Chinese bayberry leaves proanthocyanidins (BLPs) belongs to the prodelphinidin category with potent EGCG unit, whose inhibition effect on α-amylase and their interaction were investigated by in vitro digestion and enzyme kinetic analysis, multi fluorescence spectroscopies (fluorescence quenching, synchronous fluorescence, and three-dimensional fluorescence), circular dichroism spectra, Fourier transform infrared spectroscopy and in silico modelling. The results revealed that BLPs was a mixed inhibitor to α-amylase with the IC₅₀ value of 3.075 ± 0.073 μg/mL. BLPs could lead to a static fluorescence quenching of α-amylase, mainly by means of interacting with amino acids (mainly Try and Tyr residues) in one site on α-amylase molecule under the action of hydrogen bonding and/or Van der Waals force. This interaction further induced the change of secondary conformational structure, functional group structure and hydrophobicity of α-amylase, thus resulting in lowering activity. Molecular docking simulated that this binding occurred in a cavity on the surface of the α-amylase molecule, and BLPs trimer showed a relatively high binding energy. The present study provided a new insight of BLPs as an α-amylase inhibitor, which could be considered in anti-diabetic therapy.

杨梅叶原花青素（BLPs）属于具有强EGCG单元的原花青素类，通过体外消化和酶动力学分析，多荧光光谱（荧光猝灭，同步荧光和三种）研究了其对α-淀粉酶的抑制作用及其相互作用。维荧光），圆二色性光谱，傅立叶变换红外光谱和计算机模拟。结果表明，BLP与IC ₅₀混合使用是α-淀粉酶的混合抑制剂。值为3.075±0.073μg/ mL。BLP可以通过在氢键和/或范德华力的作用下与α-淀粉酶分子上一个位点的氨基酸（主要是Try和Tyr残基）相互作用来导致α-淀粉酶的静态荧光猝灭。这种相互作用进一步引起α-淀粉酶的二级构象结构，官能团结构和疏水性的改变，从而导致活性降低。分子对接模拟表明这种结合发生在α-淀粉酶分子表面的空腔中，而BLP三聚体显示出较高的结合能。本研究为BLP作为α-淀粉酶抑制剂提供了新的见解，可以在抗糖尿病治疗中加以考虑。