口源性口臭指示菌的筛选

目的从口源性口臭(Oral Malodor)相关菌种中筛选主要代表菌,用以建立口臭细菌学(Oral Bacteri-ology)临床辅助诊断的指示菌(Indicator bacteria)。方法用感官检测(鼻闻法)(Organoleptic test)、气相色谱(Gas Chromatography)、硫化物检测仪(Halimeter)和硫化氢检测仪(Easicult S)等4种方法,在实验室检测常见的8种牙周及龋病致病菌,通过检测鼻闻臭味程度、硫化物(Volatile sulfur compounds,VSCs)、硫化氢(Hydrogen sulfide,H2S)及有异味的短链脂肪酸(Short Chain Fatlf acid)含量来确定指示菌。结果鼻闻:牙龈卟啉单胞菌(P.gingivalis,P.g)、中间普雷沃菌(P.intermedius,P.i)和具核梭杆菌具核梭亚种(F.subsp nucleatum,F.n)恶臭明显,其他菌有微臭或无味。气相色谱检测:P.g、P.i、F.n和伴放线聚生杆菌(Aggregatibscter actinomycetemcomitans,A.a)中有异味的丁酸(Butyric acid)含量在40%～66%,其他菌,其他产物含量较低。硫化物检测:P.g、P.i和F.n的VSCs量在1 000ppb以上,硫化氢检测:P.g、P.i和F.n的H2S在600 ppb以上,其他菌两项检测均在36 ppb以下。结论 P.g、P.i和F,n是主要产臭菌种,可作为临床口臭的细菌学辅助诊断的指示菌,供临床进一步研究。     

益生菌组合物对大鼠龋齿的预防作用

目的 探究构建大鼠龋齿模型来考察特定益生菌组合对于龋齿的预防效果。方法 将50只雄性大鼠随机分成5组：空白对照组（CF组）、模型组（C组）以及3个预防组[漱口水组（洗必泰,P1组）、F1菌粉组（动物双歧杆菌乳亚种HN019, P2组）和F2菌粉组（动物双歧杆菌乳亚种HN019+植物乳植杆菌CECT748+植物乳植杆菌CECT7480,P3组）],每组10只,分别使用白假丝酵母和变异链球菌对大鼠牙齿进行侵染,构建大鼠龋齿模型。实验过程中CF组大鼠正常饮食,C组、P1组、P2组及P3组大鼠喂食致龋饲料和5%蔗糖蒸馏水,3个预防组分别使用洗必泰、益生菌组合物F1菌粉和益生菌组合物F2菌粉进行干预;最后检测跟踪各组大鼠口腔菌群、体质量和脏器系数、血常规指标,评估牙釉质体积和龋齿评分。结果 在动物造模成功后,CF组、C组与各预防组之间的体质量增量、主要脏器指数及血液学指标均无显著差异,表明益生菌的摄入对大鼠的健康无影响。大鼠口腔菌群计数结果发现,益生菌定植效果良好且稳定,致病菌的存在并不影响乳杆菌和双歧杆菌的定植。洗必泰和2种益生菌组合均能显著抑制变异链球菌的定植（F=29.364 8,P<...     

苦参提取物对口腔主要致龋细菌作用的实验研究

目的观察苦参提取物对口腔主要致龋细菌及其生物膜生长、黏附、产酸和产糖的影响,探寻其防龋作用机制。方法将苦参提取物按照二倍梯度稀释法测定最低抑菌浓度,0.5 g/L氯己定为阳性对照,不含药液组为阴性对照组;采用紫外分光光度计测定细菌黏附能力;通过生物膜结晶紫染色法测定生物膜抑制浓度和生物膜清除浓度;通过ΔpH法和苯酚-硫酸法分别测定细菌的产酸和合成水不溶性胞外多糖情况。结果苦参提取物对口腔主要致龋细菌的最低抑菌浓度均为4 g/L;在4 g/L时,对变形链球菌、远缘链球菌、血链球菌、粘性放线菌和内氏放线菌黏附抑制率分别为(77.6%±1.2%)、(66.7%±1.8%)、(60.68%±2.9%)、(79.8%±1.2%)和(85.1%±1.3%)。2 g/L时能够显著抑制浮游菌产酸及合成水不溶性胞外多糖能力。4 g/L时对变形链球菌、远缘链球菌、血链球菌、粘性放线菌、内氏放线菌和嗜酸乳杆菌生物膜形成抑制率分别为(87.5%±1.3%)、(85.4%±0.5%)、(89.0%±0.3%)、(77.2%±0.7%)、(87.4%±1.1%)和(80.4%±1.3%);并对以上细菌生物膜的最低清除浓度分别为16、16、16、16、8和8 g/L。苦参提取物在50%的最小生物膜清除浓度下对单菌生物膜的产酸和合成水不溶性细胞外多糖的抑制率分别为67.5%～94.1%和42.3%～60.0%。结论苦参提取物能够抑制口腔主要致龋细菌浮游和生物膜状态下的生长、黏附、产酸和产糖,其有望成为一种龋齿预防制剂。     

八肽胆囊收缩素激活钙离子通道和酪氨酸激酶诱导豚鼠心肌细胞内的游离钙增高

探讨八肽胆囊收缩素(CCK-8)对豚鼠单个心肌细胞内游离钙浓度([Ca2+]i的影响及其信号转导机制.Fluo 3-AM标记酶消化法分离的单个心室肌细胞,用激光共聚焦显微镜测定细胞内[Ca2+]i的浓度.[Ca2+]i的变化用荧光强度(Fi)和相对荧光强度(Fi/F0%)表示.实验结果如下(1)在含Ca2+1.0 mmol/L的Tyrode's液中,CCK-8(1～104pmoVL)均可引起[Ca2+]i快速显著上升(P＜0.01).(2)用钙离子鳌合剂EGTA(3 mmol/L)和钙离子通道阻断剂nisoldipine(0.5μmol/L)预孵育心肌细胞5 min,CCK-8(102pmol/L)仅可引起[Ca2+]i缓慢轻度上升(P＜0.01).(3)用非选择性CCK受体拮抗剂丙谷胺(proglumide 6μmo1/L)或酪氨酸激酶抑制剂genistein(1 μmol/L)预孵育心肌细胞5 min,则完全抑制CCK-8诱导的[Ca2+]i升高(P＜0.01).CCK-8可通过激活其受体控制的Ca2+通道,引起Ca2+内流,诱导细胞内Ca2+释放,引起豚鼠单个心肌细胞内[Ca2+]i上升,此作用可能由酪氨酸激酶介导.     

一株新的砷还原菌分离鉴定及其对天然矿物臭葱石的溶解作用

【目的】探究江汉平原土著砷还原微生物如何介导臭葱石的溶解和释放过程,以及硝酸盐和硫酸盐对该过程的影响。【方法】采集江汉平原高砷沉积物,利用多轮传代富集方法筛选出一株兼性厌氧砷还原菌;克隆其16S rRNA基因、砷还原酶基因(arsC)、硫代硫酸盐还原酶基因(phsA)、硝酸盐还原酶基因(nar)以获得其分类地位;分析该细菌的As(V)、NO3–、Fe(III)、S_2O_3~(2–)还原功能;利用microcosm技术分析该菌株催化臭葱石中不可溶砷和铁的溶解和释放作用及硝酸盐和硫酸盐对此过程的影响;采用X-射线衍射(XRD)和扫描电镜(SEM)等方法对细菌作用前后的矿物表面形貌进行分析。【结果】16S rRNA基因测序结果表明该细菌为柠檬酸杆菌属(Citrobacter sp.),故命名为Citrobacter sp. A11;在Citrobacter sp. A11作用下,0.45 mmol/L As(V)在4 d内被还原成As(III),2.0 mmol/L S_2O_3~(2–)在6 d内被还原成S~(2–),1.0 mmol/L Fe(III)在3 d内被还原成Fe(II),140.0 mg/L NO_3~–在28 h内被还原成NO_2~–;经过28 d该细菌的催化作用使得体系中不可溶砷和铁的释放量分别为33.68μmol/L、51.93μmol/L;硫酸根的加入使得砷和铁的释放量分别增长了41.04%和34.30%,硝酸根的加入则使砷和铁释放量分别降低了35.07%和53.46%。XRD、SEM-EDS分析表明,细菌作用后的臭葱石表面形貌发生明显改变,并出现细小且分散的溶解性颗粒。【结论】本次研究从江汉平原高砷沉积物中富集分离得到一株兼性厌氧砷还原细菌Citrobacter sp. A11,能有效还原As(V)、S_2O_3~(2–)、NO_3~–、Fe(III);砷还原细菌Citrobacter sp. A11能显著促进臭葱石中砷和铁的溶解和释放,硫酸根离子的存在会促进细菌介导臭葱石中固态砷、铁的释放,而硝酸根离子的存在则对此过程起明显抑制作用。     

酸煤矿水中氧化硫硫杆菌(Thiobacillus thiooxidans)的分离及其特征

1. 从河北唐山开搛煤矿和湖北香溪刘草坡煤矿的酸矿水中分离到二株参与矿水变酸的氧化硫硫杆菌(Thiobacillus thlooxidans Wak~maa et J0ffe)。该菌大小为0．6一1×0.5 微米,圆头,单个或成对,革兰氏鱼反应。严格好气,在含元素硫的无机基上发育。在一般细菌基上不生长。 2．藏菌以氧化元素硫取得能源。不能氧化硫代硫酸盐,低铁,硫化物和亚硫酸盐．也不能利用有机物如葡萄糖、酵母汁、蛋白膝、乳酸和醋酸盐为能源。 3．骸菌同化大气中二氧化碳为碳源。有机物除葡萄糖外,较高浓度的内膏、酵母汁、蛋白臁对菌的生长都有抑制作用。 4．在氮源上,加铵盐基上生长旺盛,强烈产酸,pH降到0．5左右。相反,加硝酸盐同于不加氮源对照,生长微弱,pH最多降到1.5左右。而且在生物量上,加敛盐的培养秸果 比加硝酸盐的高5一10倍,这表明只能利用铵态氮为氮源。在有机氮如尿素、天朗多素、蛋白臁存在下都发育。 5．在元素硫基上,开始菌量的增殖和酸的形成有平行的关系。当酸度提高到pH 1．5左右时,虽培养液仍保持高度混浊及一定的产酸能力,但活菌量开始迅速下降。用作接种物时最好pH达到达一点以前进行。 6．本菌发育的温度从15℃开始随着温度提高产酸速度加快,但超过35~(2就受到抑制,40℃几乎停止发育,55℃完垒抑制生长。最适温度为30—35℃菌一般在pI-I‘2．0—4．8范围内都能很好地发育,低于1．2或高于5．8,生长完垒抑制。其最适pl-I是2．5—3．3。     

两株土壤耐镉细菌的筛选分离及与CdS-TGA纳米颗粒相互作用的研究

由受重金属镉污染严重的化工厂土壤中,筛选分离获得两株镉耐受性加强的菌株,菌体长1.0~2.0μm,宽0.5~0.8μm,单个细胞呈杆状,单菌落分别呈淡黄色与乳白色,经鉴定为Enterobacter sp.与Serratia sp.。对所分离细菌的最适生长条件、镉离子最小抑制浓度及抗生素抗性进行了检测和优化,并进一步研究了硫化镉-巯基乙酸纳米颗粒与细菌的相互作用,发现纳米颗粒浓度在150μg/m L时细菌增殖基本停滞;过氧化物酶和超氧化物歧化酶酶活测试显示纳米颗粒对酶抑制性较Cd2+更为强烈,细胞形态受到严重破坏。     

Rhizopus sp.PW358菌脂肪酶固态发酵生产

研究了Rhizopus sp.PW358菌的固态生长和产脂肪酶条件。结果表明：黄豆饼粉为培养基的基本成分,用来生产脂肪酶。培养基中可加入淀粉和蛋白胨作为碳源和源,有利于脂肪酶的合成,培养基的含水量以及金属离子Ca^2 ,Mg^2 的浓度也影响Rhizopus sp.PW358菌和脂肪酶 产生。在优化条件下,12g豆粉中含1.0g淀粉及0.5g蛋白胨、15ml营养盐中Ca^2 ,Mg^2 离子浓度分别为8．0和4．0g/L,培养基含水量为55．6％,在接种后培养48h,酶活力可达最大值320IU／g干培养基。脂肪酶的基本性质研究表明,酶的最适反应温度和PH分别为35℃和7．0,酶的半失活温度为53．5℃,不同的PH环境中,30℃保温1h后酶在PH6．5－8．5范围内较为稳定。     

微生物除臭剂发酵工艺条件优化及硫素转化的研究

利用酵母菌、乳酸菌、醋酸菌三种可食性微生物复配发酵制备微生物除臭剂,研究微生物复配比、发酵时间、发酵温度、接种量四个因素对H_2S去除率的影响。以单因素实验为基础,利用Box-Behnken响应面法优化最佳发酵条件,进一步研究硫元素转化及含量动态变化。结果表明酵母菌、乳酸菌、醋酸菌质量比为1∶2∶2时,各因素对H_2S去除率的影响由高到低依次为发酵温度发酵时间接种量,最优发酵条件为发酵时间48. 5 h、发酵温度30℃、接种量12. 75%,H_2S的去除率可达到71. 84%;实验组与对照组的硫元素转化及含量动态变化相比,实验组的SO_4~(2-)含量显著较高(P0. 05),H_2S释放量显著较低(P0. 05)说明该微生物除臭剂可以调节硫元素转化,有效抑制H_2S产生。     

双歧杆菌四联活菌片 在首次根除幽门螺杆菌失败胃溃疡患者中的应用

目的探讨双歧杆菌四联活菌片在首次根除幽门螺杆菌(H.pylori)失败胃溃疡患者中的应用。方法选择2018年1月至2018年11月于我院内科首次根除H.pylori失败的H.pylori感染胃溃疡(Hp-GU)患者84例,随机分为观察组和对照组各42例。两组患者均予以兰索拉唑片(30 mg/次,1次/d)、阿莫西林胶囊(1.0 g/次,2次/d)、克拉霉素片(0.5 g/次,2次/d)和枸橼酸铋钾颗粒(220 mg/次,2次/d)口服治疗,连用2周。2周后继续使用兰索拉唑片30 mg/次,1次/d,再用4周。观察组患者在此基础上加用双歧杆菌四联活菌片1.5 g/次,3次/d,连用6周。观察两组患者治疗前后血清炎症因子[白介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)]水平的变化,并比较溃疡愈合情况、H.pylori清除率及不良反应发生率。结果治疗6周后,两组患者血清IL-6和TNF-α水平较治疗前明显下降(均P0.05),且观察组下降程度大于对照组(P0.05);同时观察组患者临床总有效率(95.24%)明显高于对照组(80.95%),H.pylori清除率(90.48%)明显高于对照组(73.81%),不良反应发生率(7.14%)低于对照组(23.81%),差异均有统计学意义(均P0.05)。结论双歧杆菌四联活菌片联合四联疗法对首次根除H.pylori失败的Hp-GU患者疗效确切,可明显降低血清炎症因子水平,抑制胃黏膜炎症反应,有利于提高溃疡的愈合率和H.pylori清除率,降低患者不良反应发生率。     

丛枝菌根真菌和施氮量对茶树生长、矿质元素吸收与茶叶品质的影响

采用盆栽法研究了不同施氮水平下接种丛枝菌根（arbuscular mycorrhiza,AM）真菌Glomus mosseae对茶树生长、矿质元素吸收及茶叶品质的影响。结果表明,适量的施氮利于AM真菌的侵染和菌根发育,当施氮过量时则会抑制菌根发育。在不同施氮水平下接种AM真菌均提高了茶树地上部、地下部和总干物质量,其中又以接种AM真菌同时施氮量为0.53g kg-1的茶树总干物质量最大,为对照的1.63倍。不同矿质元素受AM真菌和氮肥的影响不一致,在一定施氮水平下接种AM真菌可提高茶树叶片中N、P、K、Ca、Zn和Fe含量,降低Mn和Cu含量;显著增加根中N、P、K、Mg和Zn含量,降低Mn含量,施高浓度的氮（1.06 g kg-1）显著降低了根系Ca和Fe含量。不同施氮水平下AM真菌处理可增加茶叶中可溶性糖和可溶性蛋白含量,提高了茶叶中茶多酚、咖啡碱、氨基酸和水浸出物含量,降低酚氨比,显著改善茶叶品质。本实验条件下,茶树施氮量为0.53 g kg-1时,接种AM真菌改善茶叶品质的效果最佳。     

茶多酚对高糖诱导人晶状体上皮细胞凋亡的影响

目的:探讨茶多酚对高糖诱导的人晶状体上皮细胞(human lens epithelial cells,HLECs)凋亡的影响。方法:建立高糖诱导的HLECs模型,用不同浓度的茶多酚干预,MTT比色法检测细胞存活率,电子显微镜观察细胞形态,透射电镜观察细胞内超微结构变化,Western Blotting检测凋亡相关蛋白的表达水平。结果:高浓度葡萄糖抑制了HLECs活性,葡萄糖干预后细胞活性下降到42.65%±4.12%,与阴性对照组(96.07%±4.02%)比较差异具有统计学意义(P0.01)。用不同浓度茶多酚处理后,HLECs活性分别提高到55.33%±4.15%,72.90%±3.36%和76.00%±3.79%,与氧化损伤组比较差异具有统计学意义(P0.05);高浓度葡萄糖改变了HLECs形态及生长情况,而用茶多酚干预的高糖条件下的HLECs则较好的保持了上皮细胞的形态;高浓度葡萄糖诱导HLECs凋亡反应的发生,引起凋亡相关蛋白表达水平改变,茶多酚抑制了Bax水平的升高,促进了Bcl-2水平的下降。结论:茶多酚可以抑制高糖诱导的HLECs的凋亡,对糖尿病性白内障具有预防作用。     

Protective effects of green tea polyphenols on human HepG2 cells against oxidative damage of fenofibrate

The aim of this work was to investigate the protective effects of green tea polyphenols on the cytotoxic effects of hypolipidemic agent fenofibrate (FF), a peroxisome proliferator (PP), in human HepG2 cells. The results showed that high concentrations of FF induced human HepG2 cell death through a mechanism involving an increase of reactive oxygen species (ROS) and intracellular reduced glutathione (GSH) depletion. These effects were partially prevented by antioxidant green tea polyphenols. The elevated expression of PP-activated receptors alpha (PPARalpha) in HepG2 cells induced by FF was also decreased by treatment with green tea polyphenols. In conclusion, this result demonstrates that oxidative stress and PPARalpha are involved in FF cytotoxicity and green tea polyphenols have a protective effect against FF-induced cellular injury. It may be beneficial for the hyperlipidemic patients who were administered the hypolipidemic drug fenofibrate to drink tea or use green tea polyphenols synchronously during their treatment.     

Protective Effect of Green Tea Extract and Tea Polyphenols against the Cytotoxicity of 1,4-Naphthoquinone in Isolated Rat Hepatocytes

The cytoprotective effect of green tea extract and its phenolic compounds against 1,4-naphthoquinone-induced hepatotoxicity was evaluated in primary cultured rat hepatocytes. After exposure to 1,4-naphthoquinone, lactate dehydrogenase (LDH) leakage and cell viability were both improved by the presence of the tea extract and tea polyphenols. This cytoprotective effect was related to the structure of tea polyphenols, the galloyl group of (–)-epigallocatechin-3-gallate and (–)-epicatechin-3-gallate being particularly effective. The production of liquid peroxidation by 1,4-naphthoquinone was not inhibited by the tea extract nor by tea polyphenol addition. After 2h of incubation, the protein thiol concentration was reduced by 1,4-naphthoquinone, but this reduction was prevented by the tea extract and tea polyphenols. The reduction in protein thiol content of the cells closely paralleled the LDH leakage and loss of cell viability. These results suggest that the mechanism of protection by tea polyphenols against 1,4-naphthoquinone-induced toxicity to rat hepatocytes was due to the maintenance of protein thiol levels.     

茶多酚影响乳腺癌组织C-Jun蛋白表达研究

目的:观察茶多酚对移植性小鼠乳腺癌(EMT6)肿瘤组织中C-Jun原癌基因蛋白表达的影响。方法:应用小鼠可移植性乳腺癌EMT6细胞系,经培养传代后,以纯系BALB/c小鼠为荷瘤动物进行肿瘤移植;采用茶多酚灌胃及局部注射两种干预措施,以免疫组化方法检测小鼠乳腺癌组织C-Jun表达。结果:与模型对照组比较,茶多酚两种给药途径的肿瘤组织C-Jun阳性表达明显降低(P<0.05)。结论:茶多酚可明显抑制原癌基因蛋白C-Jun表达,这一环节可能是参与抑制肿瘤新生血管重要过程。     

Bioactive components from the tea polyphenols influence on endogenous antioxidant defense system and modulate inflammatory cytokines after total-body irradiation in mice

The present study aimed to evaluate the radioprotective efficacy of green tea polyphenols and the component ingredients against irradiated-induced damage in mice and elucidate the underlying mechanisms. Green tea polyphenols (GTP 50, 50 and 100 mg/kg, p.o. daily) and its four individual components (25 and 50 mg/kg, p.o. daily) were administrated to the irradiated-injured mice for 21 days. The radioprotective effect on the hematopoietic system, serum cytokines, and endogenous antioxidant enzymes was studied. GTP 50 significant revert the irradiated-induced decline in hematological parameters (RBCs, WBCs, Hb), meanwhile, protected antioxidant defense system, as evidenced by decreased of serum lipid peroxidation (malonyldialdehyde) and elevation the antioxidant enzyme superoxide dismutase (SOD). Among the GTP components, catechin showed the best effect on elevation of hematological parameters, and epigallocatechin gallate showed the best antioxidant activity. Moreover GTP and its bioactive components (catechin, epigallocatechin and epigallocatechin-3-gallate) assisted in decreasing the leukocytopenia seen after whole mice irradiation and significantly reduced the elevated serum inflammatory cytokines (TNF-α, IL-1β, and IL-6). Green tea polyphenols have a potential to be developed as radioprotective agents against irradiated-induced toxicity. Furthermore the antioxidant and anti-inflammatory activities of GTP can be attributed to the interaction of the different components through multiple and synergistic mechanisms.     

茶多酚干预乳腺癌组织及重要器官血管生成相关因子表达研究

目的:观察茶多酚对移植性小鼠乳腺癌(EMT_6)组织与重要脏器(心、脑、肾)组织血管生成相关因子表达影响。方法:应用小鼠可移植性乳腺癌EMT_6细胞株,经培养传代后,以纯系BALB/c小鼠为荷瘤动物进行移植,并采用茶多酚灌胃及局部注射两种干预措施,以免疫组化方法检测小鼠乳腺癌组织VEGF、bFGF、TIMP-2表达,并测定心、脑、肾组织中VEGF及TIMP-2表达。结果:与模型对照组比较,茶多酚两种给药途径的肿瘤组织VEGF、bFGF阳性表达明显降低(P<0.05);TIMP-2阳性表达明显增高(P<0.05);而心、脑、肾组织VEGF、TMP-2阳性表达无明显差异(P>0.05)。结论:茶多酚可明显抑制新生血管生成相关因子表达,并特异性的作用于肿瘤靶点部位,预示在肿瘤治疗领域具有广泛的应用前景。     

Microwave‐assisted water extraction of green tea polyphenols

Introduction – Green tea, a popular drink with beneficial health properties, is a rich source of specific flavanols (polyphenols). There is a special interest in the water extraction of green tea polyphenols since the composition of the corresponding extracts is expected to reflect the one of green tea infusions consumed worldwide. Objective – To develop a microwave‐assisted water extraction (MWE) of green tea polyphenols. Methodology – MWE of green tea polyphenols has been investigated as an alternative to water extraction under conventional heating (CWE). The experimental conditions were selected after consideration of both temperature and extraction time. The efficiency and selectivity of the process were determined in terms of extraction time, total phenolic content, chemical composition (HPLC‐MS analysis) and antioxidant activity of the extracts. Results – By MWE (80°C, 30 min), the flavanol content of the extract reached 97.46 (± 0.08) mg of catechin equivalent/g of green tea extract, vs. only 83.06 (± 0.08) by CWE (80°C, 45 min). In particular, the concentration of the most bioactive flavanol EGCG was 77.14 (± 0.26) mg of catechin equivalent/g of green tea extract obtained by MWE, vs 64.18 (± 0.26) mg/g by CWE. Conclusion – MWE appears more efficient than CWE at both 80 and 100°C, particularly for the extraction of flavanols and hydroxycinnamic acids. Although MWE at 100°C typically affords higher yields in total phenols, MWE at 80°C appears more convenient for the extraction of the green tea‐specific and chemically sensitive flavanols. Copyright © 2009 John Wiley & Sons, Ltd.     

Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals

With the use of the spin trapping methods, the scavenging effects of the extracts of green tea and other natural foods are studied. In stimulated polymorphonuclear leukocytes (PMN) system, water extract fraction 6 (F6) from green tea and green tea polyphenols (GTP) have the strongest scavenging effect on the active oxygen radicals, much stronger than vitamin C (Vc) and vitamin E (VE). Rosemary antioxidants (RA) and Curcumin (Cur) have weaker scavenging effects than Vc, but stronger than VE. In Fenton Reaction, Cur has the strongest scavenging effect (69%) on hydroxyl radicals. In irradiation, riboflavin system F6(74%) and GTP(72%) have very strong scavenging effects that are weaker than Vc, but much stronger than VE (23%). With the use of spin probe oxymetry, the oxygen consumption in respiratory burst of stimulated PMN were measured when the antioxidants existed in these systems. The results demonstrated that these antioxidants did not affect the respiratory burst of human polymorphonuclear leukocytes stimulated with PMA.     

Cancer chemoprevention by tea polyphenols

Tea is one of the most widely consumed beverages, second only to water. Many experimental researches in laboratory animals demonstrated that tea components had an inhibitory effect on carcinogenesis at a number of organ sites. The inhibitory effects of tea against carcinogenesis have been attributed to the biologic activities of the polyphenol fraction in tea. This review summarizes experimental data on chemopreventive effects of tea polyphenols in various tumor bioassay systems. Many laboratory studies have demonstrated the inhibitory effects of green tea polyphenols, especially (-)-epigallocatechin-3-gallate (EGCG), on carcinogenesis in animals models. The majority of these studies have been conducted in mouse skin tumor models, where tea polyphenols were used either as oral feeding in drinking water or in direct local application. Most studies used 12-O-tetradecanoylphorbol-13-acetate (TPA) or ultraviolet (UV) radiation as the tumor promoter and found anticarcinogenic effects caused by green tea polyphenols. Black tea was also found to be effective, although the activity was weaker than that of green tea in some experiments. Other studies showed that black tea polyphenols-theaflavins exhibited stronger anticarcinogenic activity than did EGCG. Caffeine in tea was also important for tea to prevent tumorigenesis. The molecular mechanisms of the cancer chemopreventive effects of tea polyphenols are not completely understood. They are most likely related to the mechanisms of biochemical actions of tea polyphenols, which include antioxidative activities, modulation of xenobiotic metabolite enzymes and inhibition of tumor promotion. In addition, we have also proposed that tea polyphenols function as cancer chemopreventive agents through modulation of mitotic signal transduction. However, the molecular mechanisms involved in this modulation need further investigation.