咖啡酸衍生物对自由基致DNA氧化损伤的联合保护作用

目的:探讨咖啡酸衍生物（CADs）:绿原酸（Chlorogenic acid,ChA）、阿魏酸（Ferulic acid,FeA）、迷迭香酸（Rosmarinic acid,RoA）对自由基致DNA损伤的联合抑制保护效果。方法:运用DPPH自由基及羟自由基反应模型观察不同组成的CADs对自由基的淬灭效应,以CuSO₄-Phen-VitC-H₂O₂-DNA化学发光体系测定不同成分的多酚类物质对·OH致DNA损伤的抑制作用。结果:在30min时间内,三种CADs联合组在浓度为25、50、100、200μg/mL时,对DPPH·清除率分别为28.93%、58.39%、83.93%和84.09%;对·OH清除率分别为33.43%、55.27%、71.23%、77.49%。在DNA化学发光体系中,在25～200μg/mL范围内,三种CADs联合组对DNA损伤产物发光抑制率为12.49%～81.09%。结论:CADs能有效清除DPPH自由基和羟自由基,抑制羟自由基引发的DNA损伤程度,并延迟其受损伤的时间。在各实验组中三种CADs联用组在对DPPH自由基清除率、DNA损伤产物发光抑制率以及保护DNA损伤的能力均最强,体现出协同作用。      

苦丁茶多酚提取物对四氯化碳诱导小鼠肝损伤的改善作用及机制研究

本文研究苦丁茶多酚提取物(PEK)对小鼠肝损伤的改善效果。通过腹腔注射CCl₄诱导小鼠肝损伤,采用苦丁茶多酚提取物(PEK)灌胃昆明小鼠,对小鼠的血清和肝组织的mRNA表达进行了检测。结果显示,PEK中多酚物质的含量为71.3%。与模型组相比,PEK能够显著降低CCl₄诱导肝损伤小鼠的肝指数和血清中天门冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)、碱性磷酸酶(ALP)、甘油三酯(TG)、总胆固醇(TC)、尿素氮(BUN)、一氧化氮(NO)和丙二醛(MDA)水平,提高白蛋白(ALB)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)水平;PEK还能够显著降低肝损伤小鼠血清中白细胞介素-6(IL-6)、白细胞介素-12(IL-12)、肿瘤坏死因子α(TNF-α)和γ-干扰素(IFN-γ)细胞因子含量(p<0.05)。病理学观察表明,PEK能够有效地降低CCl₄造成肝组织形态不完整和肝细胞坏死。逆转录聚合酶链式反应(RT-PCR)实验结果表明,PEK能够显著上调小鼠肝组织中锰超氧化物歧化酶(Mn-SOD)、铜锌超氧化物歧化酶(Gu/Zn-SOD)、CAT、GSH-Px等抗氧化酶的mRNA表达和下调环氧化酶2(COX-2)、白细胞介素-1β(IL-1β)、TNF-α表达(p<0.05)。由此可见,PEK是一类具有肝损伤改善作用的活性成分,具有较好的应用前景。     

黄曲霉毒素B1致肝脏损伤作用机制的研究进展

黄曲霉毒素B1(aflatoxin B1, AFB1)是一种毒性极强的真菌毒素, 也是诱发肝癌的重要危险因素之一。AFB1与乙肝病毒两者协同致癌作用比单因素乙肝病毒诱发肝癌高约30~60倍。AFB1进入体内后主要通过引发DNA损伤发挥毒性作用, 其中DNA-加合物是最常见的损伤形式, 而表观遗传修饰的改变在其致肝脏损伤中也发挥着显著的作用。本文综述了近年来AFB1致肝脏损伤的相关研究进展, 总结出AFB1可能的致癌机制, 以期为防治黄曲霉毒素引起的肝脏损伤提供理论依据。     

大孔树脂纯化废酒花黄腐酚及其抗DNA氧化损伤的活性

采用大孔树脂从酿造废酒花中分离纯化黄腐酚,并且检测了黄腐酚抗DNA氧化损伤的活性。结果表明:HPD100A树脂对黄腐酚的吸附率为100%,解吸率为77.69%,适合于废酒花黄腐酚的纯化。最佳工艺条件为:上样液黄腐酚质量浓度0.25mg/m L、上样量15BV、上样液p H5.5、上样流速2BV/h,洗脱剂为95%乙醇,洗脱流速2BV/h,洗脱剂用量3BV。在此条件下,可将黄腐酚纯度由纯化前的4.95%提高为51.50%,回收率为72.56%。结果表明,分离得到的黄腐酚纯化物对Phen-Cu SO4-VC诱导DNA氧化损伤的抑制作用（EC50为0.22mg/m L）显著优于抗坏血酸（EC50为0.51mg/m L）和芦丁（EC50为0.93mg/m L）,具有显著地抗DNA氧化损伤活性。      

山楂不同溶剂提取物的抗氧化活性及对DNA和蛋白质氧化损伤的保护作用

研究山楂甲醇、乙醇、丙酮、乙酸乙酯、氯仿、石油醚等不同极性溶剂提取物的总多酚、总黄酮含量及其成分组成,并分析比较不同提取物的体外抗氧化活性及其对DNA和蛋白质氧化损伤的保护效果。结果表明,山楂的不同溶剂提取物中总多酚、总黄酮含量及其生物活性不同。其中,甲醇提取物中总多酚和总黄酮含量均最高,清除DPPH自由基、ABTS自由基能力和铁还原能力最强,对蛋白质和DNA氧化损伤的保护作用亦优于其他提取物。山楂甲醇提取物主要活性成分为表儿茶素、原花青素B2、绿原酸和槲皮素。山楂提取物的总多酚、总黄酮含量与其抗氧化活性、DNA和蛋白质氧化损伤的保护效果均具有较高的相关性。     

茶叶中表没食子儿茶素没食子酸酯抑制中波紫外线诱导HaCaT细胞氧化损伤研究

目的研究茶叶中表没食子儿茶素没食子酸酯(EGCG)对中波紫外线(UVB)诱导的人表皮角质形成细胞(HaCaT)光损伤的保护作用。方法用不同浓度的EGCG对HaCaT细胞进行预处理6 h,采用60 m J/cm2的剂量照射细胞,用MTT法检测细胞生存率,吸取细胞上清液检测超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH–Px)、乳酸脱氢酶(LDH)的活性和丙二醛(MDA)含量变化,用荧光法检测细胞内ROS含量。结果 UVB辐射对Ha Ca T细胞造成严重损伤,与对照组相比,细胞活性下降21.63%;与UVB辐射模型组相比,EGCG尤其高剂量可提高UVB照射后HaCaT细胞的存活率5.89%,显著提高SOD、GSH–Px活性(P0.01),降低LDH活性(P0.01),减少自由基ROS和MDA含量(P0.01)。结论 EGCG可以减少UVB诱导HaCaT细胞的损伤和凋亡,具有光保护作用,其机制与增强细胞抗氧化能力和加速清除氧自由基有关。     

Mechanism of DNA damage induced by arecaidine: The role of Cu(II) and alkaline conditions

Betel quid chewing is a widely prevalent habit correlated with a high incidence of oral cancer. However, the underlying mechanism of the carcinogenicity of betel quid chewing is poorly understood. In the present study, the carcinogenic mechanism of action of betel quid chewing was examined by determining DNA damage induced by arecaidine and Cu(II). It was found that arecaidine alone had no significant effect on inducing DNA damage, but it caused significant DNA double stand breaks in the presence of Cu(II) ions under alkaline conditions. Further studies showed that reactive oxygen species were generated and Cu(I) was formed in the reaction. The arecaidine anion exhibited a lower IP and a higher HOMO energy than arecaidine itself, suggesting an increased ability to donate electrons under alkaline pH conditions. These results suggest that the presence of Cu(II) and alkaline conditions are two essential factors in arecaidine-induced DNA damage, a contributing factor to oral cancer occurrence.     

基于脱细胞、细胞和体内彗星试验的全氟辛酸致DNA损伤研究

目的 本研究通过体内外联合试验探索全氟辛酸（PFOA）致DNA损伤情况。方法 以脱细胞核DNA作为模型,0.00、0.13、0.25、0.50 mmol/L PFOA染毒1 h后检测脱细胞核DNA损伤情况。以YAC-1细胞系为模型,采用CCK-8法测定不同染毒剂量对细胞活性的影响。在细胞彗星试验中,PFOA终浓度设定为0、1.0×10^-8、1.0×10^-7、1.0×10^-6 mol/L,连续暴露3 d,检测DNA损伤情况。0、10、20、40 mg/kg·BW PFOA分别灌胃给予大鼠两次,间隔24 h,末次给予受试物6 h后,采用肝脏、骨髓和外周血细胞开展中性和碱性彗星试验,利用骨髓细胞开展骨髓微核试验。结果 脱细胞碱性彗星试验各剂量组尾部DNA含量显著高于对照组（P<0.05）,呈剂量-反应关系,脱细胞中性彗星试验无显著差异（P>0.05）;细胞碱性彗星试验各剂量组尾部DNA含量显著高于对照组（P<0.05）,呈剂量-反应关系,细胞中性彗星试验无显著差异（P>0.05）;体内彗星联合微核试验表明,与对照组相比,肝脏、骨髓和外周血细胞碱性和中性彗星试验各剂量组尾部DNA含量,以及骨髓微核各剂量组无显著差异（P>0.05）。结论 PFOA在体外对DNA具有损伤作用,经口染毒未见对大鼠产生DNA损伤。     

Assessment of the ability of seaweed extracts to protect against hydrogen peroxide and tert-butyl hydroperoxide induced cellular damage in Caco-2 cells

The ability of brown seaweed extracts, Ascophyllum nodosum, Laminaria hyperborea, Pelvetia canaliculata, Fucus vesiculosus and Fucus serratus to protect against tert-butyl hydroperoxide (tert-BOOH) induced stress in Caco-2 cells was investigated. Oxidative stress was determined by measuring alteration in the enzymatic activity of catalase (CAT) and superoxide dismutases (SOD) and cellular levels of glutathione (GSH). L. hyperborea, P. canaliculata and F. serratus significantly protected against tert-BOOH induced SOD reduction but did not protect against the reduction in CAT activity or the increased cellular levels of GSH. The ability of F. serratus and F. vesiculosus to protect against H₂O₂ and tert-BOOH induced DNA damage was also assessed. The DNA protective effects of the two seaweed extracts was compared to those of three metal chelators; deferoxamine mesylate (DFO), 1,10-phenanthroline (o-phen) and 1,2-Bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetrakis (BAPTA-AM). F. serratus and F. vesiculosus significantly protected (P < 0.05) against H₂O₂ (50 μM) induced DNA damage but not tert-BOOH induced damage.     

Antioxidant activity of enzymatic extracts from a brown seaweed Ecklonia cava by electron spin resonance spectrometry and comet assay

The potential antioxidant activity of enzymatic extracts from Ecklonia cava was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and alkyl radical scavenging using a electron spin resonance (ESR) spectrophotometer compared with ESR signal intensity and inhibitory effect of DNA damage on comet assay. E. cava was enzymatically hydrolyzed with five food industrial carbohydrases (AMG, Celluclast, Termamyl, Ultraflo and Viscozyme) from Novozyme Nordisk. All the tested extracts exhibited strong radical scavenging activities and the values were dose-dependent. The DPPH and hydroxyl radical scavenging activities of the enzymatic extracts were compatible with the vitamin C, which the alkyl radical scavenging activity was even higher than that of vitamin C. Also in the present study, the enzymatic extracts showed strong inhibitory effect against DNA damage in a dose dependent manner. These results indicated that the E. cava might be valuable natural antioxidative source.     

Phenolic composition and inhibitory effect against oxidative DNA damage of cooked cowpeas as affected by simulated in vitro gastrointestinal digestion

Cowpeas contain phenolic compounds with potential health benefits. The effect of simulated gastrointestinal digestion on phenolic composition of cooked cowpeas and the ability of the digests to inhibit radical-induced DNA damage was determined. A red and a cream-coloured cowpea type were used. The phenolic composition of acetone extracts and enzyme digests of cooked cowpeas was determined using UPLC-MS. Compounds such as p-hydroxybenzoic acid, p-coumaric acid, coumaroylaldaric acid and feruloylaldaric acid were present in the acetone extracts of the cooked cowpeas but were not detected in the enzyme digests. Glycosides of quercetin and myricetin decreased upon in vitro gastrointestinal digestion of cooked cowpeas whereas flavan-3-ols were hardly present except catechin glucoside. The enzyme digest of the red cowpea type was about thrice as effective as that of the cream cowpea type in protecting DNA from oxidative damage. The observation that enzyme digests of cooked cowpeas inhibited radical-induced DNA damage suggests that cowpea phenolics retain some radical scavenging activity after gastrointestinal digestion.     

免疫初乳中乳抗体对大肠杆菌和沙门氏菌所致小鼠腹泻的被动免疫保护

以24株人肠道病原菌(包括病原性大肠杆菌12株、沙门氏菌8株、志贺氏菌3株、小肠结肠炎耶尔森氏菌1株)作为抗原，对乳牛进行系统免疫，免疫乳与非免疫乳乳中IgG含量无显著差异。系统免疫并不增加乳中IgG的含量，但IgG的抗体特异性大大增强，所得的免疫初乳中乳抗体对24种不同病原菌的凝集价为2^8-2^12，为普通初乳中乳抗体凝集价的32—256倍。采用硫酸胺盐析从免疫初乳中分离乳抗体，免疫初乳中的特异性IgG乳抗体较普通初乳中的IgG可显著抑制大肠杆菌和沙门氏菌的生长。动物试验表明，免疫乳中特异性的IgG对大肠杆菌和沙门氏菌所致小鼠腹泻具有很好的保护作用，而普通乳中非特异性的IgG则无此作用，这是由于IgG的特异性所决定。     

In vitro DNA damage protection and anti‐inflammatory effects of Tartary buckwheats (Fagopyrum tataricum L. Gaertn) fermented by filamentous fungi

The present work was designed to investigate the phenolic profiles, DNA damage protection and anti‐inflammatory effects of Tartary buckwheat fermented by Rhizopus oryzae 40469, Rhizopus oryzae 40503 and Rhizopus oligosporus 3152. Six phenolic compounds were characterised and quantified. Regardless of fermentation, rutin was the dominant phenolic substance in Tartary buckwheat. Fermentation significantly enhanced total phenolic and flavonoid contents, as well as DNA scission protection. Rhizopus oryzae 40469‐fermented sample had the highest content of phenolics, while R. oligosporus 3152‐fermented sample had the strongest inhibitory effect on DNA scission. Tartary buckwheat, regardless of fermentation, inhibited nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA levels in LPS‐induced RAW 264.7 cells. Moreover, the sample fermented with R. oryzae 40503 had the strongest inhibitory activity. Those results indicated that fermented Tartary buckwheat has potential applications as a novel nutraceutical or functional food for preventing DNA damage‐induced disease and inflammation.