Natural Phenolic Compounds as Modifiers for Epoxidized Natural Rubber/Silica Hybrids

Silica is a popular filler, but in epoxidized natural rubber, can act as a cross-linking agent. Unfortunately, a high amount of silica is necessary to obtain satisfactory tensile strength. Moreover, a high amount of silica in ENR/silica hybrids is associated with low elongation at break. In our paper, we propose natural phenolic compounds, including quercetin, tannic acid, and gallic acid as natural and safe additional crosslinkers dedicated to ENR/silica hybrids to obtain bio-elastomers with improved mechanical properties. Therefore, toxic crosslinkers, such as peroxides or harmful accelerators can be eliminated. The impact of selected natural phenolic compounds on crosslinking effect, mechanical properties, color, and chemical structure of ENR/silica composite have been analyzed. The obtained results indicated that only 3 phr of selected natural phenolic compounds is able to improve crosslinking effect as well as mechanical properties of ENR/silica hybrids. Moreover, some of the prepared materials tend to regain mechanical properties after reprocessing. Such materials containing only natural and safe ingredients have a chance of becoming novel elastomeric biomaterials dedicated to biomedical applications.     

高效液相色谱法测定不同产地枇杷叶中的3种黄酮类成分

建立了高效液相色谱同时测定枇杷叶中3种黄酮类成分的分析方法。该方法分析了不同产地枇杷叶中芦丁、槲皮素和山柰酚的含量差异。枇杷叶粉末用甲醇超声提取后,加盐酸回流,制备样品测试液。采用Diamonsil C18色谱柱（250 mm×4.6 mm,5 μm）,以0.4%（v/v）磷酸水溶液-乙腈为流动相,梯度洗脱。分别对7个不同产地的枇杷叶样品中的芦丁、槲皮素和山柰酚进行测定。结果表明,芦丁、槲皮素、山柰酚在各自的质量浓度范围内线性关系良好（r>0.99）,加标回收率分别为96.33%、95.81%和95.80%,RSD分别为6.48%、0.90%和3.02%。该方法操作简单、分离度好、重复性高。不同产地枇杷叶中3种黄酮类成分的含量存在差异,其中芦丁的差异最大,而山柰酚的含量最稳定且在不同产地样品中均可检出,或可用作枇杷叶药材质量控制的标志成分。     

采用Suzuki-Miyaura偶联反应合成类黄酮碳芳基化衍生物

A variety of 4＇- and 3-C-aryl-quercetin derivatives were conveniently synthesized via Suzuki-Miyaura coupling of the corresponding quercetin-O-triflates with aryl boronic acids or boronates.     

HPLC法测定新疆贯叶连翘中芦丁及槲皮素的含量

采用高效液相色谱法测定了新疆贯叶连翘中芦丁及槲皮素的含量.以Hypers il ODS(12.5 cm×6.0mm i.d.,5μm)为色谱柱,甲醇和0.4%磷酸水溶液为流动相,检测波长为360 nm;芦丁的进样量在0.058~0.580μg范围内(r=0.999 8),槲皮素进样量在0.014~0.140μg范围内(r=0.999 9)都与峰面积线性关系良好.芦丁的回收率为99.0%,相对标准偏差RSD为0.66%(n=6),槲皮素的回收率为95.9%,相对标准偏差RSD为1.60%(n=6).实验表明该方法简便、快速、适用性好.     

Fluorescent analysis of interaction of flavonols with hemoglobin and bovine serum albumin

We have studied the fluorescent properties of flavonols (quercetin, fisetin, morin, rutin) with the aim of studying possible interaction with hemoglobin and bovine serum albumin (BSA). We observed an increase in the intensity of intrinsic fluorescence for all the flavonols except rutin in the presence of BSA. From the changes in the fluorescence spectra, we concluded that tautomeric forms are formed on interaction with hemoglobin. We determined the interconnection between the structure of related flavonols and their fluorescent properties on interaction with proteins, and we determined the binding constants for binding with BSA and hemoglobin. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 659–664, September–October, 2007.     

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NH4+基团的出现,说明了配合物中的酚羟基与NH4+发生了取代反应。     

Study on Fluorescence Characteristic of Quercetin–Nanoporous Anodic Aluminum Oxide Composites

Nanoporous Anodic Aluminum Oxide (AAO), its average diameters of porous were 50 nm, was obtained by two-step electrochemical anodization aluminum process. Highly ordered luminescence arrays formed by filling AAO nanopores with quercetin molecules has been studied by fluorescent spectroscopy in this work. AAO showed stronger adsorption capability of quercetin than Al³⁺-quercetin complex. The mechanism may be physical and chemical adsorption all together. Meanwhile, red shift of the maximum fluorescence peak of quercetin in AAO was observed. The molecular assemblies in the nanopore array are highly ordered and the fluorescence polarization dependence indicates a preferred molecular orientation along the pore axis. This maybe explains the mechanism of molecular luminescence depending on its environment.     

Quantum Chemistry Calculation of Quercetin-silver Complex

1 INTRODUCTION Quercetin(3,5,7,3?,4?-pentahydroxyflavone,see Fig. 1) is a kind of flavonol with many pharma-colo- gical actions, such as anti-flammatory, antiviral and antioxidation[1], but its antioxidation is weak. In re- cent years, it has been reported that quercetin can form metallic complexes by combining with some metal ions like copper ion, zinc ion, nickel and rare earth metals, and its antioxidative activity will be stronger than quercetin due to the existence of co- operative ef…     

染料-示波计时电位法测定天然水中的不同形态铝

槲皮素;羟基喹啉-磺酸;染料-示波计时电位法测定天然水中的不同形态铝     

Simultaneous Determination of Phenolic Compounds in Red Wines by HPLC‐UV

Abstract

Ten samples of commercially Italian red wines were analyzed in order to determine the phenolic content. Variations in wine types are largely due to differences in concentration and composition of these compounds. Polyphenolic compounds are a large and complex group of substances which constitute one of the most important quality parameters of wine. These constituents of red wine contribute to organoleptic characteristics and to antioxidant and anti‐inflammatory properties. Moderate wine consumption is associated with several beneficial physiological effects, which include anticancer activities, inhibition of platelet aggregation, and inhibition of LDL oxidation which constitutes the initial stage of the pathogenesis of arteriosclerosis.

For the analysis, reversed‐phase high performance liquid chromatography (HPLC) method coupled with UV‐Vis detection was used. The method uses a gradient elution to identify nine biologically active phenolic constituents: catechin; epicatechin; trans‐ and cis‐resveratrol; gallic, chlorogenic and caffeic acid; rutin and quercetin in red wine samples. The samples are injected directly without any pretreatment. The method is simple, fast, not expensive and shows good linearity for all constituents, and the detection limits ranged from 0.3–1.6 µg/ml for trans‐resveratrol and gallic acid, respectively. Moreover, the samples were analyzed in different times for estimation of stability of these compounds.