五味子乙素抗大鼠肝癌作用机制研究

目的研究五味子乙素对大鼠肝癌的影响,并阐明其机制。方法将50只大鼠随机分为五组,采用移植法建模,C、E、D组分别给予相同剂量的环磷酰胺、五味子乙素以及二者混合物,测定各组瘤重以及TNF-d水平。结果给药组瘤重明显低于模型组（P〈0．05）,肿瘤组TNF－α水平明显高于空白对照组（P〈0．05）,均具有统计学意义。结论五味子乙素具有良好曲抗肿瘤活性。     

不同产地的五味子中五味子乙素含量测定

目的：五味子中有效成分为五味子乙素，因此我们对该成分进行测定。方法：采用高效液相法进行测定。结果：B法最好。结论：用高效液相法测定不同产地五味子中五味子乙素含量方法简便、可靠。     

延胡索乙素抗脂质过氧化作用与对脑缺血再灌注大鼠行为及病理改变的保护

目的研究延胡索乙素（ｄｌ ｔｅｔｒａｈｙｄｒｏｐａｔｍａｔｉｎｅ,ｄｌ ＴＨＰ）抗脂质过氧化作用与对大鼠局灶性脑缺血再灌注损伤的保护作用。方法采用非开颅可逆性大鼠大脑中动脉拴塞法造成大鼠脑缺血再灌注损伤,ｄｌ ＴＨＰ１０,２０ｍｇ·ｋｇ－１在缺血前２ｍｉｎ静脉注射。结果ｄｌ ＴＨＰ可显著减轻神经功能障碍及脑组织病理损害,阻止脑组织超氧化物歧化酶（ｓｕｐｅｒｏｘｉｄｅｄｉｓｍｕｔａｓｅ,ＳＯＤ）及乳酸脱氢酶（ｌａｃｔｉｃｄｅｈｙｄｒｏｇｅ ｎａｓｅ,ＬＤＨ）活力下降,阻止外周血中ＬＤＨ活力增加并阻止脑组织脂质过氧化产物丙二醛（ｍａｌｏｎｄｉａｌｄｅｈｙｄｅ,ＭＤＡ）含量增加。结论ｄｌ ＴＨＰ对大鼠局灶性脑缺血再灌注损伤有保护作用,机制可能与抗脂质过氧化反应有关。     

五味子乙素抗氧化应激损伤作用及机制的研究进展

机体氧化与抗氧化系统失衡导致氧化应激,产生细胞毒性,引起多种疾病.五味子乙素(γ-Schizandrin B,Sch B)是中药北五味子中的一种具有高抗氧化效能的成分,现已被证明可为实验动物的各种器官组织提供广泛的保护作用以抵抗氧化损伤,为防治各种氧化应激相关疾病提供了研究前景.本研究就五味子乙素抗氧化应激损伤作用及其...     

五味子乙素对CYP450药物代谢酶诱导作用的体外研究

目的 研究五味子乙素对细胞色素P450(CYP450)酶活性和mRNA表达是否有诱导作用.方法 采用底物法测定人肝原代细胞CYP1A2、CYP2B6和CYP3A4酶的活性,荧光定量PCR检测mRNA的表达.结果 五味子乙素对CYP1A2和CYP3A4的酶活性均低于阳性对照的40%,高浓度的五味子乙素对CYP2B6的酶活性均高于阳性对照的40%;五味子乙素对CYP1A2的mRNA表达小于阴性对照的4倍,高浓度的五味子乙素对CYP2B6和CYP3A4的mRNA表达大于阴性对照的4倍.结论 五味子乙素对CYP1A2和CYP3A4的酶活性没有诱导作用,对CYP2B6的酶活性有潜在诱导作用;五味子乙素对CYP1A2的mRNA表达没有诱导作用,对CYP2B6和CYP3A4的mRNA表达有潜在诱导作用.     

五味子乙素对缺血诱导人牙髓细胞的影响及作用机制研究

目的研究五味子乙素对缺血诱导人牙髓细胞的影响及作用机制。方法采用不同浓度的五味子乙素分别处理细胞24、48、72 h后,观察牙髓细胞形态并用波形蛋白染色和角蛋白染色鉴定细胞,检测细胞增殖率和细胞凋亡情况,荧光定量聚合酶链式反应(RT-PCR)检测牙髓细胞中碱性磷酸酶(ALP)、牙本质涎磷蛋白(DSPP)、丝氨酸蛋白酶(HtrA1)、转化生长因子(TGF)-β1 mRNA的表达量,蛋白免疫印迹法(Western blot)检测牙髓细胞中局部黏着斑激酶(FAK)、细胞外调节蛋白激酶(ERK)、蛋白激酶B(AKT)的表达。结果化学染色鉴定结果发现,传代后的细胞波形蛋白染色结果显示阳性,角蛋白染色结果显示阴性,说明此细胞来源于中胚层,具有牙髓细胞的生物学特性;随着五味子乙素浓度的增加牙髓细胞的增殖率呈现上升趋势(P<0.01),而牙髓细胞凋亡率明显下降(P<0.01),且与药物浓度和时间呈现一定的依赖性;不同浓度五味子乙素处理牙髓细胞后,细胞中的ALP、DSPP、TGF-β1 mRNA相对表达量以及FAK、ERK、AKT的表达均高于空白对照组,差异具有统计学意义(P<0.05)。结论五味子乙素可以促进牙髓细胞增殖并抑制其凋亡,这一效应可能是通过FAK、ERK、AKT信号通路实现的。     

五味子三种成分的抗氧化作用

从华中五味子分离得到的五味子酮和从五味子中分离得到的五味子乙素、五味子二醇对由维生素C-NADPH或由Fe~(2+)-半胱氨酸诱发的大鼠脑、肝、肾微粒体的脂质过氧化有显著的抑制作用,其作用强度为五味子酮>五味子乙素>五味子二醇,比抗氧化剂维生素E的作用强。其机理之一可能是有效地清除了超氧阴离子。     

Action of ebselen as an antioxidant against lipid peroxidation.

The action of ebselen (2-phenyl-1,2-benzoisoselenazol-3(2H)-one) as an antioxidant was studied under various conditions to clarify how it prevents oxidative damage. It did not react with diphenylpicrylhydrazyl nor did it suppress the oxidation of methyl linoleate in acetonitrile solution or in aqueous dispersions induced by free radical initiator, suggesting that ebselen does not act as a potent radical scavenging antioxidant. On the other hand, it suppressed the oxidation of methyl linoleate emulsions in aqueous dispersions induced by iron. It also suppressed the spontaneous oxidation of rat brain and liver homogenates, but it did not suppress the oxidation of these homogenates induced by a free radical initiator. It was also found that ebselen reduced the fatty acid hydroperoxides to their corresponding alcohols and this reaction was enhanced by the presence of glutathione. These results suggest that ebselen acts as an antioxidant by reducing hydroperoxides, but that it does not act as a radical-scavenging antioxidant.     

Influence of ferulic acid on gamma-radiation induced DNA damage, lipid peroxidation and antioxidant status in primary culture of isolated rat hepatocytes

Ionizing radiation is known to induce oxidative stress through generation of reactive oxygen species (ROS) resulting in imbalance of the pro-oxidant and antioxidant activities ultimately resulting in cell death. Ferulic acid (FA) is a phytochemical commonly found in fruits and vegetables such as tomatoes, sweet corn, and ricebran. FA exhibit a wide range of pharmacological effects including antiageing, anti-inflammatory, anticancer, antidiabetic, antiapoptotic, and neuroprotective. The present work is aimed at evaluating the radioprotective effect of FA, on gamma-radiation induced toxicity in primary cultures of isolated rat hepatocytes. Hepatocytes were isolated from the liver of rats by collagenase perfusion. The cellular changes were estimated using lipid peroxidative indices like thiobarbituric acid reactive substances (TBARS), the antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH), ceruloplasmin, Vitamins A, E and C and uric acid. DNA damage was analyzed by single cell gel electrophoresis (comet assay). An increase in the severity of DNA damage was observed with increasing dose (1, 2 and 4Gy) of gamma-radiation in cultured hepatocytes. TBARS were increased significantly, whereas the levels of GSH, Vitamins C, E and A, ceruloplasmin, uric acid and antioxidant enzymes were significantly decreased in gamma-irradiated groups. The maximum damage to hepatocytes was observed at 4Gy irradiation. Pretreatment with FA (1, 5 and 10 microg/ml) significantly decrease the levels of TBARS and DNA damage. In addition, pretreatment with FA significantly increased antioxidant enzymes, GSH, Vitamins A, E and C, uric acid and ceruloplasmin levels. The maximum protection of hepatocytes was observed at 10 microg/ml of FA pretreatment. Thus, pretreatment with FA helps in protecting the hepatocytes against gamma-radiation induced cellular damage and can be developed as a effective radioprotector during radiotherapy.     

Microcystin-LR and nodularin induce intracellular glutathione alteration, reactive oxygen species production and lipid peroxidation in primary cultured rat hepatocytes

Microcystin-LR (MCYST-LR) and nodularin (NOD) produced by cyanobacteria are potent specific hepatotoxins. However, the mechanisms of their hepatotoxicity have not been fully elucidated. In the present study the effect of non cytotoxic low concentrations of MCYST-LR and NOD on intracellular reduced glutathione (GSH) alteration, reactive oxygen species (ROS) production and lipid peroxidation was investigated in primary cultured rat hepatocytes. Cell viability was determined by the methylthiazoltetrazolium (MTT) dye assay, reduced GSH was evaluated by enzymatic methods, ROS were evaluated by the dichlorofluorescein diacetate (H2DCF-DA) fluorescent probe and lipid peroxidation by dosing malondialdehyde (MDA) by the thiobarbituric acid method. The 24 h LC50 values of MCYST-LR and NOD were 48 and 62 ng/ml, respectively. Exposure of freshly isolated rat hepatocytes to MCYST-LR or NOD at non cytotoxic low concentrations (2, 10 ng/ml) for 3, 24 and 48 h periods resulted in a significant rise of GSH levels and production of ROS. NOD significantly induced in a time- and concentration-dependent lipid peroxidation. However, MCYST-LR treatment did result in a significant decrease in MDA levels compared with controls. Although MCYST-LR and NOD are closely related in terms of structure and inhibition of protein phosphatases, they induce differently the oxidative stress at non cytotoxic low concentrations. Therefore, the results indicate that oxidative stress mediated by reactive intermediates may be a mechanism by which these cyanotoxins induce their hepatotoxic effect.     

The measurement of lipid peroxidation in isolated hepatocytes

Different techniques for the measurement of lipid peroxidation in isolated hepatocytes have been compared. Measurements of ethane production, chemiluminescence and fluorescent products correlated extremely well with those of malondialdehyde formation. Of the five different techniques studied, measurements of ethane production and chemiluminescence were found to be the most sensitive indices of lipid peroxidation. Incubation of hepatocytes for up to 4 hr in the presence of ethylmorphine and aminopyrine, at concentrations known to stimulate H202 production, completely failed to increase the amount of chemiluminescence, malondialdehyde or ethane produced in these cells, indicating that the drug-stimulated production of H₂O₂ did not lead to an increased rate of lipid peroxidation in liver cells under the experimental conditions employed. The relationship between lipid peroxidation, as measured by chemiluminescence and ethane production, and the cytotoxic effects of bromobenzene and carbon tetrachloride has also been studied. The results obtained further indicate that lipid peroxidation is an important event in carbon tetrachloride hepatotoxicity, but that it appears to be only a subsequent event in bromobenzene toxicity, possibly occurring only as a result ofglutathione depletion and cell death.     

Activities of brain antioxidant enzymes,lipid and protein peroxidation

Organophosphate pesticides are known to induce oxidative stress and cause oxidative tissue damage, as has been reported in studies concerning acute and chronic intoxication with these compounds.     

Cadmium toxicity and lipid peroxidation in isolated rat hepatocytes

The toxicity of cadmium may be due to alteration in membrane structure which may be caused by peroxidation of the composite lipids. Isolated hepatocytes provide a suitable system to examine the role of lipid peroxidation in a toxic response at the cellular level. Therefore, isolated rat hepatocytes were incubated with varying cadmium concentrations (50–400 μm) for up to 75 min. An increase in lipid peroxidation due to cadmium was observed. The integrity of the cell membrane, as measured by loss of intracellular potassium ion and leakage of aspartate aminotransferase, was adversely affected in the presence of cadmium. The lactate to pyruvate ratio of hepatocyte suspensions was increased upon incubation with cadmium. Several chelating compounds were found to reduce intracellular accumulation of cadmium, cellular toxicity and lipid peroxidation. However, amelioration of toxicity was not consistently associated with inhibition of the lipid peroxidation response. The antioxidant compounds, sodium diethyldithiocarbamate and N,N′-diphenyl-p-phenylene-diamine were found to inhibit the lipid peroxidation attributable to cadmium, but did not have any consistent protective effect against loss of intracellular potassium ion. The results of this study show that the toxicity induced by cadmium in isolated rat hepatocytes can be dissociated from the concurrently observed lipid peroxidation, which indicates that the toxic response is not caused by the lipid peroxidation.     

Protective effects of antioxidant supplementation on plasma lipid peroxidation in smokers

This study was designed to investigate the possible protective effects of antioxidants (vitamin E, beta-carotene, vitamin C, and red ginseng) on lipid peroxidation in smokers (> or = 20 cigarettes/day). Male student smokers were given antioxidant supplements for 4 wk. Smokers had significantly higher plasma levels of total cholesterol, triacylglycerols, and malondialdehyde (MDA) than nonsmokers. No corresponding significant differences in lipid profiles were found between smokers and nonsmokers. Smokers had significantly lower baseline concentrations of plasma vitamin C, beta-carotene, and alpha-tocopherol. After antioxidant (200 IU vitamin E, 9 mg beta-carotene, 500 mg vitamin C, or 1.8 g red ginseng) supplementation for 4 wk, smokers had significantly higher concentrations of plasma antioxidants. After 4 wk of antioxidant supplementation with betacarotene, high-density lipoprotein (HDL) cholesterol concentrations in smokers were significantly increased. Overall, plasma MDA concentrations gradually decreased after antioxidant supplementation over the 4-wk period. Moreover, a significant reduction in plasma MDA concentrations was observed after vitamin E supplementation. The results of our study support the hypothesis that lipid peroxidation concentrations are inversely correlated with plasma antioxidant concentrations. Our data suggest that smokers have insufficient concentrations of antioxidant vitamins in plasma and that supplementation with antioxidants might protect smokers from oxidative damage.     

Effects of prochloraz on DNA damage,lipid peroxidation and antioxidant system in vitro

Prochloraz is a broad-spectrum contact imidazol fungicide used against several diseases in wheat, barley and oleaginous plants but also for treatment of flower production. Although prochloraz has endocrine disrupting and hepatocarcinogenic effects, there is lack of data on toxic effects of prochloraz. Therefore, we aimed to investigate the DNA damage effects of prochloraz in NRK-52E cells by using Ames and Comet assay. By using a standard alkaline Comet assay procedure, there was no DNA damage observed after 24?h prochloraz exposure. It also showed that prochloraz caused neither base-pair substitution nor frame shift mutations by using TA98, TA100 strains, respectively, with/without metabolic activation in Ames assay. Both Comet and Ames assays, the exposure concentrations were 12.5, 25, 50 and 100?µM. IC₅₀ value of prochloraz was determined as 110.76?µM in NRK-52E cells by MTT cytotoxicity test. Also, we evaluated possible effects of prochloraz on lipid peroxidation, reduced glutathione (GSH), oxidized glutathione (GSSG) and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) in NRK-52E cells at 1–50?µM concentrations. Prochloraz induced lipid peroxidation and altered glutathione contents and antioxidant enzyme activities in NRK-52E cells. Our results indicated that prochloraz showed no evidence of mutagenicity and DNA damage; however, some alterations were observed on lipid peroxidation and antioxidant systems in prochloraz treatment.     

Effect of phensuccinal on lipid metabolism, lipid peroxidation, and antioxidant system activity in rabbits with dithiazone-induced diabetes

A three-month administration of phensuccinal improved glucose homeostasis, decreased the levels of total cholesterol, triglycerides, fatty acids, and low-density lipoproteins in the blood serum, and reduced the lipid peroxidation rate as compared to the untreated diabetic control. In addition, phensuccinal increased the content of the antiatherogenic high-density lipoprotein fraction and the related paraoxonase enzyme activity. The preventive effect of phensuccinal with respect to diabetic dyslipidemia development, together with the antioxidant action, show this compound to be a promising therapeutic means of preventing and/or reducing macrovascular complications in diabetic patients.     

Relationships between intracellular vitamin E, lipid peroxidation, and chemical toxicity in hepatocytes

The cellular content of vitamin E was measured in isolated rat hepatocytes exposed to various types of chemical injury. Vitamin E was determined as alpha-tocopherol by HPLC with in-line uv and electrochemical detection. The cytotoxicity of diquat, a redox cycling compound, was accompanied by a decrease in cellular alpha-tocopherol and a stimulation of lipid peroxidation. Both the loss of alpha-tocopherol and the accumulation of lipid peroxidation products could be prevented by addition of either the antioxidant N,N'-diphenyl-p-phenylenediamine (DPPD) or the reducing agent dithiothreitol (DTT). DTT also prevented the oxidation of soluble and protein thiols and completely protected against cytotoxicity, while DPPD addition only delayed the onset of hepatocyte death. Cytotoxic doses of the naphthoquinone, menadione, and the pyridine compounds 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 1-methyl-4-phenyl-pyridinium ion did not deplete alpha-tocopherol levels, nor did they result in significant lipid peroxidation. On the other hand, a peroxidizing, but noncytotoxic dose of ADP-Fe3+ rapidly decreased cellular alpha-tocopherol levels. These data demonstrate that cellular alpha-tocopherol loss is neither a prerequisite for, nor a necessary consequence of toxicity. Moreover, a substantial depletion (ca. 50%) of alpha-tocopherol does not necessarily result in cell death. Although alpha-tocopherol protects against the oxidation of cellular lipids, the maintenance of hepatocyte alpha-tocopherol content does not prevent the oxidation of soluble and protein thiols. These other targets of oxidative damage seem to play a more critical role in hepatocyte toxicity.