Antioxidant activity of extract from Polygonum aviculare L

Free radicals induce numerous diseases by lipid peroxidation, protein peroxidation, and DNA damage. It has been reported that numerous plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum aviculare L. (Polygonaceae) has antioxidant activity is unknown. In this study, dried Polygonum aviculare L. was extracted by ethanol, and the extract was lyophilized. The antioxidant activities of extract powder were examined by free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays. The results show that the IC50 value of Polygonum aviculare L. extract is 50 microg/ml in free radical scavenging assays, 0.8 microg/ml in superoxide radical scavenging assays, and 15 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum aviculare L. extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 677.4 +/- 62.7 microg/g and 112.7 +/- 13 microg/g. The results indicate that Polygonum aviculare L. extract clearly has antioxidant effects.     

虎杖提取物对弹性蛋白酶的抑制作用研究

本文主要研究了虎杖提取物对弹性蛋白酶的抑制作用。实验利用热水浸渍法提取虎杖得到粗提取物1(CE1),聚酰胺柱层析后得到粗提取物2(CE2),并进行一系列的定性及定量分析。分别用紫外分光光度法和荧光光谱法研究了提取物对弹性蛋白酶的抑制作用和荧光猝灭作用。实验结果表明CE1和CE2中均含有虎杖苷,含量分别为41.01%和69.57%。CE1、CE2和虎杖苷对弹性蛋白酶有一定的抑制作用,当浓度为2.0 mg/mL时,它们对弹性蛋白酶的抑制率分别为53.56%、61.27%和82.53%。CE1、CE2和虎杖苷对弹性蛋白酶均有明显的内源荧光猝灭作用,当浓度为0.1 mg/mL时,荧光猝灭率分别为70.38%、72.90%和75.99%。     

虎杖中白藜芦醇的酶法制备

以白藜芦醇得率为指标,通过对酶制剂的筛选和酶解条件的考察,分别选出酶法提取和酶法转化制备虎杖中白藜芦醇的最佳条件,并对两种酶法进行比较.结果显示:(1)酶法提取最佳酶解条件为:酶解温度45℃,酶解时间60 min,最适pH 5.0,底物浓度17%;酶法转化最佳酶解条件为:酶解温度40℃,酶解时间48 h,最适pH 5.0,底物浓度15%.(2)与空白样品(不加酶)相比,酶法提取白藜芦醇得率增加了3.12 mg/g;酶法转化白藜芦醇得率增加了12.72 mg/g.研究表明,两种方法与不加酶提取相比均提高了白藜芦醇的得率,但酶法转化效果更显著,可用于白藜芦醇的制备.     

Enhancement of fluoride activity against Streptococcus mutans biofilms by a substance separated from Polygonum cuspidatum

Polygonum cuspidatum is a plant with spreading rhizomes and numerous reddish-brown stems that has been used in Korean folk medicine to improve oral hygiene. Nevertheless, there are no reports related to its possible effect on the virulence of dental biofilms. In this study, the ability of a fraction (F1) separated from P. cuspidatum, alone or in combination with fluoride, to disrupt virulence factors and the composition of Streptococcus mutans biofilms was examined. F1 was mainly composed of resveratrol, emodin and physcion (approximately 16.2%, 18.9% and 2.07% of the weight of F1, respectively). F1 showed inhibitory effects on acid production and F-ATPase activity of S. mutans in biofilms, and could enhance fluoride activity against acid production and acid tolerance of S. mutans in biofilms. When S. mutans biofilms were briefly treated with F1 (10 min, a total of five times), the biomass accumulation, water-insoluble polysaccharides and intracellular iodophilic polysaccharides were reduced. Furthermore, the fluoride activity against biomass accumulation was enhanced by F1. These results suggest that F1 may be useful in the control of dental biofilms and in improving the cariostatic properties of fluoride without increasing its exposure.     

Enhancement of fluoride activity against Streptococcus mutans biofilms by a substance separated from Polygonum cuspidatum

Polygonum cuspidatum is a plant with spreading rhizomes and numerous reddish-brown stems that has been used in Korean folk medicine to improve oral hygiene. Nevertheless, there are no reports related to its possible effect on the virulence of dental biofilms. In this study, the ability of a fraction (F1) separated from P. cuspidatum, alone or in combination with fluoride, to disrupt virulence factors and the composition of Streptococcus mutans biofilms was examined. F1 was mainly composed of resveratrol, emodin and physcion (approximately 16.2%, 18.9% and 2.07% of the weight of F1, respectively). F1 showed inhibitory effects on acid production and F-ATPase activity of S. mutans in biofilms, and could enhance fluoride activity against acid production and acid tolerance of S. mutans in biofilms. When S. mutans biofilms were briefly treated with F1 (10 min, a total of five times), the biomass accumulation, water-insoluble polysaccharides and intracellular iodophilic polysaccharides were reduced. Furthermore, the fluoride activity against biomass accumulation was enhanced by F1. These results suggest that F1 may be useful in the control of dental biofilms and in improving the cariostatic properties of fluoride without increasing its exposure.     

Lipid-lowering effects of polydatin from Polygonum cuspidatum in hyperlipidemic hamsters

Hyperlipidaemias are common in obese people, and they increase the risk of cardiovascular diseases such as coronary heart disease (CHD) and atherosclerosis (AS). Previous studies have shown that several drugs can depress serum cholesterol. However, they could cause serious side effects in various clinical settings. The objective of the present study was to evaluate the lipid-lowering effects of polydatin in high-fat/cholesterol (HFC)-fed hamsters. The levels of lipids in hamsters were measured enzymatically before and after the administration of polydatin. Significant differences between HFC and HFC+polydatin were detected for those concentrations. Decreased levels of serum TC, TG and LDL-C and the concentrations of hepatic TG were found. Experimental results also showed that polydatin elevated LDL-C/HDL-C and TC/HDL-C ratios. In concert with other effects, serum cholesterol-lowering effect in hamsters may contribute to the regulation properties attributed to polydatin.     

虎杖鞣质的糖苷酶抑制作用研究

本文研究了虎杖鞣质对-αD-葡萄糖苷酶、蔗糖酶、乳糖酶和α-淀粉酶的抑制活性,以探讨其降血糖机制。结果显示虎杖鞣质除对α-淀粉酶几乎没有抑制活性外,对其余糖苷酶均显示不同程度的抑制活性,其降血糖机理可能是通过调控糖苷酶活性实现的。     

Intravacuolar Spherical Bodies in Polygonum cuspidatum

The vacuoles in the epidermal cells of light-grown seedlingsof Polygonum cuspidatum were found to contain intensely pigmentedspherical bodies (anthocyanoplasts). Dark-grown seedlings containedsimilar spherical bodies that were unpigmented. The unpigmentedspherical bodies accumulated anthocyanin and turned into anthocyanoplastswhen dark-grown seedlings were irradiated. The unpigmented sphericalbodies of dark-grown seedlings were heavily stained upon treatmentof seedlings with neutral red. The absorption spectra of sphericalbodies and vacuoles showed that the contents of the sphericalbody were different from those of the vacuole. The sphericalbody was stable in darkness or at low temperature but was unstableat 25°C in the light. There was no correlation between theamount of anthocyanin and the percentage of cells that containedspherical bodies, suggesting that, in P. cuspidatum, the sphericalbody is not the main site of anthocyanin synthesis. ²Present address: Department of Applied Biology, Faculty ofTextile Science and Technology, Shinshu University, Ueda, 386Japan     

MPLC测定虎杖中白藜芦醇含量

建立测定虎杖中白藜芦醇含量的反相中压高效液相色谱分析方法。实验采用SOURCE 5RPC ST 4.6/150预装拄,以乙腈:水(体积比30:70 V/V)溶液为流动相、流速l mL/min、检测波长308 nm。结果表明白藜芦醇对照品浓度在0.6~1.6 mg/mL时,浓度与峰面积呈良好的线形关系(R=0.9919);加样回收率为103.0~90.4%,RSD=7.21%。采用中压高效液相色谱法测定虎杖中白藜芦醇含量,操作方便,准确性和实用性好。     

HPLC法测定虎杖中白藜芦醇的含量

本文采用高铲液相色谱法测定虎杖白藜芦醇含量。测量条件：ODS－C18柱,流动相为甲醇－水（35：65）,检测波长：300nm。结果表明：白藜芦醇在0.4－2.0μg范围内具良好的线性关系,相关系数γ=0.9998,平均回收率为98.19％。     

Two new bacterial DNA primase inhibitors from the plant Polygonum cuspidatum

The 70% aqueous methanolic extract of the Peruvian plant Polygonum cuspidatum sp. was found to contain two novel phenolic saccharides 1 and 2, which were identified as inhibitors of the bacterial DNA primase enzyme. Structures of these two compounds were established based on high resolution NMR studies. Compound 1 and 2 inhibited the primase enzyme with an IC(50) of 4 and 5 microM, respectively.     

大孔吸附树脂分离虎杖中白藜芦醇的研究

目的:采用大孔吸附树脂对虎杖粗提物中白藜芦醇进行初步富集、分离和纯化.方法:考察18种树脂对白藜芦醇的吸附量和解吸率,选择吸附量大、解吸率高的数种树脂进行吸附动力学研究,确定最佳的脱附工艺.结论:HPD-500树脂对白藜芦醇的吸附量可达58.67mg/g,解吸率为92.6%,经大孔吸附树脂的吸附与解吸,白藜芦醇的含量由粗提物中9.25%提高至39.5%.     

Phytoestrogens from the roots of Polygonum cuspidatum (Polygonaceae): structure-requirement of hydroxyanthraquinones for estrogenic activity.

The methanolic extract from the roots of Polygonum (P.) cuspidatum was found to enhance cell proliferation at 30 or 100 microg/mL in MCF-7, an estrogen-sensitive cell line. By bioassay-guided separation from P. cuspidatum with the most potent activity, emodin and emodin 8-O-beta-D-glucopyranoside were isolated as active principles. The methanolic extracts from Polygonum, Cassia, Aloe, and Rheum species, which were known to contain anthraquinones, also showed the MCF-7 proliferation. As a result of the evaluation of various anthraquinones from plant sources and synthetic anthraquinones, aloe-emodin, chrysophanol, chrysophanol 8-O-beta-D-glucopyranoside, and 1,8-dihydroxyanthraquinone showed weak activity. On the other hand, alizalin and 2,6-dihydroxyanthraquinone as well as emodin having the 2- and/or 6-hydroxyl groups showed potent activity. These results show that the unchelated hydroxyl group is essential for strong activity. Emodin and 2,6-dihydroxyanthraquinone also inhibited 17beta-estradiol binding to human estrogen receptors (ERs) with K(i) values of 0.77 and 0.31microM for ERalpha and 1.5 and 0.69 microM for ERbeta. These findings indicate that hydroxyanthraquinones such as emodin are phytoestrogens with an affinity to human estrogen receptors.     

虎杖苯亚甲基丙酮合酶PcPKS2的表达纯化和晶体生长

植物类型Ⅲ聚酮合酶超家族(PKSs),又称查尔酮合酶(Chalcone synthase,CHS)超家族,催化合成多种植物次生代谢产物的分子骨架。苯亚甲基丙酮合酶(Benzalacetone synthase,BAS)催化4-香豆酰辅酶A与丙二酰辅酶A通过一步脱羧缩合反应生成苯亚甲基丙酮,是一系列具有重要生物学活性苯丁烷类化合物及其衍生物的前体化合物。前期工作从虎杖中分离出苯亚甲基丙酮合酶BAS(PcPKS2)和1个具有CHS和BAS活性的双功能酶(PcPKS1)。两者与超家族其他成员序列经比较,在包括门卫氨基酸Phe215和Phe265在内的重要氨基酸序列存在一定差异。已有蛋白晶体学研究结果表明,PKSs家族不同成员的功能多样性来自于酶催化位点的非常微小的构象变化。为了能够从结构上比较PcPKS2和Pc PKS1双功能酶活性差异可能产生的机制,以确定其高效BAS活性的分子机理,研究利用了大肠杆菌原核表达系统过量表达了C-端融合有His6标签的重组蛋白,经纯化得到了高纯度蛋白。经过对其晶体生长条件进行摸索和优化,得到了能用于X-射线衍射的单晶,为其结构解析、催化机理研究、了解虎杖聚酮类化合物生物合成机制和该类酶在基因工程中的应用提供了基础。     

Antioxidant activity of 50% aqueous--ethanol extract from Acantholippia deserticola

The antioxidant properties oí Acantholippia deserticola, a herb used in traditional northern Chilean medicine was studied using free radical-generating systems. The 50% aqueous-ethanol extract oí Acantholippia deserticola protected against non-enzymatic lipid peroxidation in microsomal membranes of rat, induced by an Fe++-ascorbate system and measured spectrophotometrically by the TBARS test, and had strong free radical scavenging capacities on stable ABTS and DPPH radicals. The results shows that the IC50 value of the 50% aqueous-ethanolic extract of A.deserticola is 18 +/- 0.5 microg/mL in DPPH radical-scavenging, 15 +/- 0.8 microg/mL in lipid peroxidation , Total Antioxidant Activity (TAA) is 0.95 mM of Trolox per mg/mL of extract. The total phenolics content of extract is 725 +/- 12 mg of gallic acid equivalent per g of dried extract. The results indicate that the 50% aqueous-ethanol extract of Acantholippia deserticola clearly has antioxidant properties.     

Antioxidant flavonoids from leaves of Polygonum hydropiper L

Ten flavonoid compounds were isolated from the dried leaves of Polygonum hydropiper L. (Laksa leaves), and identified as 3-O-alpha-L-rhamnopyranosyloxy-3',4',5,7-tetrahydroxyflavone; 3-O-beta-D-glucopyranosyloxy-4',5,7-trihydroxyflavone; 6-hydroxyapigenin; 6"-O-(3,4,5-trihydroxybenzoyl) 3-O-beta-D-glucopyranosyloxy-3', 4', 5, 7-tetrahydroxyflavone; scutillarein; 6-hydroxyluteolin; 3',4',5,6,7-pentahydroxyflavone; 6-hydroxyluteolin-7-O-beta-D-glucopyranoside; quercetin 3-O-beta-D-glucuronide; 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin; quercetin. Evaluation of the antioxidative activity, conducted in vitro, by using electron spin resonance (ESR) and ultraviolet visible (UV-vis) spectrophotometric assays, showed that these isolated flavonoids possess strong antioxidative capabilities. Measurement of the Trolox equivalent antioxidant capacity (TEAC) values, against ABTS (2,2'-azinobis(3-ethyl-benzo-thiazoline-6-sulphonic acid) radicals and phenyl-tert-butyl nitrone (PBN) azo initiator (AI) also showed strong anti-oxidative activity. The most powerful of the antioxidants was 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin (galloyl quercitrin). A combination of two flavonoid compounds was tested for synergistic anti-oxidative capacity, but no significant improvement was observed.     

湘西虎杖抑菌活性成分提取研究

对湘西虎杖抑菌活性物提取条件进行研究,通过抑菌实验得到最佳提取条件为90%乙醇、60℃、3 h,该条件下的提取物对细菌生长的抑制活性最强,但对酵母菌无明显的效果,对金黄色葡萄球菌、大肠杆菌、痢疾杆菌的最小抑菌浓度（MIC）为0.25 g/mL～0.5 g/mL.提取物经85℃、100℃,15 min或pH 2～8处理后仍具有较强的抑菌活性.     

虎杖不同部位白藜芦醇含量的分析

白藜芦醇(反-3,4,5-三羟基二苯乙烯,resveratrol)是一种活性多酚物质,也称芪三酚,1940年从毛叶藜芦(Veratrum puberulum Loes. f.)的根中最先得到.有研究认为,白藜芦醇及其苷是植物体在恶劣环境下或遇到病原侵害时自身分泌的一种抗毒素,因此有“植物杀菌素”之称[1].