alpha -Glucosidase (ACH) inhibitory study by natural anthocyanin extracts was done. As the result of a free AGH assay system, 12 anthocyanin extracts were found to have a potent AGH inhibitory activity; in particular, Pharbitis nil (SOA) extract showed the strongest maltase inhibitory activity, with an IC50 value of 0.35 mg/mL, as great as that of Ipomoea batatas (YGM) extract (IC50 = 0.36 mg/mL). Interestingly, neither extract inhibited the sucrase activity at all. For the immobilized assay system, which may reflect the pharmacokinetics of AGH at the small intestine, SOA and YGM extracts gave more potent maltase inhibitory activities than those of the free AGH assay, with IC50 values of 0.17 and 0.26 mg/mL, respectively. Both extracts also inhibited alpha -amylase action, indicating that anthocyanins would have a potential function to suppress the increase in postprandial glucose level from starch.