刺五加提取物在自由基模型中的活性作用

背景与目的： 研究刺五加醇提物和水提物在几种自由基体外模型中的抗氧化作用。 材料与方法： 建立DPPH体系,观察刺五加不同浓度的醇提物和水提取物对DPPH自由基的抑制作用;建立·OH和O2 两种化学发光体系观察刺五加不同浓度的两种提取物对发光强度的抑制作用;采用CHP、VC／Fe2＋和CC14／NADP作为激发剂,建立微粒体脂质过氧化(LPO)损伤模型,观察不同浓度的刺五加两种提取物对MDA生成的抑制作用。 结果：在DPPH体系中,刺五加两种提取物对DPPH的抑制率均显著高于对照组 (P<0.01),呈明显剂量-效应关系,刺五加醇提物和水提物对DPPH的IC50分别为0.18 mg/ml和0.09 mg/ml;在两种化学发光的体系中,除了0.625 mg/ml的刺五加醇提物与对照组的差异无统计学意义(P=0.102),其它浓度的两种提取物对O2 和·OH的抑制率均显著高于对照组(P<0.01),呈明显剂量-效应关系,刺五加醇提物的IC50分别为0.488 mg/ml和1.29 mg/ml;水提物为 0.24 mg/ml和0.37 mg/ml;在CHP模型中,1.25 mg/ml的刺五加水提物表现出了一定的促氧化作用,但差异无统计学意义 (P>0.05)。3种LPO损伤模型中刺五加两种提取物各浓度组的MDA含量均显著低于对照组(P<0.05),且有一定的剂量-效应关系。 结论： 刺五加在几种体外模型中均具有较强的抗氧化作用,在DPPH和两种化学发光体系中,刺五加水提物的抗氧化活性强于醇提物;而在3种LPO模型中,刺五加醇提物的抗氧化活性强于水提物。     

川芎提取物的多模型体系抗氧化活性测定

目的：研究川芎醇提物和水提物在几种自由基体外模型中的抗氧化作用位点与活性强度,以及此两种提取物在小鼠氧化损伤模型中的综合抗氧化作用。方法：建立DPPH体系,观察川芎醇提物和水提物对DPPH自由基的清除率;建立OH和O_2~-化学发光体系观察川芎的两种提取物对发光强度的抑制作用;采用CHP、Vc/Fe~（2＋）和CCl_4/NADP~＋作为激发剂,建立微粒体脂质过氧化（LPO）损伤模型,观察川芎两种提取物对MDA生成的抑制作用。建立小鼠氧化损伤模型,观察川芎两种提取物对SOD和CAT蛋白表达水平的影响,以及对MDA生成的抑制作用。结果：在DPPH体系中,川芎的醇和水两种提取物对DPPH的清除率均显著高于对照组（P〈0.01）,且呈明显剂量-效应关系,川芎醇提物和水提物对DPPH的IC_（50）分别为3.47和6.19 mg/ml;在两种化学发光体系中,川芎的醇提物和水提物对O_2~-和OH的清除率均显著高于对照组（P〈0.01）,且呈明显剂量-效应关系,川芎醇提物对O_2~-和OH的IC_（50）分别为2.56和4.21mg/ml,水提物对O_2~-和OH为2.34和2.80mg/ml;3种LPO损伤模型中川芎两种提取物各浓度组的MDA含量均显著低于对照组（P〈0.05）;在体内实验中,与对照组相比,川芎水提物和醇提物组均明显降低肝组织和血清内MDA的含量（P〈0.05）;川芎水提物和醇提物能明显提高肝组织内SOD蛋白表达水平;川芎醇提物可以提高肝组织内CAT蛋白表达水平。结论：川芎提取物在几种体外模型和体内模型中均具有较好的抗氧化作用。     

过氧化氢对不同时相HepG2细胞氧化作用的研究

背景与目的:研究过氧化氢(H2O2)对不同时相HepG2细胞作用的选择性,以进一步探讨H2O2:诱导肿瘤细胞凋亡的机制.材料与方法:以胸腺嘧啶核苷(TdR)阻断法获得不同细胞周期时相的同步化细胞,分别加入800 μmol/L的H2O2作用3 h,并检测各组细胞的丙二醛(MDA)含量、黄嘌呤氧化酶(XOD)和5'核苷酸酶(5'NT)的活性及抗羟自由基(抗·OH)和抗超氧阴离子自由基(抗O2)的活性.结果:经H2O2处理的各组MDA含量和XOD、抗·OH、抗O2活性显著高于对照组,其差异均具有统计学意义(P均＜0.01),5'NT活性低于对照组(P＜0.01).与未同步化组比较,同步化于S期和G2/M期的细胞MDA含量和XOD、5'NT、抗·OH和抗O2活性显著升高,其差异均具有统计学意义(P均＜0.01),而同步化于G1期的细胞MDA含量、XOD、5'NT和抗O2-活性显著降低,差异均具有统计学意义(P均＜0.01).结论:H2O2作用同步化HepG2细胞后,代谢产生自由基的酶活性,脂质过氧化产物含量以及抗氧化水平均表现出细胞周期特异性,这可能是过氧化氢对不同时相HepG2细胞损伤作用不同的原因.     

中药提取物在肝微粒体和相关自由基模型中反应性的筛选

背景与目的 :检验“抗氧化剂复合链”假说指导筛选的复合抗氧化剂在大鼠肝微粒体自由基反应模型中的反应性。材料与方法 :微粒体模型和动物模型和微粒体脂质过氧化活化体系包括 :CCl4、Vc/Fe 、CHP、耗氧量等模型以及相关自由基反应模型包括羟胺竞争法发生超氧阴离子自由基和抗坏血酸/铜产生羟自由基等模型 ,筛选和测定了中药的水和乙醇提取物的抗氧化活性 ,以及经过筛选组成的复合抗氧化剂对自由基的综合抑制效应。结果 :当归、人参、枸杞、黄芪、党参的水提取液在微粒体CCl4、VC/Fe 、CHP激发模型及自由基模型中 ,均呈现不同程度的脂质过氧化的抑制作用 ,但是 ,人参水提取液除了对VC/Fe 激发模型的抑制作用较弱外 ,均表现出较强的抗氧化作用 ;枸杞、党参、黄芪水提取液除了对超氧阴离子自由基(O-.)模型和枸杞乙醇提取液对CHP模型呈现较强的过氧化刺激作用外 ,各种乙醇提取液对CCl4、VC/Fe 、CHP和摄氧量激发模型均表现为不同程度的抑制作用。复合抗氧化剂_安体欣对所选模型均呈现较强的自由基生成抑制作用。结论 :中药当归、人参、枸杞、黄芪、党参的水或乙醇单独提取物的抗氧化作用存在局...     

葡萄籽提取物对老龄大鼠MDA、GSH-Px、SOD的影响

背景与目的:探讨不同浓度的葡萄籽提取物(GSE)对老龄大鼠抗氧化的作用.材料与方法:取wistar大鼠40只,设葡萄籽提取物0.1、0.5、2.5 g/kg 3个剂量组和1个溶剂对照组,每组10只,灌胃给予受试物,每天1次,连续60 d.于第61 d股静脉取血并杀鼠取肝脏制备肝匀浆,分别测定血清过氧化脂质(MDA)和谷胱甘肽氧化酶(GSH-Px)、肝组织超氧化歧化酶(SOD).结果:3个剂量组SOD活性与溶剂对照组比较差异均无统计学意义(P＞0.05).仅2.5 g/kg剂量组所测的MDA含量和GSH-Px与溶剂对照组比较差异均有统计学意义(P＜0.01).结论:葡萄籽提取物有降低雌性老年大鼠(鼠龄15个月)血清中MDA含量、升高血清中GSH-Px活性的作用,提示其具有一定的抗氧化作用.     

萌动激活赤灵芝孢子粉对肿瘤组织中MDA水平的影响

丙二醛(malondialdehyde,MDA)是脂质过氧化反应的分解产物.肿瘤组织中MDA的检测可以直接反映肿瘤引起的脂质过氧化程度,从而反映自由基在体内的水平.目前有关灵芝孢子粉对自由基影响的报道较少,本文对此作以报道.     

放、热疗对荷瘤鼠肿瘤及肝MDA含量SOD活性的影响

目的探讨局部放热疗对S180荷瘤小鼠肿瘤及肝脏脂质过氧化水平及抗氧化能力的影响.方法本文采用硫代巴比妥酸(TBA)法及亚硝酸盐法,测定经局部放射、加温、放射合并加温后荷瘤小鼠肿瘤及肝脏丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性.各组数据采用SPSS软件包作两两比较分析.结果肿瘤组织MDA含量及SOD活性各组无差异(P＞0.05).肝组织加温组MDA含量高于放射组及实验对照组(P＜0.05),其它各组间MDA含量未见显著差异.加温组及放射合并加温组SOD活性均显著低于放射组及实验对照组(P＜0.01),其它各组间SOD活性未见显著差异.结论局部加温可能使荷瘤小鼠肝脏产生大量自由基,使SOD活性降低,MDA含量升高.因此,脂质过氧化损伤可能是加温对机体造成损伤的机制之一.     

红景天提取物对微粒体LPO模型的影响

背景与目的： 探讨红景天醇提物和水提物的抗氧化作用及其剂量反应关系。 材料与方法： 回流法和煎煮法分别制备红景天醇提物和水提物。钙沉淀法提取雄性SD大鼠肝微粒体。采用四种激发剂Vc/Fe2＋、过氧基异丙苯(Cumine hydroperoxide,CHP)、 CCl4/辅酶Ⅱ(Nicotinamide-adenine dinucleotide phosphate, NADP)和还原型辅酶Ⅱ(Reduced form of nicotinamide-adenine dinucleotide phosphate,NADPH)-腺苷二磷酸(Adenosine diphosphate,ADP)／Fe2＋建立微粒体脂质过氧化(Lipid peroxidation,LPO)模型,加入浓度为 25 mg/ml、12.5 mg/ml、6.25 mg/ml、3.13 mg/ml、1.56 mg/ml的红景天醇提物和水提物,观察在4 种模型系统中抗氧化作用。在VC/Fe2＋、CHP、 CCl4/NADP模型中通过比色法测定对丙二醛(Malondialdehyde,MDA)的抑制作用,NADPH-ADP／Fe2＋模型通过氧电极法测定对耗氧量的抑制作用。 结果： 红景天水提物在浓度为6.25～25.00 mg/ml范围内,其CHP模型中的MDA含量显著低于阳性模型对照组。在 Vc/Fe2＋、CHP和CCl4/NADP 模型中,红景天醇提物和水提物各浓度组MDA含量均非常显著低于对照组,并且在一定终反应浓度内有剂量-反应关系。在NADPH-ADP／Fe2＋模型中,最高浓度的醇提物和水提物的抑制率分别达到76％和43％。 结论： 红景天的两种提取物都具有较强的抗氧化作用,并存在一定的剂量效应关系。其中红景天醇提物对酶参与性反应的作用强于水提物。该研究初步探讨了红景天抗氧化作用的机制,其结果为红景天在自由基损伤中的保护作用提供了实验依据。     

三七醇提物对大鼠肝组织体内外抗氧化作用的研究

目的：研究三七（panax notoginseng,PNG）醇提物对大鼠肝组织的体内外抗氧化作用。方法：采用羟自由基（·OH）和超氧阴离子自由基（O_2~-）两种化学发光体系,观察三七醇提物对化学发光强度的抑制作用;采用过氧基异丙苯（cumene hydroperoxide,CHP）、维生素C（V_c）/硫酸亚铁（Fe~（2＋））和四氯化碳（CCl_4）/还原型辅酶Ⅱ（NADPH）作为激发剂,建立3种微粒体脂质过氧化（lipid peroxidation,LPO）损伤模型,观察三七醇提物对内二醛（MDA）生成的抑制作用。用~（60）Coγ射线辐照大鼠建立氧化损伤模型,观察三七醇提物对肝组织的氧化型谷胱甘肽（GSSG）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）含量及活性的影响,以及对MDA生成的抑制作用。结果：在两种化学发光的体系中,三七醇提物对O_2~-和·OH的抑制率均显著高于阴性对照组（P〈0.05）,且呈明显剂量-效应关系,三七醇提物对O_2~-和·OH的IC_（50）分别为1.25和0.625/mg/ml;3种LPO损伤模型中三七醇提物不同浓度组的MDA含量均显著低于对照组（P〈0.05）;在体大鼠氧化损伤模型实验的肝组织中,三七醇提物不同剂量灌胃组[（50、225和450mg/（kg·d）],其MDA的含量均较阳性对照组（仅做~（60）Coγ照射）降低（P〈0.05）;225和450mg/（kg·d）剂量组CAT活性较阳性对照组显著升高（P〈0.05）;其450mg/（kg·d）剂量组SOD的活性较阳性对照组显著升高（P〈0.05）;而225和1450mg/（kg·d）剂量组GSSG含量较阳性对照组显著降低（P〈0.05）。结论：三七醇提物对体外氧化损伤模型具有很强的抗氧化作用,对辐射引起的大鼠体内肝脏氧化损伤具有一定的抗氧化修复功效,并呈剂量-效应关系。     

扶正解毒汤对硫酸镍诱导16HBE细胞微核形成的抑制作用

背景与目的:研究中药扶正解毒汤(FJD)对硫酸镍(NiSO4)诱导人支气管上皮细胞(16HBE)微核形成的抑制作用.材料与方法:分别以NiSO4暴露、不同浓度FJD含药血清与NiSO4共同处理体外培养的16HBE细胞,观察其微核率的变化,并采用激光扫描共聚焦显微镜检测不同处理组细胞内Ni2+、Mg2+、Zn2+浓度及自由基含量的变化.结果:与阴性对照组相比,NiSO4(400 μmol/L)暴露组细胞微核率、细胞内Ni2+浓度及自由基含量均明显增高(P＜0.01),而细胞内Mg2+、Zn2+浓度则明显降低(P＜0.01).与NiSO4暴露组相比,低、中、高剂量FJD血清与NiSO4共处理组细胞微核率分别为(62.4±11.5)‰、(35.2±7.1)‰及(27.6±5.6)‰,显著低于NiSO4暴露组(P＜0.05,P＜0.01),细胞内Ni2+浓度及自由基含量下降,Mg2+、Zn2+浓度升高(P＜0.05,P＜0.01).结论:FJD对镍诱导16HBE细胞微核形成有明显的抑制作用,其机制可能与调节染镍细胞内某些金属元素含量变化及清除自由基有关.     

Chemopreventive activity of a macrofungus Phellinus rimosus against N-nitrosodiethylamine induced hepatocellular carcinoma in rat

Chemoprevention is an important alternative approach to control cancer. Chemical substances with multiple inhibitory properties would be a welcome addition to the class of chemopreventive drugs. In this study, we investigated the antioxidant, anti-inflammatory, antimutagenic and cancer preventive activities of aqueous extract of a macrofungus Phellinus rimosus (Berk) Pilat. The extract exhibited superoxide anion (O2-), hydroxyl radical (*OH), nitric oxide (NO*) scavenging and lipid peroxidation inhibiting activities. The inhibitory concentrations required by the extract to scavenge 50% (IC50) of the superoxide anion, hydroxyl radical and nitric oxide generated were 126 +/- 5.1, 71 +/- 4.7 and 31 +/- 4.5 microg/ml respectively. The concentration required to inhibit 50% of Fe2+ induced lipid peroxidation in rat liver homogenate was 318 +/- 2.4 microg/ml. The extract showed significant (P<0.05) anti-inflammatory activity in a dose dependent manner. Extract (100 mg/kg body wt, p.o) inhibited 44.5, 45.4 and 47% carrageenen, dextran and formalin induced inflammations respectively. The antimutagenic activity was determined by the Ames' Salmonella mutagenecity assay using histidine mutant Salmonella typhimurium strains. The extract at concentration of 5 mg/plate showed antimutagenecity against benzo[a]pyrene (B[a]P) and 4-nitro-o-pheneylenediamine (NPDA) induced mutations of TA98 and TA100 respectively. Anticarcinogenic activity was evaluated using N-nitrosodiethylamine (NDEA) induced hepatocellular carcinoma (HCC) in rats. Serum gamma glutamyl transpeptidase (GGT), glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and alkaline phosphatase (ALP) activities and lipid peroxidation level (MDA) were elevated significantly (P<0.05) in the NDEA alone treated group of animals. Treatment of the extract (25 and 50 mg/kg body wt, p.o.) prior to the NDEA administration decreased the serum GGT, GOT, GPT and ALP activities and MDA level in a dose dependent manner. The NDEA alone treated animals showed altered serum albumin/globulin ratio (A:G ratio), hyperfibrinogenaemia, increased hepatic glutathione S-transferase (GST) activity, glutathione-peroxidsae (GPx) activity and reduced glutathione (GSH) level compared to the extract plus NDEA treated group. The extract also inhibited in vitro aniline hydroxylase (AH) activity of rat liver induced by phenobarbitone in a dose dependent manner. The results, thus suggest the significant chemopreventive properties of the aqueous extract of the Phellinus rimosus against NDEA induced hepatocellular carcinoma by its antioxidant, anti-inflammatory and antimutagenic activities.     

Microsomal lipid peroxidation induced by Adriamycin,epirubicin, daunorubicin and mitoxantrone: a comparative study

Summary Rat-liver microsomes and NADPH could reduce Adriamycin, epirubicin and daunorubicin to their free radical forms, which enhanced peroxidation of microsomal lipids less than 2-fold in air but 3- to 5-fold at a pO₂ of 4 mm Hg. Mitoxantrone was not reduced by microsomes and had no effect on microsomal peroxidation. Daunorubicin caused more lipid peroxidation than similar concentrations of either Adriamycin or epirubicin, which were equally efficient. In each case peroxidation was iron-dependent and could be catalysed by ferritin. The antioxidants -carotene and -tocopherol inhibited lipid peroxidation at low or high pO₂. The dose-for-dose difference in the cardiotoxicity of epirubicin compared with Adriamycin is not explained by its effect on microsomal lipid peroxidation. However, the lower incidence of cardiotoxicity with mitoxantrone may be a consequence of its inability to form free radical species and promote lipid peroxidation.     

Dietary flavonoids, quercetin, luteolin and genistein, reduce oxidative DNA damage and lipid peroxidation and quench free radicals

Several dietary flavonoids such as quercetin, luteolin and genistein have been suggested to have cancer chemopreventive effects, although the mechanisms are not fully understood. In the present study, the effects of these flavonoids as antioxidants were investigated in the following systems: (1) production of hydrogen peroxide (H2O2) and superoxide anion (O2*-), (2) lipid peroxidation induced by FeCl2 in rat liver, and (3) formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) induced by either UV or Fenton reaction in calf thymus DNA. The results showed that quercetin and luteolin were equally potent in scavenging H2O2, with genistein having a moderate effect. Quercetin and luteolin had a potent inhibitory effect on O2*- generation by xanthine/xanthine oxidase while genistein had a moderate effect. Quercetin and luteolin were potent in inhibiting lipid peroxidation induced by FeCl2 in rat liver while genistein had a very weak inhibitory effect. All the test compounds had a potent quenching effect on 8-OHdG formation induced by UV light irradiation, with the order of effects being genistein > luteolin > quercetin. Of the test compounds, luteolin exhibited the most potent quenching effect on Fenton-induced 8-OHdG formation. The scavenging of oxygen free radicals, the inhibitory effect on lipid peroxidation and the quenching effect on 8-OHdG formation by quercetin, luteolin and genistein may, at least in part, be responsible for their anticarcinogenic effects.     

NTP technical report on the toxicity and metabolism studies of chloral hydrate (CAS No. 302-17-0). Administered by gavage to F344/N rats and B6C3F1 mice

Chloral hydrate is widely used as a sedative and a hypnotic in pediatric medicine. It is also a byproduct of water chlorination. Chloral hydrate has been shown to be genotoxic in numerous prokaryotic and eukaryotic assay systems including human lymphocytes in vitro. One of its metabolites, trichloroacetic acid, has demonstrated hepatocarcinogenic activity in mice. Trichloroethylene and perchloroethylene, both of which are metabolized to chloral hydrate, have been shown to be carcinogenic in rats and/or mice. Because of this evidence of carcinogenicity and because of the wide-spread use of chloral hydrate, 16- or 17-day range-finding toxicity studies and separate 16- or 17-day metabolism studies were performed in F344/N rats and B6C3F1 mice in preparation for further long-term rodent studies. In addition, in vitro studies of the metabolism and DNA-binding capacity of chloral hydrate and its metabolites were performed. Genetic toxicity studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, Drosophila melanogaster, and mouse bone marrow cells. For the range-finding studies, groups of eight male and eight female F344/N Nctr BR rats and B6C3F1/Nctr BR (C57BL/6N x C3H/HeN MTV-) mice were administered 0, 50, 100, 200, 400, or 800 mg chloral hydrate per kg body weight in water by gavage 5 days per week for 17 days (rats) or 16 days (mice) for a total of 12 doses. One male rat receiving 800 mg/kg died after five doses. Two 800 mg/kg female rats died after dosing ended but before study termination. One male mouse in each group except the 400 mg/kg group died before the end of the study. Two 800 mg/kg female mice also died before the end of the study. The final mean body weight of 800 mg/kg male rats and the mean body weight gains of 400 and 800 mg/kg males were significantly less than those of the vehicle controls. The mean body weight gains of all groups of dosed male mice were significantly greater than that of the vehicle control group. The only clinical finding in rats and mice attributed to chloral hydrate treatment was light sedation in the 400 mg/kg groups and heavy sedation in the 800 mg/kg groups; sedation subsided within 30 minutes or 3 hours, respectively. The liver weights of 400 mg/kg male mice and 800 mg/kg male and female mice were significantly greater than those of the vehicle control groups. No chemical-related lesions were observed in rats or mice. Male and female rats and mice were administered a single dose of 50 or 200 mg chloral hydrate per kg body weight in water by gavage, or 12 doses of 50 or 200 mg/kg over 17 days (rats) or 16 days (mice). Plasma concentrations of chloral hydrate and its metabolites were determined 15 minutes, 1, 3, 6, and 24 hours, and 2, 4, 8, and 16 days after receiving 1 or 12 doses. Maximum concentrations of chloral hydrate were observed at the initial sampling point of 15 minutes. By 1 hour, the concentrations had dropped substantially, and by 3 hours, chloral hydrate could not be detected in rats or mice. Trichloroacetic acid was the major metabolite detected in the plasma. In rats, the concentrations rose slowly, with the peaks occurring between 1 and 6 hours after treatment. In mice, the peak concentrations were found 1 hour after dosing. The concentrations then slowly decreased such that by 2 days the metabolite could no longer be detected in rats or mice. Trichloroethanol was assayed both as the free alcohol and its glucuronide. In rats, the maximum concentrations of free trichloroethanol occurred at 15 minutes, while the peak concentrations of trichloroethanol glucuronide were found at 1 hour; by 3 hours, concentrations of both metabolites approached background levels. In mice, the maximum concentrations of both metabolites occurred at 15 minutes, and by 1 to 3 hours concentrations approached background levels. The plasma concentrations of chloral hydrate and its metabolites were dose dependent in rats and mice. In mice, plasma concentrations of trichloroacetic acid were significantly higher after a single dose than after 12 doses. None of the metabolic parameters appears to account for species differences that may exist in hepatocarcinogenicity. The data from the study of metabolism and DNA adduct formation indicated that in vitro metabolism of 200 microM to 5 mM chloral hydrate by male B6C3F1 mouse liver microsomes (control microsomes) generated free radical intermediates that resulted in endogenous lipid peroxidation, forming malondialdehyde, formaldehyde, acetaldehyde, acetone, and propionaldehyde. Similar concentrations of trichloroacetic acid and trichloroethanol, the primary metabolites of chloral hydrate, also generated free radicals and induced lipid peroxidation. Lipid peroxidation induced by trichloroacetic acid nearly equaled that induced by chloral hydrate, while that from trichloroethanol was three- to fourfold less. Metabolism of 200 microM to 5 mM chloral hydrate, trichloroacetic acid, and trichloroethanol by liver microsomes of B6C3F1 mice pretreated with pyrazole (pyrazole-induced microsomes) yielded lipid peroxidation products at concentrations two- to threefold greater than those from liver microsomes of untreated mice. Additionally, chloral hydrate-induced lipid peroxidation catalyzed by control and pyrazole-induced microsomes was reduced significantly by 2,4-dichloro-6-phenylphenoxyethylamine, a general cytochrome P450 inhibitor. Human lymphoblastoid transgenic cells expressing cytochrome P(450)2E1 metabolized 200 to 5,000 micrograms/mL chloral hydrate to reactants inducing mutations, whereas the parental cell line was inactive. The malondialdehyde-modified DNA adduct, 3-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrimido[1,2 alpha]purin-10(3H)-one (MDA-MG-1), formed from the metabolism of 1 mM chloral hydrate, trichloroacetic acid, and trichloroethanol by control B6C3F1 mouse liver microsomes, mouse pyrazole-induced microsomes, male F344/N rat liver microsomes, and human liver microsomes in the presence and absence of calf thymus DNA was also determined. When incubated in the absence of calf thymus DNA, the amount of malondialdehyde formed from metabolism by pyrazole-induced mouse microsomes was twice that from rat or human liver microsomes. Amounts of chloral hydrate-induced and trichloroacetic acid-induced lipid peroxidation products formed from metabolism by rat and human liver microsomes were similar, and these quantities were about twice those formed from the metabolism of trichloroethanol. The quantity of MDA-MG-1 formed from the metabolism of chloral hydrate, trichloroacetic acid, and trichloroethanol by mouse, rat, and human liver microsomes exhibited a linear correlation with the quantity of malondialdehyde formed under incubation conditions in the absence of calf thymus DNA. Chloral hydrate was shown to be mutagenic in vitro and in vivo. At doses from 1,000 to 10,000 micrograms/plate, it induced mutations in S. typhimurium strain TA100, with and without S9 activation; an equivocal response was obtained in S. typhimurium strain TA98 in the absence of S9, and no mutagenicity was detected with strain TA1535 or TA1537. Chloral hydrate at doses from 1,700 to 5,000 micrograms/mL induced sister chromatid exchanges; at doses from 1,000 to 3,000 micrograms/mL, chromosomal aberrations were induced in cultured Chinese hamster ovary cells, with and without S9. Results of a sex-linked recessive lethal test in D. melanogaster were unclear; administration of chloral hydrate by feeding produced an inconclusive increase in recessive lethal mutations, results of the injection experiment were negative. An in vivo mouse bone marrow micronucleus test with chloral hydrate at doses from 125 to 500 mg/kg gave a positive dose trend. In summary, due to the absence of chloral hydrate-induced histopathologic lesions in rats and mice, no-observed-adverse-effect levels (NOAELs) were based on body weights of rats and liver weights of mice. The NOAELs for rats and mice were 200 mg/kg. Chloral hydrate was rapidly metabolized by rats and mice, with trichloroacetic acid occurring as the major metabolite. Peak concentrations of trichloroacetic acid occurred more quickly in mice. Plasma concentrations of chloral hydrate were dose dependent, but metabolic rates were unaffected by dose or sex. Chloral hydrate was mutagenic in vitro and in vivo. Metabolism of chloral hydrate and its metabolites produced free radicals that resulted in lipid peroxidation in liver microsomes of mice, rats, and humans. Induction of cytochrome P(450)2E1 by pyrazole increased the concentrations of lipid peroxidation products; inhibition of cytochrome P(450)2E1 by 2,4-dinitrophenylhydrazine reduced these concentrations. Metabolism of chloral hydrate and its metabolites by mouse, rat, and human liver microsomes formed malondialdehyde, and in the presence of calf thymus DNA formed the DNA adduct MDA-MG-1.     

The Effects of Vernonia cinerea Less Extracts on Antioxidant Gene Expression in Colorectal Cancer Cells

Objectives: To investigate the capability of Vernonia cinerea extracts to disrupt the intracellular oxidative-antioxidative status in colorectal cancer cells. Methods: All experiments were conducted on two colorectal cancer cell lines (SW620 and HT29) with aqueous and ethanol extracts of Vernonia cinerea (VC). The cytotoxicity of both extracts was evaluated using MTT assay. Cells were treated for 1, 4, and 7 days with different concentrations of aqueous and ethanol extracts ranging from 100-700 and 10-150 μg/ml respectively. The antioxidant capacity of cell lysates was determined by the 2, 2’-azino-bis-(3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt (ABTS), 2, 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activities, and malondialdehyde (MDA) inhibitory effect. The possible action mechanism was also investigated through gene expression of antioxidant enzymes, i.e. superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Results: Both aqueous and ethanol extracts showed dose/time-dependent manners in all assays. Ethanol extract had a higher potency for cytotoxicity with obviously lower IC50 and a higher antioxidant capability in cytoplasmic content than aqueous extract, especially at 4-day treatment. Low MDA content and gene expression alteration of four enzymes involved in antioxidant status were found in cells treated with ethanol extract compared to aqueous extract. Conclusions: Ethanol VC extracts can cause cytotoxicity to human colorectal cancer cells, possibly be involved in oxidative stress, and/or interfere with oxidative-antioxidative balance by radical scavenging in vitro.     

Droloxifene (3-hydroxytamoxifen) has membrane antioxidant ability: potential relevance to its mechanism of therapeutic action in breast cancer.

Droloxifene (3-hydroxytamoxifen), is a triphenylethylene derivative recently developed for the treatment of breast cancer. Droloxifene was found to exhibit a membrane antioxidant ability in that it inhibited Fe(III)-ascorbate dependent lipid peroxidation in rat liver microsomes and ox-brain phospholipid liposomes. It also inhibited microsomal lipid peroxidation induced by Fe(III)-ADP/NADPH. Droloxifene was a better inhibitor of lipid peroxidation than tamoxifen, but was less effective than 17 beta-oestradiol in the two microsomal systems and in the preformed liposomal system. When introduced into ox-brain phospholipid liposomes, droloxifene inhibited Fe(III)-ascorbate induced lipid peroxidation to approximately the same extent as similarly introduced cholesterol and tamoxifen, although to a lesser extent than 17 beta-oestradiol. This inhibition of lipid peroxidation by droloxifene may result from a membrane stabilization that could be associated in cancer cells with decreased plasma membrane fluidity. This mechanism may be related to the clinically important antiproliferative action of droloxifene on cancer cells.     

Antioxidant,Anticancer and Anticholinesterase Activities of Flower,Fruit and Seed Extracts of Hypericum amblysepalum HOCHST

Background: Cancer is an unnatural type of tissue growth in which the cells exhibit unrestrained division,leading to a progressive increase in the number of dividing cells. It is now the second largest cause of death in theworld. The present study concerned antioxidant, anticancer and anticholinesterase activities and protocatechuic,catechin, caffeic acid, syringic acid, p-coumaric acid and o-coumaric concentrations in methanol extracts offlowers, fruits and seeds of Hypericum amblysepalum. Materials and Methods: Antioxidant properties includingfree radical scavenging activity and reducing power, and amounts of total phenolic compounds were evaluatedusing different tests. Protocatechuic, catechin, caffeic acid, syringic acid, p-coumaric acid and o-coumaricconcentrations in extracts were determined by HPLC. Cytotoxic effects were determined using the MTT test withhuman cervix cancer (HeLa) and rat kidney epithelium cell (NRK-52E) lines. Acetyl and butyrylcholinesteraseinhibitory activities were measured by by Ellman method. Results: Total phenolic content of H. amblysepalumseeds was found to be higher than in fruit and flower extracts. DPPH free radical scavenging activity of theobtained extracts gave satisfactory results versus butylated hydroxyanisole and butylated hydroxytoluene ascontrols. Reducing power activity was linearly proportional to the studied concentration range: 10-500 μg/mL LC50 values for H. amblysepalum seeds were 11.7 and 2.86 respectively for HeLa and NRK-52E cell lines.Butyryl-cholinesterase inhibitory activity was 76.9 ± 0.41 for seed extract and higher than with other extracts.Conclusions: The present results suggested that H. amblysepalum could be a potential candidate anti-cancerdrug for the treatment of human cervical cancer, and good source of natural antioxidants.