Claasen Birgit, Xiong Mengyao, Mayer Pia S, Sogl Greta, Buchweitz Maria
Analytical Department, Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart 70569, Germany.
Department of Food Chemistry, Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Allmandring 5b, Stuttgart 70569, Germany.
J Agric Food Chem. 2025 Apr 16;73(15):9047-9061. doi: 10.1021/acs.jafc.4c13178. Epub 2025 Apr 4.
For flavan-3-ols, significant effects to prevent the development of diabetes mellitus are postulated. , this is attributed to inhibitory effects on the intestinal α-amylase, in particular for high-molecular-weight procyanidins. In order to gain a deeper insight into the mode of interaction and the resulting α-amylase inhibition, the interaction between the monomers (+)-catechin (CAT) and (-)-epicatechin (EC), the dimers procyanidin (PC) B1 and PC B2, and the trimer PC C1 and their inhibition of porcine pancreatic α-amylase were investigated. Weak interactions were determined by isothermal titration calorimetry (ITC), with no clear difference between monomers and dimers and even no observable interaction with PC C1. Data from saturation transfer difference (STD)-NMR experiments supported these results with respect to reversible interactions. The detailed NMR signal assignments revealed that the formation of rotamers is solvent-dependent, which might explain the differences in the interaction strength between both diastereomers. The results for interaction were in contrast to the accumulating inhibitory strength with an increasing degree of polymerization when monitoring hydrolysis of the natural substrate starch in a novel continuous approach by ITC. By combining the data from the interaction and inhibition studies, we propose that protein aggregation occurs in the presence of flavan-3-ol oligomers, which are responsible for the inhibitory effects. This rather irreversible interaction is not susceptible to detection by ITC and STD-NMR and was also not observable by CD spectroscopy.
对于黄烷-3-醇，推测其对预防糖尿病的发展具有显著作用。这归因于对肠道α-淀粉酶的抑制作用，特别是对高分子量原花青素而言。为了更深入地了解相互作用模式以及由此产生的α-淀粉酶抑制作用，研究了单体（+）-儿茶素（CAT）和（-）-表儿茶素（EC）、二聚体原花青素（PC）B1和PC B2以及三聚体PC C1之间的相互作用及其对猪胰腺α-淀粉酶的抑制作用。通过等温滴定量热法（ITC）测定了弱相互作用，单体和二聚体之间没有明显差异，甚至与PC C1没有可观察到的相互作用。饱和转移差（STD）-NMR实验的数据在可逆相互作用方面支持了这些结果。详细的NMR信号归属表明，旋转异构体的形成取决于溶剂，这可能解释了两种非对映异构体之间相互作用强度的差异。当通过ITC以一种新颖的连续方法监测天然底物淀粉的水解时，相互作用的结果与随着聚合度增加而累积的抑制强度形成对比。通过结合相互作用和抑制研究的数据，我们提出在黄烷-3-醇低聚物存在下会发生蛋白质聚集，这是产生抑制作用的原因。这种相当不可逆的相互作用不易通过ITC和STD-NMR检测到，通过圆二色光谱法也未观察到。
