大豆异黄酮对α-葡萄糖苷酶和α-淀粉酶的抑制作用

目的 ]研究大豆异黄酮类对α 葡萄糖苷酶 (EC 3.2 .1.2 0 )和α 淀粉酶 (EC 3.2 .1.1)的抑制作用 ,以期为揭示大豆异黄酮类在糖尿病中的作用及机理提供依据 .方法 ]以C18柱层析和高效液相色谱法分离大豆异黄酮类 ,以薄层色谱法、高效液相色谱法和核磁共振检测各组分 ,并用比色法测定各单体组分对酵母α 葡萄糖苷酶和猪α 胰淀粉酶的抑制活性 .抑制酶活性 5 0 %时所需的抑制剂浓度定义为半抑制浓度 .结果 ]大豆异黄酮具有很强的α 葡萄糖苷酶抑制作用 ,其半抑制浓度值为 2 0～ 15 0μmol/L,其中金雀异黄素的为最强 ,而大豆异黄酮葡萄糖苷形式对α 葡萄糖苷酶的抑制活性较其游离配糖体形式为弱 ,其半抑制浓度值为 2 0 0～ 6 0 0 μmol/L .大豆异黄酮及其糖苷形式均具有α 淀粉酶抑制作用 ,当抑制剂浓度为 1g/L时 ,对α 淀粉酶的抑制率为 10 %～ 2 0 % .大豆异黄酮的丙二酰葡萄糖苷形式则无α 葡萄糖苷酶和α 淀粉酶抑制作用 .结论 ]大豆异黄酮类具有α 葡萄糖苷酶和α 淀粉酶抑制活性 ,且呈剂量依赖性 .表明 ,食用富含异黄酮类的大豆及其制品对改善非胰岛素依赖型糖尿病症状、防止血糖升高有利

Inhibition of alpha-glucosidase and alpha-amylase by soybean isoflavonoids

OBJECTIVE To study the inhibitory effects of isoflavonoids on alpha-glucosidase (EC 3.2.1.20) and alpha-amylase (EC 3.2.1.1) and supply a scientific basis for the development and use of isoflavonoids for the patient with diabetes mellitus. METHODS The isolation and identification of isoflavonoids were performed by ODS column chromatography, TLC, HPLC and NMR. Assays for inhibition of alpha-glucosidase and alpha-amylase were investigated by colorimetric method. The concentration of the given inhibitor required to inhibit 50% of enzyme activity under the assay conditions was defined as the IC 50value. RESULTS Isoflavone aglycones show strong inhibitory activities against yeast alpha-glucosidase with the IC 50 values of 20～150 μmol/L, whi le isoflavone glycosides showed a little lower potency than their aglycones(IC 50 value was about 200～600 μmol/L). Isoflavones also tended to inhibit porcine pancreatic alpha-amylase activities. The inhibitory activities of isoflavones were about 10%～20% at the concentration of 1 g/L. Malonylated isoflavone glycosides showed no inhibition on both alpha-glucosidase and alpha-amylase. CONCLUSION The isoflavones, which exhibit alpha-glucosidase and alpha-amylase inhibitory activities, seem physiologically useful for suppressing postprandial hyperglycemia in patients with diabetes mellitus.