流动注射-抑制化学发光法测定绿茶中的茶多酚含量

茶多酚是茶中的酚类化合物 ,药用价值较高 ,有抗氧化、抗肿瘤、抗动脉粥样硬化、抑菌等药理作用。其测定方法主要有酒石酸亚铁比色法 (标准法 ) [1] 、分光光度法[2 ] 等。流动注射 抑制化学发光法测定茶多酚尚未见报道。本文用茶多酚还原Ｈ2 Ｏ2 ,抑制鲁米诺 Ｈ2 Ｏ2 ＫＩＯ4 体系[3 ] 的化学发光 ,在碱性条件下 ,其抑制程度的大小与茶多酚的含量成线性关系。与其他方法相比 ,本法具有线性范围宽、灵敏度高、简单、快速的优点 ,用于实际样品测定 ,结果令人满意。材料与方法仪器与试剂　ＩＦＦＬ Ｄ型流动注射化学发光仪(西安瑞科电子设…     

顺铂对机体损伤及茶多酚的拮抗作用

目的：初步探讨茶多酚（TP）对顺铂（DDP）致机体突变作用的影响。方法：观察小鼠外周血淋巴细胞DNA的受损情况、精子畸形率及体重变化。结果：顺铂＋茶多酚组较用顺铂组的外周血淋巴细胞DNA受损情况有不同程度减轻。顺铂茶多酚组较同剂量顺铂组粗子畸形率下降,有减缓顺铂引起体重下降趋势。结论：茶多酚在一定程度上对顺铂的致突变作用和体重减轻有一定的拮抗作用。     

THE INFLUENCE OF COFFEE WITH MILK AND TEA WITH MILK ON THE BIOAVAILABILITY OF TETRACYCLINE

The effect of milk added to coffee or black tea on the bioavailability of tetracycline was evaluated in 12 healthy volunteers according to a crossover design. Results showed that even a small volume of milk containing extremely small amounts of calcium severely impair the absorption of the drug, so that the presence of this metal ion should be carefully controlled in order to avoid decreasing the available tetracycline. © 1997 John Wiley & Sons, Ltd.     

甲壳质衍生物916对家兔实验性动脉粥样硬化的预防作用

本文研究了９１６对高血症的新西兰白兔的动脉粥样硬化的抑制作用。在用高脂饲料喂养家兔的同时,分别连续给以４,２０,４０ｍｇ．ｋｇ＾－１的９１６共１１ｗ。     

中国人参茎叶皂甙对大鼠行为的影响

人参茎叶皂甙５０ｍｇ／ｋｇ灌胃给大白鼠，每天１次，连续７天，于末次给药后１ｈ，采用主动回避反应；被动回避反应；分辨学习等训练方法对受试物进行研究，结果表明人参茎叶皂甙对正常大鼠学习、记忆过程仅有微弱易化作用。通过探索行为研究表明，人参茎叶皂甙明显增加每个训练日大白鼠第１分钟探索活动次数并加速探索活动的适应。对电休克大鼠短期记忆障碍有明显改善作用。     

Effect of tea catechins on erythrocyte Ca++-pump in type 2 diabetes mellitus

An altered intracellular calcium metabolism is known to play an essential role in the pathophysiology of diabetes and its complications. Tea [Camellia sinensis L. (Theaceae)] contains polyphenolic compounds collectively known as catechins belonging to the flavonoids family. Catechins have been reported to possess several biological properties including an antidiabetic effect. The present paper reports the effect of tea catechins on erythrocyte membrane Ca⁺⁺-pump in normal and type 2 diabetic patients. The activity of erythrocyte Ca⁺⁺-ATPase was significantly decreased in type 2 diabetes. In vitro incubation with tea catechins (10^?3-10^?8 M) caused an increase in the activity of Ca⁺⁺-ATPase in both normal and type 2 diabetic subjects; the effect was more pronounced in type 2 diabetes and was observed at much lower concentrations (10^?5 M) compared to normal (10^?3 M). The order of effectiveness of individual catechins was in the order: EGCG > ECG > EC > EGC. The increase in Ca⁺⁺-ATPase activity after incubation with tea catechins may be explained on the basis of alteration in fluidity due to a direct effect of catechins on the membrane.     

红碎茶发酵过程中多酚类物质含量变化的研究

用云南大叶群体种作材料，控制在一定温湿度等环境条件下，用仿制C．T．C揉切机砌碎。每隔20min取一次发酵叶烘干，后然对不同处理的茶样进行生化测定，测定出茶多酚（多酚类化合物）总量、儿茶素的总量都 着发酵时间的延长而逐渐减少，儿茶素的次级氧化物产物茶黄素（TF）、茶红素（TR）的含量是随着发酵时间延长而逐渐增加，当含量积累到高峰期时，又随着发酵时间的延长而降低，茶红素含量高峰期的于茶加，当含量积累到高峰期时，又随着发酵时间的延长而降低，茶红素含量高峰期后于茶黄素，茶褐素（TB）的含量是随着发酵时间的延长而逐渐增加，从茶化分析结合感官审评的结果，温度在22－26℃，地湿度在90％以上，发酵时间在80min左右，制出的红碎茶品质最好。     

HPLC法测定茶叶中儿茶素类及咖啡因的含量

目的:建立茶叶中6种儿茶素类成分(EGC、DC、EGCG、EC、GCG、ECG)和咖啡因(CAF)的 HPLC 同时定量方法,并测定23个茶叶样品中七组分的含量,为茶叶的质量评判以及茶多酚与其原料绿茶之间的关系探讨奠定基础。方法:采用 Supelco~Discovery C_(18)(250 mm×4.6 mm,5 μm)色谱柱,含0.1%甲酸的水-甲醇的梯度洗脱系统,流速0.5 mL·min~(-1),检测波长278nm。结果:在所选择的分析条件下,样品中的各组分获得了理想分离,且各组分的线性关系良好。结论:该方法准确、稳定,重复性好,可用于茶叶中七组分的定量分析。     

HPLC法同时检测茶叶中八种儿茶素

建立一种茶叶中多组分儿茶素的HPLC测定方法。将茶叶用80℃热水超声提取20min,提取液离心分离后,采用Kromasil C18(250mm×4.6mm,5μm)色谱柱分离,以水-乙腈-磷酸(49.95:50:0.05,V:V)为流动相A,水-乙腈-磷酸(95.45:4.5:0.05,V:V)为流动相B,进行梯度洗脱,流速为0.5mL/min,柱温25℃,紫外检测波长231nm。在给定的浓度范围内,各儿茶素组分的峰面积与其相应浓度呈现良好的线性相关,R2>0.9950。添加已知儿茶素含量的回收试验结果显示,各组分儿茶素的平均回收率为94.8%～110.8%,相对标准偏差≤2%。     

Evaluation of toxicity of green tea catechins with 90-day dietary administration to F344 rats

Green tea catechins (GTC), polyphenols extracted from the stalks and leaves of Camellia sinensis, are found in the different types of tea beverages and as antioxidant additives to many foods, snacks, fats and fatty oils. As a part of their safety assessment, subchronic toxicity was investigated in male and female F344 rats with dietary administration at concentrations of 0 (control), 0.3%, 1.25% and 5.0% for 90 days. The average daily intakes of GTC in each group were 180, 764 and 3525 mg/kg body weight/day, respectively for males, and 189, 820 and 3542 mg/kg body weight/day, respectively for females. No mortality or obvious clinical signs were observed throughout the experimental period but body weights were reduced from week 1 to the end of the experiment in 5.0% males. In serum biochemistry, alanine transaminase and alkaline phosphatase in 5.0% males and females and aspartate transaminase in 5.0% females were increased, together with the relative liver weights in both sexes receiving 5.0%. Although decreases were evident for total cholesterol in 0.3–5.0% males and triglycerides in 1.25% and 5.0% males and 5.0% females, these changes were not considered to be adverse. Hematology and histopathological observation revealed no GTC-related toxicological changes. Based on above findings, the no observed adverse effect level (NOAEL) of GTC was estimated to be 1.25% (764 mg/kg body weight/day for males and 820 mg/kg body weight/day for females).     

中国人参茎叶皂甙对大白鼠条件性行为的作用

中国人参茎叶皂甙可以提高大白鼠在MG-2型迷宫中条件性回避反应的出现率和分辨学习的正确率,并且前者的提高程度较后者更为显著。     

Green tea polyphenols in drug discovery: a success or failure?

Green tea is made from unfermented dried leaves from Camellia sinensis and has been consumed by humans for thousands of years. For nearly as long, it has been used as a folk remedy for a wide array of diseases. More recently, a large number of in vitro and in vivo scientific studies have supported this ancient contention that the polyphenols from green tea can provide a number of health benefits. As these compounds are clearly safe for human consumption and ubiquitous in the food supply, they are highly attractive as lead compounds for drug discovery programs. However, as drugs, they are far from optimum. They are relatively unstable, poorly absorbed, and readily undergo a number of metabolic transformations by intestinal microbiota and human enzymes. Further, as these compounds target a wide array of biological systems, in vivo testing is rather difficult as effects on alternative pathways need to be carefully eliminated. The purpose of this review is to discuss some of the challenges and benefits of pursuing this family of compounds for drug discovery.     

花卷茶提取物对高胆固醇血症大鼠血脂和内皮功能的影响

目的研究花卷茶提取物对高胆固醇血症大鼠血脂和内皮功能的影响及机制。方法雄性SD大鼠高脂饲养4周诱发高胆固醇血症,其中实验组在高脂饲料饲养2周后开始每日灌胃给予不同剂量的花卷茶系列之十两茶水提物（50、100和200mg.kg-1）,持续2周。实验结束后,颈动脉取血测定血脂、一氧化氮（NO）、非对称二甲基精氨酸（ADMA）和丙二醛（MDA）含量;分离胸主动脉检测血管内皮依赖性舒张功能。结果十两茶提取物能呈剂量依赖性降低高脂血症大鼠血清总胆固醇和低密度脂蛋白及甘油三酯水平。十两茶提取物能显著改善高脂所诱导的血管内皮舒张功能障碍,降低血浆ADMA和MDA含量以及增加NO水平,且呈剂量依赖性。结论花卷茶系列之十两茶提取物具有降低血脂和保护血管内皮功能作用,其作用与抑制脂质过氧化、调节ADMA/NO系统有关。     

Can Tea Consumption be a Safe and Effective Therapy Against Diabetes Mellitus-Induced Neurodegeneration?

Diabetes mellitus (DM) is a metabolic disease that is rapidly increasing and has become a major public health problem. Type 2 DM (T2DM) is the most common type, accounting for up to 90-95% of the new diagnosed DM cases. The brain is very susceptible to glucose fluctuations and hyperglycemia-induced oxidative stress (OS). It is well known that DM and the risk of developing neurodegenerative diseases are associated. Tea, Camellia sinensis L., is one of the most consumed beverages. It contains several phytochemicals, such as polyphenols, methylxanthines (mainly caffeine) and L-theanine that are often reported to be responsible for tea’s health benefits, including in brain. Tea phytochemicals have been reported to be responsible for tea’s significant antidiabetic and neuroprotective properties and antioxidant potential. Epidemiological studies have shown that regular consumption of tea has positive effects on DM-caused complications and protects the brain against oxidative damage, contributing to an improvement of the cognitive function. Among the several reported benefits of tea consumption, those related with neurodegenerative diseases are of great interest. Herein, we discuss the potential beneficial effects of tea consumption and tea phytochemicals on DM and how their action can counteract the severe brain damage induced by this disease.     

Protective role of tea catechins against oxidation-induced damage of type 2 diabetic erythrocytes

1. Oxidative stress is recognized as a major contributing factor for the development of late complications of diabetes. 2. Tea contains polyphenolic compounds (catechins), which have many important biological properties, including strong anti-oxidant activity. 3. The present study was undertaken to evaluate the effect of tea catechins (epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC)) on markers of oxidative stress (malondialdehyde (MDA), reduced glutathione (GSH) and membrane -SH group) in erythrocytes from type 2 diabetics. 4. Oxidative stress was induced in normal and type 2 diabetic erythrocytes by incubating with tert-butyl hydroperoxide (t-BHP). 5. Diabetic erythrocytes have higher MDA and decreased GSH and membrane -SH groups compared with normal erythrocytes. 6. Our results show that tea catechins protect erythrocytes from t-BHP-induced oxidative stress, the effect being more pronounced in diabetic erythrocytes. The relative effectiveness of individual catechins are in the order of EGCG>ECG>EGC>EC. 7. We hypothesise that a higher intake of catechin-rich food by diabetic patients may provide some protection against the development of long-term complications of diabetes.     

28-Day oral (gavage) toxicity studies of green tea catechins prepared for beverages in rats.

The beneficial health effects associated with drinking green tea are widely considered to be due primarily to tea catechins. Heat treatment of marketed green tea beverages for sterilization causes epimerization and/or polymerization of tea catechins. Safety studies on heat-treated tea catechins are limited. The objective of the present study was to evaluate potential adverse effects, if any, of two standardized green tea catechin (GTC) preparations: one that underwent heat sterilization (GTC-H) and one that was not heat-sterilized (GTC-UH). A decaffeinated preparation of the GTC-H (GTC-HDC) was also evaluated to ascertain if any effects were due to caffeine. The GTC preparations were administered to rats once daily at levels up to 2000 mg/kg/day for 28 days. There were no deaths attributable to the GTC preparations. The clinical condition of the animals, functional observational battery, motor activity, clinical pathology evaluations, organ weights, and gross necropsy findings were unaffected by any of the GTC preparations. GTC-HDC or GTC-UH dosing had no effects on body weights or microscopic findings, whereas lower body weights and food consumption were observed in the 1000 and 2000 mg/kg/day GTC-H group males. The no observed-adverse-effect level (NOAEL) for localized gastric effects for GTC-H was 1000 mg/kg/day. No other target organs were identified. Thus, the NOAEL for systemic toxicity following oral administration was 2000 mg/kg/day for GTC-H, GTC HDC, and GTC-UH under the conditions of this study.     

Interaction of green tea catechins with renal organic cation transporter 2

1.?Green tea extract (GTE) and EGCG have previously shown to increase the uptake of MPP⁺ into Caco-2 cells. However, whether GTE and its derivatives interact with renal basolateral organic cation transporter 2 (Oct2) which plays a crucial role for cationic clearance remains unknown. Thus, this study assessed the potential of drug-green tea (GT) catechins and its derivatives interactions with rat Oct2 using renal cortical slices and S2 stably expressing rat Oct2 (S2rOct2).

2.?Both GTE and ECG inhibited MPP⁺ uptake in renal slices in a concentration-dependent manner (IC₅₀?=?2.71?±?0.360?mg/ml and 0.87?±?0.151?mM), and this inhibitory effect was reversible. Inhibition of [³H]MPP⁺ transport in S2rOct2 by either GTE or ECG (IC₅₀?=?1.90?±?0.087?mg/ml and 1.67?±?0.088?mM) was also observed.

3.?The weak and reversible interactions of GTE and ECG with rOct2 indicate that consumption of GT beverages could not interfere with cationic drugs secreted via renal OCT2 in humans. However, the rise of therapeutic use of GTE and ECG might have to take into account the significant possibility of adverse drug–green tea catechins interactions which could alter renal organic cation drug clearance.     

降胆固醇药物F400的研究——Ⅱ.F400的分离与鉴别

从红曲霉属的Monascus sp F400菌株的发酵液中分离得到了一个具有显著降胆固醇作用的活性物质F400。测定了它的理化性质并与已知的降胆固醇药物作了鉴别,比较结果表明F400与高效广谱降胆固醇药物Lovastatin或Monacolin K为同一物质。