Effects of supplementation of green tea extract on the milk performance of peripartal dairy cows and the expression of stress response genes in the liver

Background: We hypothesised that supplementation of green tea extract(GTE) in dairy cows during the transition period can attenuate proinflammatory conditions and prevent endoplasmic reticulum(ER) stress in the liver of these cows. Thirty Holstein cows with an average parity of 3.06(± 1.31, SD) were divided into a control group and a group that received a daily amount of 10 g of GTE from d 7 before the calving day and a daily amount of 20 g of GTE from the day of calving until d 7 of lactation.Results: Cows supplemented with GTE did not show differences in energy intake or milk yield in weeks 2–7 of lactation. However, these cows had a lower milk fat concentration and a lower energy corrected milk yield than the control cows and showed a trend of improved energy balance. The relative m RNA concentrations of proinflammatory genes, genes involved in the acute phase reaction and antioxidant genes in the liver in weeks 1, 4 and 7 of lactation were not different between the two groups of cows. The concentrations of α-tocopherol and the Trolox equivalent antioxidant capacity in plasma were not different between the two groups. However, the group supplemented with GTE showed significant reductions of some genes of the unfolded protein response(UPR) in week 1 and a trend of lower liver triacylglycerol(TAG) concentrations in the liver compared to the control group.Conclusions: This study shows that supplementation of GTE in dairy cows lowers the fat concentration in the milk but overall has no effect on the expression of inflammatory genes and the antioxidative status in dairy cows during early lactation. The finding of reduced m RNA levels of genes involved in the UPR at week 1, however, supports other results showing that supplementation of polyphenols could prevent the development of ER stress in the liver of cows during early lactation. The finding of a tendency towards a reduced TAG concentration in the liver of cows supplemented with GTE might be due to an improved energy balance in these cows.

Inhibitory Effect of Green Tea Extract on the Carcinogenesis Induced by Asbestos Plus Benzo(a)pyrene in Rat

In this experiment lung carcinoma was induced by crocidolite plus benzo(a)pyrene in rat. From the cancer models, we observcd that the incidcnce (16.0%) of lung carcinomas was lowel, and the survival time (376 days) of the first case of carcinoma and the mean survival time (758 days) of the rats with carcinoma were higher in the group of rats drinking 2% green tea extract for life than in the positive group (without drinking green tea extract). The mortality ratio (0.5047) was smaller in the cxperimental group than in the positive control group, and the survival curve of the experimental group significantly raised up, in comparison with the positive group.

Green tea extract:A potential cause of acute liver failure

The use of herbal products has increased significantly in recent years.Because these products are not subject to regulation by the Food and Drug Administration and are often used without supervision by a healthcare provider,the indication for and consumption of these supplements is quite variable.Moreover,their use is generally regarded as safe and natural by the lay-public.Unfortunately,there has been an increase in the number of reported adverse events occurring with the use of herbal products.We present a case of acute impending liver failure in an adolescent male using a weightloss product containing green tea extract.Our case adds to the growing concern surrounding the ingestion of green tea extract and serves to heighten healthcare provider awareness of a potential green tea extract hepatotoxicity.Despite the generally touted benefits of green tea as a whole,clinical concern regarding its use is emerging and has been linked to its concentration in multiple herbal supplements.Interestingly,the suspected harmful compounds are those previously proposed to be advantageous for weight-loss,cancer remedy,and anti-inflammatory purposes.Yet,we emphasize the need to be aware of not just green tea extract,but the importance of monitoring patient use of all dietary supplements and herbal products.

Applications of Green Tea Extract in Bakery Products

Green tea extract(GTE) is a rich source of tea catechins with antioxidative,anticarcinogenic and antiarteriosclerotic activities and it has been applied in food such as bakery products to provide health benefits and extend the shelf life.This review outlines the stability of green tea catechins during baking process of bakery products supplemented with GTE and the effects of GTE on the functional properties,sensory properties,physical characteristics and Maillard reaction of bakery products.

Oxidative Stability of Green Tea Extract-Enriched Rice Bran Oil During Storage

Adding green tea extract to rice bran oil was expected to improve its oxidative stability,so this study was conducted to investigate oxidative stability of green tea extract-enriched rice bran oil(RBOG) during storage at 60℃ for 15 days compared to rice bran oil(RBO),olive(OL),canola(CN),and grape-seed oil(GS).Acid values did not increase during storage,and the highest value was found for OL.The peroxide values of RBOG,RBO,CN,OL,and GS increased for up to 15 days.The highest average rate constant for the change in peroxide value was found for RBO(0.282).TBARS increased continually during storage of RBOG,RBO,CN,and OL;however,the value increased for up to 9 days and then decreased for GS.The highest average rate constant of change in TBARS was found for CN.Overall,the results suggest that green tea extract improves oxidative stability of rice bran oil.

Efficacy of green tea extract on PC3 prostate cancer cells through upregulation of miR-195 expression and suppression of epithelial to mesenchymal transition

OBJECTIVE: To evaluate anticancer efficacy of green tea extract(GTE) on PC3 prostate cancer cells. METHODS: By using quantitative real-time polymerase chain reaction(qRT-PCR) and Western blot methods, the expression of miR-195 and the epithelial to mesenchymal transition(EMT) markers such as E-cadherin and vimentin was analyzed. RESULTS: Based on the results of 2D and 3D cell culture models, the inhibition of EMT and up regulation of miR-195 expression were detected. CONCLUSIONS: Our findings will be helpful to design anti-tumor regimens with natural product original, and more studies will be required to identify the related mechanisms involving anticancer activities of green tea via miRNAs.

Antifi brotic effects of green tea on in vitro and in vivo models of liver fibrosis

AIM: To examine the protective effect of green tea extract (GT) on hepatic fi brosis in vitro and in vivo in dimethylnitrosamine (DMN)-induced rats.METHODS: HSC-T6, a rat hepatic stellate cell line, was used as an in vitro assay system. Cell proliferation, collagen content, and type 1 collagen expression were examined in activated HSC-T6 cells. Collagen was determined by estimating the hydroxyproline content. In rats with DMN-induced hepatic fi brosis, serum aspartate aminotransferase and alanine aminotransferase concentrations, liver hydroxyproline and lipid peroxides were determined. Pathologic changes were examined by hematoxylin & eosin staining.RESULTS: GT administration prevented the development of hepatic fibrosis in the rat model of DMN-induced liver fi brosis. These results were confi rmed both by liver histology and by quantitative measurement of hepatic hydroxyproline content, a marker of liver collagen deposition. Accordingly, inhibition of proliferation, reduced collagen deposition, and type 1 collagen expression were observed in activated HSC-T6 cells following GT treatment. These results imply that GT reduced the proliferation of activated HSC and down regulated the collagen content and expression of collagen type 1, thereby ameliorating hepatic fibrosis.CONCLUSION: This study demonstrates that greentea administration can effectively improve liver fibrosis caused by DMN, and may be used as a therapeutic option and preventive measure against hepatic f ibrosis.

干燥方式对绿碎茶多酚提取物体外抗氧化和抗糖尿病及乙酰胆碱酯酶抑制活性的影响

研究不同干燥方式处理的绿碎茶多酚提取物体外抗氧化和抗糖尿病活性及对乙酰胆碱酯酶抑制作用。以绿碎茶为试验材料,采用蒸干结合真空干燥与真空冷冻干燥2种干燥工艺对绿碎茶乙酸乙酯萃取相进行干燥处理,比较研究了2种提取物的色泽,DPPH自由基、ABTS阳离子自由基、羟自由基(·OH)清除能力和铁离子还原能力以及α-淀粉酶、α-葡萄糖苷酶、乙酰胆碱酯酶的抑制能力和抗糖基化能力。结果表明,真空冷冻干燥绿碎茶多酚提取物(BGTE-FD)较蒸干结合真空干燥绿碎茶多酚提取物(BGTE-SVD)颜色相对偏黄,具有较强的DPPH自由基、ABTS阳离子自由基、·OH清除能力和铁离子还原能力,其IC_(50)值分别为2.64、5.17、247.01、27.73 mg/L。同时,BGTE-FD具有较高的α-淀粉酶、乙酰胆碱酯酶和α-葡萄糖苷酶抑制作用,IC_(50)值分别为85.84、416.45、4.38 mg/L,且其对α-葡萄糖苷酶的抑制能力显著强于阿卡波糖(IC_(50)值为929.59 mg/L)。此外,BGTE-FD和BGTE-SVD对晚期糖基化终产物抑制率分别高达65.28%和63.66%,略低于氨基胍(71.81%)。因此,真空冷冻干燥绿碎茶多酚提取物具有较强的体外抗氧化和抗糖尿病活性及一定的乙酰胆碱酯酶抑制能力,绿碎茶可作为降血糖和抗痴呆产品的潜在资源。

磁固相萃取结合超高效液相色谱串联质谱法检测绿茶中19种有机磷农药残留

本文采用化学共沉淀法合成磁性石墨烯(Fe_(3)O_(4)@G),并将其作为一种磁固相萃取剂用于绿茶中有机磷农药的萃取富集,结合超高效液相色谱串联质谱技术,建立同时检测绿茶中19种有机磷农药残留的分析方法。本实验选择吸附剂用量为40 mg,萃取时间20 min,样品溶液pH为7,3.0 mL丙酮解吸,氯化钠用量为4 g。结果表明,在5~500μg/L范围内,线性相关系数大于0.999,制备的Fe_(3)O_(4)@G材料具有良好的稳定性和可重复利用性。检出限(LOD)在5.0~6.0μg/kg,定量限(LOQ)在15.0~20.0μg/kg。当样品加标水平为20.0、40.0、200.0μg/kg时,回收率在61.2%~94.9%之间,相对标准偏差(RSD,n=6)在2.6%~10.2%之间。本方法适用范围广,前处理易操控,有机溶剂用量少,经济,安全,材料可重复使用,该磁分散固相萃取技术在茶叶中农药的富集分离有很好的应用前景。

碎茶末制备速溶绿茶提取工艺研究

为提高碎茶末利用价值,优化速溶绿茶提取工艺,以安康绿茶加工过程中产生的碎茶末为原料,采用超声波提取技术制备速溶绿茶,考察浸提时间、浸提温度、茶水比对速溶绿茶品质及提取率的影响,通过单因素及正交试验确定速溶绿茶的最优提取工艺。结果表明,超声波提取时间20 min,提取温度30℃,茶水比1︰25为最佳提取条件。在此条件下,速溶绿茶得率为24.67%,茶多酚含量为13.78%、游离氨基酸含量为2.30%、咖啡碱含量为3.32%、可溶性糖总量为9.04%。所制得的速溶绿茶干茶色泽嫩绿,汤色黄绿尚亮,滋味醇厚鲜爽,溶解性良好。经优化后的速溶绿茶超声波提取工艺设计合理、稳定可行且重复性高,所制速溶绿茶品质较优。

三种广西不同地区绿茶中总黄酮的提取及其抗氧化活性研究

为研究广西不同地区绿茶的总黄酮提取工艺及其抗氧化活性,该试验以三种广西不同地区(桂北、桂中、桂南)绿茶为原料,采用微波辅助提取法提取总黄酮,在单因素试验的基础上,通过正交试验对三种绿茶总黄酮的微波辅助提取条件进行优化,并根据1,1-二苯基-2-三硝基苯肼(DPPH)、羟基自由基清除能力评价其抗氧化活性。结果表明,桂北地区绿茶最佳提取条件为乙醇体积分数为60%、料液比为1∶60(g∶mL)、微波功率为600 W;桂中地区绿茶最佳提取条件为乙醇体积分数为50%、料液比为1∶50(g∶mL)、微波功率为500 W;桂南地区绿茶最佳提取条件为乙醇体积分数为50%、料液比为1∶50(g∶mL)、微波功率为600 W。在此优化条件下,三种绿茶的总黄酮得率分别为(12.29±0.56)%、(12.51±0.39)%、(14.32±0.42)%。体外抗氧化试验结果表明,三种绿茶总黄酮清除DPPH自由基能力较强,对羟基自由基有一定的清除能力。

藜芦根茎提取物可溶液剂防治茶绿盲蝽田间药效试验

为确定藜芦根茎提取物可溶液剂(藜芦胺)对防治茶绿盲蝽的效果,进行了不同浓度田间药效试验。结果表明,药后3 d,各处理防效和对照药剂防效均达最高值,0.5%藜芦根茎提取物可溶液剂600倍液处理的防效最高,为80.43%,各处理与0.3%苦参碱水剂无显著差异。本试验结果总体来看,0.5%藜芦根茎提取物可溶液剂防治茶绿盲蝽速效性、持效性相对较好,对茶园主要害虫茶小绿叶蝉也有较好的兼治作用;同时,对茶园主要益虫无明显不良影响。

基于HS-SPME-GC-MS对不同等级双井绿茶香气物质的研究

为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一级和双井绿茶二级四个不同等级的双井绿茶的香气物质进行了检测分析。结果表明,从四个不同等级的双井绿茶中共鉴定出70种香气物质,主要包括醇类、烯烃类、烷烃类、酯类等化合物。不同等级的双井绿茶中香气物质组成及相对含量均有差异,通过主成分分析(Principal component analysis,PCA)和偏最小二乘法-判别分析(Partial least squares-discriminant analysis,PLS-DA),可以有效区分不同等级的双井绿茶。不同等级双井绿茶香气差异主要由反式-β-金合欢烯、香叶醇、水杨酸甲酯、茉莉酮、苯乙醇等14种关键化合物差异引起。在不同等级双井绿茶中关键香气物质表现出不同的分布规律,随着芽叶开展,α-椰油烯、石竹烯及己酸乙酯含量降低,而顺式-3-己烯醇、香叶醇及水杨酸甲酯含量呈增加趋势,芳樟醇、茉莉酮、反式-橙花叔醇含量从低到高,随后含量又迅速下降。本文研究了不同等级双井绿茶中香气物质的组成特征及关键香气物质的分布规律,为今后双井绿茶生产提供了理论依据。

市售冷泡绿茶主要品质成分冷泡浸出规律研究

“冷泡茶”(Cold-brewing tea)因其最大程度保留了茶叶的鲜爽味且兼具饮用便利性,已成为消费者追捧的新型茶饮。文章系统研究了7个市售冷泡绿茶以及1个自制冷泡龙井茶的主要品质成分及其冷水浸出规律。结果表明,冷泡茶的含水率在4.12%~12.95%之间,差异较大;水浸出物、茶多酚、游离氨基酸和咖啡碱含量范围分别在34.06%~45.32%、23.99%~32.04%、3.03%~4.22%和2.78%~3.21%。随着冷水浸泡时间延长,茶汤中主要品质成分含量均逐渐增加。冷水浸泡40 min,所有样品的茶汤中水浸出物溶出率为19.7%~51.4%、茶多酚溶出率5.3%~19.0%、氨基酸溶出率24.4%~93.1%、咖啡碱溶出率在18.4%~39.3%。冲泡方式显著影响茶叶中茶多酚、氨基酸和咖啡碱的溶出率,冲泡20 min后茶多酚冷/热水溶出比为0.30~0.60、咖啡碱冷/热水溶出比为0.18~0.34、游离氨基酸冷/热水溶出比超过0.70,冷水浸泡茶汤中游离氨基酸溶出率较茶多酚和咖啡碱高,是冷泡绿茶口感更加鲜爽的主要原因。本研究结果可为冷泡茶产品质量标准制定和新型冷泡茶产品开发提供理论依据。

绿茶籽水溶性提取物的物化性质研究

利用水提法提取绿茶籽水溶性物质(TSW),通过热凝胶法制备质量分数15%的TSW凝胶。使用DPPH法和试剂盒法,测定提取物自由基清除率和总抗氧化能力;利用乳析指数和显微观察判断其稳定乳液的能力,测定TSW凝胶的凝胶指数和凝胶保水性。结果表明:TSW质量分数为0.3%时,DPPH清除率最大,为17.53%,证实TSW质量分数越大,抗氧化能力越强;油相体积分数增加可提高TSW乳液的储存稳定性;质量分数15%的TSW溶液在90℃完全成胶,室温下凝胶保水性均大于98%。

红曲绿茶提取物硒复合制剂降血脂作用的研究

为了辅助降血脂将红曲、绿茶提取物以及硒制成复合制剂,选择符合受试要求的高血脂志愿受试者120人,按血脂水平随机分成对照组(服用安慰剂)、试食组(连续服用复合制剂30 d)对其总胆固醇、甘油三酯等指标进行检测。结果表明,30 d后试食组血清总胆固醇、甘油三酯分别平均下降11.08%和15.75%,显著低于对照组和试验前自身的水平;试食组总有效率为50.9%,且受试者的血液、大小便等其他临床检查指标均无异常。该红曲绿茶提取物硒复合制剂具有辅助降血脂的功能,对受试人群健康无损害作用。

绿茶在水醇复合体系中的浸提规律研究

为探究绿茶在水醇复合体系中的浸提规律,以绿碎片茶为原料,研究绿茶在酒精度45%vol的白酒和不同浓度乙醇溶液中浸提的总浸提率、浸提液中茶多酚和游离氨基酸含量,以及浸提液的色差值。结果表明,绿茶在酒精度45%vol的白酒中浸提50 min,料液比1∶20(g/mL)、1∶30(g/mL)和1∶40(g/mL)对应的总浸提率分别为29.29%、30.02%和32.19%;浸提液中茶多酚含量分别为9.72 mg/mL、6.43 mg/mL和5.07 mg/mL;浸提液中游离氨基酸含量分别为1.96 mg/mL、1.50 mg/mL和0.91 mg/mL;随着浸提时间延长,浸提液色差L^(*)值逐渐降低,a^(*)值和b^(*)值逐渐增大。绿茶在乙醇浓度为40%时总浸提率最大为29.93%;乙醇浓度为50%时浸提液中的茶多酚浓度最高为6.17 mg/mL;乙醇浓度为30%的浸提液中游离氨基酸浓度最大为1.53 mg/mL。结合产业分析,可以选择乙醇浓度50%左右的酒溶液浸提绿茶,料液比1∶30(g/mL),时间为50 min。

Effects of green tea-and amla extracts on quality and melanosis of Indian white prawn(Fenneropenaeus indicus,Milne Edwards,1837)during chilled storage

Effect of ethanol extracts of green tea(Camellia sinensis L.)and amla(Phyllanthus emblica Linn)were investigated on quality and melanosis of chilled stored Indian white prawn(Fenneropenaeus indicus)during 28 days.Extracts were subjected to antioxidant assays viz.1,1-diphenyl-2-picryl hydrazyl radical reducing power methods(DPPH),total antioxidant capacity(TAC),total phenolic content(TPC)and ferric reducing antioxidant power(FRAP)to evaluate antioxidant potentiality and fourier-transform infrared spectroscopy(FT-IR)to identify organic constituents.Polyphenol oxidase(PPO)inhibition was assessed to check the efficacy of the extracts as anti-melanogenic agents.Biochemical(total volatile nitrogen,free fatty acid and peroxide values),bacteriological(aerobic counts),melanosis inhibition and sensory quality of chilled stored shrimp were addressed to investigate the efficacy of extracts as preservative and anti-melanogenic remedy.Free reducing power of green tea-and amla extracts were in a range of 28.72-65.67%and 17.38-66.95%,respectively.Phenolic content level was almost same for green tea and amla extract(2.46±0.002 and 2.51±0.036 mg GAE/gram).Total antioxidant capacity of green tea(210.33±4.63 mg EqAsc/g)was slightly higher than that of amla extracts(145.56±1.98 mg EqAsc/g).FRAP value revealed that green tea(477.49±3.25 mgE Fe(II)/g)had more ferric reducing power than amla(324.39±5.85 mgE Fe(II)/g).FT-IR analysis revealed the presence of essential organic bioactive compounds,which play an important role in reducing lipid oxidation and quality loss,and both extracts possess an encouraging PPO inhibition ability.Treatment by green tea-and amla extracts on chilled stored shrimp showed promising effects on biochemical and microbiological parameters followed by melanosis inhibition and enhanced sensory attributes.Treated Indian white prawn with green tea-and amla extract revealed significantly(P<0.05)lower value of biochemical indices and microbial load during chilled storage compared to untreated sample.

连翘绿茶不同加工阶段提取物的抑菌及抗氧化活性分析

连翘绿茶的加工主要包括鲜叶摊放、杀青、捻揉和干燥4个过程。为探究连翘绿茶不同加工阶段所得产物的提取物对食源性细菌的抑制作用及抗氧化活性,以连翘鲜叶、杀青叶、捻揉叶和干燥茶叶为研究材料,7种常见食源性细菌为供试菌株,通过测定抑菌圈直径和DPPH、ABTS+自由基清除率及总抗氧化能力,明确不同产物提取物的抑菌及抗氧化活性,为连翘绿茶加工工艺的进一步优化提供科学指导,也为连翘绿茶的深度开发提供理论依据。结果表明,连翘绿茶不同加工阶段提取物对蜡样芽孢杆菌和金黄色葡萄球菌具有明显抑制效果,对大肠埃希氏菌、肠沙门氏菌肠亚种、福氏志贺氏菌、阪崎氏年轻泰坦杆菌和痢疾志贺氏菌5种细菌无明显抑制效果,说明连翘鲜叶、杀青叶、捻揉叶和干燥茶叶对革兰氏阳性菌抑制效果较好,其中,鲜叶和干燥茶叶提取物对蜡样芽孢杆菌和金黄色葡萄球菌的最小抑菌质量浓度均为125 mg/mL,鲜叶和干燥茶叶提取物对蜡样芽孢杆菌的最小杀菌质量浓度均为250 mg/mL,鲜叶和干燥茶叶提取物对金黄色葡萄球菌最小杀菌质量浓度均为500 mg/mL;杀青叶对DPPH、ABTS+自由基的清除率及总抗氧化能力最高,分别为98.2%、90.3%和92.5%。连翘绿茶具有良好的抗细菌能力,但其抗氧化活性经高温处理后有所降低。

绿茶提取物可致特异质型肝损伤?——与美国最新版药物性肝损伤指南商榷

近年来,绿茶提取物的潜在肝毒性越来越多的引起了人们的关注。本文通过现有绿茶提取物肝损伤相关研究,结合最新药物肝毒性分类,对其肝损伤的客观性和成因机制进行了系统的阐述和分析。进一步根据绿茶提取物致肝损伤的主要风险因素,提出了安全合理使用此类产品的相关建议,以期为绿茶提取物肝损伤机制的深入研究和风险的防控提供有价值的见解,同时,也为绿茶提取物改善健康状况的治疗性使用提供重要的参考。