α-Amylase inhibition by four dietary organic acids was characterized by inhibition assay, kinetics, fluorescence quenching and molecular docking. Tartaric acid was found as an uncompetitive inhibitor, with 2,3-OH playing an important role in binding with the enzymic non-active site. Although caffeic acid had a low inhibitory activity, caffeoyl substitution at 2,3-OH of tartaric acid gradually increased its competitive inhibition character. As a result, caftaric acid (one caffeoyl-substituted) and chicoric acid (two caffeoyl-substituted) were suggested as mixed-type and competitive inhibitors, respectively, despite that the substitution decreased the inhibitory activity of tartaric acid. Fluorescence quenching was only observed for compounds with caffeoyl(s), and the effect increased with the moiety number increasing, consistent with the changing trend in number of active fluorescent residues involved in ligand-enzyme interactions. These results suggest that caffeoyl moiety entered into α-amylase active pocket. Therefore, caffeoyl has potentials as a functional-factor in α-amylase inhibition for alleviating type-II diabetes symptoms.

通过抑制分析，动力学，荧光猝灭和分子对接来表征四种饮食有机酸对α-淀粉酶的抑制作用。发现酒石酸是一种非竞争性抑制剂，其中2,3-OH在与酶非活性位点的结合中起着重要作用。尽管咖啡酸具有较低的抑制活性，但酒石酸在2,3-OH处的咖啡酰取代逐渐增加了其竞争抑制特性。结果，尽管取代降低了酒石酸的抑制活性，但仍建议将其分别作为混合型抑制剂和竞争性抑制剂，分别是咖啡酸（一个咖啡酰基取代的）和癸二酸（两个咖啡酰基取代的）。仅对具有咖啡酰的化合物观察到荧光猝灭，并且随着部分数量的增加，效果增强。与参与配体-酶相互作用的活性荧光残基数量变化趋势一致。这些结果表明咖啡酰部分进入了α-淀粉酶活性口袋。因此，咖啡酰具有作为α-淀粉酶抑制作用的功能因子以减轻II型糖尿病症状的潜力。