茶儿茶素体外氧化产物分析

采用体外模拟发酵, 对从绿茶中提取的茶多酚( 其中儿茶素含量为78-09 % ) 进行酶促氧化、化学氧化和自动氧化, 制取茶色素, 经HPLC分析, 结果表明, 酶促氧化和化学氧化的产物吸收峰均能得到明确分辨, 其保留时间与红茶汤中茶色素成分相吻合, 而自动氧化的产物中则缺少TFs。优化的化学氧化法制得的茶色素中, TFs 和TRs1 含量高于酶促氧化制品。     

儿茶素氧化产物的分离鉴定及其抗氧化活性研究

采用H2O2模拟氧化体系制备儿茶素氧化产物，经多级柱色谱分离得到一相对纯组分（t_R为9．825min），HPLC-MS分析结果表明，所得级分主要含m／z 471及m／z 939两种产物，     

茶儿茶素类物质对大豆脂肪氧化酶活性的影响

油脂和含油脂的食品在贮存和加工期间会发生酸败而产生醇、醛、酮、酸类物质,使食品的色、香、味发生劣变。酸败主要是因有脂肪的存在而发生自动氧化、酶促氧化和脂肪分解。自动氧化反应的最初引发,如形成氢过氧化物,涉及光、γ射线和χ射线,光敏染料,过渡金属离子和游离基等,因此冷藏、避光、添加抗氧化剂有利于食品保存。由于抗氧化剂可以抑制油脂的自动氧化,延缓氧化物的生成而被广泛应用于食品行业。然而,自动氧化并不是油脂和含油脂食物变质的唯一原因,解脂变质也     

普洱茶加工过程中儿茶素变化规律的研究

本文对普洱茶加工阶段样中五种儿茶素组分ECG、EGCG、EGC、EC、( )-C的含量进行分析,探讨普洱茶加工过程中儿茶素的变化规律,为普洱茶的质量评判提供参考。     

茶儿茶素的功效特性与开发利用探讨

茶儿茶素是茶叶中的主要功效成分。茶儿茶素在生物体内的吸收和分布情况,以及它们在体内进行的多种生物代谢过程,对茶儿茶素的功效有着重要影响。结合茶儿茶素在生物体内的作用机制和功效机理,开发利用茶儿茶素,将可能挖掘出茶儿茶素防御疾病的巨大潜力。     

茶儿茶素制剂祛黄褐斑人体试食研究

对100例黄褐斑受试者,按黄褐斑颜色、面积情况随机分为受试组和对照组(各50例),分别食用茶儿茶素制剂和安慰剂,每日2次,每次3粒。结果:受试组连续食用茶儿茶素制剂30天,黄褐斑颜色积分下降及黄褐斑面积减少均有显著性差异,与对照组比较也有显著性差异,总有效率56%,与对照组(12%)比较有显著性差异,并且未观察到新的黄褐斑产生。表明:茶儿茶素制剂具有祛黄褐斑作用,并对试食者身体健康无明显影响。     

茶儿茶素影响细胞外多糖合成和变形链球菌附着的研究

通过菌斑量的测定、胞外多糖的提取和测定,对受儿茶素作用后降低酶活性的变形链球菌附着能力进行了体外观察。结果显示,儿茶素浓度在０．１２５％—１．０００％时,细菌附着能力下降,菌斑形成量减少,细菌总蛋白也下降,菌斑中胞外葡聚糖含量降低。由此可见,儿茶素的抗菌斑作用主要表现在抑制胞外葡聚糖产生。     

四种茶儿茶素在蒸馏酒和水中的变化研究

儿茶素作为茶叶中尤为重要的功能成分备受关注,探讨其在食品体系中的变化对于儿茶素的应用和含儿茶素类食品品质尤为重要和必要.针对食品硬饮料中茶儿茶素变化相关研究缺乏,选用茶叶中四种主要儿茶素(EGCG、EGC、ECG、EC)单体和茶多酚,采用统一浓度添加法,分别探讨在蒸馏酒(酒精度45.5％)和水两种体系中于25℃避光、密封条件下的稳定性.结果表明,四种儿茶素无论是在蒸馏酒还是水体系中均有所下降;在蒸馏酒中四种单体含量呈线性下降趋势且推测降低原因而非单体间转化导致,按初始浓度降低50％的时间排序为EGCG相似文献   

红碎茶发酵过程中儿茶素及其氧化产物含量变化的研究

研究表明,红碎茶发酵过程儿茶素总量逐步减少,前期减少速率较快,发酵80分钟以后,减少速率变缓慢,在儿茶素组成中,发酵过程含量减少最多的是L—EGCG,其次为L—EGC和L—ECG,其它儿茶素含量减少相对较少。发酵叶添加乙酸钠、氯化纳、柠檬酸钠和硫酸铵四种盐类成分处理,均提高了儿茶素保留量,其中乙酸钠处理,即提高TF、TR保留量,又降低了TB含量,其它处理虽降低TB含量,但对提高TF和TR含量效果不明显或没效果。     

茶多糖提纯、精制及其生理活性研究进展

综述了茶多糖的提纯精制方法、多糖组成及药理作用。目前多用水提法制茶多糖粗品;经除蛋白、脱色初步纯化;用沉淀法、超滤法或柱层析法等进一步纯化;多糖组成因原料及分离纯化方法不同有较大差别。茶多糖具有降血糖、降血脂、抗血栓、降血压及增强机体免疫力等功能,可用于糖尿病、心脑血管病的辅助治疗。     

Applicability of lignins from different sources as antioxidants based on the protective effects on lipid peroxidation induced by oxygen radicals

Increasing evidence suggest that excessive concentrations of reactive oxygen species in the human body are involved in a number of pathological events and that oxidative damage to cell components may play an important pathophysiological role in many types of human diseases. Several studies have shown the possible benefits of antioxidants from plant sources in altering, reversing or forestalling the negative effects of oxidative stress.The study was designed to evaluate whether lignins prevent H₂O₂-induced lipid peroxidation. The protective effect of industrial lignins obtained from different sources against hydrogen peroxide induced oxidation was investigated in normal human red blood cells (RBCs). RBCs, preincubated with different amounts of lignins and challenged with hydrogen peroxide were analyzed for lipid peroxidation. The high molecular weight can be considered as one of the main factors decreasing the radical scavenging activity. When comparing different lignins the inhibitory effects against lipid peroxidation were notably related to their molecular weights. In this sense bagasse with the lowest Mn was the greatest antioxidant and lignosulfonate with the highest Mn was the lowest antioxidant lignin.These results open the possibility of new applications of lignins. The potential health benefits and industrial applications of lignins make them a promising research resource.     

Cytochrome-P450 enzymes and autoimmunity: expansion of the relationship and introduction of free radicals as the link

The Cytochrome-P-450 enzymes (CYP) are among the most important xenobiotic-metabolizing enzymes, which produce reactive oxygen species (ROS) as the result of metabolizing xenobiotics.ROS are believed to play important roles in the pathophysiology of autoimmune diseases. ROS can alter the structure of cellular antigens to produce a "neo-antigen" which could mount an autoimmune response against the original antigen through molecular mimicry. ROS are involved in apoptosis, activation of antigen presenting cells and initiation or amplification of diverse immunologic reactions.Taking all these facts together, it could be speculated that CYP may be involved in the initiation and/or amplification of autoimmune phenomena.     

Antioxidant activity of oak (Quercus) leaves infusions against free radicals and their cardioprotective potential

The aim of present study was to evaluate antioxidant capacity and cardioprotective potential of leaves infusions and partially purified fractions of Quercus sideroxyla and Q. eduardii (red oaks) and Q. resinosa (white oak). Consumption of polyphenol-rich beverages derived from plants, such as oak may represent a beneficial diet in terms of cardiovascular protection. Infusions from Oak leaves were obtained and probed for total phenolics by Folin-Ciocalteu, DPPH and hydroxyl radicals scavenging by DPPH test and Deoxy-D-ribose method, the antioxidant capacity was evaluated by FRAP and ORAC tests, inhibitions of Low Density Lipoproteins (LDL) oxidation and Angiotensin Converting Enzyme (ACE) activity were measured. A HPLC analysis was performed by HPLC-MS. Bioactive polyphenols such as gallic and ellagic acids, catechin, quercetin and derivatives: naringenin and naringin were detected in Quercus infusions. A distinctive HPLC profile was observed among the red and white oak samples. Q. resinosa infusions have exhibited the highest antioxidant activity in comparison with the other species, although in the inhibition of LDL oxidation no differences were observed. In the inhibition of the ACE, Q. resinosa was more effective (IC50, 18 ppm) than Q. sideroxyla, showing same effect as the control Captopril. From the results it is possible to postulate that not only chelating activity is important in these infusions, especially in Q. resinosa.     

低温胁迫下茉莉两栽培品种叶细胞自由基的产生及保护酶的变化

在不同低温胁迫下,对茉莉两栽培品种叶中活性氧(O2·)、H2O2、膜脂过氧化产物丙二醛(MDA)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)等保护酶活性的动态变化过程进行了测定。结果表明,随着温度的降低,SOD、CAT和POD的活性逐渐降低,自由基含量(O2·和H2O2)和MDA含量逐渐升高,从其趋势可以推测,单瓣茉莉和双瓣茉莉抗零下低温的能力都比较弱,但双瓣茉莉抗零上低温的能力比单瓣茉莉强。     

茶尺蠖防治技术研究进展及展望

茶树虫害是茶叶高产、优质、高效的重要制约因素之一。茶树害虫种类繁多,全世界已记载有1000多种,我国常见害虫有400多种,其中重要的50～60种,常年造成茶叶产量损失约15%。茶尺蠖(EctropisobliquaProut),又称拱拱虫、量寸虫、吊丝虫。张汉鹄(2001年)认为该虫属鳞翅目(Lepidoptera)尺蛾科(Geometriidae)霜尺蛾亚科(Ennominae)。幼虫食叶,暴发时可将成片茶园食成光杆,致茶叶减产60%以上,还严重影响成茶品质。朱俊庆等(1999年)认为该虫在国内主要分布于浙江、江苏、安徽、江西、湖南、湖北和福建等省。但夏英三(1999年)于1988年发现山东日照…     

Temperature,cyanide, and oxygen effects on the respiration,chip color,sugars, and organic acids of stored tubers

The possibility that sugar accumulation of potatoes stored at low temperatures may be linked to activation of cyanide-resistant respiration (CRR) was investigated. After a lag period of several days, continuous HCN treatment stimulated CO₂ production of tubers stored in 20% O₂. At 1°C in 20% O₂, HCN treatment increased respiration over that effected by low temperature treatment. After several weeks of treatment, cyanide-stimulated CO₂ production was greater at 1°C than at 10°C. Sucrose and malate levels of HCN treated tubers were sometimes higher than those of the 10°C control tubers, but they were always lower than those of the 1°C control tubers. This indicated that CRR alone could not account for the sugar increases at 1°C. Storage in 2% O₂ blocked the increase in CO₂ production and changes in constituents associated with HCN treatments in 20% O₂. HCN treatment had no significant effect on chip color. The level of CRR was measured in freshly cut slices from Monona, Norchip, and Kennebec tubers previously stored at 10°, 5°, or 1°C for several months. Slices from tubers previously stored at 1°C had increased CRR, but there was no difference in CRR between the 5°C and 10°C treatments. Sugars accumulated at 5°C, again indicating that sugar accumulation in potatoes stored at low temperatures was at least partially independent of the activation of CRR.     

Effect of dispersing agents on synthesis of nano titanium oxide and its application for antimicrobial property

With the growing demand for comfortable, clean and hygienic textile goods, an urgent need for production of antimicrobial textiles has arisen. In this work, synthesis of nano titanium oxide has been done by sol gel method and the effect of dispersing agents with varying ionic character during synthesis on the particle size of the synthesised nano particles in terms of crystallinity and particle size was studied. It was observed that cationic as well as non-ionic dispersing agents led to reduction in size of the titania particles produced whereas anionic dispersing agent led to increase in the particle size. This method provides a simple method for reduction in size of titanium dioxide particles with a minor modification of a standard process. The synthesized nano titanium dioxide particles were successfully applied onto cotton to obtain Antimicrobial activity. The Durability of the antimicrobial activity was upto 10 washes with the help of Binder. The effect of the application of nano titanium oxide on the physical properties of the substrate, such as tensile strength, bending length, and crease recovery angle has been analysed.     

Potato composition: III. Tissue selection and its effects on total nitrogen,free amino acid nitrogen and enzyme activity (polyphenolase,monophenolase, peroxidase and catalase)

Russet Burbank, Norchip, Kennebec, White Rose, Red La Soda and Lenape tubers were sampled at harvest, after storage for 2 and 4 mo at 7 C, and after 3 wk at 20 C following each storage treatment. Freeze-dried tissue from the bud-end, stem-end and core was analyzed for total, and free amino acid nitrogen, and for monophenolase, polyphenolase, peroxidase, and catalase activities. Significant differences among cultivars and among different parts of the tuber were found for all nitrogen fractions and all enzyme activities. Storage treatments significantly changed the total and free amino acid nitrogen contents and polyphenolase, peroxidase, and catalase activities. When compared for total nitrogen content and catalase activity, differences among different parts of the tuber which were statistically significant were similar in all cultivars. However, when compared for free amino acid content, and monophenolase, polyphenolase and peroxidase activities, differences among different parts of the tuber which were statistically significant were dependent upon which cultivar was examined. The differences among cultivars which were statistically significant for all nitrogen fractions and all enzyme activities, except peroxidase, were not significantly changed by storage treatment. The differences among different parts of the tuber which were statistically significant for quantity of both nitrogen fractions and for all enzyme activities were not significantly changed by storage.