Search results for " peroxides"
showing 10 items of 35 documents
The use of cultured hepatocytes to investigate the metabolism of drugs and mechanisms of drug hepatotoxicity.
2001
Hepatotoxins can be classified as intrinsic when they exert their effects on all individuals in a dose-dependent manner, and as idiosyncratic when their effects are the consequence of an abnormal metabolism of the drug by susceptible individuals (metabolic idiosyncrasy) or of an immune-mediated injury to hepatocytes (allergic hepatitis). Some xenobiotics are electrophilic, and others are biotransformed by the liver into highly reactive metabolites that are usually more toxic than the parent compound. This activation process is the key to many hepatotoxic phenomena. Mitochondria are a frequent target of hepatotoxic drugs, and the alteration of their function has immediate effects on the ene…
Purification of hydroperoxide lyase from green bell pepper (Capsicum annuum L.) fruits for the generation of C6-aldehydes in vitro.
2002
The aim of this work was to compare the efficiency of different extracts of hydroperoxide lyase from green bell peppers in producing aldehydes: a crude extract, a chloroplastic fraction, and a purified enzyme were investigated. From a crude extract, the HPO lyase was purified by ion-exchange chromatography with a 22.3-fold increase in purification factor. Analysis by SDS-PAGE electrophoresis under denaturating conditions showed only one protein with a molecular weight of 55 kDa, whereas size-exclusion chromatography indicated a molecular weight of 170 kDa. A maximum of 7500 mg of aldehydes per g of protein was obtained with the purified enzyme within 20 min of bioconversion compared to 392 …
A Polyunsaturated Fatty Acid Diet Lowers Blood Pressure and Improves Antioxidant Status in Spontaneously Hypertensive Rats
2001
gamma-Linolenic acid [GLA, 18:3(n-6)], eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)] have been reported to prevent cardiovascular diseases. However, they are highly unsaturated and therefore more sensitive to oxidation damage. We investigated the effects of a diet rich in these polyunsaturated fatty acids (PUFA) on blood pressure, plasma and lipoprotein lipid concentrations, total antioxidant status, lipid peroxidation and platelet function in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Five-week-old SHR and WKY rats were fed for 10 wk either a diet containing Isio 4 oil or a diet rich in GLA, EPA and DHA (5.65, 6.39 and…
Pro-oxidant activity of indicaxanthin from Opuntia ficus indica modulates arachidonate metabolism and prostaglandin synthesis through lipid peroxide …
2014
Macrophages come across active prostaglandin (PG) metabolism during inflammation, shunting early production of pro-inflammatory towards anti-inflammatory mediators terminating the process. This work for the first time provides evidence that a phytochemical may modulate the arachidonate (AA) metabolism in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, promoting the ultimate formation of anti-inflammatory cyclopentenone 15deoxy-PGJ2. Added 1 h before LPS, indicaxanthin from Opuntia Ficus Indica prevented activation of nuclear factor-κB (NF-κB) and over-expression of PGE2 synthase-1 (mPGES-1), but up-regulated cyclo-oxygenase-2 (COX-2) and PGD2 synthase (H-PGDS), with final product…
Effects of taurine on pulmonary responses to antigen in sensitized Brown-Norway rats.
2001
Oxidative stress appears relevant to asthma. Therefore, the effects of the antioxidant taurine (oral, 1 and 3 mmol x kg(-1) x day(-1) for 7 days before challenge) were examined on antigen-induced responses in sensitized Brown-Norway rats. Taurine did not reduce the bronchospasm produced by aerosol antigen but prevented airway hyperreactivity to 5-hydroxytryptamine (5-HT) at 24 h after antigen exposure, and reduced the eosinophils (from 0.178+/-0.038x10(6) to 0.044+/-0.014x10(6)* and 0.048+/-0.013x10(6)* cells ml(-1) in antigen and antigen+taurine 1 or 3 mmol x kg(-1), respectively; *P0.05 vs. antigen), lipid hydroperoxides, and Evans blue dye extravasation in bronchoalveolar lavage fluid. T…
Quantitative evaluation of ethane and n-pentane as indicators of lipid peroxidation in vivo.
1983
The use of exhalation of ethane and n-pentane in experimental animals as parameters of lipid peroxidation led to an examination of pharmacokinetics of both compounds in rats. When rats were exposed, in a closed desiccator jar chamber, to a wide range of ethane concentrations, linear elimination pharmacokinetics were observed. n-Pentane, when concentrations higher than 100 ppm were applied, displayed saturation kinetics. These were formally explained by action of two competing metabolizing pathways or enzymes. Application of preexisting models could describe exhalation of both ethane and n-pentane by untreated control rats. Stimulation of lipid peroxidation by ferrous ions or by carbon tetra…
4-Hydroxynonenal, a lipid peroxidation product, induces relaxation of human cerebral arteries.
1994
The relaxant effect of 4-hydroxynonenal (4-HNE), a lipid peroxidation product, on human cerebral arteries was studied. Addition of 4-HNE to artery rings promoted no contraction, and after stimulation with prostaglandin F2α (PFG2α; 10−7-3 × 10−6 M), 100% relaxation was obtained with 3 × 10−5 M 4-HNE. Inhibition of nitric oxide formation with NG-nitro-l-arginine methyl ester hydrochloride (l-NAME; (10−4 M), as well as prostaglandin synthesis with indomethacin (3 × 10−6 M), partially prevented 4-HNE-induced relaxation, but each of these substances separately failed to inhibit complete relaxation. Addition of both inhibitors together reduced 4-HNE-induced relaxation to ≈50%, but relaxation cou…
Effect of acidosis and anoxia on iron delocalization from brain homogenates.
1992
Abstract Cortical homogenates were prepared from rat brain in Krebs-Ringer phosphate media adjusted to pH 7, 6 or 5 and incubated for 1 hr under aerotic or anaerobic conditions in the presence of dipyridyl, an iron chelator. Low molecular weight species (LMWS) iron was measured spectrophotometrically after passing of the homogenates through a 10,000- M , ultrafiltration membrane. Following aerobic incubation, LMWS iron reached 1.24 μg/g tissue at pH 7, and increased 1.7-fold at pH 6 and 3.1-fold at pH 5. Anoxia enhanced significantly the amount of ultrafiltrable iron at the three pH values, the LMWS iron level being increased by 190% at pH 7, by 113% at pH 6, and by 77% at pH 5. Addition of…
Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats
1986
Chronic daily intake of 0.5% H2O2 in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H2O2 intake decreased activity of catalase in rat skeletal muscle. H2O2 intake or water deprivation caused no changes in these enzyme activities in mice.
Endurance training reduces the susceptibility of mouse skeletal muscle to lipid peroxidation in vitro
1983
Selected estimates of the lipid peroxidative capacity were assayed in the red and white skeletal muscles of control and endurance-trained mice. Endurance training decreased the lipid peroxidation rate in vitro in both muscle types. The concentration of lipids susceptible to Fe2+-induced lipid peroxidation was greater in the red than in the white skeletal muscle and increased after endurance training in the red muscle. Endurance training, however, decreased highly significantly the sensitivity of red muscle to in vitro stimulated lipid peroxidation. The activity of catalase and the concentration of vitamin E were considerably higher in the red muscle, whereas the activity of glutathione pero…