Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine.
Department of Pharmacology, Bohomolets National Medical University, Kyiv, Ukraine.
J Biomol Struct Dyn. 2020 Jul;38(10):2865-2883. doi: 10.1080/07391102.2019.1645734. Epub 2019 Aug 2.
Quercetin is an important flavonoid compound, usually extracted from plants, vegetables and fruits such as blueberries, apples, green tea, wine, onions and possessing broad range of pharmacological properties, in particular, powerful antioxidant, antitoxic, antiinflammation and antimicrobial effects due to its various reactive sites. The structure of this phenolic compound consists of three (A + C) and B rings, bearing five hydroxyl groups. Primarily, the chemical structure of quercetin determines its physico-chemical properties. Earlier, it was established that isolated quercetin molecule can acquire 48 stable conformations (24 planar and 24 non-planar) due to the mobility of its hydroxyl groups and (A + C) and B rings with relative Gibbs free energies in the range of 0.0-25.3 kcal·mol under normal conditions (Brovarets' et al., 2019c). In this work by quantum-mechanical calculations at the MP2/6-311++G(2df,pd)//B3LYP/6-311++G(d,p) level of theory and Bader's 'Quantum Theory of Atoms in Molecules', we have theoretically modeled the interconversions in the 24 pairs of the conformers of the quercetin molecule, occuring the rotation of its non-deformable (A+С) and B rings around the С2-С1' bond through the quasi-orthogonal transition state with low values of the imaginary frequencies (28-33/29-36 cm) and Gibbs free energies of activation in the range of 2.17-5.68/1.86-4.90 kcal·mol in the continuum with dielectric permittivity = 1/ = 4 under normal conditions. Also, we studied the changes of the number of physico-chemical characteristics of all intramolecular-specific contacts - hydrogen bonds and attractive van der Waals contacts during these conformational rearrangements.Communicated by Ramaswamy H. Sarma.
槲皮素是一种重要的类黄酮化合物，通常从蓝莓、苹果、绿茶、葡萄酒、洋葱等植物、蔬菜和水果中提取，具有广泛的药理特性，特别是由于其各种反应位点，具有强大的抗氧化、解毒、抗炎和抗菌作用。这种酚类化合物的结构由三个（A+C）和 B 环组成，带有五个羟基。槲皮素的化学结构主要决定了其物理化学性质。早些时候，人们已经确定，由于其羟基和（A+C）和 B 环的可移动性，分离出的槲皮素分子可以获得 48 种稳定构象（24 种平面构象和 24 种非平面构象），在正常条件下，其相对吉布斯自由能在 0.0-25.3 kcal·mol 范围内（Brovarets' 等人，2019c）。在这项工作中，我们通过在 MP2/6-311++G(2df,pd)//B3LYP/6-311++G(d,p)理论水平和 Bader 的“分子中的原子量子理论”上进行量子力学计算，理论上模拟了在槲皮素分子的 24 对构象之间的转化，其非变形（A+C）和 B 环围绕 C2-C1'键的旋转通过具有低虚频（28-33/29-36 cm）和活化吉布斯自由能的准正交过渡态进行，在介电常数为 1/=4 的连续相中，活化吉布斯自由能的范围为 2.17-5.68/1.86-4.90 kcal·mol。此外，我们研究了在这些构象重排过程中所有分子内特定接触——氢键和吸引力范德华接触的物理化学特性数目的变化。由 Ramaswamy H. Sarma 传达。
