苦丁茶叶制虫茶粗多酚对HepG2人肝癌细胞的凋亡诱导效果

茶多酚是茶叶中的功能性成分。虫茶作为传统饮品也含有这些化合物,这些多酚类物质的抗癌效果有待科学的研究。本研究对苦丁茶叶制虫茶粗多酚（CPKMI）的癌细胞凋亡诱导作用进行了测定。采用MTT法对CPKMI对癌细胞的体外生长抑制作用进行了分析,然后进一步采用RT-PCR检测对CPKMI的癌细胞凋亡诱导效果进行了实验。经过25、50和100μg/m L的CPKMI处理癌细胞48h,Hep G2人肝癌细胞的增殖被抑制,其中100μg/m L的CPKMI表现出最高的抑制率（72.8%）。CPKMI也可以通过上调caspase-3、caspase-9、p53、p21、E2F1、p73和下调HIAP-1,HIAP-2基因的mRNA的表达对Hep G2癌细胞起到显著的凋亡诱导效果（p<0.05）。由此可见,CPKMI表现出强的体外癌细胞凋亡诱导效果。      

牛磺酸降低高胆固醇HepG2细胞内胆固醇的作用机制研究

目的:探讨牛磺酸对高胆固醇Hep G2细胞胆固醇降解作用及其机制。方法:以0.02 mmol/L胆固醇加入培养液中建立高胆固醇细胞模型后,分别加入1、10、20 mmol/L牛磺酸培养48 h,测定细胞内总胆固醇（TC）、游离胆固醇（FC）、胆固醇酯（EC）及细胞内总胆汁酸（TBAc）和培养液总胆汁酸（TBAm）水平;并检测20 mmol/L牛磺酸作用24 h后细胞CYP7A1及其调控分子的蛋白表达水平。结果:10 mmol/L和20 mmol/L牛磺酸作用48 h可显著降低细胞内TC、FC和EC（p<0.01）,同时升高了TBAc和TBAm（p<0.05或p<0.01）;20 mmol/L牛磺酸作用24 h时使CYP7A1显著增加（p<0.05）;20 mmol/L牛磺酸作用24 h后MAPK、ERK、JNK、c-jun和p-c-jun表达明显降低（p<0.05）,而对HNF4α则无显著影响。结论:牛磺酸可抑制高胆固醇Hep G2细胞MAPK/ERK和MAPK/JNK表达水平,降低c-jun蛋白表达及c-jun磷酸化水平,促进CYP7A1蛋白表达升高,从而加速胆固醇转化为胆汁酸。      

蜂胶醇提物对人肝癌细胞Hep G2增殖及凋亡的影响

为探讨蜂胶醇提物对人肝癌细胞Hep G2 增殖和凋亡的影响,采用MTT 法检测蜂胶醇提物对Hep G2 细胞增殖的抑制作用,用荧光倒置显微镜和流式细胞仪分析蜂胶醇提物对Hep G2 细胞凋亡的影响。结果表明：12.5～200μg/mL 质量浓度的蜂胶醇提物作用24、48h 后,均能不同程度地抑制Hep G2 细胞的增殖,呈明显的时间、剂量依赖关系,半数抑制质量浓度(IC50)分别是115、78μg/mL。作用8h 后,Hep G2 细胞出现不同程度的凋亡,凋亡率由6.36% 上升到21.9%,呈现出剂量依赖关系。故蜂胶醇提物可显著抑制人肝癌细胞Hep G2 的生长,诱导其凋亡。     

反油酸处理对人HepG2细胞代谢组的影响

本研究以人细胞（Hep G2）为模型,通过MTT实验研究反油酸对Hep G2细胞存活率的影响,选择1.2 mmol/L和1.5 mmol/L的反式油酸处理Hep G2细胞6和12 h,利用UPLC-MS/MS和GC-MS对Hep G2细胞的代谢组进行检测,以了解人细胞对反式油酸的代谢反应。结果表明,反油酸处理引起了Hep G2细胞代谢水平的广泛变化。反油酸处理促进了脂肪酸合成,引起细胞磷脂代谢显著变化及细胞膜的重构,也增加了胆固醇和酰基甘油代谢中间产物的水平;同时,反油酸引起糖类和氨基酸代谢途径的增强,为脂肪酸合成提供原料。本研究获得的体外代谢组水平的变化为揭示反式脂肪酸与人类健康的不良关系提供了新的证据。      

黄连中阿魏酸对小檗碱在HepG2细胞中降糖活性的影响

为了考察黄连中酸性成分对小檗碱降糖作用的影响,用柱层析法分离鉴定酸性成分,以Hep G2细胞建立高糖细胞模型,用MTT法测定细胞的生长,细胞消耗的葡萄糖用试剂盒检测。结果从酸性组分中分离出阿魏酸,其结构经光谱与色谱确证。阿魏酸在高效液相色谱图中有明显的信号,与小檗碱在黄连浸膏中的质量比约为32∶1。细胞实验中,含小檗碱的培养液中加入阿魏酸后,细胞存活率和细胞消耗的葡萄糖明显增加;在含36mg/L小檗碱的培养液中加入64mg/L阿魏酸,可使细胞的存活率上升到69%,细胞消耗的葡萄糖增加29.4%。此结果说明黄连中酸性成分阿魏酸能促进小檗碱处理的Hep G2细胞对葡萄糖的吸收生长,并降低小檗碱对Hep G2细胞的毒性,显示一定的协同增效作用。      

煎炸油中总极性物质对细胞抑制和诱导凋亡的影响

研究煎炸油中总极性物质(TPM)对细胞的生长抑制和诱导凋亡。结果表明:1.0mg/m L的TPM作用于Hep G2细胞24、48、72h后,细胞增殖抑制率分别为9.8%、12.6%、16.1%;流式细胞仪结果显示,随着TPM浓度的增加,加药组细胞凋亡率逐渐增加,G0/G1期细胞数目逐渐减少,S期细胞数目逐渐增多,说明TPM对He PG2细胞增殖的抑制发生在S期。      

Assessment of dietary exposure to flavouring substances via consumption of flavoured teas. Part 1: occurrence and contents of monoterpenes in Earl Grey teas marketed in the European Union

Estimations of dietary exposure via the consumption of flavoured foods play a central role in the safety evaluation of flavouring substances. To assess uncertainties, actual data regarding the occurrence and concentration levels of flavouring substances were determined in commercially available flavoured foods, using Earl Grey tea as an example. The contents of the consistently occurring monoterpenes linalyl acetate, linalool, limonene, β-pinene and γ-terpinene were determined in 90 tea samples purchased in 10 European Union member states. Rather narrow frequency distributions were observed for the major compounds linalyl acetate and linalool. The factors (1) country of purchase, (2) source of the products (national/international brands versus private label brands versus speciality tea shops), and (3) enantiomeric purities of the flavouring substances had no significant impact on the contents of the flavouring substances. Only in teas sold as loose leaves were the median contents of linalyl acetate and linalool (66% and 39%, respectively) higher than in teas offered in tea bags. Significant losses of flavouring substances were observed on storage of teas, indicating an impact of the type of packaging and the flavouring technology on the contents of flavouring substances in the product finally consumed.     

Tea components influencing bioavailability of fluoride and potential transport mechanism in the Caco-2 cell line model

Previous work showed that the bioavailability of fluoride in dark tea was lower than NaF solution. However, limited information is available indicating the effects of tea components on the fluoride bioavailability. In this study, the effects of the components in tea on the bioavailability of fluoride were evaluated in the Caco-2 cell line model. Additionally, the mechanism of effect of aluminium on fluoride transport was investigated. The result showed that 10–100 μm of epigallocatechin gallate (EGCG) could not influence fluoride transport. Al³⁺ significantly decreased fluoride transport in both apical-basolateral and basolateral-apical directions. Moreover, aluminium could form different forms of aluminium fluoride complexes, which were transported through Caco-2 cells by different pathways. F⁻ transport was mainly dependent on the paracellular pathway and active transport involving Cl⁻ channels. The paracellular pathway played a predominant role in transport of AlF₃. The paracellular pathway and active transport both participated in AlF₂⁺ transport.     

Spaghetti making potential of Indian durum wheat varieties in relation to their protein,yellow pigment and enzyme contents

The research was carried out to evaluate spaghetti making potential of 12 Indian durum wheat varieties in relation to their protein and yellow pigment content and peroxidase, polyphenol oxidase, lipoxygenase, and protease activities. The protein content of the durum wheat varieties varied from 12.1% to 15.9% and their yellow pigments content ranged from 3.8 to 7.2 ppm. The peroxidase activity in these wheat varieties varied from 269 to 1010 U/g and polyphenol oxidase activity from 58.8 to 78.3 U/g. The lipoxygenase activity of durum wheats ranged between 1.44 and 6.88 U/g. Protease activity was in the range of 1.1–5.1 U/ g. The data for varieties MACS-1967, MACS-3125, MACS-2846, DWR-2006, HI-8498 and N-59 were indicative of their potential for the preparation of pasta products.     

不同加工方式的铁核桃油对HepG2细胞胆固醇合成的影响及机制初探

研究不同加工方式的铁核桃油对HepG2细胞胆固醇合成的影响,并探索其降胆固醇的作用机制。不同加工方式制备铁核桃油,亚甲基蓝法测定不同加工方式的铁核桃油对HepG2细胞活性的影响,采用CHO试剂盒检测铁核桃油对HepG2细胞总胆固醇含量的影响,荧光定量PCR检测不同加工方式的铁核桃油对HepG2细胞胆固醇合成基因HMGCR、SREBP-2和CYP51基因表达的影响。结果 HepG2细胞的DMSO安全添加量为0.10%,铁核桃油对HepG2细胞作用的最佳终浓度为500μg/mL,与对照组相比,核桃油能降低HepG2细胞总胆固醇的含量,下调HMGCR、SREBP-2和CYP51 mRNA的表达量。铁核桃油通过抑制胆固醇合成基因HMGCR、SREBP-2和CYP51的表达,起到降胆固醇的作用,铁核桃油中的微量伴随物可能是引起降胆固醇功效差异的主要原因。     

酶法生产葡萄糖基维生素C的产酶条件及转化条件优化

本课题采用单因素实验确立微生物发酵法产糖基转移酶培养基的基本成分，利用此酶催化维生素C和糖基供体生成葡萄糖基维生素C（AA-2G），并通过正交实验考察不同底物，加酶量、反应温度、pH等因素，确立葡萄糖苷转移酶合成产物的最佳条件为：以CMC-Na作为葡萄糖基的供体，浓度为0．04mol／L维生素C作为受体，酶量是25mL，pH值4．0，温度60℃下反应16h。     

Chlorophylls and degradation products in orthodox and CTC black teas and their influence on shade of colour and sensory quality in relation to thearubigins

Chlorophylls and concomitant pigments along with catechins were analysed in shoots from various Tocklai released clones with pronounced genetic variation and in the corresponding orthodox black teas. Comparison of these values with tasters' score showed that the shade of colour of an orthodox black tea is influenced mostly by pheophytin and thearubigins. The degradation of chlorophyll into pheophytin and pheophorbide was also studied in orthodox and crush - tear - curl (CTC) teas. The observations indicated that both pheophytin and pheophorbide are always higher in orthodox than in CTC teas made from the same leaf source.     

Cu~(2+)-钨酸盐-罗丹明6G体系共振散射光谱法测定面粉和茶叶中微量铜

利用Cu2+和钨酸盐形成的铜钨杂多酸阴离子与罗丹明6G阳离子结合生成离子缔合物的反应,建立一种测定Cu2+的共振散射光谱法。该反应在聚乙烯醇存在条件下,于589 nm波长处产生的共振散射光强度与Cu2+质量浓度在0.05~1.0 ng/m L范围内有良好的线性关系,线性回归方程为ΔI=4.38+77.12c(r=0.997 1),方法的仪器检出限为0.026 ng/m L。方法简单、快速、灵敏度高,且大量存在的常见离子对Cu2+的测定不干扰,将其用于面粉和茶叶样品中铜的测定,相对标准偏差在3.5%以内,回收率在96.7%~104.1%之间。     

凝胶净化液相色谱法同时检测高油脂食品中黄色2G、奶油黄和柑橘红2色素

研究了采用凝胶色谱法净化,HPLC-DAD同时测定高油脂食品中黄色2G、奶油黄和柑橘红2色素的方法。样品经环已烷/乙酸乙酯（1+1）萃取,Bio-BeadsSX3凝胶层析柱净化去除油脂、天然色素等大分子干扰物质。采用C18（4.6mm×250mm,5μm）色谱柱,以甲醇和水溶液为流动相梯度洗脱,二极管阵列检测器多波长同时检测这三种色素。黄色2G、奶油黄和柑橘红2工作曲线在0.5～10.0mg/L范围内峰面积与进样量呈良好的线性关系,线性相关系数大于0.999,回收率在78.6%～97.6%之间,相对标准偏差在1.23%～4.20%之间。黄色2G、奶油黄和柑橘红2色素的检出限分别为2.0、1.0、2.0mg/kg。      

Investigation of the cytotoxicity of food-grade nanoemulsions in Caco-2 cell monolayers and HepG2 cells

Nanoemulsions represent one of the emerging formulations for nutraceutical delivery. However, the possible toxicity associated with the small droplet size (diameter <200 nm) is still unknown. In this study, three nanoemulsions emulsified by modified starch, Tween 20 and whey protein isolate, respectively, were prepared and their cytotoxicity was examined by comparing with the corresponding micron-sized emulsions. Caco-2 cell monolayers were used to mimic the small intestine epithelium. Integrity of the cell membrane and tight junctions was tested by measuring the lactate dehydrogenase leakage and transepithelial electrical resistance, respectively. All three nanoemulsions did not reveal significant difference from their micron-sized counterparts, suggesting no apparent toxicity of the nanoemulsions on the small intestine. Meanwhile, the possible hepatic toxicity was investigated using MTT assay on HepG2 cells. It was found that nanoemulsions made with modified starch and whey protein isolate, but not Tween 20, affected the cell viability/proliferation more than did the micron-sized emulsions. Further in vivo investigation is required to examine the possible hepatic toxicity of nanoemulsions.     

Effects of ready to drink teas on AhR- and PXR-mediated expression of cytochromes P450 CYP1A1 and CYP3A4 in human cancer cell lines and primary human hepatocytes

A variety of xenobiotics are taken in the diet and they can interfere with regulatory pathways of drug metabolizing enzymes in humans. This can result in food-drug interactions, which is undesirable clinical situation where drug pharmacokinetics are influenced by dietary compounds. Xenobiotics-mediated food-drug interactions include the induction of drug metabolizing cytochromes P450. The expression of the most important inducible cytochromes CYP1A and CYP3A4 are regulated by xenoreceptors PXR and AhR.We examined extracts from 17 different flavoured ready to drink teas (RDTs) for their capabilities to activate PXR and AhR receptors and to induce CYP3A4 and CYP1A genes. Primary cultures of human hepatocytes and cancer cell lines HepG2 and LS174T were used as in vitro models. Gene reporter assays, RT-PCR and Western blots were performed.We identified three RDTs that induced CYP3A4 mRNA and protein, implying a potential for food-drug interactions. Several RDTs slightly elevated CYP1A1 expression or activated AhR.     

Gallic acid induces G2/M phase cell cycle arrest via regulating 14‐3‐3β release from Cdc25C and Chk2 activation in human bladder transitional carcinoma cells

Scope: Cell cycle regulation is a critical issue in cancer treatment. Previously, gallic acid (GA) has been reported to possess anticancer ability. Here, we have evaluated the molecular mechanism of GA on cell cycle modulation in a human bladder transitional carcinoma cell line (TSGH‐8301 cell). Methods and results: Using flow cytometer analysis, exposure of the cells to 40 μM GA resulted in a statistically significant increase in G2/M phase cells, which was accompanied by a decrease in G0/G1 phase cells. GA‐treated cells resulted in significant growth inhibition in a dose‐dependent manner accompanied by a decrease in cyclin‐dependent kinases (Cdk1), Cyclin B1, and Cdc25C, but significant increases in p‐cdc2 (Tyr‐15) and Cip1/p21 by western blotting. Additional mechanistic studies showed that GA induces phosphorylation of Cdc25C at Ser‐216. This mechanism leads to its translocation from the nucleus to the cytoplasm resulting in an increased binding with 14‐3‐3β. When treated with GA, phosphorylated Cdc25C can be activated by ataxia telangiectasia‐mutated checkpoint kinase 2 (Chk2). This might be a DNA damage response as indicated by Ser‐139 phosphorylation of histine H2A.X. Furthermore, treatment of the cells with a Chk2 inhibitor significantly attenuated GA‐induced G2/M phase arrest. Conclusion: These results indicate that GA can induce cell cycle arrest at G2/M phase via Chk2‐mediated phosphorylation of Cdc25C in a bladder transitional carcinoma cell line.