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本试验是探讨绿茶热水浸提物对离体血小板胶原诱导凝聚物的影响。以相关剂量方法实验证明不同浓度的热水浸提物能不同程度地降低血小板的凝聚及延长滞后时间。将浸提物分馏后试验,证明儿茶素(单宁)是抑制的主要活性成分,且酯型儿茶素比简单儿茶素更有效。在酯型儿茶素中,表没食子儿茶素没食子酸酯(EGCG)在0.2mg/ml(=0.45mM)浓度时,就能完全抑制胶原诱导血小板凝聚。比设EGCG和阿司匹林两者的IC_(50)值,我们发现EGCG的效能比得上阿司匹林。EGCG还能抑制凝血酶和血小板活性因子(PAF)诱导的凝聚作用。在用EGCG处理的血小板中没有发现环3’,5’——磷酸腺苷(CAMP)水平提高。茶叶被普遍地作为日常饮料而饮用,它有多种功效,如提神、利尿、退热和止血,这些主要是咖啡碱和儿茶素(单宁)的功用。最近有报道:茶叶能抑制血小板凝聚。血小板在外伤止血和血栓形成中起主要作用,它们也引起动脉粥样硬化。因此能影响血小板功能的化合物将会用于临床治疗。在本试验中,我们试图查明绿茶浸提物对血小板凝聚抑制作用的主要活性成分,结果发现儿茶素,尤其酯型儿茶素是主要的抗凝聚物。 相似文献
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儿茶素的富集及单体分离研究进展 总被引:3,自引:0,他引:3
茶叶儿茶素是茶叶中重要的一类天然活性物质 ,具有较强的抗氧化作用和广泛的药理功效。其中表没食子儿茶素没食子酸酯 ( epigallocatechi gal-late,EGCG)以其独特的分子结构而在预防突变、抗肿瘤、防止癌细胞增殖及其转移等方面占有重要地位。然而 ,目前在 EGCG生产方面 ,难以实现高纯度产品的工厂化生产 ,且技术很不稳定 ,以致 EGCG单体售价十分昂贵。本文就儿茶素的富集与 EGCG单体分离的一些新技术进行综述 ,为儿茶素以及EGCG的生产与研究提供技术指导。1 盐析汪健等[1] 报道将粗制的茶多酚溶于未饱和的食盐水中 ,除去沉渣 ,然… 相似文献
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中国食品土畜进出口商会茶叶分会 《广东茶业》2004,(4):21-21
日本九州大学研究生院立花宏文副教授于3月中旬发现了绿茶的主要活性成分——EGCG发挥抗癌作用的中介蛋白质,对于开发治疗癌症新药具有一定帮助。 EGCG是茶中多酚类化合物的主要活性成分,其中文名称是“表没食子儿茶素没食子酸酯”;这种蛋白质名为“67LR”,一般癌细胞表面存在这种蛋白质的可能性很大。实验过程中,研究人员在人的肺癌细胞中单独 相似文献
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茶叶抗氧化剂是从茶叶中提取制备的新型天然抗氧化剂,广泛应用于油脂及含油食品的抗氧化保鲜。其主要成分是儿茶素类物质,其中又以酯型儿茶素EGCG为主。但是起主要抗氧化作用的EGCG其氧化电位较低,本身易被氧化失去抗氧化作用。因此,有必要进行茶抗氧化剂中EGCG的稳定性和耐热性研究。本文用薄层色谱分离茶抗氧化剂中的EGCG,排除儿茶素氧化物干扰,用双波长扫描法研究EGCG随温度和时间的含量变化。测得EGCG在不同温度下氧化反应的速度常数和稳定期以及反应活化能E,该方 相似文献
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EGCG纳米载体制备技术及其对EGCG活性影响的研究进展 总被引:1,自引:0,他引:1
表没食子儿茶素没食子酸酯(EGCG)是绿茶中最重要的生物活性成分,在肿瘤形成的各个阶段都有抑癌活性。纳米化途径是提高EGCG稳定性和生物利用度的有效技术之一。已有较多的研究表明,多类材料可用于制备纳米粒子作为EGCG载体,并在改善EGCG生物活性方面效果显著。本文按制备纳米粒子主要材料的不同,对各类纳米粒子的制备方法、特性及其在改善EGCG的生物活性方面的研究进行了分述,并对各种纳米粒的增效作用进行了归纳总结。 相似文献
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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
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高EGCG的茶树种质资源筛选简报 总被引:2,自引:0,他引:2
EGCG(epigallocatechln—3—gallate,表没食子儿茶素没食子酸酯)是茶叶品质最关键的核心成分之一;是茶多酚具有生理活性和广阔用途的最关键的成分。迄今为止,高EGCG的茶树特异资源的筛选在国内外尚未见研究报道。我国茶树种质资源极为丰富,居世界之首,若能从中筛选出高EGCG(>13%)的品种或株系,对于EGCG的工厂化生产、茶树新品种选育、提高茶树鲜叶或干茶的品质、组织培养材料选择等方面都具有重要意义。 相似文献
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Composite films based on EVA with CMF were prepared and characterized for their solvent transport nature. CMF were derived from Hibiscus sabdariffa by steam explosion technique and incorporated in the EVA matrix by extrusion. Solvent transport by the composites was analyzed using hexane, heptane and octane as penetrant molecules. The solvent uptake behavior of EVA/CMF composites is explained on the basis of the penetrant size, temperature and the filler loading. The composite had improved barrier property compared with unfilled EVA. This in turn is an indication of good fiber-matrix interaction in the composite system. Diffusion parameters such as diffusion coefficient, permeation coefficient and Arrhenius activation parameters and thermodynamic parameters such as enthalpy and entropy were evaluated in detail. The mode of transport was found to be Fickian. 相似文献
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Xiansheng Zhang Xiaoning Tang Ran Wang Rui Wang Xiong Yan Meiwu Shi 《Fibers and Polymers》2017,18(8):1421-1430
Thermal degradation behaviors and fire retardant properties of poly(1,3,4-oxadiazole)s (POD) and poly(m-phenylene isophthalamide) (PMIA) fibers were investigated. The thermal gravimetric analysis (TGA) demonstrated that POD exhibited higher onset thermal degradation temperature (Tonset) than PMIA, exceeding nearly 80 °C. The thermal degradation kinetics, evaluated by the modified Coats-Redfern method, displayed that the apparent activation energy (Ea) of POD and PMIA fibers was similar when the conversion rate (α) ranges from 0.2 to 0.5, while with the α from 0.6 to 0.8, the Ea of POD was significantly lower than that of PMIA. The fire retardant performance of POD and PMIA fibers were evaluated by cone calorimeter under heat fluxes of 35, 50 and 75 kW/m2, during which the temperature of the fibers were monitored by a thermocouple. Surprisingly, POD fibers showed inferior fire retardant performance in comparison with PMIA, with lower time to ignition (TTI) and higher peak heat release rate (PHRR). The origin of the different fire retardant properties of both fibers was revealed by analyzing the residual chars and gaseous products during thermal pyrolysis. The morphology confirmed that stable and compact chars can be formed in PMIA. In addition, the Fourier Transform Infrared Spectroscopy (FTIR) characterization of the residual char revealed that POD can form carbonaceous chars at the heat flux of 50 kW/m2, while the heat flux of PMIA was 75 kW/m2. The pyrolysis products characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that POD can be pyrolyzed completely at 600 °C, while the temperature of PMIA was 700 °C. 相似文献
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《Journal of Crop Improvement》2013,27(2):287-298
Summary It is well known that C4 crops have a lower water requirement than C3 crops. Reasons for the difference are not well understood. Therefore, hydraulic resistance of sorghum [Sorghum bicolor (L.) Moench] (C4) and sunflower (Helianthus annuus L.) (C3) was determined to see if it might be one explanation for the lower water use of crops with the C4 photosynthetic pathway. Plants were grown under greenhouse conditions in pots with soil, which was well watered (soil matric potential of ~0 MPa) or allowed to dry (soil matric potential of ?0.038 MPa and ?0.065 MPa for sorghum and sunflower, respectively). Hydraulic resistance was calculated in two ways: (1) using the classic Ohm's law analogue, which assumes that the relation between flux (transpiration) and difference in water potentials of the soil and plant is linear and (2) using an equation that considers diurnal changes in leaf water content along with transpiration and difference in water potentials. Because change in leaf-water content during a day was small, hydraulic resistances calculated by the two methods resulted in similar values. Sorghum had a linear relationship between flux and difference in potentials (constant hydraulic resistance), but sunflower had a nonlinear one (variable hydraulic resistance). The hydraulic resistance of watered sunflower increased only slightly during a day and averaged about 40 MPa m2 s mol?1, which was 3.5 times less than that of watered or water-stressed sorghum (-140 MPa m2 s mol?1). The hydraulic resistance of water-stressed sunflower increased steeply during a day and by the end of the day it had a hydraulic resistance that approached that of sorghum. 相似文献
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The population density of Closterotomus trivialis (Costa) and its damage potential were studied in citrus and olive orchards of Crete. C. trivialis was found to be most abundant in wild radish Raphanus raphanistrum L., annual mercury Mercurialis annua L., Urtica sp. and upright pellitory Parietaria officinalis L. compared to mallow Malva sylvestris L., prickly goldenfleece Uropermum picroides (L.), sowthistle Sonchus oleraceus L., citrus or olive trees. Its damage potential on the setting of olive fruit was investigated at the early inflorescence stage. When 1, 5 or 10 adults of C. trivialis were enclosed with stems at the 55th and 57th phenological growth stages, the number of fruits was significantly reduced compared to controls.The developmental biology of individuals of C. trivialis was studied on R. raphanistrum at seven constant temperatures 15, 20, 25, 30, 32.5, 35 and 37 °C, under laboratory conditions. No nymphs survived above 35 °C. The highest nymph to adult survival (89.6%) was found at 20 °C and the lowest (40.6%) at 32.5 °C. Mean developmental time as well as adult longevity decreased with increasing temperature. The developmental time from 1st nymphal instar to adult ranged from at least 9.0 at 32.5 °C to 27.8 days at 15 °C. The adults lived from 2.9 days at 32.5 °C to 45.3 days at 15 °C. It required 212.7 degree-days to complete development above a minimum threshold of 7.72 °C as estimated by linear regression and 8 °C as estimated by nonlinear model. The importance of these findings in the management of this species through the prediction of its seasonal appearance is discussed. 相似文献
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野生大豆(G.Soja)、半野生大豆(G.Gracilis)和栽培大豆(G.max)的核型分析 总被引:2,自引:0,他引:2
本文应用数量统计的方法,分析野生大豆16份,半野生大豆5份和栽培大豆2份的核型。结果表明、野生大豆、半野生大豆和栽培大豆染色体数目为2n=40,核型为2n=24m+14sm+2st(SAT)。虽然三者的核型相似,但单倍染色体组长是有差别的,经X~2测定表明,这种差异是由于种间差异引起。因此,大豆核型的研究,对探讨大豆的进化具有重要意义。 在野生大豆中观察到一具有四随体类型,从进化观点看,具四随体类型较具二随体类型物种原始,同时为确定大豆是二倍体还是多倍体植物、提供有价值的材料。 野生大豆、半野生大豆和栽培大豆的Giemsa—C带分析表明,三种大豆的带型极其相似,基本带型为:第一组12条染色体有一条着丝点带;第二组12条染色体有一条中间带;第三组12条染色体有一条端带;第四组4条染色体有二条带。 相似文献
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本文记述桔狭胸天牛Philus antennatus(Gyllenhal)幼虫形态特征及发生、为害情况。 相似文献