Effect of a Commercial Extract of Green Tea and a Pure Catechin on Two Veillonella strains

The catechin Epigallocatechin-3-O-Gallate (EGCG) which is found in of Green Tea extracts (GTE), displays a variety of microbicidal properties. It is largely believed that EGCG inhibits the growth of cariogenic and periodontopathic bacteria. Objective: In this paper we compared the inhibitory activity of EGCG and a commercial GTE on the growth of Veillonella parvula. Chlorhexidine was used as positive control. Methodology: V. parvula ATCC 10790 and a clinical isolate obtained from a periodontal disease patient were cultured in the presence of EGCG or a commercial GTE, and the measurements of bacterial growth inhibition were compared to the values obtained with 0.12 and 0.2% chlorhexidine. Results: Chlorhexidine inhibited bacterial growth, however in contrast to a previous report, neither EGCG nor the GTE showed any effect on bacterial growth. Conclusions: The data show and confirm that chlorhexidine is a growth inhibitor of V. parvula while EGCG and GTE do not display such effect.

Qualitative analysis of catechins from green tea GMB-4 clone using HPLC and LC-MS/MS

Objective:To identify the bioactive compounds in catechins isolation and its components from green tea GMB-4 clone.Methods:Green tea GMB-4 clones were extracted with distilled water at 90C.Samples were eluted into the column with 10%ethanol.Subsequently,the column was eluted with95%ethanol and evaporated separately.Green tea extract was identified by thin layer chromatography.Catechins were separated by the stationary phase in column chromatography using polyamide with 10%ethanol eluent and 95%ethanol.The results of isolations were analyzed by high performance liquid chromatographic(HPLC)and LCMS/MS.Analysis of catechins by HPLC was done by external standard.Results:Fraction from 10%ethanol showed that four major peaks at retention time of1.663,2.367,2.950 and 4.890,indicated the presence of four catechins components including catechin,epicatechins,gallocatechin and epigallocatechin.Whereas,fraction from 95%ethanol showed two main peaks at retention time of 5.167 and 9.82,which indicated the presence of epigallocatechin gallate(EGCG)and epicatechin gallate(ECG).EGCG(m/z 459),epigallocatechin(m/z 307),ECG(m/z 443),and epicatechin(m/z 291)were isolated and separated successfully using HPLC and LC-MS/MS.Conclusions:The HPLC and LC-MS/MS methods were successfully tuned for the qualitative analysis of green tea extract with EGCG and ECG.Four major catechins were separated and identified by LC-MS/MS,such as EGCG,epigallocatechin,ECG and epicatechin.The result of HPLC analysis showed that EGCG and ECG were main components from catechins isolation of green tea GMB-4 clone.

Influence of Tea Leaf Particle Size on Catechin Extraction and Green Tea Sensory Acceptance

The intensity of the bitterness of catechins increases with increased concentration, but the taste palatability decreased in green tea extract. The aim of this study was to investigate whether a blend of tea leaf particles of various sizes would result in a good balance between catechin content and appreciable taste. The control is common tea (CT) with 6 - 10 mm long leaves. Blend tea (BT) was prepared by mixing 5 mm and 120 - 130 mm long tea leaves in a ratio of 3:2. The catechin content of hot water extracts was analyzed by HPLC, and the sensory test was conducted with 99 volunteers. In BT, the total catechin content was significantly higher than that in CT. The sensory test results revealed that BT was less bitter and had more preferable color than CT. More catechins were extracted from BT, but it tasted less bitter. Thus, the recalibration of the tea leaf particle size can result in good balance between catechin content and palatability.

Green tea catechins inhibit microglial activation which prevents the development of neurological disorders

The over-activated microglial cells induce neuroinflammation which has the main role in neurological disorders.The over-activated microglia can disturb neuronal function by releasing inflammatory mediators leading to neuronal dysfunctions and death.Thus,inhibition of over-activated microglia may be an effective therapeutic approach for modulating neuroinflammation.Experimental studies have indicated anti-neuroinflammatory effects of flavonoids such as green tea catechins.The current research was aimed to review the effect of green tea catechins in inhibiting microglial cells,inflammatory cascades,and subsequent neurological diseases.

Study on the Retention Rate of Green Tea Catechins Components and Tea Polyphenol by Different Processing Technology

The aim of this research was to explore the effect of fixation,rolling,and drying processing technology on the retention rate of green tea catechins components and tea polyphenol.Different fixation processes(rotary drumfiring,microwave,steam-blasting),rolling process(weight of rolling,gently press rolling and traditional rolling),drying process(stove drying,roasting dehydration,baked fried drying) were adopted.The effect of different tea processing technology on the retention rate of catechins component and tea polyphenol was analyzed.It showed that the microwave fixation process,gently press rolling process,baked fried dry process were beneficial to keep high levels of EGCG,C,EGC,EC,ECG.

A review of pharmacological activity and application potential in food of tea polyphenols

Tea polyphenols(TP)is a class of polyhydroxy compounds isolated from tea.Modern biological and medical studies have shown that TP has many pharmacological activities,such as anti-inflammatory,anti-virus,anti-oxidation,anti-tumor and anti-radiation.Furthermore,these substances can be used as a potential drug component to positively guide the occurrence and development of certain diseases.Furthermore,because of the activities of TP,such as anti-oxidation and anti-bacteria,it can be applied in food preservation,color preservation,deodorization,and treatment of food processing by-products.Based on the research progress of TP in recent years,this paper summarizes the pharmacological activities of TP and expounds on its application potential in the field of food.In order to provide a theoretical reference for the research,development and utilization of TP.

Stability of Tea Catechins and Antioxidant Properties of Green Tea Extracts as Affected by Boiling-treatment

Stability of tea catechins and the antioxidant properties of green tea extracts as affected by boiling-treatment from 1 to 5h were studied.Green tea catechins were partially epimerized from epi-form to nonepi-form under boiling-treatment.Total phenolic compounds of the samples under the boiling-treatment for 1 to 4h showed the same statistically significant(P > 0.05) comparing with the untreated samples and there was no significant reduction(P > 0.05) of total catechins when the green tea extracts were boiling-treated for 1h.There were no significant(P > 0.05) reduction of the antioxidant capacity when the samples were boiling-treated for 1h,no significant(P> 0.05) reduction of the scavenging ability against DPPH and O-·2when treated for 2h,and no difference on scavenging ability against OH when treated even for 5h.The results indicated that boiling-treatment for 1h had limited effect on total catehins and phenols content in green tea extracts.Green tea extracts still remained excellent in antioxidant properties and free radical scavenging activity after boiling-treated for 1 h.

AB016:Metabolomic studies of green tea catechins and its applications in ocular research

Tea is the second most popular beverage worldwide after water.Green tea has the highest nutraceutical values with well-established general health benefits and wide safety margins.Natural polyphenols found in green tea,including(+)-catechin(C),(-)-epicatechin(EC),(+)-gallocatechin(GC),(-)-epigallocatechin(EGC),(-)-epicatechin-3-gallate(ECG),(-)-gallocatechin-3-gallate(GCG)and(-)-epigallocatehin-3-gallate(EGCG).They have many potent biological properties and therapeutic effects in human health and diseases.These small molecules have high bioavailability and specific therapeutic potential in eye tissues.Recently some researchers studied the metabolomic responses to the green tea.In this talk,summary of these studies will be reviewed and its potential applications in the ocular research will be discussed.

Pharmacological potential of ampelopsin in Rattan tea

Rattan tea,made from the leaves of Ampelopsis grossedentata,may potentially perform multiple pharmacological roles,including anti-bacterial,anti-cancer,antioxidant,hepatoprotective and anti-hypertension functions.These beneficial functions of Rattan tea are strongly associated with the bioactivity of ampelopsin,a major flavonoid compound in Rattan tea.In this review,we summarize current research related to the bioactivity and pharmacological mechanisms of ampelopsin,which will provide a better reference for its potential application in the prevention of chronic diseases.©2012 Production and hosting by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.

Identification of miRNAs and target genes regulating catechin biosynthesis in tea (Camellia sinensis)

Micro RNAs（miRNAs） are endogenous non-protein-coding small RNAs that play crucial and versatile regulatory roles in plants. Using a computational identification method, we identified 55 conserved miRNAs in tea（Camellia sinensis） by aligning miRNA sequences of different plant species with the transcriptome library of tea strain 1005. We then used quantitative real-time PCR（qRT-PCR） to analyze the expression of 31 identified miRNAs in tea leaves of different ages, thereby verifying the existence of these miRNAs and confirming the reliability of the computational identification method. We predicted which miRNAs were involved in catechin synthesis using ps RNAtarget Software based on conserved miRNAs and catechin synthesis pathway-related genes. Then, we used RNA ligase-mediated rapid amplification of c DNA ends（RLM-RACE） to obtain seven miRNAs cleaving eight catechin synthesis pathway-related genes including chalcone synthase（CHS）, chalcone isomerase（CHI）, dihydroflavonol 4-reductase（DFR）, anthocyanidin reductase（ANR）, leucoanthocyanidin reductase（LAR）, and flavanone 3-hydroxylase（F3H）. An expression analysis of miRNAs and target genes revealed that miR529d and miR156 g-3 p were negatively correlated with their targets CHI and F3H, respectively. The expression of other miRNAs was not significantly related to their target genes in the catechin synthesis pathway. The RLM-RACE results suggest that catechin synthesis is regulated by miRNAs that can cleave genes involved in catechin synthesis.

Interaction of catechins with aluminum in vitro

Tea is one of the most popular beverages, consumed by over two thirds of the world's population; but the aluminum accumulation property of tea plant is becoming the focus of many researches because of aluminum's known adverse effect on human health. Investigation of the interactions of catechins with A1^3+ showed that during the interaction of catechins with A1^3+, the UV-vis spectrum of catechins was changed. Absorption of EGCG at 274 nm decreased and increased at 322 nm; EC and C's at 278 nm changed little. The ratio of A1^3+ to EGCG was 1:1 in pH 5.0 buffer solution; in pH 6.2 buffer solution, the ratio in the A1-EGCG complex was 1:1. Interestingly, while the ratio reached to over 2, after the complex of A1-EGCG started polymerization, the ratio in the polymer was 2:1. In pH 6.2 buffer solution, the complex behavior of C with A1^3+ was the same as that of EGCG, with a little difference for EC. When the ratio of A1^3+ to EC was<1, the complex in ratio was 1:2, but, the complex polymerized when the ratio of A13+ to EC was >1. It was found that the ratio of A1^3+ to EC in the polymer was 1:1. Polymerization of A1-catechin complexes might reduce aluminum absorption in the intestine. Kow value was also employed to study the properties of aluminum species in tea infusion (at gastric and intestine pH condition) and the effect of catechins and tea polyphenols on Kow in buffer solution. Results showed that Kow value rose much higher at the intestine pH than at the gastric pH. Tea polyphenols and catechins could greatly reduce aluminum Kow value in acetic buffer,indicating that these compounds may reduce aluminum absorption during tea intake.

Tyrosinase Biosensor Used for the Determination of Catechin Derivatives in Tea: Correlation with HPLC/DAD Method

Tea, one of the most popular consumed worldwide beverages, is known to be rich in polyphenols, more particularly in catechins. An amperometric biosensor based on tyrosinase was developed in order to monitor the phenolic content in black and green teas. The enzyme was immobilised by coreticulation with glutaraldehyde on carbon screen-printed electrodes (CSPE). Initially, the performances of the biosensor were evaluated referring to catechol as a model substrate. This analytical tool exhibits a high sensitivity (217 nA/μM), low limit of detection (LOD) = 0.03 μM, good intra-electrode and inter-electrode reproducibilities with RSD lower than 3% (n = 5 injections) and RSD = 8.14% (n = 12 sensors) respectively. The storage stability was also studied;the biosensor retained successively 85% and 70% of its initial response after 34 and 53 days. Subsequently, several catechin derivatives frequently found in teas were tested and classified relatively to their sensitivities. For tea samples, the results obtained with the biosensors were compared to high performance liquid chromatography (HPLC) analysis. A good correlation between the two methods was obtained. The calculated recovery was between 90% and 96%, proving that the proposed tyrosinase biosensor can be an alternative analytical tool for global determination of catechin derivatives in tea.

Variation in Catechin Composition of Popularly Cultivated Tea Clones in East Africa (Kenya)

Tea polyphenols and catechins have gained prominence in determination of tea quality. Tea leaves contain large amounts of catechins and their derivatives and these have shown positive effects on human health. An experiment was carried out to determine the level of catechins and polyphenols in 20 new clones found in two distinct tea growing areas. The trial comprising twenty clones was established in two distinct sites in Kenya using randomized complete block design with three replicates and consisted of 10 popular cultivars widely cultivated in the Lake Victoria Basin and additional 10 newly improved clones. Tea leaf samples were collected across two seasons;dry and wet seasons. Tea quality parameters entailing catechins, caffeine and total polyphenols was generated for the 20 clones across the two seasons and sites. The ISO 14502-1 and ISO 14502-1:2005 procedures were used for polyphenol and catechin analyses, respectively. The ANOVA results generated indicated that the level of catechins and polyphenols in tea were significantly different (p 0.05) and varietal dependent. Generally, the assam varieties had higher levels of catechins and polyphenols than the chinary and cambod varieties, indicating why they are popularly cultivated in the East African region and whose tea quality is highly regarded. Furthermore, the results from principle component analysis (PCA) grouped the clones into three major clusters with one comprising of high quality assam varieties, a mixture of moderate quality assam, cambod and chinary varieties and low catechin content assam anthocyanin-rich variety. It is concluded that the level of catechins in tea plants are varietal dependent, although environmental stress has effects on the synthesis of flavanoids. The results demonstrated that the differences in the accumulation of catechins among the tea clones could be important for the discrimination of clonal diversity.

绿茶及其副产物在蛋鸡生产中的应用研究进展

在饲料禁抗和畜禽绿色健康养殖的趋势下,研究和开发新型植物源饲料原料和饲料添加剂备受关注。绿茶及其副产物含有茶多酚、茶多糖、茶氨酸和咖啡碱等多种生物活性物质,具有抗氧化、抗菌、降血脂和改善肉蛋品质等生理功能以及作为一种植物源饲料或添加剂在畜禽生产中应用的潜在价值。文章综述了绿茶及其副产物的营养成分、生物活性物质与生理功能及其在蛋鸡生产中的应用研究进展,旨在为其在蛋鸡生产中的应用提供参考。

茶儿茶素稳定血糖作用及机理研究进展

随着现代社会饮食结构的变化,糖尿病及其并发症已成为全球关注的公共卫生问题,中国患病总人数已位居世界第一。现代科学证明茶叶是降血糖天然多酚的重要来源,作为健康饮品在糖尿病膳食治疗中发挥重要作用。儿茶素是茶叶中关键功能物质,能够通过抑制外源碳水化合物水解、调控葡萄糖转移、促进葡萄糖氧化分解、抑制糖异生过程、调控糖原合成及分解过程、促进胰岛素分泌、改善胰岛素抵抗、改善氧化应激状态等不同途径有效调节血糖水平。本文在总结国内外有关儿茶素对肥胖、糖尿病及代谢综合症作用研究的基础上,梳理了儿茶素稳定血糖生理机制的研究进展,旨在为儿茶素的精准化开发提供理论依据及应用参考。

茶叶微生物发酵过程中没食子酸代谢研究进展

没食子酸是茶叶中的主要酚酸类化合物,在渥堆发酵、厌氧发酵和仓储陈化过程中均呈增加趋势,并与酯型儿茶素水解存在密切相关。黑曲霉、冠突散囊菌、烟曲霉、溜曲霉、Aspergillus pallidofulvus促进茶叶微生物发酵过程中没食子酸的生物合成,这与其分泌的单宁酶等胞外酶有关。在液态发酵中,枯草芽孢杆菌、植物乳杆菌同样能分泌单宁酶,提高没食子酸含量。本文概述目前国内外关于茶叶微生物发酵过程中没食子酸代谢研究进展,阐述没食子酸的生物合成机制和保健功效,以期为微生物作用下没食子酸代谢调控机理的研究提供参考。

HPLC-MS/MS法测定茶叶中儿茶素类、茶黄素类物质

针对同时测定茶叶中儿茶素、茶黄素的方法较少的现状,该研究建立了同时定性和定量测定茶叶中8种儿茶素类和4种茶黄素类物质的高效液相色谱-串联质谱法。研究采用Agilent Eclipse Plus C18(2.1 mm×100 mm,1.8μm)色谱,甲酸-乙腈为流动相,流量为0.2 mL/min进行梯度洗脱,采用ESI源正、负离子扫描模式,多反应监测(MRM)。结果表明,儿茶素类和茶黄素类物质分别在10~10000μg/L和25~5000μg/L范围内线性关系良好,相关系数R>0.99,回收率在96.53%~106.08%之间,精密度的相对标准偏差均小于10%。相较于分别检测儿茶素类和茶黄素类物质的国家标准方法,该方法提高了检测效率且具有更低的检出限和定量限,能够提供更加准确、全面的检测结果。

基于细胞模型和网络药理学探究儿茶素抗炎、抗癌的构效关系

目的:系统揭示茶叶儿茶素的抗炎、抗癌构效关系,并初步探究其背后的分子作用机制。方法:利用脂多糖诱导的小鼠巨噬细胞RAW264.7和人结肠癌细胞HCT116为体外炎症、癌症模型,采用格里斯试剂法与四甲基偶氮噻唑蓝比色法分析比较儿茶素的体外抗炎、抗癌活性,借助网络药理学预测各儿茶素抗炎、抗癌的关键靶点与通路,并通过分子对接技术模拟各儿茶素与关键靶点蛋白的相互作用,比较各单体与关键靶点的结合能力。结果:8种儿茶素单体均有较强的体外抗炎、抗癌活性,酯型儿茶素的没食子酰基、焦酚型儿茶素B环的邻苯三酚结构和反式儿茶素C_(2)、C_(3)的反式构象使其具有更强的抗炎、抗癌活性,但酯型、焦酚型儿茶素的没食子酰基与其B环的邻苯三酚结构间存在拮抗效应;8种儿茶素通过多靶点、多通路发挥抗炎、抗癌活性,且没食子酰基有利于儿茶素与其关键抗炎、抗癌靶蛋白IL6、TNF、AKT1通过氢键结合。本文揭示了儿茶素的体外抗炎、抗癌活性及构效关系,为系统、深入阐释儿茶素的功能特性与分子结构等关系提供了理论和技术借鉴。

近红外光谱法快速测定晒青毛茶三种儿茶素组分含量

为了实现晒青毛茶儿茶素含量的快速检测,该研究利用高效液相色谱技术(High Performance Liquid Chromatography,HPLC)测定了50份晒青毛茶样品中的表没食子茶素没食子酸酯(Epigallocatechin Gallate,EGCG)、表没食子儿茶素(Epigallocatechin,EGC)、没食子酸(Gallic Acid,GA)三种儿茶素单体含量,结合样品的近红外光谱,分别建立了晒青毛茶三种儿茶素单体含量的偏最小二乘法(Partial Least Squares,PLS)模型,并对模型进行验证。实验结果表明,基于EGCG、EGC、GA含量所建立近红外模型的决定系数(Coefficient of Determination,R2)分别为99.99%、99.99%、99.92%;校正标准差(Root Mean Square Error of Calibration,RMSEC)分别为0.17、0.15、0.10;相对标准差(Relative Standard Deviation,RSD)分别为0.19%、0.27%、0.56%;外部验证的结果显示,三种儿茶素单体含量模型的预测值与真实值的平均绝对误差分别为0.13、0.12、0.07;平均相对误差分别为0.17、0.25、0.45。实验结果表明,该研究建立的近红外分析模型具有较高的预测准确度和稳定性,在快速检测晒青毛茶儿茶素方面具有潜在应用价值。

表没食子儿茶素没食子酸酯的生物学功能及其在畜禽生产中的应用

表没食子儿茶素没食子酸酯(EGCG)约占儿茶素的50%~60%,是茶多酚中含量最多的活性成分。EGCG具有多种生物功能,具有巨大的开发潜力。文章总结了EGCG在抗氧化、抑菌、抗炎、抗病毒方面的功能和作用机制,以及EGCG在畜禽生产中的应用,以期为EGCG在畜禽饲料中的精准应用提供理论依据。