This study compared the inhibitory activity of a-amylase inhibitor (aAI) extracted from common bean
(Phaseolus vulgaris L.) variety Hwachia, its nine mutants and two introduced varieties by using threephase
partitioning (TPP). A commercially prepared Phase 2 was also used to serve as a comparative reference.
The optimal purification parameters for TPP were 30% saturation ammonium sulphate and pH
5.25. Considerable variations were detected in aAI content, total inhibitory activity and specific inhibitory
activity of aAI purified from different common beans. Mutant SA-05 had the aAI inhibitory activity of
6267 units g1 dry seed weight, which was higher than Hwachia (5062 units g1 dry seed weight) and
Phase 2 (3200 units g1 dry weight). Moreover, it had an extremely lower IC50 (0.40 lg) than Phase 2
(10.22 lg). Thus, the mutant SA-05 may be used as raw material in commercial preparation of aAI
extracts for controlling appetite and energy intake.