Inhibition of aminoacylase 3 protects rat brain cortex neuronal cells from the toxicity of 4-hydroxy-2-nonenal mercapturate and 4-hydroxy-2-nonenal

4-Hydroxy-2-nonenal (4HNE) and acrolein (ACR) are highly reactive neurotoxic products of lipid peroxidation that are implicated in the pathogenesis and progression of Alzheimer's and Parkinson's diseases. Conjugation with glutathione (GSH) initiates the 4HNE and ACR detoxification pathway, which generates the mercapturates of 4HNE and ACR that can be excreted. Prior work has shown that the efficiency of the GSH-dependent renal detoxification of haloalkene derived mercapturates is significantly decreased upon their deacetylation because of rapid transformation of the deacetylated products into toxic compounds mediated by β-lyase. The enzymes of the GSH-conjugation pathway and β-lyases are expressed in the brain, and we hypothesized that a similar toxicity mechanism may be initiated in the brain by the deacetylation of 4HNE- and ACR-mercapturate. The present study was performed to identify an enzyme(s) involved in 4HNE- and ACR-mercapturate deacetylation, characterize the brain expression of this enzyme and determine whether its inhibition decreases 4HNE and 4HNE-mercapturate neurotoxicity. We demonstrated that of two candidate deacetylases, aminoacylases 1 (AA1) and 3 (AA3), only AA3 efficiently deacetylates both 4HNE- and ACR-mercapturate. AA3 was further localized to neurons and blood vessels. Using a small molecule screen we generated high-affinity AA3 inhibitors. Two of them completely protected rat brain cortex neurons expressing AA3 from the toxicity of 4HNE-mercapturate. 4HNE-cysteine (4HNE-Cys) was also neurotoxic and its toxicity was mostly prevented by a β-lyase inhibitor, aminooxyacetate. The results suggest that the AA3 mediated deacetylation of 4HNE-mercapturate may be involved in the neurotoxicity of 4HNE.     

二甲基胂酸致小鼠肺肿瘤促进作用中诱发氧化应激

目的研究无机砷在体内甲基化代谢的主要产物二甲基胂酸(dimethylarsinic acid,DMA)在致肺肿瘤促进作用过程中是否诱发氧化应激。方法应用免疫组织化学方法和免疫电子显微镜胶体金染色法,检测400 ppm DMA经饮水给药0~25周,小鼠肺组织中脂质过氧化的主要代谢产物4-羟烯酸(4-hydroxy-2-nonenal,4HNE)的表达及定位。结果DMA给药25周,肺组织的姬姆(HE)染色与对照组比较未观察到明显的形态学改变。免疫组织化学方法检测到肺终末细支气管上皮细胞胞浆中有棕色颗粒的4HNE阳性染色,染色细胞数明显高于对照组(P<0.05)。从DMA给药8周开始4HNE阳性染色细胞数随给药时间延长而增多,并且与对照组比较,差异有统计学意义(P<0.05)。免疫电子显微镜胶体金染色法观察到肺终末细支气管上皮细胞中呈阳性染色的为无纤毛的Clara细胞。DMA给药导致小鼠肺Clara细胞发生滑面内质网扩张、增生及核周水肿等超微结构的形态学改变。结论口服DMA诱发氧化应激,并且在DMA诱发肿瘤促进作用过程中一直起着十分重要的作用。我们首次指出,口服DMA致小鼠肺肿瘤促进作用过程中,DMA诱发的氧化应激特异地发生在肺肿瘤的靶细胞Clara细胞。     

Identification of alkylation-sensitive target chaperone proteins and their reactivity with natural products containing michael acceptor

Molecular chaperones have a crucial role in the folding of nascent polypeptides in endoplasmic reticulum. Some of them are known to be sensitive to the modification by electrophilic metabolites of organic pro-toxicants. In order to identify chaperone proteins sensitive to alkyators, ER extract was subjected to alkylation by 4-acetamido-4'-maleimidyl-stilbene-2,2'-disulfonate (AMS), and subsequent SDS-PAGE analyses. Protein spots, with molecular mass of 160, 100, 57 and 36 kDa, were found to be sensitive to AMS alkylation, and one abundant chaperon protein was identified to be protein disulfide isomerase (PDI) in comparison with the purified PDI. To see the reactivity of PDI with cysteine alkylators, the reduced form (PDIred) of PDI was incubated with various alkylators containing Michael acceptor structure for 30 min at 38 degrees C at pH 6.3, and the remaining activity was determined by the insulin reduction assay. Iodoacetamide or N-ethylmaleimide at 0.1 mM remarkably inactivated PDIred with N-ethylmaleimide being more potent than iodoacetamide. A partial inactivation of PDIoxid was expressed by iodoacetamide, but not N-ethylmaleimide (NEM) at pH 6.3. Of Michael acceptor compounds tested, 1,4-benzoquinone (IC50, 15 microM) was the most potent, followed by 4-hydroxy-2-nonenal and 1,4-naphthoquinone. In contrast, 1,2-naphthoquinone, devoid of a remarkable inactivation action, was effective to cause the oxidative conversion of PDIred to PDIoxid. Thus, the action of Michael acceptor compounds differed greatly depending on their structure. Based on these, it is proposed that PDI, one of chaperone proteins in ER, could be susceptible to endogenous or xenobiotic Michael acceptor compounds in vivo system.     

Protective effects of garlic powder against potassium dichromate-induced oxidative stress and nephrotoxicity.

Potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative stress. In the present work the effect of garlic powder, a recognized antioxidant, on K(2)Cr(2)O(7)-induced nephrotoxicity and oxidative stress was studied. Rats were fed a 2% garlic powder diet for 1 month. A single injection of K(2)Cr(2)O(7) (15 mg/kg) to rats induced tubule interstitial damage and an increase in the following markers of renal injury 2 days later: blood urea nitrogen (4.6-fold), serum creatinine (9.7-fold), proteinuria (35.9-fold), urinary excretion of N-acetyl-beta-d-glucosaminidase (12.9-fold) and glutathione-S-transferase (2.3-fold) and a decrease of 65% in serum glutathione peroxidase activity. In addition, K(2)Cr(2)O(7) injection increased the following nitrosative and oxidative stress markers in kidney: 3-nitrotyrosine (1.9-fold), 4-hydroxy-2-nonenal (2.1-fold), malondialdehyde (1.8-fold) and protein carbonyl content (1.7-fold). It was found that garlic powder feeding was able to prevent by 44-71% the alterations in the markers of renal injury studied, by 55% the histological damage, and by 47-100% the increase in markers of oxidative and nitrosative stress. It is concluded that the ability of garlic powder to ameliorate K(2)Cr(2)O(7)-induced renal injury is associated with its antioxidant properties. Our data support the use of garlic powder as a renoprotective agent.     

Effect of silymarin on biochemical parameters of oxidative stress in aged and young rat brain

Silymarin (SM), the active complex of milk thistle, is a lipophilic fruit extract and is composed of several isomer flavonolignans. Flavonoids are antioxidants found molecules capable of intercepting reactive oxygen species (ROS). The oxidative stress (OS) is caused by imbalance between antioxidant defenses and production of ROS causing oxidative damage to macromolecules. Brain is susceptible to oxidative stress and it is associated with age-related brain dysfunction. This study evaluated the effect of SM on biochemical parameters that evaluate OS in aged and young rat brain. For measures of OS were used measures of total oxyradical scavenging capacity (ACAP) through the concentration of ROS by fluorescence, lipid peroxidation (LPO), via FOX and TBARS, proteins oxidation by Western blot (WB). Rats were treated with SM at doses of 200 and 400 mg/kg/day (SM200 and SM400). The LPO analyzed through FOX was increased in the hippocampus of aged animals treated with SM400, but in the cortex of young and aged, the highest dose of SM decreased LPO analyzed through TBARS. Both doses have seemed most effective in the reduction of oxidized proteins in aged brain. These results suggest that SM may contribute to the prevention of aged-related and pathological degenerative processes in the brain.     

金银花总黄酮对氧化应激中肝星状细胞的保护作用

目的:研究金银花总黄酮对氧化应激中肝星状细胞(HSC)的保护作用。方法:培养大鼠HSC为模型。实验分为空白对照(DMEM培养基)组、模型(DMEM培养基)组与金银花总黄酮1、2、3、4(12.5、25.0、50.0、100.0μg/ml)组。检测MTT抑制率;测定超氧化物歧化酶(SOD)与乳酸脱氢酶(LDH)活性、丙二醛(MDA)含量、总抗氧化能力(T-AOC)。结果:与空白对照组比较,模型组MTT抑制率降低,MDA含量增加,LDH活性增强,SOD活性减弱,T-AOC减弱,差异有统计学意义(P<0.01或P<0.05);与模型组比较,金银花总黄酮1、2、3、4组MTT抑制率升高,MDA含量减少,LDH活性减弱,SOD活性增强,T-AOC增强,差异有统计学意义(P<0.01或P<0.05)。结论:金银花总黄酮具有抑制肝纤维化形成的作用,其作用机制可能与抑制HSC的增殖及抗氧化应激,以及抑制脂质过氧化反应有关。     

Binding pattern and toxicological effects of lectins from genus Canavalia on bovine sperm

The aim of this study was to determine the binding patterns of Canavalia ensiformis (ConA), Canavalia boliviana (ConBol) and Canavalia brasiliensis (ConBr) lectins to bovine sperm and their effects on sperm motility, viability, lipid peroxidation, reactive oxygen species production and fertilization ability. ConA bound to whole spermatozoa, with the exception of the equatorial segment, ConBol did not interact with the acrosome region and ConBr exhibited a fragmented binding pattern. The three lectins decreased sperm motility but did not affect cell viability or lipid peroxidation. Nevertheless, ROS production was increased in comparison to controls and a reduction in the cleavage and blastocyst ratio was induced in comparison to controls. In conclusion, this study determined that structurally similar lectins interact differently with bovine sperm and affect sperm motility, viability, lipid peroxidation, ROS production and fertilization ability in various ways.     

4-苯基丁酸对高果糖喂养大鼠肝脏脂质沉积及氧化应激的影响

目的：观察内质网应激(ERS)抑制剂4-苯基丁酸(4-PBA)对高果糖饮食喂养大鼠肝脏氧化应激的影响,以探讨ERS在高果糖喂养诱导脂肪肝中的介导作用及其与氧化应激的关系。方法雄性Wistar大鼠分为对照组、高果糖组和4-PBA组[自高果糖喂养4周后给予4-PBA 0.35 g/(kg·d)],8周后处死大鼠并测定肝脏甘油三酯(TG)含量。 PCR法检测ERS标志物葡萄糖调节蛋白78(GRP78)的基因表达。测定细胞中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性及细胞中丙二醛(MDA)的含量。 Western blot法检测肝C/EBP同源蛋白( CHOP)。结果与对照组相比,高果糖组的肝脏TG含量、GRP78基因表达、CHOP蛋白表达显著增加(P<0．01),与高果糖组比较,4-PBA上述指标显著降低(P<0．01)。与对照组相比,高果糖组大鼠的SOD、GSH-Px、CAT活性下降,MDA含量升高(P均<0.01),而4-PBA组的SOD、GSH-Px、CAT活性高于高果糖组,MDA含量低于高果糖组(P均<0.01)。结论长期高果糖喂养可诱导肝脏ERS和氧化应激,ERS抑制剂4-PBA可改善高果糖饮食诱导的肝脏氧化应激。     

Effect of S-adenosylmethionine on hepatic injury from sequential cold and warm ischemia

We investigated whether S-adenosylmethionine (SAM) treatment improved ischemic injury using perfused rat liver after sequential periods of 24 h cold and 20 min re-warming ischemia. SAM (100 micromol/L) was added to University of Wisconsin (UW) solution and Ringers lactate solution. After cold and sequential warm ischemia, releases of lactate dehydrogenase (LDH) and purine nucleoside phosphorylase (PNP) markedly increased during reperfusion. The increase in PNP was significantly reduced by SAM treatment. While the concentration of reduced glutathione (GSH) in ischemic livers significantly decreased, the concentration of glutathione disulfide (GSSG) increased. This decrease in GSH and increase in GSSG were suppressed by SAM treatment. Lipid peroxidation was elevated in cold and warm ischemic and reperfused livers, but this elevation was also prevented by SAM treatment. Hepatic ATP levels were decreased in the ischemic and reperfused livers to 42% of the control levels. However, treatment with SAM resulted in significantly higher ATP levels and preserved the concentration of AMP in ischemic livers. Our findings suggest that SAM prevents oxidative stress and lipid peroxidation and helps preserve hepatic energy metabolism.     

Type 2 Diabetes Mellitus-Induced Hyperglycemia in Patients with NAFLD and Normal LFTs: Relationship to Lipid Profile, Oxidative Stress and Pro-Inflammatory Cytokines

Type 2 diabetes mellitus is associated with dyslipdemia, insulin resistance and non alcoholic fatty liver disease. The purpose of the current study was to assess whether type 2 diabetes mellitus-induced hyperglycemia has an effect on the lipid profile and release of oxidative stress markers and inflammatory mediators in patients with non alcoholic fatty liver disease and normal liver function tests which may in turn lead to enhancing the pathogenicity of this liver disease. For this purpose, one hundred and five outpatients, matched in age and weight, were classified into two groups: the first group consisted of patients with non alcoholic fatty liver disease and the second group consisted of patients with non alcoholic fatty liver disease in conjunction with hyperglycemia due to the presence of type 2 diabetes mellitus. In all patients, lipid profile, oxidative stress, and inflammatory mediators were assessed by measuring serum concentrations of triglycerides, low density lipoprotein, hydrogen preroxide, malondialdehyde, tumor necrosis factor-alpha and interleukin-6, respectively. In the studied population, it was found that the presence of type 2 diabetes mellitus-induced hyperglycemia significantly impaired lipid profile, and significantly enhanced the formation of hydrogen preroxide and malondialdehyde as well as significantly increased the release of tumor necrosis factor-alpha and interleukin-6 in the second group of patients. In addition, plasma glucose level showed significant positive correlation with hydrogen peroxide, malondialdehyde, tumor necrosis factor-alpha and interleukin-6. From the previous results, it was concluded that the presence of type 2 diabetes mellitus-induced hyperglycemia results in significant increase in lipid profile, oxidative stress markers and inflammatory mediators in patients with non alcoholic fatty liver disease and normal liver function tests. For this reason, further research studies may be essential to evaluate the benefit of adding suitable antioxidant and anti-inflammatory drugs to the treatment regimen for this group of patients. In addition, regular monitoring of blood glucose levels and liver function tests should be advised to this category of patients to reduce liver fat deposition and avoid the development of non alcoholic steatohepatitis, cirrhosis or liver cancer and their related complications.     

Hypertriglyceridemia: A Review of Clinical Relevance and Treatment Options: Focus on Cerivastatin

SUMMARY

The triglyceride (TG) level is one of several lipid parameters that can aid prediction of coronary heart disease (CHD) risk. An elevated plasma TG level is strongly associated with an increased risk of CHD.

Hypertriglyceridemia, the second most common dyslipidemic abnormality in hypertensive subjects after increased low-density lipoprotein cholesterol (LDL-C), is defined by the National Cholesterol Education Programme (NCEP) as a fasting TG level of >2.26?mmol/l (>200?mg/dl) and is recognised as a primary indicator for treatment in type IIb dyslipidemia. Raised TG levels can be present in individuals at risk for CHD when the total cholesterol is normal. However, not all individuals with raised TG levels have increased risk of CHD. Factors such as: diet, age, lifestyle, and a range of medical conditions, drug therapy and metabolic disorders, can all affect the TG level. In some of these circumstances, other factors protect against the risk of CHD, and can minimise or negate the effect of the risk factors present.

Although TG reducing therapy has been shown to be associated with an improved clinical outcome, more research is needed to determine whether this is an independent effect of TG reduction or an effect of normalising the overall lipid profile in hypertriglyceridemic patients. Further trials are required to quantify the clinical benefits of lowering TG to ‘target’ levels and to confirm targets defined by NCEP-II (shown in Table 1).

The role of TG in CHD pathogenesis is thought to involve several direct and indirect mechanisms, such as effects on the metabolism of other lipoproteins, transport proteins, enzymes, and on coagulation and endothelial dysfunction. More research is required to fully elucidate the role of TG, the ways in which it can influence other risk factors and the mechanism of its own more direct role in the atherogenic process.

Patients with hypertriglyceridemia have been shown to respond well to dietary control and to the use of lipid lowering drugs such as 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG CoA) reductase inhibitors (known as statins), fibrates and nicotinic acids. However, recent retrospective real-life clinical studies show that only 38% of patients receiving some form of lipid-lowering therapy achieved NCEP-defined LDL-C target levels, demonstrating the need for the use of more aggressive treatment.

In hypertriglyceridemic patients, the newer statins, cerivastatin and atorvastatin, have shown comparable efficacy in reducing TG compared with the older statins. Achieving NCEP target lipid levels has been shown to reduce the risk of cardiovascular disease in dyslipidemic individuals, including high-risk patient groups such as those with additional risk factors, existing heart disease, diabetes mellitus and metabolic syndrome.

Although the latest clinical studies investigating combination therapies, i.e. dual therapy with both a statin and a fibrate, have demonstrated them to be effective for overall control of lipid parameters and reducing coronary events, it is not yet clear whether this offers any significant advantage over monotherapy. Results from ongoing longer-term end-point clinical studies may provide further information in this area and consequent reviews of primary care management policies for dyslipidemia. Statin monotherapy may be a reliable option for primary care treatment of dyslipidemia (including hypertriglyceridemia).     

Absorption of andrographolides from Andrographis paniculata and its effect on CCl4-induced oxidative stress in rats

A simple and validated high-performance liquid chromatography (HPLC) method with UV detection has been used to determine the content of andrographolide (AP) and 14-deoxy-11,12-didehydroandrographolide (DIAP) in rat plasma after oral dose of methanol extract (1 g/kg body weight) of Andrographis paniculata leaf. An increase in plasma concentration of AP and DIAP was observed from 30 min to 3 h after oral administration of the extract. The maximum plasma concentrations of AP and DIAP were 1.42 ± 0.09 μg/ml and 1.31 ± 0.04 μg/ml, respectively. Fourteen days oral treatment of rats with the methanol extract (1 g/kg body weight) followed by CCl₄ administration preserved catalase (CAT), and superoxide dismutase (SOD) activities in erythrocytes, whereas plasma lipid peroxidation, alanine transaminase (ALT) and aspartate transaminase (AST) activities were restored to values comparable with control values. Treatment of rats with CCl₄ did not showed significant alteration (p > 0.05) in plasma total antioxidant status (TAS) as compare to values of control group.     

珠子参总皂苷对大鼠心肌缺血／再灌注损伤的保护作用及机制研究

目的：研究珠子参总皂苷预处理对大鼠心肌缺血再灌注损伤（Myocardiumischemia／Reperfusioninjury,MI／RI）的保护作用及可能的作用机制。方法：实验大鼠随机分为假手术组、缺血／再灌注模型组、珠子参总皂苷100和200mg／kg组。治疗组各组大鼠分别给予相应的药物,给药7d后,行冠状动脉结扎术,结扎30rain后,再灌注24h。记录再灌注后30min内心律失常发生情况,24h后进行血流动力学测定,然后取血进行乳酸脱氢酶（LDH）、肌酸激酶（CK）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH—Px）、丙二醛（MDA）和过氧化氢酶（CAT）含量分析;心脏经TTC染色和HE染色,计算心肌梗死面积和心肌组织形态学观察。实时定量PCR检测SOD／GPX／CAT反应系统SODl～SOD3、GPXl和CAT基因表达,Westernblot检测细胞质和细胞核Nrf2蛋白表达。结果：珠子参总皂苷（100、200mg／kg）可显著降低心律失常发生率（P〈0．01）,能明显改善心功能,降低血液中CK、LDH含量和MDA水平,增加SOD、GSH—Px、CAT酶的活性;减轻ROS所致心肌氧化应激损伤,降低心肌梗死面积（P〈0．05,P〈0．01）和改善心脏组织形态学;上调SOD／GPx／CAT反应系统基因表达水平和促进Nrf2核移位,增加心肌细胞核内Nrf2的表达水平（P〈0．01）。结论：珠子参总皂苷对MI／RI具有较好的保护作用,激活Nrf2抗氧化途径和抗脂质过氧化可能是其作用机制之一。     

Evaluation of l-arginine on kidney function and vascular reactivity following ischemic injury in rats: Protective effects and potential interactions

BackgroundThere is an interaction between many cell types involved in the pathophysiology of ischemic acute renal failure. Nitric oxide (NO) precursors, especially l-arginine, may have protective effects on tissue ischemia/reperfusion injury (IRI); however, their molecular mechanisms are unclear. In the present study, the interaction between l-arginine, cyclo-oxygenase (COX)-2 and reactive oxygen species (ROS) in the pathogenesis of ischemic acute renal failure was investigated.MethodsIschemia/reperfusion injury model in rats was used and various biochemical parameters examined. The rat isolated aortic rings served as model for hypoxia/reoxygenation where endothelium dependent and independent relaxations were exerted.ResultsPre-treatment of rats subjected to IRI with l-arginine (125 mg/kg) significantly reduced kidney MDA levels, elevated kidney SOD activity, GSH level and total NO levels at 24 and 48 h after reperfusion. Kidney COX-2 level was only different in the l-arginine-treated group 48 h after reperfusion compared to the IRI group. Pre-treatment with l-arginine (10⁻² M) alone or in combination with celecoxib significantly potentiated the acetylcholine (Ach)-induced relaxations in control and hypoxic rings. The effect of the combination was synergistic only in hypoxic rings. Addition of ascorbic acid to the celecoxib–arginine combination did not produce further potentiation. Sodium nitroprusside-induced relaxations in control and hypoxic rings were potentiated by l-arginine or celecoxib–arginine combination but not by ascorbic acid.ConclusionsThe protective effect of l-arginine may result from the interaction between NO and ROS and increased NO bioavailability. The protective effects of combined celecoxib and l-arginine against IRI could be attributed to their antioxidant activity which exceeded that of ascorbic acid.     

Fate in digestion in vitro of several food components, including some toxic compounds coming from omega-3 and omega-6 lipids

In this study it was proved the formation of oxygenated alpha,beta-unsaturated aldehydes (OαβUAs) of 6, 7, 9 and 10 carbon atoms during the thermal treatment (190 °C with aeration) of a commercial vegetable oil rich in omega-3 and omega-6 acyl groups, which also contained small amounts of added proteins and carbohydrates to produce barbecue aroma when heated. The OαβUAs detected by Solid Phase Microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS) were: 4-hydroxy-2-hexenal, 4-oxo-2-hexenal and 4,5-epoxy-2-heptenals, coming from omega-3 acyl groups; and 4-hydroxy-2-nonenal, 4-oxo-2-nonenal and 4,5-epoxy-2-decenals, coming from omega-6 acyl groups. Mixtures of this oil, either thermodegraded or not, with standard food were submitted to an in vitro digestion model. The study of the digestion products obtained revealed that OαβUAs remained unaltered, being bioaccessible in the gastrointestinal tract and so able to reach the systemic circulation. Besides, it was evidenced that during digestion Maillard, esterification and oxidation reactions take place.     

Improving the ex vivo stability of drug ester compounds in rat and dog serum: Inhibition of the specific esterases and implications on their identity

In drug development, it has been noticed that some drug compounds, especially esters, are unstable in serum samples ex vivo. This can lead to a substantial underestimation of the actual drug concentration.