Inhibition of free radical induced oxidative hemolysis of red blood cells by green tea polyphenols

The in vitro oxidative hemolysis of human red blood cells (RBC) was used as a model to study the free radical induced damage of biological membranes and the inhibitory effect of natural antioxidants. The hemolysis was induced by a water-soluble free radical initiator 2,2′-azo(2- asmidinopropane)dihydrochloride (AAPH) and inhibited by the principal polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicat- echin gallate (ECG), (-)-epigallocatechin gallate (EGCG) and gallic acid (GA). Addition of AAPH at 37°C caused fast hemolysis after a short period of inhibition period, while addition of the green tea polyphenols efficiently suppressed the hemolysis in the activity sequence of EGCG＞EGC＞ECG≈EC＞GA, demonstrating that these green tea polyphenols are effective antioxidants which could protect biological membranes from free radical induced oxidative damage.     

Apoptosis of RKO induced by catechins and GA through Ca<Superscript>2+</Superscript> and LIP

The anti-tumor effects of catechins and gallic acid （GA） in-vitro was investigated in this paper. Fluo-3AM, Calcium-AM （Ca-AM）, 2＇, 7＇ -dichlorofluorescein-diacetate（DCFH-DA）, 4＇ ,6-dia- midino-2- phenylindole （DAPI） and Ca-AM plus colbat were used to characterize intracellular calcium, labile iron pool （LIP）, reac- tive oxygen species （ROS）, nuclei morphology and mitochondrial permeability transition pore （mPTP） opening, respectively. High performance liquid chromatography （HPLC） was used to quanti- tare catechins and GA in the cultural medium. The results indi- cated that each of them showed dose response inhibition of cell growth, provoking nuclei condensation, intracellular calcium ele- vation, mPTP opening, LIP reduction, and cytochrome c （Cyt-C） to release into cytosol. The caspase inhibitors, 2-aminoethox- ydiphenol borate （APB） or Fe3＋ could inhibit lethal effects of GA and （-）-epigallocatechin （EGC）, but failed to affect （-）-epigalloca- techin gallate （EGCG） and （-）-epicatechin gallate （ECG）. Level of ROS presented negative growth while their concentration de- creased in the medium. In conclusion, our findings suggest that viability of RKO decreased because of their good correlation with elevation of calcium and loss of L1P and ROS in cytosol.     

基于HPLC和模式识别的绿茶分类

为判别不同绿茶的类别,利用高效液相色谱分析茶叶中儿茶素和咖啡因等内部有效成分的质量分数,根据其质量分数利用模式识别方法进行分类.试验以5种中国绿茶为研究对象,首先,采用高效液相法分析茶叶中表没食子儿茶素、(+)-儿茶素、表儿茶素、表没食子儿茶素没食子酸酯、表儿茶素没食子酸酯和咖啡因等6种有效成分的质量分数.在此基础上,分别运用线性判别分析(LDA)、K最邻近(KNN)和人工神经网络(ANN)等模式识别方法建立相关模型对5种绿茶进行判别分析,试验结果表明ANN判别模型效果最好,模型训练和预测时的判别率分别达到98%和92%.研究结果表明,利用HPLC分析茶叶中的儿茶素和咖啡因等质量分数,再结合ANN模式识别的方法可以对不同类别的绿茶进行定性判别.     

茶叶中儿茶素,咖啡因和叶绿素的提取和分析鉴定

茶叶中儿茶素、咖啡因和叶绿素的提取和分析鉴定吴明光，王金茂（化学系）茶叶中的儿茶素咖啡因和叶绿素无论作为保健食品或医药、化妆品中的添加剂都具有不可忽视的应用前景。因而引起国内外有关专家的关注，已有不少研究结果发表，但多侧重于儿茶素类或多酚类化合物等的...     

用HPLC方法对中国茶叶中茶多酚等成分含量的定量分析

本研究中用HPLC方法对6种中国茶叶的茶多酚和生物碱类等成分含量进行了定量分析．分析结果表明：6种中国茶叶中总儿茶素含量按照绿茶、白茶、黄茶、青茶、红茶、黑茶的顺序有降低的趋势．生物碱类的咖啡因和茶黄素的含有量与茶叶种类的不同而变化不大．     

五峰夏秋茶主要呈味成分分析研究

为了研究五峰春茶、夏茶和秋茶的主要呈味成分和品质的差异, 以五峰春茶、夏茶和秋茶为样品,利用重量法对五峰春茶、夏茶和秋茶的水分、水浸出物进行测定和比较;利用紫外分光光度法和高效液相色谱法(High Performance Liquid Chromatography, HPLC)测定样品的主要呈味成分,包括茶多酚、儿茶素、表没食子儿茶素没食子酸酯(Epigallocatechin gallate, EGCG)、咖啡因和氨基酸含量.研究结果表明,五峰春茶、夏茶和秋茶的主要呈味成分存在差异.茶多酚、儿茶素、EGCG含量：春茶 < 夏茶 < 秋茶;咖啡因、茶氨酸、总氨基酸含量：春茶 > 夏茶 > 秋茶.不同季节的茶叶呈味成分成分之间存在较大差异,可能是导致五峰夏秋茶苦涩味偏重的主要原因.     

用没食子酸酯萃取分离酯型儿茶素单体

以疏水性没食子酸酯为萃取剂研究天然酯型儿荼素单体在水-有机醇两相体系中的分配行为，考察没食子酸酯烷基链长度、没食子酸酯浓度、萃取温度和振荡时间等因素对分配系数和分离因子的影响。研究结果表明：没食子酸酯与表儿萘素没食子酸酯形成复合物的稳定性比与其他2种单体（表没食子儿萘素没食子酸酯和没食子儿萘素没食子酸酯）形成的复合物的稳定性强，且当没食子酸正十二酯浓度为0．15mol／L，温度为20℃，振荡时间为30min时，表没食子儿荼素没食子酸酯、表儿茶素没食子酸酯和没食子儿萘素没食子酸酯的分配系数KEGCG，KECG和KGCG分别为13．32，6．04和1．65；分离因子α1和α2分别为3．7和2．2。     

茶多酚的制备及在化妆品中的应用

研究了提取过程中萃取剂种类、用量、萃取次数对茶多酚收率的影响 ,得到了安全无毒的复配体系来去除色素及咖啡因。高效液相色谱 (HPLC)分析表明 :用 80 %乙醇浸提 3次、用TPB2 83复配体系洗涤、乙酸乙酯萃取后茶多酚中儿茶素含量达 81 3 % ,咖啡因含量仅为 0 8%。所得产品经化妆品应用实验表明 :3 %茶多酚添加物可改善皮肤色素沉着 ,对黄褐斑的有效率达 40 % ,且可以有效改善化妆品的使用性能。     

多花勾儿茶中儿茶素的提取分离与HPLC测定

以多花勾儿茶果实、叶及自制绿茶为原料,采用水浴法提取儿茶素,研究其最佳提取工艺.提取液经石油醚脱脂溶性色素后,采用大孔吸附树脂D941进行吸附分离,静态吸附和解析条件研究得出纯净水洗脱效果较好.多花勾儿茶果实、叶及自制绿茶吸附分离的纯化液,用色谱柱:Boston Green ODS PC18(4.6×250mm,5μm),检测波长279nm,流动相乙腈-0.4%磷酸(w(乙腈)∶w(0.4%磷酸)=13∶87),柱温35℃,流速1 mL/min,一次进样10μL来进行高效液相色谱(HPLC)检测,其结果显示,多花勾儿茶果实中儿茶素含量最低,自制绿茶中的儿茶素含量最高.     

利用大孔树脂吸附法分离儿茶素EGCG和咖啡因

考察了S-8、X-5、XAD-200等树脂对绿茶水提液中儿茶素EGCG和咖啡因的吸附性能,结果显示,具有高比表面积的弱极性吸附树脂XAD-200对EGCG和咖啡因的吸附差异较大,动态吸附过程中发生层析分离,儿茶素EGCG在1.5 BV后即开始泄漏,而咖啡因在6 BV后才开始泄漏.收集1.5～6 BV处的流出液可得w（咖啡因）＜0.30％的儿茶素,EGCG的质量分数由48.65％提高至66.37％.在最佳上样量下,EGCG的收率可达65.21％.     

英红1号、英红9号和祁门茶树芽叶中嘌呤生物碱和茶多酚的HPLC-DAD-MS/MS

 采用HPLC-DAD-MS/MS技术对英红1号、英红9号和祁门茶树的芽叶进行了分析,鉴定出了2种嘌呤生物碱,7种儿茶素类化合物以及2种非儿茶素类茶多酚。对这3个茶树品种的嘌呤生物碱和儿茶素类成分质量分数进行比较分析,结果表明三者的儿茶素类总质量分数均大于20%,其中英红1号和祁门红茶品种在儿茶素类成分的组成上较为接近,EGCG质量分数均为最高;而英红9号质量分数最高的是ECG。     

Electrochemical exfoliation for few-layer graphene in molybdate aqueous solution and its application for fast electrothermal film

There are still serious barriers from laboratory exploration to large-scale production of commercializing highquality graphene, especially by environmental-friendly methods. In this study, a simple and efficient electrochemical method for the preparation of high-quality water-dispersible graphene has been developed using molybdate aqueous solutions as the electrolyte. The exfoliation of graphite paper could be achieved in the electrolyte with a high yield of a few layers graphene(1–5 layers, 76%) and uniform lateral size(1–6 μm, 90%).The as-obtained few layers graphene well dispersed in aqueous solution with a solubility of ～4 mg mL~(-1) and stability for at least 2 months. It provides a new green method to prepare high-quality graphene. The as-prepared water-dispersible graphene films exhibit significant electrothermal performance, with a steady-state temperature of 147 °C under voltage of 10 V and a maximum heating rate achieved of 11.8 °C s~(-1).     

广西六堡茶主要特征成分分析

分析了产于广西梧州地区的7种六堡茶及其毛茶的主要特征性成分,旨在为合理评价六堡茶的品质提供理论参考.结果显示:六堡茶与其毛茶的特征性成分有显著差异.渥堆发酵导致毛茶的总酚含量显著下降、总黄酮略有降低、咖啡因及游离态儿茶素类物质含量降低、总可溶性糖及总游离氨基酸含量上升、茶褐素大量形成.这些成分的改变是六堡茶汤色红、味甘醇、口感圆润的主要原因.清除羟自由基能力的差异显示,六堡茶因含有较多的茶褐素而比毛茶具有更强的抗氧化能力.     

几种天然材料对茶多酚和咖啡因的吸附与分离特性

用HPLC法测定表没食子儿茶素没食子酸酯(EpigaUocatechin-3-gallate,EGGG)和咖啡因含量,分光光度法测定总茶多酚含量,研究了几种天然材料对茶提取物中茶多酚和咖啡因的吸附与分离特性.谷壳和丝瓜络对茶多酚的吸附率分别为65%和62%,稍低于最佳吸附大孔树脂DM130(73%)和最佳分离树脂聚酰胺树脂(81%)的吸附率;对咖啡因的吸附率分别为24%和18%,介于DM130(68%)和聚酰胺(15%)之间.红砖粉、矿石粉末和河沙对茶多酚和咖啡因的吸附率都很低,分别为38%,29%,3%和24%,15%,15%.用1 BV水、20%乙醇、40%乙醇和3 BV 80%乙醇梯度洗脱,测定了它们对EGCG和咖啡因的柱层析分离效果.DM130不能将两者分离开,94%～96%的EGCG和咖啡因同时存在于40%和80%的乙醇相中.聚酰胺树脂能够很好地分离这两种成分,90%咖啡因在水和20%E,醇洗脱相中,而90%EGCG在80%乙醇相中.谷壳和丝瓜络对EGCG和咖啡因的分离效果介于DM130和聚酰胺之间.谷壳为吸附剂时,92%咖啡因在水,20%和40%乙醇相中,84%的EGCG在80%乙醇相中.丝瓜络吸附剂时,87%咖啡因在水,20%和40%乙醇相中,76%的EGCG在80%乙醇相中.调整和控制好洗脱条件和洗脱剂用量,可较好地分离EGCG和咖啡因.结果表明,谷壳和丝瓜络可用作EGCG和咖啡因的吸附分离材料,具有对环境和健康安全、廉价易得等特点.     

Binding and endocytosis of monoterbium transferrin by K562 cells

Human serum apotransferrin is the major iron-tran- sport protein in blood. The protein binds iron as Fe3+ at two similar, but not identical, high-affinity binding sites. Although iron bound to human serum apotransferrin is less then 0.1% (~3 mg) of the total body iron, dynamically it is the most important iron pool with the highest rate of turnover. The turnover of transferrin iron is in the order of 30 mg per day and, normally, about 80% of this iron are transported to the bone marrow for hem…     

Photoluminescence of ZnO nanorods grown by hydrothermal method on Si substrate

ZnO nanorods were grown on Si substrate by hydrothermal method under various reaction time (12, 24, and 36 h), Zn²⁺ concentrations (0.01, 0.02, and 0.05 mol/L) and reaction temperatures (70–95 °C). Their photoluminescence (PL) tests were taken at room temperature. Nanorods grown under longer reaction times or higher temperatures can emit stronger UV light and depressed green light, suggesting better crystallization of ZnO nanorods. Higher Zn²⁺ concentration results in stronger green band emitting, whereas the UV peak is depressed with the Zn²⁺ concentration over 0.02 mol/L. This indicates that excessive interstitial Zn defects may be introduced into the nanorods in Zn-rich environment.     

贮藏时间对武夷岩茶金锁匙生化成分及感官品质的影响

以轻火、中火武夷岩茶金锁匙为实验材料,研究不同贮藏时间对其生化成分及感官品质的影响,为武夷岩茶的科学品饮、储藏、运输、营养保持等提供理论参考。结果表明:贮藏过程中轻火、中火金锁匙茶多酚、儿茶素、咖啡碱、水浸出物含量(生化成分与干物质质量比)均呈下降趋势,水分含量呈上升趋势,氨基酸含量呈先增加后减少的趋势。贮藏12个月轻火、中火金锁匙茶多酚、儿茶素、酯型儿茶素、非酯型儿茶素、咖啡碱含量分别降低21.03%、19.48%;21.87%、17.24%;30.58%、26.76%;10.25%、6.45%;17.60%、13.36%。轻火金锁匙贮藏6个月氨基酸含量最高,达2.32%;中火金锁匙贮藏8个月氨基酸含量最高,达2.25%。贮藏前期,轻火、中火金锁匙火气逐渐退去,感官品质得到提升;贮藏后期,其滋味变得更加甘醇,但香气鲜锐度略有下降,因此感官品质得分先增加后略有降低。轻火金锁匙贮藏6个月感官品质得分最高,中火金锁匙贮藏8个月感官品质得分最高。研究结果表明,合理贮藏有利于提高武夷岩茶的感官品质。     

A novel thermophilic endoglucanase from a mesophilic fungus Fusarium oxysporum

Cellulose is an abundant and renewable energy re- source on earth. Microorganisms produce multiple en- zymes to degrade cellulose, known as cellulase sys- tem[1]. Components of cellulase system were first clas- sified based on their modes of catalytic act…     

盐酸阿米替林与固绿的相互作用及其分析应用

在弱酸性条件下,盐酸阿米替林和固绿依靠静电作用形成离子缔合物,使体系的共振光散射明显增强.据此建立了一种测定盐酸阿米替林的共振光散射法.研究了体系的紫外-可见吸收光谱和共振光散射光谱,并考察了各因素对体系的影响.在最佳条件下,体系的最大散射峰位于344 nm处.共振光散射增强的程度与盐酸阿米替林的浓度在7.50×10-3~3.75×10-2mg.mL-1之间呈良好的线性关系.该方法的检测限为1.81×10-4mg.mL-1.将方法用于片剂中盐酸阿米替林的测定,并与药典法进行了对照,经t-检验证明两种方法无显著性差异.     

荷移反应分光光度法测定咖啡因

研究了咖啡因和茜素红形成荷移络合物的反应．在pH7．5的水溶液中,咖啡因能与茜素红发生荷移反应,形成物质的量比为1：1的络合物．λmax=523．00nm,咖啡因在0．6—5．8mg／L的范围内符合比耳定律,线性回归方程A=0．00263＋0．1082c（c：μg／mL）,相关系数R=0．9987,ε=2．1×10^4L／（mol·cm）．荷移反应分光光度法试剂易得,可直接在水溶液中进行,操作简单,灵敏度高,重现性好．用于茶叶中咖啡因含量的测定,取得满意的结果．