Department of Physics and Biophysics, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland.
Department of Chemistry, Wrocław University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland.
Molecules. 2017 Sep 11;22(9):1520. doi: 10.3390/molecules22091520.
Quercetin (Q) was used as substrate for regioselective glycosylation at the C-7 position catalyzed by AM278 strain. As a result the glycoside quercetin 7--β-d-(4″--methyl)glucopyranoside (Q 7-MeGlu) was formed. The goal of the studies was to determine the anti-oxidative (liposome membrane protection against free radicals IC = 5.47 and IC = 4.49 µM) and anti-inflammatory (COX-1 and COX-2 enzymes activity inhibition) properties of Q 7-MeGlu as compared to Q. Every attempt was made to clarify the antioxidant activity of these molecules, which are able to interact with egg phosphatidylcholine liposomes, using a fluorometric method (by applying the probes MC540, TMA-DPH and DPH). The results indicated that Q 7-MeGlu and Q are responsible for increasing the packing order, mainly in the hydrophilic but also in hydrophobic regions of the membrane (Q > Q 7-MeGlu). These observations, confirmed by a ¹H-NMR method, are key to understanding their antioxidant activity which is probably caused by the stabilizing effect on the lipid membranes. The results showed that Q 7-MeGlu and Q have ability to quench the human serum albumin (HSA) intrinsic fluorescence through a static quenching mechanism. The results of thermodynamic parameters indicated that the process of formation complexes between studied molecules and HSA was spontaneous and caused through Van der Waals interactions and hydrogen bonding.
槲皮素（Q）被用作 AM278 菌株催化的 C-7 位区域选择性糖基化的底物。结果形成了糖苷槲皮素 7--β-d-(4″--甲基)吡喃葡萄糖苷（Q 7-MeGlu）。研究的目的是确定 Q 7-MeGlu 相对于 Q 的抗氧化（脂质体膜对自由基的保护作用 IC = 5.47 和 IC = 4.49 µM）和抗炎（COX-1 和 COX-2 酶活性抑制）特性。为了澄清这些分子的抗氧化活性，我们尝试使用荧光法（应用探针 MC540、TMA-DPH 和 DPH）来阐明这些分子与卵磷酯脂质体相互作用的能力。结果表明，Q 7-MeGlu 和 Q 负责增加膜的有序性，主要是在亲水区，也在疏水区（Q > Q 7-MeGlu）。这些观察结果通过 ¹H-NMR 方法得到了证实，是理解其抗氧化活性的关键，其抗氧化活性可能是由于对脂质膜的稳定作用。结果表明，Q 7-MeGlu 和 Q 能够通过静态猝灭机制猝灭人血清白蛋白（HSA）的固有荧光。热力学参数的结果表明，研究分子与 HSA 之间形成复合物的过程是自发的，是通过范德华相互作用和氢键引起的。
