摘要:

A previous study has demonstrated that the hydrophilic (α-tocopherol analogue, MDL 74, 405, attenuates postischemic myocardial dysfunction (“stunning”) in dogs. The present study was undertaken to determine directly whether the salutary effect of this drug on myocardial stunning results from inhibition of the generation of oxygen-derived free radicals. Open-chest dogs undergoing a 15-min coronary artery occlusion and 3 h of reperfusion received an intravenous infusion of either saline (controls,n= 7) or MDL 74, 405 (n = 6) starting 30 min before coronary occlusion and ending 60 min after reflow at a dose of 0.3 mg/kg/h. To measure free radical production, all dogs received an intravenous infusion of the spin trapα-phenylN-tert-butyl nitrone (PBN) and local coronary venous plasma was analyzed by electron paramagnetic resonance (EPR). In control dogs, the myocardial production of PBN adducts exhibited an initial burst immediately after the onset of reflow and remained elevated until 10 min after reperfusion. Dogs treated with MDL 74, 405 demonstrated a marked decrease in PBN adduct production. This effect of MDL 74, 405 could not be attributed to nonspecific factors such as differences in ischemic zone size, collateral flow, arterial pressure, heart rate, coronary flow or other hemodynamic variables. These results demonstrate that the hydrophilic vitamin E analogue, MDL 74, 405, inhibits free radical generation after myocardial ischemia-reperfusionin vivo. This finding provides direct evidence that the salutary effects of MDL 74, 405 on myocardial stunning are due to attenuation of oxidative stress.

ISSN:1071-5762    

DOI:10.3109/10715769509145641

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

Levels of certain antioxidants namely reduced glutathione (GSH), ascorbic acid (Vit C),α-tocopherol (Vit E) and antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were compared in monkey and rat brain microvessels which constitute the blood-brain barrier (BBB). The BBB of both the species contains appreciable amounts of the antioxidants to protect against oxidative damage. The level of protection in rat seems to be more efficient than monkey since rat microvessels contain higher concentrations of some of the bio-antioxidants. The comparative status of enzymatic and non-enzymatic protective system against oxidation in the brain microvessels has been discussed.

ISSN:1071-5762    

DOI:10.3109/10715769509145642

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

Phenolic and non phenolic derivatives of phenyl styryl ketones were synthesized and evaluated asin vitroinhibitors of iron and cumene hydroperoxide dependent lipid peroxidation in rat brain homogenates. The compounds were also tested for antioxidant activity in phosphatidylcholine liposomes. Phenyl 3, 5-ditert-butyl-4-hydroxystyryl ketone was found to be the most potent inhibitor of peroxidation among all the compounds tested. It was found to be more active than vitamin E. It also reduced the stable free radical l,l-diphenyl-2-picrylhydrazyl to an appreciable extent.

ISSN:1071-5762    

DOI:10.3109/10715769509145643

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

ICRF-187 (dexrazoxane) is currently in clinical trials as a cardioprotective agent for the prevention of doxorubicin-induced cardiotoxicity. ICRF-187 likely acts through its strongly metal ion-binding rings-opened hydrolysis product ADR-925 by removing iron from its complex with doxorubicin or by chelating free iron. The ability of NADPH-cytochrome-P450 reductase to promote hydroxyl radical formation by iron complexes of ADR-925 and EDTA was compared by EPR spin trapping. The iron-EDTA complex produced hydroxyl radicals at six times the rate that the iron-ADR-925 complex did. The aerobic oxidation of ferrous complexes of ADR-925, its tetraacid analog, EDTA and DTPA was followed spectropho-tometrically. The iron(II)-ADR-925 complex was aerobically oxidized 700 times slower than was the EDTA complex. It is concluded that even though ADR-925 does not completely eliminate iron-based hydroxyl radical production, it likely protects by preventing site-specific hydroxyl radical damage by the iron-doxorubicin complex.

ISSN:1071-5762    

DOI:10.3109/10715769509145644

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

A HPLC method has been developed to measure phosphatidylcholine (PC) containing reactive carbonyl functions in the sn-acyl residue in order to study processes in which such reactive carbonyls can be formed due to e.g. oxidative fragmentation. The method has been applied to determine PC-bound carbonyls as 2, 4-dinitrophenylhydrazones (DNPH) in plasma of burn patients. Plasma from healthy volunteers served as controls. Additionally,in vitrooxidation experiments (A: plasma, buffer diluted; B: plasma + iron-EDTA complex and C: plasma + iron-EDTA complex + H2O2) have been performed to obtain and to identify 2, 4-dinitrophenylhydrazine derivatizable carbonyl functions in plasma PC. Both, the PC-aldehydes and PC-aldehyde DNPH derivatives were cleavable with phospholipase C. Quantification was based on thin-layer chromatography purified soybean phosphatidylcholine, which was identically oxidized and derivatized as the plasma lipidsin vitro.

ISSN:1071-5762    

DOI:10.3109/10715769509145645

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

A quantified maximum entropy method is applied to the optimisation of analytical information from FPR spectra of free radicals. Statistically meaningful errors are produced for the positions and intensities of all spectral peaks and considerable improvements in sensitivity compared with conventional spectral enhancement procedures are obtained with measurements of the intensities of spectra of known radicals.

ISSN:1071-5762    

DOI:10.3109/10715769509145646

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

Potassium ferrate. K2FeO4, is found to oxidize phenol in aqueous solution (5.5±pH±10) by a process which is second order in both reactants; -d[Fevt]/dt=ki[FeVI][phenol], kI = 107M−1s−1. Product analysis by HPLC showed a mixture of hydroxylated products, principally paraquinone. and biphenols that indicate that oxidation of phenol occurs by both one-electron and two-electron pathways. The two-electron oxidant. producing both para- and ortho-hydroxylated phenols is considered to be ferrate(V) which is itself produced by the initial one-electron reduction of ferrate(VI). The rate of ferrate(V) reaction with phenol was determined by pre-mix stopped flow pulse-radiolysis and found to be k7 = (3.8±0.4)±105M−1s−1.

ISSN:1071-5762    

DOI:10.3109/10715769509145647

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

Superoxide generation by polymorphonuclear leukocytes (PMNs) in suspension, or adherent to glass or plastic, after stimulation with /V-formylmethionyl-leucyl-phenylalanine or phorbol myristate acetate was measured by cytochromec reduction and spin trapping. Amounts of superoxide generated by adherent PM Ns were inversely related to cell density. The generation of hydrogen peroxide was also inhibited at higher cell densities. In contrast to adherent cells, superoxide released by PMNs in suspension linearly increased with respect to cell number over a wider range. Microscopic observation indicated that the number of cells in mutual contact increased rapidly at cell densities higher than 4×104cells/cm2, and inhibition of superoxide became apparent at higher cell densities. Mediators which could be released by PMNs, such as NO and adenosine, were not the cause of inhibition. Thesedatu suggest that mutual contact of PMNs suppresses their generation of superoxide. Survival rates of PMNs after stimulation increased at higher densities, indicating that the mutual contact-induced inhibition of superoxide generation by PMNs may be physiologically relevant at sites of inflammation.

ISSN:1071-5762    

DOI:10.3109/10715769509145648

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The relative antioxidant activities, against radicals generated in the aqueous phase, of a range of plant-derived polyphenolic flavonoids, constituents of fruit, vegetables, tea and wine, have been assessed. The results show that compounds such as quercetin and cyanidin, with 3′,4′dihydroxy substituents in the B ring and conjugation between the A and B rings, have antioxidant potentials four times that of Trolox, the vitamin E analogue. Removing the ortho-dihydroxy substitution, as in kaempferol, or the potential for electron deloculisation by reducing the 2.3 double bond in the C ring, as in catechin and epicatechin, decreases the antioxidant activity by more than 50%. but these structures are still more effective thanα-tocopherol or ascorbate. The relative significance of the positions and extents of hydroxylation of the A and B rings to the total antioxidant activity of these plant polyphenols is demonstrated.

ISSN:1071-5762    

DOI:10.3109/10715769509145649

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor