高效液相色谱法测定茶叶中茶多酚

应用高效液相色谱法测定了茶叶,特别是绿茶中的8种多酚,包括儿荼素(C)、表没食子儿茶素(EGC)、没食子儿荼素(GC)、表儿茶素(EC)、表没食子儿茶素没食子酸酯(EGCG)、没食子儿荼素没食子酸酯(GCG)、表儿茶素没食子酸酯(ECG)及儿茶素没食子酸酯(CG).在C18>反相柱(250 min×4.6 mm,5 μm)上进行分离,用不同体积比混合的流动相A及流动相B的混合液作梯度淋洗,流速为1.0 mL·min-1,柱温为40℃,在280 nm波长处进行紫外检测.上述8组分在0.004～4.0 g·L-范围内呈线性关系,方法的检出限在0.6～2.6 mg·L-1范围内,平均回收率为83%.     

高效液相色谱/质谱分析茶树老叶中儿茶素

1　引　　言儿茶素是一类能改进血管渗透性能 ,增强心肌 ,降低血压 ,并具有抗脂肪肝、抗癌和Ｖｐ样作用的天然活性物质 ,采用高效液相色谱 质谱 (ＬＣ ＭＳ)联用法分析儿茶素至今未见报道。本文采用ＬＣ ＭＳ联用法 ,优化了色谱条件 ,同时分离了茶树老叶中 7种儿茶素 ,并以ＨＰＬＣ与ＬＣ ＥＳＩ ＭＳ联合定性 ,鉴定出 7种儿茶素分别为表没食子儿茶素 (ＥＧＣ)、没食子儿茶素 (ＧＣ)、表没食子儿茶素 3 没食子酸酯 (ＥＧＣＧ)、表儿茶素 (ＥＣ)、没食子儿茶素 3 没食子酸酯 (ＧＣＧ)、表儿茶素 3 没食子酸酯 (ＥＣＧ)、儿茶素 3 没食子…     

半制备型液相色谱法分离纯化茶叶鲜叶中7种儿茶素类化合物

建立了从茶叶鲜叶中分离纯化7种儿茶素类化合物(没食子儿茶素(GC)、表没食子儿茶素(EGC)、儿茶素(C)、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素(EC)、表没食子儿茶素3-O-(3-O-甲基)没食子酸酯(EGCG3"Me)和表儿茶素没食子酸酯(ECG))的半制备色谱法。铁观音鲜叶经甲醇超声浸提、浓缩、氯仿萃取后,向水相中加入碱式醋酸铅沉淀,得到茶多酚粗品。分别以甲醇-水、乙腈-水作为流动相,采用半制备色谱法纯化7种儿茶素类化合物,纯度均达到90%。此外,利用同样的方法分离纯化另外两种茶叶鲜叶中的7种儿茶素类化合物,得到相似的结果。该方法以溶剂提取、离子沉淀结合半制备色谱,适于简单、高效地同时分离制备多种儿茶素类化合物。     

高效液相色谱-串联质谱法检测红葡萄酒中功效成分

建立了高效液相色谱-串联质谱法快速测定葡萄酒中白藜芦醇、黄酮类、多酚类功效成分的分析方法。葡萄酒样品直接稀释后进样,用C18柱进行分离,以乙腈-0.1%(体积分数)甲酸水溶液为流动相进行梯度洗脱,通过多反应监测(MRM)模式进行检测。13种功效成分在各自线性范围内呈良好的线性关系,相关系数均大于0.99。除表没食子儿茶素、没食子儿茶素、儿茶素没食子酸酯、花旗松素的检出限为1.0、1.0、3.0、3.0μg/L外,其他9种化合物的检出限均小于1.0μg/L。回收率为80.9%~112.3%,相对标准偏差小于10%。该方法快速、准确、灵敏度高,适用于葡萄酒中功效成分的快速分析。对实际样品的检测表明,所测葡萄酒样品中均含有儿茶素、表儿茶素、表没食子儿茶素、没食子儿茶素、表儿茶素没食子酸酯/儿茶素没食子酸酯、白藜芦醇、大豆黄素等功效成分,不同品种葡萄酒中这些功效成分含量差异显著。     

高效液相色谱-质谱-二苯基三硝基苯肼在线筛选与鉴别茶叶中抗氧化活性成分

将基于在线高效液相色谱-二苯基三硝基苯肼(HPLC-DPPH)快速筛选自由基清除剂的方法与电喷雾飞行时间质谱(ESI-TOF/MS)结合,建立了茶叶粗提物中抗氧化活性成分在线筛选与鉴别的方法.本方法是在HPLC色谱柱分离后进行分流,一路进入ESI-TOF/MS用于各化合物的快速鉴别,另一路流出液与稳定的自由基DPPH混合,实现在线筛选自由基清除剂的作用.本方法用于茶水中抗氧化成分的快速筛选与鉴别,筛选出11个具有明显DPPH自由基清除作用的化合物,通过ESI-TOF/MS在线分析获得的质谱信息,结合相关文献和数据库,实现了各化合物的快速鉴别.11个化合物分别为茶氨酸、Theogallin、没食子儿茶素、茶碱、色氨酸、表没食子儿茶素、表没食子儿茶素没食子酸酯、表儿茶酚、没食子酸酯、没食子儿茶素没食子酸酯及儿茶素没食子酸酯.本方法效率高、稳定性好,是复杂天然产物中抗氧化剂快速筛选与鉴别的有力工具.     

脉冲辐解研究茶多酚4个组分清除羟自由基机理

采用脉冲电子辐解瞬态吸收光谱法 ,在pH 7的磷酸缓冲水溶液中测定茶多酚 4个组分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)和表儿茶素 (EC)的清除羟自由基速率常数分别为 1 .5× 1 0 10 ,1 .4× 1 0 10 ,9.7× 1 0 9和 9.2× 1 0 9dm3 ·mol-1·s-1,并提出了EGCG和ECG在清除羟自由基的过程中存在一个脱没食子酸基团的机理     

高效液相色谱法分析元宝枫叶中儿茶素类物质

本文建立了元宝枫树叶中儿茶素种类及其含量的高效液相色谱(HPLC)测定方法。采用反相C18色谱柱,以甲醇/水(含0.5%乙酸)=25/75(V/V)为流动相,对没食子儿茶素(GC)、表没食子儿茶素(EGC)、儿茶素(C)、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素(EC)和没食子儿茶素没食子酸酯(GCG)进行定性、定量分析;以甲醇/水(含0.5%乙酸)=35/65(V/V)为流动相,对表儿茶素没食子酸酯(ECG)和儿茶素没食子酸酯(CG)进行定性分析,柱温均为35℃,检测波长为278 nm,流速为1.0mL/min。结果表明:元宝枫叶中有EGC、EC和GCG,其它五种则无。EGC平均含量为0.0389 mg/g,方法精密度(RSD)为0.42%(n=6);EC平均含量为0.0289 mg/g,方法RSD为1.5%(n=6);GCG平均含量为0.284 mg/g,方法RSD为0.32%(n=6)。该方法简便、准确、分离效果好,为元宝枫叶开发成茶叶、饮料以及医疗保健品提供重要依据。     

高效液相色谱法测定绿茶中茶多酚及咖啡因

应用高效液相色谱法测定绿茶中没食子酸(GA)、咖啡因(CAF)及5种儿茶素类化合物,包括儿茶素(C)、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)、没食子儿茶素没食子酸酯(GCG)。对国家标准方法GB/T 8313-2008中流动相组成进行了调整,用0.5%乙酸代替2%的乙酸,在AT.Lichrom ODS色谱柱(4.6mm×250mm,5μm)上进行分离,流量为1.0mL.min-1,在波长278nm处进行紫外检测。7种组分在40min内达到完全分离。7种组分的质量浓度分别在一定的范围内与其峰面积呈线性关系。方法用于绿茶的分析,7种组分的加标回收率在96.0%～102.8%之间。     

反相高效液相色谱法同时测定茶叶中六种儿茶素组分的研究

采用反相高效液相色谱法同时测定茶叶中L (+) 表儿茶素(L EC),L (-) 表儿茶素没食子酸酯(L ECG),L (-) 表没食子儿茶素没食子酸酯(L EGCG),L (-) 表没食子儿茶素(L EGC),(+) 没食子儿茶素没食子酸酯(GCG),DL 儿茶素(DL C)六种儿茶素组分,以乙醇∶乙酸∶水=14.5∶1.0∶84.5(体积比)为流动相(1.0ml·min-1),C18柱,UV检测器(278nm)。六种儿茶素组分的相对标准偏差分别为0.67%,0.45%,0.24%,0.56%,3.11%,4 41%,回收率分别为95.2%,98.2%,101.3%,97.0%,98.3%,97.5%。该法采用乙醇、乙酸等无毒溶剂作流动相,回收率高,用于实际样品测定,结果满意。     

改性木粉填充柱对茶多酚与咖啡因分离应用的研究

用乙基纤维素、己二酸和丙烯酰胺制成浆液改性剂,对木粉进行改性.研究对比了木粉在改性前后对茶多酚(TP)与咖啡因(Caf)的分离效果.研究结果表明,已改性的木粉对TP中3种主要成分(EGC,EGCG和ECG)与Caf的分离效果优于未改性木粉.改性后的木粉可用于TP各组分与Caf分离时的前处理.通过该前处理可将绿茶提取液分离为两部分:一部分主要由咖啡因和表没食子儿茶素(EGC)组成,另一部分主要由表没食子儿茶素没食子酸酯(EGC)和表儿茶素没食子酸酯(ECG)组成.     

Decrease in concentration of free catechins in tea over time determined by micellar electrokinetic chromatography

Cancer chemoprevention is a new and important medical science and much interest has been focused on catechins, not only for their antioxidant activity, but also because of their known antimutagenic and antitumorigenic properties. Green tea and black tea, which are among the most popular beverages consumed worldwide, contain many different catechins. Due to the instability of catechins in solutions with neutral or basic pH values the concentrations of catechins in tea decrease in time. In this presentation we used micellar electrokinetic chromatography to determine the real concentration of catechins between 0 and 60 min after the tea was brewed.     

Extraction and isolation of catechins from tea

Tea is a major source of catechins, which have become well known for their antioxidant potential. Numerous human, animal, and in vitro studies have linked tea catechins with prevention of certain types of cancers, reduction of the risks for obesity, diabetes, and cardiovascular disease, and improvement of the immune system. Tea catechins are widely used in various neutraceuticals, pharmaceuticals, and cosmetics for either enhancing product shelf-life or for enhancing human health. Thus, the demand for catechins has increased considerably. Catechins have been extracted and isolated from tea leaves by numerous methods through several steps including: treatment of the tea leaves, extraction of catechins from teas into solvents, isolation of catechins from other extracted components, and drying the preparations to obtain catechin extracts in a powder form. This paper outlines the physical and chemical properties of the tea catechins and reviews the extraction steps of the various extraction methods, as a basis to improve and further develop the extraction and isolation of the tea catechins.     

Protective role of tea catechins on erythrocytes subjected to oxidative stress during human aging

Antioxidant effect of tea catechins has been shown in many epidemiological studies. In the present study we report the protective mechanism of tea catechins (EGCG, ECG, EGC, EC) on various oxidative stress parameters, which are elevated during aging in humans. We hereby report the in vitro effect of tea catechins on erythrocyte malondialdehyde (MDA), reduced glutathione (GSH), and on membrane sulphydryl (-SH) group in humans. Results show an age-dependent increase in erythrocyte MDA level and a decrease in GSH and membrane-SH group concentration. We report that tea catechins show significant protection to erythrocyte against oxidative stress induced by tert-butyl hydroperoxide (t-BHP). The effect was more pronounced in older age group compared to lower age group. The findings suggest a possible role of tea catechins as anti-aging compounds.     

Optimizing conditions for the extraction of catechins from green tea using hot water

Six different factors involved in the extraction of catechins from green tea using water were examined for their impact on the yield of catechins and on the efficiency of water use. The best temperature and time combination for catechin extraction was at 80°C for 30 min. The yield of catechins was also optimal with a tea particle size of 1 mm, a brewing solution pH <6 and a tea‐to‐water ratio at 50:1 (mL/g). In terms of efficient use of water in a single extraction, a water‐to‐tea ratio of 20:1 (mL/g) gave the best results; 2.5 times less water was used per gram of green tea. At the water‐to‐tea ratio of 20:1 mL/g, the highest yield of catechins per gram of green tea was achieved by extracting the same sample of green tea twice. However, for the most efficient use of water, the best extraction was found to be once at a water‐to‐tea ratio of 12:1 (mL/g) and once at a water‐to‐tea ratio of 8:1 (mL/g). Therefore, all six of the factors investigated had an impact on the yield of catechins extracted from green tea using water and two had an impact on the efficiency of water use.     

Analysis of catechins and caffeine in tea extracts by micellar electrokinetic chromatography

Cancer chemotherapy is a new and important medical science and much interest has been focused on catechins, not only for their antioxidant activity, but also because of their known antimutagenic and antitumorigenic properties. Green tea and black tea, which are among the most popular beverages consumed worldwide, contain many different catechins. We developed an analytical method capable of separating six different catechins and caffeine in tea by micellar electrokinetic chromatography in only 20 min without extensive sample preparation. Furthermore, we compared the amount of catechins and caffeine in several teas and different preparation modes.     

Effects of different steeping methods and storage on caffeine, catechins and gallic acid in bag tea infusions

Bag teas, packed 3g of ground black, green, oolong, paochoung and pu-erh tea leaves (the particle size used was 1-2mm), were steeped in 150 mL of 70, 85 or 100 degrees C hot water to study the effects of the number of steeping (the same bag tea was steeped repeatedly eight times, 30s each time, as done in China for making ceremonial tea) and varied steeping durations (0.5-4 min) on caffeine, catechins and gallic acid in tea infusions. The changes in tea infusions during storage at 4 or 25 degrees C for 0-48 h and the variations in these compounds of bag tea infused with 150 mL of 4 or 25 degrees C cold water for 0.5-16 h were also investigated. A HPLC method with a C18 column and a step gradient solvent system consisting of acetonitrile and 0.9% acetic acid in deionized water was used for analysis. Results for all kinds of tea samples showed that the second tea infusion contained the highest contents of caffeine, catechins and gallic acid when bag teas were steeped in 70 degrees C water. It was different from that steeped at 85 and 100 degrees C, the highest contents existed in the first infusion. These compounds decreased gradually in later infusions. Higher amounts of caffeine, catechins and gallic acid could be released from bag teas as hotter water was used. As steeping duration prolonged, these ingredients increased progressively, however, their levels were lower than that cumulated from the infusions with the identical bag tea prepared recurrently at the same temperature and time points. (-)-Gallocatechin gallate and (+)-catechin existed in these tea infusions rarely and could not be detected until a certain amount of them infusing. Except gallic acid that showed a significant increase and caffeine that exhibited no significant change, all kinds of catechins decreased appreciably after tea infusions were stored at 25 degrees C for 36 h; nevertheless, all of them showed no evident changes at 4 degrees C storage. The caffeine, catechins and gallic acid in tea infused with cold water also increased with increasing duration. Their contents in 25 degrees C steeped tea were higher than that made at 4 degrees C; moreover, their infusion rates from bag teas to cold water were markedly lower than that steeped in hot water. Infusing efficiencies of non-gallated catechins were higher than gallated catechins under cold water steeping.     

High-throughput analysis of catechins and theaflavins by high performance liquid chromatography with diode array detection

Increased interest in potential health-protective activities of flavonoid-rich tea has created the need to take advantage of HPLC column and system advances in order to optimize methodologies for flavonoid analysis. Two new RP-C18 methods for HPLC-DAD analysis of tea flavonoids were developed to facilitate separation of catechins within 5 min and separation of catechins and theaflavins within 10 min total analysis time. Calibration results indicate that these methods have on-column limits of detection on the order of 1-10 pmol for most tea catechins, and method replication generally resulted in intraday and interday peak area variation of <5% for catechins and <9% for theaflavins in green and black tea infusions. These new methods are therefore sensitive, reproducible, and represent a 2-4-fold reduction in HPLC analysis time from existing analytical methods. These improvements are readily achievable with commonly used HPLC equipment, thus facilitating increased sample throughput and efficiency across a broad range of experimental applications.     

绿茶儿茶素的最新合成进展

简要介绍了绿茶儿茶素的组成及活性, 重点综述了有关儿茶素及其衍生物合成研究的最新进展.     

Constituents of the green tea seeds of Camellia sinensis

Green tea (Camellia sinensis) leaves are known to contain active ingredients such as catechins and caffeine, and are widely useful materials. Recently, green tea flowers also have been in the spotlight. However, little attention has been paid to the tea seeds. In this work, the constituents of green tea seeds and green tea leaves were compared. Caffeine was found in the seeds, whereas catechins (usually obtained from green tea leaves) were not observed. Next, we investigated the constituents of hexane extracts and methanol extracts of green tea seeds. We found that the hexane extracts contained high amounts of oleic glyceride (79.9%) in addition to linoleic glyceride (20%). We confirmed the structures of these glycerides by NMR spectroscopy and by synthesis from a fatty acid and glycerol. The methanol extract was found to contain naringenin glucosides by mass spectrometry and NMR spectroscopic analysis.