Comparisons of alpha-amylase inhibitors from seeds of common bean mutants extracted through three phase partitioning

This study compared the inhibitory activity of alpha-amylase inhibitor (alpha AI) extracted from common bean (Phaseolus vulgaris L) variety Hwachia, its nine mutants and two introduced varieties by using three-phase 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 alpha AI content, total inhibitory activity and specific inhibitory activity of alpha AI purified from different common beans. Mutant SA-05 had the alpha AI inhibitory activity of 6267 units g(-1) dry seed weight, which was higher than Hwachia (5062 units g(-1) dry seed weight) and Phase 2 (3200 units g(-1) dry weight). Moreover, it had an extremely lower IC(50) (0.40 mu g) than Phase 2 (10.22 mu g). Thus, the mutant SA-05 may be used as raw material in commercial preparation of alpha AI extracts for controlling appetite and energy intake. (C) 2011 Elsevier Ltd. All rights reserved