反相高效液相色谱法分析化妆品用白色茶多酚

采用反相高效液相色谱法测定化妆品用白色茶多酚中的多种活性成分。色谱柱:HypersilBDSC184 6×200mm;流动相:梯度洗脱,A相为0 5%HAc水溶液与乙腈体积比为95∶5,B相为甲醇与乙腈与0 5%醋酸水溶液体积比为50∶30∶20;流速为0 8mL/min;检测波长为280nm。结果表明:该方法能同时测定儿茶素没食子酸酯、表没食子儿茶素、右旋儿茶素、表没食子儿茶素没食子酸酯、表儿茶素、没食子儿茶素没食子酸酯、表儿茶素没食子酸酯和咖啡因,这8种组分的质量分数与峰面积有良好的线性关系(r=0 9982～0 9999),加样回收率为86 9%～106 6%(n=5)。     

茶多酚生产应用与开发前景

茶多酚,简称TP。茶多酚是茶叶中的多酚类物质,主要由表儿茶素(L-EC)、表儿茶素没食子酸酯(L-ECG)、表没食子儿茶素(L-EGC)、表没食子儿茶素没食子酸酯(L-EGCG)等4种成分组成。茶多酚产品中儿茶素一般占60％～80％,此外,还含有没食子酸等酚酸类化合物、儿茶氧化物和缩聚产物及咖啡等生物碱类物质。 迄今,在众多的由茶叶及其副产品深加工而得的产品中,除速溶茶外,被人们研究和认识最为深刻和广泛的就是茶多酚了。茶多酚是     

茶多酚的经皮渗透特征及其对UVA致HSF氧化损伤的保护作用

研究了茶多酚的经皮渗透特征,探究茶多酚对长波紫外线（UVA）诱导的人皮肤成纤维细胞氧化损伤的保护作用机理。采用Franz扩散池,以大鼠皮肤为屏障,建立了完善的检测方法,用高效液相色谱检测茶多酚中儿茶素、表儿茶素、表儿茶素没食子酸酯、表没食子儿茶素没食子酸酯的经皮渗透指标;通过建立UVA损伤HSF细胞模型,探究了茶多酚对细胞活性氧含量、丙二醛水平、超氧化物歧化酶和谷胱甘肽过氧化物酶活力的影响。结果表明该检测方法具有较好的专属性、精密度和加样回收率,且茶多酚中的儿茶素、表儿茶素、表儿茶素没食子酸酯、表没食子儿茶素没食子酸酯4种物质均可较好地作用于皮肤,其中表儿茶素在透皮释放方面具有明显优势。茶多酚通过降低UVA辐照后HSF细胞中的ROS含量和MDA水平,可提高细胞内SOD和GSH-Px活力,对UVA诱导的HSF细胞氧化损伤具有良好的保护作用。     

茶多酚的提取及在医药方面应用

茶多酚，英文名Tea Ployphenols，简称TP。茶多酚是茶叶中三十几种酚类物质的总称，按照其化学结构可分为4类：儿茶类、黄酮及黄酮醇类、花白素及花青素、酚酸和缩酚酸类。其中活性物质儿茶类约占多酚总量的80％，主要有4种：表儿茶素（EG）、表儿茶素没食子酸酯（ECG）、表没食子儿茶素（EGC）、表没食子儿茶素没食子酸酯（EGCG），其中EGCG具有很强的抗氧化活性和清除自由基能力。     

茶多酚生产应用及开发前景

茶多酚，英文名Teanloyphenols，简称TP，茶多酚是茶叶中的多酚类物质，主要由表儿茶素（I。－EC）、表儿茶素没食子酸酯（I。一ECG）、表没食子儿茶素（L一EGC）、表投食子儿茶素投食子酸酯（I。一EGCG）等4种成分组成。在茶多酚产品中儿茶素一般占6O％～SO％，此外，还含有没食子酸多酚酸类化合物、儿茶素氧化物和缩聚产物及咖啡因等生物碱类物质。国内外对茶多酚的研究开发始于SO年代，到gO年代逐渐形成热点和高潮。最初茶多酚只是作为抗氧化剂来研究，但随着研究应用的深入，又发现茶多酸具有诸多生理活性和药理功能，并开拓…     

从茶叶中提取茶多酚的浸提条件选择

从茶叶中提取茶多酚的浸提条件选择王丹南化（集团）公司研究院关键词茶多酚，茶叶，浸提近代科学证明，茶的饮用价值较高，其药效成份主要是茶多酚（其成份为表儿茶素、表没食子儿茶素、表儿茶素没食子酸酯等）类物质，它具有较强的还原能力和生理活性，并具有抗氧化、抗...     

普洱熟茶化学成分研究

从云南西双版纳大度岗茶厂生产的普洱熟茶中分离得到9个化合物,通过波谱分析分别鉴定为:咖啡因、芦丁、水杨酸、没食子酸、牡荆素、(+)-儿茶素、(-)-表儿茶素-3-O-没食子酸酯、(-)-表没食子儿茶素没食子酸酯、槲皮素。     

高效液相色谱快速测定茶叶中儿茶素的含量

分析了酸的种类及 pH对高效液相色谱 (HPLC)法测定表儿茶素 (EC)、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯 (ECG)、表没食子儿茶素 (EGC)、儿茶素 (C)和咖啡因的影响 ,实验表明 :酸尤其是乙酸不仅能改善各组分的峰形 ,而且对保留时间和出峰顺序均有较大的影响。确定了简单、快速分析 5种儿茶素及咖啡因的高效液相色谱分析方法。采用C18反相柱 ,水 -甲醇 -乙酸 ( 73. 0 / 2 3. 0 / 2 . 0 )为流动相 ,在流速为 1. 0mL·min-1,柱温 30℃ ,检测波长 2 80nm时等度洗脱分析样品 ,分析时间仅为 2 5min ,线性范围为 0 . 8～ 90mg·mL-1(r =0 998～ 0 999) ,回收率为 98. 2 %～ 10 0 . 3%,检测限为 5～ 10ng。     

表没食子儿茶素没食子酸酯(EGCG)的氧化研究

茶多酚是茶叶中最为重要的活性物质,儿茶素类物质是茶多酚的主要成分,约占茶多酚总量的70%以上。表没食子儿茶素没食子酸酯是儿茶素中的主要活性物质,具有很大的研究价值,但其化学结构不稳定,易在自然条件下氧化成为其它的物质,主要研究不同条件(温度、时间和pH等)氧化EGCG对其氧化物产率的影响,最终得到最佳氧化条件为pH值为5,氧化时间0.5小时,温度25℃反应时,氧化产物产率达最大值,纯度可达98.52%。     

国外有关塑料助剂研究的期刊文摘

正聚L-乳酸/聚L-乳酸接枝马来酸酐/表没食子儿茶素没食子酸酯共混物制备抗菌食品包装膜[Journal of Plastic FilmSheeting,2017,33(1):10-34.]本研究检测了由聚(L-乳酸)/聚(L-乳酸)接枝马来酸酐共聚物和表没食子儿茶素没食子酸酯(EGCG)共混物制成的塑料膜的抗菌活性。通过直接接触法、固体和液体培养基方法检测了EGCG在掺入量为0.03,0.5,5和10wt%并作为天然抗菌剂时的抗菌效果。研究中针对两种细菌(革兰     

Peanut Skin Color: A Biomarker for Total Polyphenolic Content and Antioxidative Capacities of Peanut Cultivars

Attempts to establish a relationship between peanut skin color (PSC) and total flavonoid (TF) content have produced inconclusive results. This study investigated the potential of PSC as a biomarker for polyphenol content and antioxidant capacity. Peanut cultivars were objectively evaluated for their skin color, total phenolic (TP), flavonoid (TF), proanthocyanidin (TPC) contents and antioxidant capacities (AC). Their relationship was determined by Pearson’s correlation analyses. TP had stronger correlations with CIE a*, hue angle and AC (r² = 0.77, 0.82 and 0.80, respectively) compared to TF. Therefore, hue angle of peanut skin may be used as a biomarker for TP content rather than TF.     

Preformed and Induced Chemical Resistance of Tea Leaf Against <Emphasis Type="Italic">Exobasidium vexans</Emphasis> Infection

Levels of (−)-epicatechin in tea cultivars resistant to blister blight leaf disease were significantly higher than those in susceptible cultivars, while the reverse was true for (−)-epigallocatechin gallate, suggesting that epicatechin was involved in the resistance mechanism. The content of the methylxanthines, caffeine and theobromine, in the leaf increased in the initial translucent stage of the disease, probably as a defense response to fungal attack. Epicatechin and epigallocatechin levels were less than in healthy tissues at this stage, but increases in the corresponding gallate esters suggested that they were being converted into esters. Although epicatechin and epigallocatechin levels decreased from translucent to mature blister stages, the decrease was not significant. The decrease in levels of epicatechin, epigallocatechin, and their esters on infection and the formation of cyanidin and delphinidin on oxidative depolymerization of the blisters suggests that proanthocyanidins may play a role in the defense mechanism. The high resistance of a purple green leafed cultivar is attributed to the additional catechin source provided by the high levels of anthocyanins present.     

Study on the structure of mangrove polyflavonoid tannins with MALDI-TOF mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a suitable method for examining polyflavonoid tannin oligomers as it is capable to determine aspects of their oligomeric structure and characteristics, which are otherwise too difficult to determine by other techniques. It has been possible to determine by MALDI-TOF for Rhizophora apiculata mangrove polyflvonoid tannins that: (i) procyanidins oligomers formed by catechin/epicatechin, epigallocatechin, and epicatechin gallate monomers are present in great proportions; (ii) oligomers, up to nonamers, in which the repeating unit at 528–529 Da is a catechin gallate dimer that has lost both the gallic acid residues and an hydroxy group which are the predominant species; (iii) oligomers of the two types covalently linked to each other also occur. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

没食子酸酯类抗氧化剂对生物柴油氧化稳定性能的比较分析

以没食子酸及醇类物质为原料制备了7种不同酯基结构的没食子酸酯类抗氧化剂并进行了红外光谱表征，同时研究了7种抗氧化剂对22种生物柴油的抗氧化效果。研究结果表明：22种生物柴油的氧化稳定性能差别较大，7种不同酯基结构的没食子酸酯类抗氧化剂对22种生物柴油的抗氧化效果提升明显，其中酯基不同，对生物柴油的抗氧化效果差别较大，如添加没食子酸甲酯（a）后，小桐子生物柴油的诱导期从0.96h提高到9.79h，而添加没食子酸异丁酯（f），诱导期则从0.96h提高到5.92h，两者相差3.87h。a对生物柴油的抗氧化效果最好，在添加a后，22种生物柴油的诱导期均要大于其余6种没食子酸酯类抗氧化剂添加后的诱导期。同一种没食子酸酯类抗氧化剂对不同生物柴油的抗氧化效果有所不同，差别也较大，如a对香薷籽油生物柴油的抗氧化效果最好，使其诱导期时间从0.79 h提高到9.07 h，抗氧化效果提高了10.48倍；对棕榈油生物柴油的抗氧化效果最差，但也使其诱导期时间从7.82 h提高到55.68 h，其抗氧化效果也提高了6.12倍。支链酯基的没食子酸酯类抗氧化剂与直链酯基的没食子酸酯类抗氧化剂对生物柴油的抗氧化效果相差不大。     

The relationships between biological activities and structure of flavan-3-ols

Flavan-3-ols are involved in multiple metabolic pathways that induce inhibition of cell proliferation. We studied the structure-activity relationship of gallic acid (GA) and four flavan-3-ols: epigallocatechin gallate (EGCG), epigallocatechin (EGC), catechin (C), and epicatechin (EC). We measured the cell viability by the MTT assay and we determined the concentration of testing compound required to reduce cell viability by 50% (IC(50)). All tested compounds showed a dose-dependent and time-dependent inhibitory antiproliferative effect on Hs578T cells; IC(50) values varying from the 15.81 to 326.8 μM. Intracellular ROS (reactive oxygen species) were quantified using a fluorescent probe 2',7'-dichlorofluorescin diacetate (DCFH-DA). Only the treatment with 10 μM EGC and EGCG was able to induce a significant decrease of ROS concentration and increased levels of ROS were registered for 100 μM EGCG, EGC and GA. Flavans-3-ols and GA induced apoptosis in a dose- and time-dependent manner, which indicated that the induction of apoptosis mediated their cytotoxic activity at least partially. The galloylated catechins have shown a stronger antiproliferative activity and apoptotic effect than the one produced by non galloylated catechins. The galloylated flavan-3-ols are potential therapeutic agents for patients with triple negative breast cancer via induction of apoptosis.     

Antioxidant Activity of Added Phenolic Compounds in Freeze-Dried Microencapsulated Sunflower Oil

This study was aimed at evaluating the effectiveness of phenolic antioxidants with a similar structure but having a different polarity in dried microencapsulated sunflower oil. The antioxidants tested were, on one hand, α-tocopherol and its water soluble analogue, Trolox, and on the other, gallic acid and its ester derivatives, propyl gallate and dodecyl gallate. At a moderate temperature (40 °C), the samples were oxidized under accelerated conditions by using Cu(II) as an oxidation catalyst. The progress of oxidation was followed up over time in the free and encapsulated oil fractions. The peroxide value, the total content of polymers and, when appropriate, the content of α-tocopherol were determined. Quantitative analysis of the total fraction of the non-volatile oxidation products and their distribution in oligomers, dimers and monomers was applied to samples to obtain a complete evaluation of oxidation. Finally, as a complementary measure, the antioxidants were also assessed by direct application of the Rancimat test at 100 °C on the dried microencapsulated oil samples. Results showed that the antioxidants of lower polarity in each series, i.e. tocopherol and dodecyl gallate, were to a great extent the most protective antioxidants. The results obtained by the Rancimat test were consistent with those found during oxidation at moderate temperature. Furthermore, the addition of Cu(II) reduced proportionally the oxidative stability index of the dried microencapsulated samples.     

Major Phenolic Compounds, Antioxidant Capacity and Antidiabetic Potential of Rice Bean (Vigna umbellata L.) in China

Interest in edible beans as nutraceuticals is increasing. In the present study, the individual phenolic acids, the total phenolic content (TPC), the total flavonoid content (TFC), and the antioxidant and antidiabetic potential of 13 varieties of rice beans from China were investigated. Eight phenolic compounds (catechin, epicatechin, p-coumaric acid, ferulic acid, vitexin, isovitexin, sinapic acid, quercetin) were analyzed on an ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) system. The rice bean varieties had significant differences in total phenolic compounds (ranging from 123.09 ± 10.35 to 843.75 ± 30.15 μg/g), in TPC (ranging from 3.27 ± 0.04 to 6.43 ± 0.25 mg gallic acid equivalents (GAE)/g), in TFC (ranging from 55.95 ± 11.16 to 320.39 ± 31.77 mg catechin (CE)/g), in antioxidant activity (ranging from 39.87 ± 1.37 to 46.40 ± 2.18 μM·TE/g), in α-glucosidase inhibition activity (ranging from 44.32 ± 2.12 to 68.71 ± 2.19) and in advanced glycation end products formation inhibition activity (ranging from 34.11 ± 0.59 to 75.75 ± 0.33). This study is the first report on phytochemistry and biological activities in rice beans.     

紫外法和皮粉法测定塔拉单宁含量的对比研究

分别采用紫外法和皮粉法对5种不同含量的塔拉单宁进行对比研究,并利用SPSS软件对单宁含量测定结果进行显著性检验,结果表明：高纯度塔拉单宁（93%）分别用紫外法和皮粉法测定单宁含量时实验结果并未显著差异（P>0.05）,而4种纯度为60%左右塔拉单宁的实验结果均具有显著性差异（P < 0.05）,皮粉法测得的单宁含量均比用紫外法测得的结果高,差值约为1.5%~2.0%,并由此计算出紫外法测定塔拉单宁含量计算公式中的矫正常数p为1.03。紫外-可见吸收光谱与HPLC分析结果表明：塔拉单宁与五倍子单宁的最大吸收峰均为276 nm,同质量浓度下塔拉单宁的吸收峰强度高于五倍子单宁,塔拉单宁成分出峰时间主要在20~40 min,五倍子单宁主要在30~45 min。     

Partition behaviour of antioxidative phenolic compounds in heterophasic systems

Differences in the efficiency of antioxidants in dispersed lipid systems may be related to the differential solubility of the antioxidants within the physically distinct phases of colloidal food systems. This study determined the partitioning of antioxidants in water/oil systems, surfactant solutions (dodecyltrimethylammonium bromide, DTABr, sodium dodecylsulfate, SDS, polyoxyethylenesorbitan monolaurate, Tween 20), and emulsions. There were significant differences in the partition of the antioxidants between oil, water and interfacial phases both as a function of pH and surfactant. The proportions of hydrophilic antioxidants (ferulic acid, caffeic acid, gallic acid, propyl gallate, catechin and Trolox) showed significant decreases in the aqueous phase when lowering the pH from 7.0 to 3.0 in Tween 20 emulsions. DTABr lowered the proportion of all antioxidants in the unbuffered aqueous phase to a higher extent than SDS or Tween 20. Changing the ionic strength (5mM NaCl to 50mM NaCl) did not cause significant differences in water/oil systems. Therefore, the effectiveness of hydrophilic antioxidants in heterophasic systems is influenced by their partition into the different phases of water/oil, surfactant and emulsion systems.     

食品抗氧化剂没食子酸丙酯的合成

研究了以硫酸氢钠为催化剂，没食子酸和正丙醇为原料合成没食子酸丙酯，并考察影响反应的因素。结果表明，没食子酸、正丙醇和硫酸氢钠摩尔比为1：14：0．058，反应时间5h是最佳的反应条件，酯收率达93．8％。