraction was purified by ethanol precipitation and affinity chromatography on chitosan beads column from white common bean (Phaseolus vulgaris) extract, and then its in vitro interaction with porcine pancreatic α-amylase (PPA) was studied. A commercially available amylase inhibitor, Phase 2, was also used to serve as a comparative reference. The results showed that inhibitory activity of the αAI extracted from white kidney bean was much higher than that of Phase 2. The purified inhibitor displayed significant heat stability, so that remaining inhibitory activity was ~80%, even at 60 °C for 30 min incubation. Fraction 3 retained ~84% of its initial activity after long term (45 days) dry storage at room temperature. Due to potency and appropriate heat/storage stability, this αAI preparation may be reconsidered as raw material for preparation of commercial αAI to control appetite and energy intake.