Reaction of Bioflavonoids with Copper(II) Acetate in Aqueous Solution

The reaction of dihydroquercetin, quercetin, and rutin with Cu(II) acetate in aqueous solution is studied. Quercetin and dihydroquercetin form complexes with Cu. The water-insoluble complexes are characterized as chelates of the 3,4-positions of the main -pyrone ring. Electronic spectroscopy showed the presence of stable polynuclear rutin complexes of composition rutin :Cu = 1:x, where x > 2.     

槲皮素-Sn(Ⅱ)配合物荧光、紫外及红外光谱的测量与分析

以NH4Cl-NH3·H2O为缓冲液,十六烷基三甲基溴化铵(CTAB)为荧光增强剂,用荧光分光光度计分别采集槲皮素、槲皮素-Sn(Ⅱ)配合物溶液、槲皮素-Sn(Ⅱ)-NH4Cl-NH3·H2O、槲皮素-Sn(Ⅱ)-NH4Cl-NH3·H2O-CTAB溶液以及将其溶液分别静置7h和21h后的荧光光谱,并对光谱进行分析.在不加CTAB的条件下,用紫外分光光度计分别测量加入缓冲液前后的紫外光谱.用漫反射方法测定配合物的红外光谱,并对其结构进行初步分析.在缓冲液的作用下,槲皮素-Sn(Ⅱ)配合物的结构发生了变化;通过分析,发现与缓冲液发生反应的主要基团为酚羟基,红外光谱中酚羟基的消失和NH 4基团的出现,说明了配合物中的酚羟基与NH 4发生了取代反应.     

槲皮素及其异构体分子的结构性质研究

槲皮素是一类有着重要药理活性的黄酮类化合物。本文在B3LYP/6-31G**水平上对槲皮素及其14种异构体进行了几何优化,得到各种异构体的结构与性质。由电荷布居数分析出B环是此类多羟基化合物的活性部分,3位-OH的存在抑制了A、C环的活性。同时,表明此类化合物中必有分子内氢键形成。并给出了最稳构型、槲皮素和标准结构三类分子的振动光谱。探讨了它们的构效关系。     

槲皮素-3-O-丙基衍生物的合成及生物活性研究

槲皮素是具有丰富生物活性的黄酮类化合物,药理活性显著。本文以槲皮素为先导物,选择性对C环3位羟基进行修饰,以廉价的芦丁为原料,经苄基保护、Williamson成醚反应,再经Pd/C催化加氢脱苄基得到28个未见文献报道的槲皮素-3-O-丙基衍生物,其结构经¹H NMR、¹³C NMR、ESI-MS进行确证。采用MTT法考察了所合成化合物对人食管鳞癌（EC109）、人胃癌（HGC27）、人乳腺癌（MCF-7）、小鼠黑色素瘤（B16-F10）的增殖抑制作用。结果显示,通过化学方法对槲皮素结构进行修饰后,其体外抗肿瘤活性增强。其中,化合物F3(IC₅₀=5.23±0.37μmol/L)、F5(IC₅₀=2.63±0.09μmol/L)对小鼠黑色素瘤（B16-F10）抑制作用比5-氟尿嘧啶(IC₅₀=14.38±0.27μmol/L)好,值得进一步研究。     

l-Arginine Improves Solubility and ANTI SARS-CoV-2 Mpro Activity of Rutin but Not the Antiviral Activity in Cells

The COVID-19 pandemic outbreak prompts an urgent need for efficient therapeutics, and repurposing of known drugs has been extensively used in an attempt to get to anti-SARS-CoV-2 agents in the shortest possible time. The glycoside rutin shows manifold pharmacological activities and, despite its use being limited by its poor solubility in water, it is the active principle of many pharmaceutical preparations. We herein report our in silico and experimental investigations of rutin as a SARS-CoV-2 Mpro inhibitor and of its water solubility improvement obtained by mixing it with l-arginine. Tests of the rutin/l-arginine mixture in a cellular model of SARS-CoV-2 infection highlighted that the mixture still suffers from unfavorable pharmacokinetic properties, but nonetheless, the results of this study suggest that rutin might be a good starting point for hit optimization.     

Chemical profiling and quantification analysis of flavonoids in different varieties of Euryales Semen by ultra-high-performance liquid chromatography with tandem mass spectrometry

Euryales Semen was a traditional Chinese medicine, which has been commonly used to treat spermatorrhea, enuresis, and frequent urination. Flavonoids were a critical ingredient in determining the function and quality of Euryales Semen. At present, no effective method has been established for the qualitative of Euryales Semen flavonoids. In this study, an ultra-high-performance liquid chromatography-quadrupole-time of flight-mass spectrometry method was established for flavonoids. By comparison with standard or literature data, 32 flavonoid compounds have been identified in Euryales Semen. Based on the qualitative results, an ultra-high-performance liquid chromatography-triple quadrupole tandem mass spectroscopy method was developed for the main components, and the linearity, the limit of detection, limit of quantification, repeatability, precision, stability, and recovery of the method were verified. The principal component analysis and the hierarchical clustering heatmaps analysis showed that the 30 batches of samples were distinctly separated into the North Gordon Euryale and South Gordon Euryale, and the measured contents of the six flavonoids in North Gordon Euryale were more abundant than in South Gordon Euryale, especially isoquercitrin, hesperetin, and quercetin. It provided a scientific basis for the quality control of Euryales Semen and a theoretical basis for the rational utilization of Euryales Semen resources.     

液相色谱法同时测定维药蜀葵花中芦丁、槲皮素和山柰酚

维药是祖国医药学不可分割的组成部分。维药现代化,即利用现代技术研究维药的有效成分,是维药科学化、标准化、规范化、商品化和产业化的必经之路。本文建立了维药蜀葵花中有效成分芦丁、槲皮素和山柰酚的选择性提取方法,优化了高效液相色谱法(HPLC)同时测定这3种有效成分的分析条件。采用HC-C₁₈色谱柱(250 mm×4.6 mm, 5 μm)和甲醇-0.4%磷酸(50:50, v/v)流动相,在柱温30 ℃和流速1.00 mL/min的条件下实现了3种物质之间以及和干扰物之间的基线分离。维药蜀葵花中芦丁、槲皮素及山柰酚的线性范围分别为12.5~150 μg/mL (r=0.9998), 12.5~125 μg/mL (r=0.9999)及12.5~125 μg/mL (r=0.9988),加标回收率(n=5)分别为100.3%(RSD=1.1%)、97.60%(RSD=0.47%)、97.75%(RSD=0.71%)。该方法实现了同时测定维药蜀葵花中芦丁、槲皮素及山柰酚,为其他黄酮类物质的开发应用提供了科学依据,同时也可为其他维药分析提供借鉴。     

非水介质毛细管电泳电导检测舒血宁片中槲皮素含量

以甲醇：水＝70：30的体系为分离介质，柠檬酸－三（羟甲基）氨基甲烷（Citric acid-Tris)为支持电解质，使用电导检测，对槲皮素及其制剂舒血宁片进行了毛细管电泳分离检测，对电泳介质的种类、浓度、表观pH值以及操作电压和进样时间对分离的影响进行了研讨，并对分离检测机理进行了探讨。建立的测定槲皮素的方法的线性范围为：8．0－160．0mg/L；峰面积的RSD（n=6)为1．7％，检出限为1．0mg/L；样品加标回收率为92．8％－98．2％。     

铋(Ⅲ)-槲皮素极谱络合吸附波及微量铋的测定

在ｐＨ＝３．８，０．４ ｍｏｌ／Ｌ的ＨＣＯＯＨＨＣＯＯＮａ缓冲溶液中，铋与槲皮素的络合物在单扫极谱仪上能形成灵敏的络合物吸附波。该波在Ｂｉ３＋离子浓度为４ × １０－８～６×１０－６ｍｏｌ／Ｌ范围内与波高 ｈｐ成正比关系，检出限达到１×１０－８ｍｏｌ／Ｌ。对电极反应的机理进行了研究。利用该极谱波测定了铅基轴承合金中的铋含量。     

On the Thermodynamic Thermal Properties of Quercetin and Similar Pharmaceuticals

The thermodynamic properties of pharmaceuticals are of major importance since they are involved in drug design, processing, optimization and modelling. In this study, a long-standing confusion regarding the thermodynamic properties of flavonoids and similar pharmaceuticals is recognized and clarified. As a case study, the thermal behavior of quercetin is examined with various techniques. It is shown that quercetin does not exhibit glass transition nor a melting point, but on the contrary, it does exhibit various thermochemical transitions (structural relaxation occurring simultaneously with decomposition). Inevitably, the physical meaning of the reported experimental values of the thermodynamic properties, such as the heat of fusion and heat capacity, are questioned. The discussion for this behavior is focused on the weakening of the chemical bonds. The interpretations along with the literature data suggest that the thermochemical transition might be exhibited by various flavonoids and other similar pharmaceuticals, and is related to the difficulty in the prediction/modelling of their melting point.