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

This study compared the inhibitory activity of α-amylase inhibitor (αAI) 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 αAI content, total inhibitory activity and specific inhibitory activity of αAI purified from different common beans. Mutant SA-05 had the αAI 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 IC₅₀ (0.40 μg) than Phase 2 (10.22 μg). Thus, the mutant SA-05 may be used as raw material in commercial preparation of αAI extracts for controlling appetite and energy intake.