槲皮素金属配合物及其抗肿瘤作用研究进展

槲皮素是一种具有广泛药理活性的天然独特分子结构的槲皮素多酚类黄酮,对多种肿瘤具有预防和治疗作用,是多种金属离子的良好螯合配体。研究表明,槲皮素与金属离子配合,能显著提高其抗氧化和抗肿瘤等作用,降低其金属毒性。综述了近10年合成的具有抗肿瘤活性的槲皮素金属配合物及其抗肿瘤作用机制,为槲皮素金属配合物开发成为预防与治疗癌症的药物提供理论参考。     

槲皮素金属配合物的研究进展

槲皮素具有广泛的生物活性和多方面的药理作用,有完整的大π键共轭体系、强配位氧原子及合适的空间构型,可与多种金属离子螯合成稳定的环状配合物。研究表明:槲皮素金属配合物具有抗癌、抗炎、抗氧化、清除自由基和降血糖等作用。槲皮素金属配合物生物活性明显高于槲皮素,药理作用显著。综述了槲皮素金属配合物的研究进展,介绍了槲皮素与主族、副族和稀土金属元素形成配合物的研究现状,为此类化合物的研究提供科学依据。     

槲皮素锑的制备

以槲皮素与三氯化锑为原料制备槲皮素锑配合物,研究合成槲皮素锑的最佳反应条件。试验分别考察了温度、pH及反应时间对槲皮素锑收率的影响,并通过紫外光谱、红外光谱对槲皮素锑进行了表征。结果显示：槲皮素与三氯化锑在甲醇溶液中,在pH=8.6的室温条件下反应2h收率最高,达到62%。     

镝纳米荧光材料合成及光学性质的研究

利用DFT/B3LYP/6-31G的方法对槲皮素结构参数、分子轨道能量的数据及羟基氢原子电荷分布分析,结果表明C4位酚羟基具有较强抗氧化活性,证明此位点的羟基氢参与自由基清除得可能性最大,从量子计算的角度阐释了槲皮素具有抗氧化的药理活性的量子原理。采用常规方法合成纳米镝稀土配合物,通过测量其红外光谱、紫外光谱、荧光光谱特征以及电化学分析和量子计算来研究它。研究表明,镝稀土元素可以与槲皮素生成化学性质稳定的配合物且具有生物活性,可广泛应用于疾病患者的治疗与诊断。     

槲皮素镍的合成、表征及其生物活性研究

介绍了标题化合物的合成方法。通过紫外光谱、红外光谱、氢谱、同步热分析对其结构进行了表征。通过DPPH法测定了槲皮素镍清除自由基的能力,实验显示,槲皮素镍清除自由基的能力比槲皮素低。槲皮素与镍离子在室温下就可以反应生成稳定的配合物,提示在日常生活中经常食用一些含有槲皮素的黄酮类食物,如苹果、洋葱、茶叶、银杏、荞麦等,可清除体内的自由基,使机体免受自由基的损伤,对降低人体内重金属离子的含量起着重要的作用。     

槲皮素镧配合物与牛血清白蛋白相互作用的荧光光谱分析

通过荧光光谱法研究槲皮素镧配合物(La L3·6H2O,L=槲皮素)与牛血清白蛋白(BSA)之间的相互作用。荧光光谱结果表明:槲皮素镧配合物与BSA形成基态复合物并引起荧光的静态猝灭,主要通过作用于BSA酪氨酸残基处引起BSA构象发生的变化。     

多核铜槲皮素配合物的制备及抗肿瘤活性测试

通过摩尔配比法,应用槲皮素与新戊酸铜合成新型配合物;通过元素分析、红外以及热重法对配合物进行分析;采用MTT法体外实验研究配合物对肝癌细胞Hep3B的抗肿瘤活性。结果表明摩尔配比法得到两种铜和槲皮素的配合物。MTT实验显示配合物对肝癌细胞Hep3B具有明显的抑制作用。     

荧光法研究钙离子存在下槲皮素与牛血清白蛋白的相互作用

用荧光法研究了钙离子存在下槲皮素与牛血清白蛋白的相互作用。结果表明,与槲皮素一样,槲皮素-钙离子以形成配合物的形式静态猝灭牛血清白蛋白的内源性荧光,钙离子在一定范围内对槲皮素与牛血清白蛋白的结合起着重要的作用,槲皮素与牛血清白蛋白、槲皮素-钙离子与牛血清白蛋白的表观结合常数/结合位点数分别为5.905×105L.mol-1/1.012、1.245×106L.mol-1/1.037。     

槲皮素-锆(Ⅳ)-柠檬酸-十二烷基磺酸钠体系荧光光度法测定槲皮素的研究

在 0 .5 4 mol/L盐酸介质中 ,有十二烷基磺酸钠的存在下 ,槲皮素与锆 ( )和柠檬酸形成多元荧光配合物 ,其组成比为槲皮素∶锆 ( )∶柠檬酸 =1∶ 2∶ 2。配合物的激发与发射波长分别为432和 495 nm时 ,槲皮素浓度在 1 .0× 1 0 -6～ 1 .0× 1 0 -5mol/L范围内与荧光强度成线性关系 ,检出限为 2 .34× 1 0 -7mol/L。该法用于鸡骨草中黄酮类化合物的测定 ,结果满意     

槲皮素糖苷衍生物的合成研究进展

槲皮素广泛存在于自然界中,具有抗氧化,抗炎,抗菌,抗病毒等多种生物活性,但由于水溶性差,生物利用度低问题,制约了槲皮素的应用。槲皮素糖苷化可以增大水溶性,提高其生物代谢稳定性,改善其治疗效果,成为了国内外的研究热点。近年来通过化学合成,生物合成方法合成槲皮素糖苷衍生物取得了巨大进展,本文将以槲皮素糖苷的化学合成为主,对近年来国内外合成槲皮素糖苷衍生物的研究做一个简要综述。     

Synthesis and evaluation of a metal‐complexing imprinted polymer for Chinese herbs quercetin

In this study, a metal‐complexing imprinted polymer has been prepared using the complex of Quercetin and Co(II) (Qu‐Co(II)) as template (Quercetin is a kind of flavonoid, which is a class of important active ingredients of Chinese herbs.). The polymers were synthesized in the mixed solution of methanol and tetrahydrofuran by photo‐ and thermal‐initiated polymerization, respectively. The complex ratio between Qu and Co(II), as well as the ternary complexation of Qu, Co(II), and acrylamide, was assessed in differential UV absorption spectrometry. Fourier transform infrared spectra (FTIR) were useful to verify whether the polymers prepared in two ways had the same molecular structure. The effect of initiation mode was studied by the transmission electron microscopy (TEM) and equilibrium binding experiments. Isothermal adsorption and selectivity experiments showed that molecularly imprinted polymers exhibited high affinity and specific recognition for Qu by introducing cobalt ion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A Model Compound Study: The Formation of Colored Metallic Extractive Complexes and Their Effect on the Brightness of Tmp Pulp

Abstract

Flavonoids, such as Quercetin, are the main polyphenol compounds found in extractives. When complexing with transition metal ions, these extractives may induce a significant discoloration to mechanical pulps. In this study, the effect of metallic extractive complexes was investigated using a model compound, Quercetin. It was confirmed that the complexes formed between some metal ions and Quercetin are strongly colored. However, most of the strong absorbance in visible light due to metallic Quercetin complexes, can be eliminated by the addition of diethylenetriaminepentaacetic acid (DTPA). The metal ions studied were Fe(III), Cu(II), Mn(II) and AI(III).     

Antioxidant properties of myricetin and quercetin in oil and emulsions

The effect of quercetin and myricetin on the stability of sunflower oil and oil-in-water emulsions was studied by storage experiments monitored by measurement of peroxide values, conjugated dienes, and headspace volatile analysis. Myricetin showed strong antioxidant activity in oils stored at 60 or 30°C and in oil-in-water emulsions stored at 30°C, whether tocopherols or citric acid were present or not; however, quercetin showed similar antioxidant activity in stripped sunflower oil but no activity in oils that contained tocopherols and citric acid. This showed that myricetin is effective owing to strong radical scavenging and metal-chelating properties, whereas quercetin has weaker radical scavenging activity, although it is also active by metal-chelation. The effects of copper and iron salts on the antioxidant activity of myricetin and quercetin were studied in sunflower oil and oil-in-water emulsions. Quercetin and myricetin enhanced the prooxidant effect of cupric chloride in oil-in-water emulsions (pH 7.4), but this effect was not observed with cupric stearate. The addition of myricetin to emulsions that contained ferric chloride at pH 5.4 also produced a strong prooxidant effect, and small prooxidant effects of flavonols were also detected in the presence of cupric chloride under these conditions. However, myricetin and quercetin reduced the prooxidant effect of ferric palmitate in oils. Myricetin also showed a strong antioxidant effect in oil that contained cupric stearate, although quercetin had no significant effect on the oxidative stability of this system. It therefore appears that flavonols may exert a prooxidant effect in the presence of metal salts, but the nature of the metal salt is important in determining whether a prooxidant effect occurs.     

槲皮素酯类衍生物的研究进展

槲皮素,属黄酮醇类化合物,广泛存在于诸如蔬菜、水果、茶和葡萄酒等很多食物中.它是一种极强的天然抗氧化剂,具有抗血栓、抗炎、抗病毒、抗肿瘤等作用.但是,由于其水溶性差,生物利用度低,限制了它的临床应用.近年来,国内外合成了一些槲皮素酯类衍生物,不但改善了槲皮素的水溶性,而且还具有明显的生物活性,如QCI2作为一种水溶性抗...     

O/W型微乳液对槲皮素增溶作用的研究

考察了吐温-80/正丁醇/丁酸乙酯/水微乳液体系对水难溶性药物槲皮素的增溶作用。结果表明,槲皮素在以丁酸乙酯为油相的微乳液和其相应的胶束溶液中溶解度明显增大。同时随着载药微乳液浓度的增加,微乳液的粒径有增大趋势;而随着放置时间的延长,粒径有减小的趋势。在对载药微乳液稳定性的考察中发现,载药微乳液在室温和低温下放置比较稳定,其外观性状和药物含量均没有明显变化。     

HPLC法同时测定水解前后杜仲叶黄酮苷元的含量

建立快速检测杜仲中两种黄酮苷元槲皮素与山奈酚的高效液相色谱方法,并测定水解前后杜仲叶与杜仲素黄酮苷元的含量。采用HPLC法同时测定黄酮苷元,色谱柱为Diamonsil C18(4.6 mm×250 mm,5μm),以甲醇-0.2%磷酸(63∶37)为流动相,检测波长为370 nm,流速1.0 mL/min,柱温为30℃。槲皮素和山奈酚分别在0.5~80μg/mL和0.5~18μg/mL内线性关系良好,该检测方法能迅速、准确检测水解前后杜仲叶和杜仲素中槲皮素和山奈酚的含量;水解工艺可明显提高杜仲黄酮苷元含量。     

Physicochemical characterization and antioxidant activity of quercetin‐loaded chitosan nanoparticles

Quercetin is an abundant flavonoid in food plants with numerous biological activities and widely used as a potent antioxidant. Being sparingly soluble in water and subject to degradation in aqueous intestinal fluids, the absorption of quercetin is limited upon oral administration. In the present study, chitosan nanoparticles and quercetin‐loaded nanoparticles were prepared based on the ionic gelation of chitosan with tripolyphosphate anions. The encapsulation of quercetin in the chitosan nanoparticles were confirmed by differential scanning calorimetry, X‐ray powder diffractometry, Fourier transformed infrared spectroscopy, ultraviolet‐visible spectrum, and fluorescence spectrum. The morphology of the nanoparticles was characterized by atomic force microscopy. The antioxidant activity of the quercetin‐nanoparticles was also evaluated in vitro by two different methods (free radical scavenging activity test and reducing power test), which indicates that inclusion of quercetin in chitosan nanopaticles may be useful in improving the bioavailabilty of quercetin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

N‐Acylethanolamines Bind to SIRT6

Sirtuin 6 (SIRT6) is an NAD+‐dependent histone deacetylase enzyme that is involved in multiple molecular pathways related to aging. Initially, it was reported that SIRT6 selectively deacetylated H3K9Ac and H3K56Ac; however, it has more recently been shown to preferentially hydrolyze long‐chain fatty acyl groups over acetyl groups in vitro. Subsequently, fatty acids were demonstrated to increase the catalytic activity of SIRT6. In this study, we investigated whether a series of N‐acylethanolamines (NAEs), quercetin, and luteolin could regulate SIRT6 activity. NAEs increased SIRT6 activity, with oleoylethanolamide having the strongest activity (EC₅₀ value of 3.1 μm ). Quercetin and luteolin were demonstrated to have dual functionality with respect to SIRT6 activity; namely, they inhibited SIRT6 activity with IC₅₀ values of 24 and 2 μm , respectively, and stimulated SIRT6 activity more than sixfold (EC₅₀ values of 990 and 270 μm , respectively).     

Matrix Metalloproteinases and Their Role in Mechanisms Underlying Effects of Quercetin on Heart Function in Aged Zucker Diabetic Fatty Rats

Several mechanisms may contribute to cardiovascular pathology associated with diabetes, including dysregulation of matrix metalloproteinases (MMPs). Quercetin (QCT) is a substance with preventive effects in treatment of cardiovascular diseases and diabetes. The aim of the present study was to explore effects of chronic QCT administration on changes in heart function in aged lean and obese Zucker Diabetic Fatty (ZDF) rats and that in association with MMPs. Signaling underlying effects of diabetes and QCT were also investigated. In the study, we used one-year-old lean and obese ZDF rats treated for 6 weeks with QCT. Results showed that obesity worsened heart function and this was associated with MMP-2 upregulation, MMP-28 downregulation, and inhibition of superoxide dismutases (SODs). Treatment with QCT did not modulate diabetes-induced changes in heart function and MMPs. However, QCT activated Akt kinase and reversed effects of diabetes on SODs inhibition. In conclusion, worsened heart function due to obesity involved changes in MMP-2 and MMP-28 and attenuation of antioxidant defense by SOD. QCT did not have positive effects on improvement of heart function or modulation of MMPs. Nevertheless, its application mediated activation of adaptive responses against oxidative stress through Akt kinase and prevention of diabetes-induced negative effects on antioxidant defense by SODs.