茶儿茶素类体内代谢动力学研究进展

儿茶素类作为绿茶的主要成分,具有广泛的生物学行为和药理功能.众多研究表明虽然儿荼素类在体外细胞体系中呈现较强的生物学活性,但其体内与体外表现不尽相同.本文对儿茶素类在生物体内的吸收、分布、代谢产物等进行综述,并对儿荼素类体内研究的前景进行展望,以期为儿荼素类作为药物或辅助药物的开发提供理论依据.     

大肠杆菌分子伴侣GroE系统及其协助的Rubisco蛋白装配

分子伴侣协助蛋白质在体内正确组装,对分子伴侣结构和作用机制的研究不仅在生物大分子结构和功能研究中具有重要的理论意义,而且还具有广泛的应用价值。大肠杆菌分子伴侣GroE系统是迄今为止研究得最为透彻的分子伴侣。本文侧重总结了GroE系统的作用机制以及在该系统的帮助下光合细菌核酮糖1,5二磷酸羧化/加氧酶(Rubisco蛋白)的装配情况。     

降血压乳酸菌发酵乳对原发性高血压大鼠的降压效果

目的对具有血管紧张素转化酶(ACE)抑制活性的乳酸菌DM9057发酵乳的抗胃肠道酶解能力及原发性高血压大鼠(SHR)体内降压效果进行研究。方法以10 ml/kg和2.5 ml/kg发酵乳一次性和连续灌胃原发性高血压大鼠。结果 DM9057发酵乳具有较好的抗胃肠道酶能力,并且2个剂量均具有较好的降血压效果,其中以10 ml/kg剂量效果最为显著,一次性和连续灌胃后,最大降压值为(17.97±3.82)、(25.46±5.06)mmHg。结论乳酸菌DM9057发酵乳具有较强的抗胃肠道能力,同时在原发性高血压大鼠体内能够发挥一定的降血压作用。     

大肠杆菌分子伴侣GroF系统及其胁助的Rubisco蛋白装配

分子伴吕协助蛋白质在体内正确组装,对分子伴侣结构和作用机制的研究不仅在生物大分子结构和功能研究中具有重要的理论意义,而且还具有广泛应用价值。大肠杆菌分子伴侣ＧｒｏＥ系统是迄今为止研究得最为透彻的分子伴侣。本文侧重总结了ＧｒｏＥ系统的作用机制及在该系统的帮助下光合细菌核酮糖１,５－二磷酸羧化／加氧酶（Ｒｕｂｉｓｃｏ）的装配情况。     

鱼类生长的神经内分泌调控

个体生长是由调控体内包括能量代谢和肌肉生长等多种生理信号通路共同影响的多基因调控性状.在参与脊椎动物生长过程的主要调控信号通路中,生长的内分泌调控轴及其组成信号起主要的作用.鱼类生长的内分泌调控轴和其生长调控的研究深受重视,包括生长激素、上游下丘脑激素、胰岛素样生长因子和下游分子等.许多的信号分子在体内不仅具有促进组织生长的作用,还具有对许多营养物质的代谢调控作用.体内其他内分泌调控轴也会对生长调控轴产生不可忽视的影响.本文主要归纳了近期硬骨鱼类生长内分泌调控轴的最新研究进展,包括最近利用遗传操作技术获得的相关体内模式的研究结果,并通过对这些最新研究的归纳,展示当前鱼类生长内分泌调控轴研究领域的新认识和新挑战.     

前列腺癌体内实验模型的研究进展

前列腺癌是男性最为常见的恶性肿瘤之一。近年来有关前列腺癌的相关研究取得了较大突破,但由于缺少有效的体内实验模型,导致研究成果向临床应用的转化受到严重阻碍。人源性前列腺癌移植(patient derived prostate tumor xenograft,PDPTX)模型是将患者新鲜的肿瘤组织移植于免疫缺陷小鼠而建立的体内模型,该模型能较好地复制原发肿瘤的异质性,保持肿瘤在分子学、基因学和病理学的复杂性。特别是采用肾包膜移植建立PDPTX模型的方法较好地解决了传统皮下移植建模成功率低、低级别肿瘤成瘤难、无法实现移植瘤转移等缺点,为前列腺癌研究提供了更为理想的体内模型。尤其是在靶向治疗、新型药物筛选、个体化治疗等方面具有不可取代的优势。     

新生隐球菌生物膜动物感染模型的构建及其活性的检测

目的 构建一种简便易行的新生隐球菌生物膜感染动物模型.方法 采用大鼠皮下置管法构建新生隐球菌生物膜感染动物模型,并使用电子扫描显微镜观察新生隐球菌体内形成生物膜的结构;采用MTT法对获得的体内生物膜结构进行活性的检测.结果 成功构建了新生隐球菌生物膜大鼠感染模型;MTT法检测体内生物膜活性表明,随着体内培养时间的延长,生物膜活性增强,与直接镜检和电镜观察结果一致.结论 新生隐球菌生物膜大鼠模型简单易行,便于操作,对于研究新生隐球菌生物膜体内活性的研究具有一定的实际应用价值.     

卫星遥感珊瑚礁白化概述

珊瑚礁白化是由于珊瑚失去体内共生的虫黄藻或者共生的虫黄藻失去体内色素而导致五彩缤纷的珊瑚礁变白的现象,严重的白化可以带来珊瑚礁的死亡.国内外研究表明海水温度升高和珊瑚礁白化关系最为紧密.卫星遥感能够提供大范围、同步与连续的海洋数据,如海水表层温度和海色数据,从而能够及时监测和预测珊瑚礁的白化.基于AVHRR (Advanced Very High Resolution Radiometer),NOAA(National Oceanic and Atmospheric Administration,US)开发了全球监测珊瑚礁白化的方法,热点(HotSpot)和周热度(DHW)两种主要指数.目前,我国珊瑚礁白化现象的监测和研究明显滞后于国际动态,迫切需要发展和利用卫星遥感的方法监测南海珊瑚礁白化状况.     

蜈蚣草羽叶中砷及植物必需营养元素的分布特点

采用同步辐射X射线荧光(SRXRF)分析了砷超富集植物蜈蚣草羽叶中As及6种植物必需营养元素的分布特点, 以及各元素分布之间的相互关系. 结果显示, 元素在羽叶中的分布与其迁移能力有密切的关系. As在羽叶中的分布表明, 蜈蚣草羽叶中As具有较强的木质部运输和木质部卸载能力. 植物体内移动性较强的大量元素K的分布与As最为相似, 而移动性较弱的Fe和Ca的分布与As呈相反的趋势.     

99mTc标记丝状噬菌体肽库及其在正常小鼠体内的分布

利用噬菌体展示技术已选出了多条与靶结合的肽.然而,即使是体内直接筛选得到的,肽与肿瘤或靶器官的体内结合并不理想.为了更好地理解噬菌体在体内的循环,通过MAG399mTc标记噬菌体肽库,研究了肽库在体内分布.体内分布实验结果显示,99mTc-噬菌体主要分布在肝和脾中,而心脏、肌肉、脑和胰腺这些器官或组织中的分布非常低.99mTc-噬菌体在胃、肠和骨中的累积,随着时间延长在不断升高,其他器官中的吸收则在不断降低.从5min到30min,99mTc-噬菌体在血中清除迅速.当噬菌体在体内循环足够长的时间后,一些噬菌体颗粒可以穿透血管进入并内化在器官或组织中.总之,为了筛选具有高特异性和亲和性的肽,应该根据靶器官和筛选部位的不同,在筛选前确定合适的噬菌体在体内的循环时间.     

Extraction behavior of caffeine and EGCG from green and black tea

A dipping method was developed to extract the catechins (EGCG) and alkaloids (caffeine) from green tea (Korea) and black tea (Sri Lanka). The effects of the solvent composition (water vs. ethanol), extraction time, temperatures, and solvent pH on the amount of catechins (EGCG) and alkaloids (caffeine) extracted from green and black tea were investigated. Reversedphase high-performance liquid chromatography (RP-HPLC) was used to analyze the catechins (EGCG) and alkaloids (caffeine) extracted. The content of EGCG and caffeine in green tea extracts was in the range of 2.04∼0.30 and 10.22∼0.85 mg/g, respectively. The amount of EGCG and caffeine in black tea extracts was in the range of 0.32∼0.24 and 5.26∼1.01 mg/g, respectively. The amount of caffeine extracted from green and black tea was greater than the amount of EGCG. Pure water is the best solvent for extracting EGCG and caffeine from green tea. The amount of caffeine extracted from green and black tea increased as the temperature, extraction time, and hydrogen ion concentration of the solvent increased. Although the amount of EGCG extracted from green tea increased as the temperature increased, the amount of EGCG extracted from black tea was not affected by temperature. The extraction of EGCG from both green and black tea was not affected by the hydrogen ion concentration of the solvent.     

Measurement of catechin and gallic acid in tea wine with HPLC

First a kind of fermented tea wine was prepared from Dancong tea. The content of four major catechins and gallic acid (EC, EGC, EGCG and ECG) in tea wine was measured with HPLC. The results showed that the content of EC, EGC, EGCG, ECG and catechins in tea wine decreased when compared with that before fermentation. The content of EC decreased the most, reaching 26.79%, while the content of GA changed the least with a decrease of only 13.56%. Nevertheless, tea wine still contains a relatively large amount of catechins, thus proper consumption of tea wine may be salubrious.     

The antioxidant effect of Green Tea Mega EGCG against electromagnetic radiation-induced oxidative stress in the hippocampus and striatum of rats

Electromagnetic radiation (EMR) of cellular phones may affect biological systems by increasing free radicals and changing the antioxidant defense systems of tissues, eventually leading to oxidative stress. Green tea has recently attracted significant attention due to its health benefits in a variety of disorders, ranging from cancer to weight loss. Thus, the aim of the present study was to investigate the effect of EMR (frequency 900 MHz modulated at 217 Hz, power density 0.02 mW/cm², SAR 1.245 W/kg) on different oxidative stress parameters in the hippocampus and striatum of adult rats. This study also extends to evaluate the therapeutic effect of green tea mega EGCG on the previous parameters in animals exposed to EMR after and during EMR exposure. The experimental animals were divided into four groups: EMR-exposed animals, animals treated with green tea mega EGCG after 2 months of EMR exposure, animals treated with green tea mega EGCG during EMR exposure and control animals. EMR exposure resulted in oxidative stress in the hippocampus and striatum as evident from the disturbances in oxidant and antioxidant parameters. Co-administration of green tea mega EGCG at the beginning of EMR exposure for 2 and 3 months had more beneficial effect against EMR-induced oxidative stress than oral administration of green tea mega EGCG after 2 months of exposure. This recommends the use of green tea before any stressor to attenuate the state of oxidative stress and stimulate the antioxidant mechanism of the brain.     

Epigallocatechin-3-gallate (EGCG): chemical and biomedical perspectives

The compound (-)-epigallocatechin-3-gallate (EGCG) is the major catechin found in green tea [Camellia sinensis L. Ktze. (Theaceae)]. This polyphenolic compound and several related catechins are believed to be responsible for the health benefits associated with the consumption of green tea. The potential health benefits ascribed to green tea and EGCG include antioxidant effects, cancer chemoprevention, improving cardiovascular health, enhancing weight loss, protecting the skin from the damage caused by ionizing radiation, and others. The compound EGCG has been shown to regulate dozens of disease-specific molecular targets. Many of these molecular targets are only affected by concentrations of EGCG that are far above the levels achieved by either drinking green tea or consuming moderate doses of green tea extract-based dietary supplements. In spite of this, well-designed double-blinded controlled clinical studies have recently demonstrated the efficacy of green tea extracts and purified EGCG products in patients. Therefore, this review highlights results from what the authors believe to be some of the most clinically significant recent studies and describes current developments in the stereoselective total synthesis of EGCG.     

Role of epigallocatechin gallate (EGCG) in the treatment of breast and prostate cancer

Green tea and its major constituent epigallocatechin gallate (EGCG) have been extensively studied as a potential treatment for a variety of diseases, including cancer. Epidemiological data have suggested that EGCG may provide protective effects against hormone related cancers, namely breast or prostate cancer. Extensive in vitro investigations using both hormone responsive and non-responsive cell lines have shown that EGCG induces apoptosis and alters the expression of cell cycle regulatory proteins that are critical for cell survival and apoptosis. This review will highlight the important in vitro mechanistic actions elicited by EGCG in various breast and prostate cancer cell lines. Additionally, the actions of green tea/EGCG in in vivo models for these cancers as well as in clinical trials will be discussed.     

Radio-modulatory effects of green tea catechin EGCG on pBR322 plasmid DNA and murine splenocytes against gamma-radiation induced damage

Green tea is rich in polyphenols, like catechins, which are thought to contribute to the health benefits of tea. The aim of this study was to evaluate the radioprotective effect of EGCG (epigallocatechin-3-gallate), a green tea catechin on γ-radiation induced cell damage. Under acellular condition of radiation exposure, pBR322 plasmid DNA was protected by EGCG in a concentration dependent manner. Treatment of murine splenocytes with EGCG 2h prior to radiation (3Gy), protected the cellular DNA against radiation-induced strand breaks. EGCG also inhibited γ-radiation induced cell death in splenocytes. EGCG pretreatment to the cells decreased the radiation induced lipid peroxidation and membrane damage. The levels of phase II enzymes, glutathione and lactate dehydrogenase were restored with EGCG treatment prior to radiation. Our results show that pretreatment with EGCG offers protection to pBR322 DNA under acellular condition and normal splenocytes under cellular condition, against γ-radiation induced damage and is better radioprotector in comparison to quercetin and vitamin C.     

Enhanced oxidation of flavan-3-ols and proanthocyanidin accumulation in water-stressed tea plants

(-)-Epicatechin (EC) and (-)-epigallocatechin gallate (EGCG), two major tea flavan-3-ols, have received attention in food science and biomedicine because of their potent antioxidant properties. In plants, flavan-3-ols serve as proanthocyanidin (PA) building blocks, and although both monomeric flavan-3-ols and PAs show antioxidant activity in vitro, their antioxidant function in vivo remains unclear. In the present study, EC quinone (ECQ) and EGCG quinone (EGCGQ), the oxidation products of EC and EGCG, increased up to 100- and 30-fold, respectively, in tea plants exposed to 19 days of water deficit. Oxidation of EC and EGCG preceded PAs accumulation in leaves, which increased from 35 to 53 mg gDW(-1) after 26 days of water deficit. Aside from the role monomeric flavan-3-ols may play in PAs biosynthesis, formation of ECQ and EGCGQ strongly negatively correlated with the extent of lipid peroxidation in leaves, thus supporting a protective role for these compounds in drought-stressed plants. Besides demonstrating flavonoid accumulation in drought-stressed tea plants, we show for the first time that EC and EGCG are oxidized to their respective quinones in plants in vivo.     

Neutrophil restraint by green tea: inhibition of inflammation,associated angiogenesis,and pulmonary fibrosis

Neutrophils play an essential role in host defense and inflammation, but the latter may trigger and sustain the pathogenesis of a range of acute and chronic diseases. Green tea has been claimed to exert anti-inflammatory properties through unknown molecular mechanisms. We have previously shown that the most abundant catechin of green tea, (-)epigallocatechin-3-gallate (EGCG), strongly inhibits neutrophil elastase. Here we show that 1) micromolar EGCG represses reactive oxygen species activity and inhibits apoptosis of activated neutrophils, and 2) dramatically inhibits chemokine-induced neutrophil chemotaxis in vitro; 3) both oral EGCG and green tea extract block neutrophil-mediated angiogenesis in vivo in an inflammatory angiogenesis model, and 4) oral administration of green tea extract enhances resolution in a pulmonary inflammation model, significantly reducing consequent fibrosis. These results provide molecular and cellular insights into the claimed beneficial properties of green tea and indicate that EGCG is a potent anti-inflammatory compound with therapeutic potential.     

茶树表没食子儿茶素-3-O-(3-O-甲基)没食子酸酯研究进展

表没食子儿茶素-3-O-(3-O-甲基)没食子酸酯(EGCG3"Me)是茶叶中最常检测到的甲基化表没食子儿茶素没食子酸酯(EGCG"Me),具有较表没食子儿茶素没食子酸酯(EGCG)更好的保健功效。本文对EGCG3"Me的理化性质、制备方法、保健功效、茶树EGCG3"Me含量影响因素、EGCG3"Me体内合成路径等国内外研究现状进行了综述,展望EGCG3"Me的体内代谢途径及其深加工产品研发将成为研究热点。     

Induction of poly(ADP-ribosyl)ation and DNA damage in human peripheral lymphocytes after treatment with (-)-epigallocatechin-gallate

With regard to a future use of tea polyphenols in intervention trials with individuals at high cancer risk, the effects of the tea ingredient (-)-epigallocatechin gallate (EGCG) on poly(ADP-ribose) (PAR) levels and on DNA damage were investigated in human lymphocytes. A dose- and time-dependent elevation of both PAR formation as assessed by quantitative immunofluorescence analysis and DNA damage as assessed by the comet assay were observed after treatment with EGCG at 20, 40 and 80 microM for 10-240 min. Maximum levels of PAR formation and of DNA damage were observed after 10 min at all concentrations tested. Increased PAR levels were still detectable by 240 min in the 40 and 80 microM groups. At the lowest concentration, which is near the physiological peak values found after tea ingestion, PAR formation was not correlated with DNA damage. Here, EGCG led to pronounced PAR levels, whereas the comet assay was almost negative. In contrast, such marked differences in time course and extent of both genotoxicity and PAR formation following EGCG treatment were not detected after gamma-irradiation. Our results suggest that the known chemopreventive effects of EGCG, the main constituent of tea, may be partly attributed to an induction of PAR formation.