scholarly journals Reactions of Adriamycin with haemoglobin. Superoxide dismutase indirectly inhibits reactions of the Adriamycin semiquinone

1982 ◽  
Vol 203 (1) ◽  
pp. 155-160 ◽  
Author(s):  
D A Bates ◽  
C C Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Detrimental Effect ◽  
Reversible Reaction ◽  
Red Cell ◽  
Rapid Reaction ◽  
The Right

The Adriamycin semiquinone produced by the reaction of xanthine oxidase and xanthine with Adriamycin has been shown to reduce both methaemoglobin and cytochrome c. In air, but not N2, both reactions were inhibited by superoxide dismutase. With cytochrome c, superoxide formed by the rapid reaction of the semiquinone with O2, was responsible for the reduction. However, even in air, methaemoglobin was reduced directly by the Adriamycin semiquinone. Superoxide dismutase inhibited this reaction by removing superoxide and hence the semiquinone by displacing the equilibrium: Semiquinone + O2 in equilibrium or formed from quinone + O2-. to the right. This ability to inhibit indirectly reactions of the semiquinone could have wider implications for the protection given by superoxide dismutase against the cytotoxicity of Adriamycin. Oxidation of haemoglobin by Adriamycin has been shown to be initiated by a reversible reaction between the drug and oxyhaemoglobin, producing methaemoglobin and the Adriamycin semiquinone. Reaction of the semiquinone with O2 gives superoxide and H2O2, which can also react with haemoglobin. Catalase, by preventing this reaction of H2O2, inhibits oxidation of oxyhaemoglobin. Superoxide dismutase, however, accelerates oxidation, by inhibiting the reaction of the semiquinone with methaemoglobin by the mechanism described above. Although superoxide dismutase has a detrimental effect on haemoglobin oxidation, it may protect the red cell against more damaging reactions of the Adriamycin semiquinone.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

Cytochrome c, an ideal antioxidant

2003 ◽  
Vol 31 (6) ◽  
pp. 1312-1315 ◽  
Author(s):  
M.O. Pereverzev ◽  
T.V. Vygodina ◽  
A.A. Konstantinov ◽  
V.P. Skulachev
Keyword(s):  
Superoxide Dismutase ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Cytochrome Oxidase ◽  
The Other ◽  
Other Hand ◽  
O2 Reduction

Generation of Δψ (membrane potential) by cytochrome oxidase proteoliposomes oxidizing superoxide-reduced cytochrome c has been demonstrated. XO+HX (xanthine oxidase and hypoxanthine) were used to produce superoxide. It was found that the generation of Δψ is completely abolished by cyanide (an uncoupler) or by superoxide dismutase, and is enhanced by nigericin. Addition of ascorbate after XO+HX causes a further increase in Δψ. On the other hand, XO+HX added after ascorbate do not affect Δψ, indicating that superoxide does not have measurable protonophorous activity. The half-maximal cytochrome c concentration for Δψ generation supported by XO+HX was found to be approx. 1 μM. These data and the results of some other researchers can be rationalized as follows: (1) O2 accepts an electron to form superoxide; (2) cytochrome c oxidizes superoxide back to O2; (3) an electron removed from the reduced cytochrome c is transferred to O2 by cytochrome oxidase in a manner that generates ΔμH+ (transmembrane difference in electrochemical H+ potential). Thus cytochrome c mediates a process of superoxide removal, resulting in regeneration of O2 and utilization of the electron involved previously in the O2 reduction. It is important that cytochrome c is not damaged during the antioxidant reaction, in contrast with many other antioxidants.

Oxygen-derived free radicals, endothelium, and responsiveness of vascular smooth muscle

1986 ◽  
Vol 250 (5) ◽  
pp. H815-H821 ◽  
Author(s):  
G. M. Rubanyi ◽  
P. M. Vanhoutte
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Smooth Muscle ◽  
Free Radicals ◽  
Vascular Smooth Muscle ◽  
Xanthine Oxidase ◽  
Isometric Tension ◽  
Oxygen Derived Free Radicals ◽  
Major Shift ◽  
The Right

Experiments were designed to determine the role of oxygen-derived free radicals in modulating contractions of vascular smooth muscle and endothelium-mediated relaxations to acetylcholine. The effects of generating or scavenging these radicals were studied in rings of canine coronary arteries suspended for isometric tension recording. Xanthine oxidase plus xanthine caused relaxations, which were greater in rings with endothelium than in rings without endothelium; the relaxations were not affected by superoxide dismutase or mannitol, but could be prevented by catalase. Xanthine oxidase plus xanthine depressed endothelium-mediated relaxations to acetylcholine; this effect was prevented by superoxide dismutase, but was not affected by catalase or mannitol. Exogenous hydrogen peroxide induced catalase-sensitive relaxations, which were depressed by the removal of the endothelium. Superoxide dismutase evoked catalase-sensitive relaxations only in rings with endothelium. Endothelium-mediated relaxations to acetylcholine were slightly depressed by superoxide dismutase or catalase alone; the combination of the two enzymes or mannitol caused a major shift to the right of the concentration-response curve to acetylcholine. In rings without endothelium, relaxations caused by sodium nitroprusside were not affected by the scavengers (alone or in combination) but were augmented by xanthine oxidase plus xanthine. These data suggest that the endothelium-derived relaxing factor released by acetylcholine is not likely to be an oxygen-derived free radical; hydrogen peroxide has a direct inhibitory action on coronary arterial smooth muscle and triggers endothelium-dependent relaxations; and superoxide anions depress and hydroxyl radicals facilitate endothelium-dependent relaxations caused by activation of muscarinic receptors.

scholarly journals Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

1982 ◽  
Vol 207 (3) ◽  
pp. 609-612 ◽  
Author(s):  
C C Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Reduced Glutathione ◽  
Direct Reaction ◽  
Cytochrome C Reduction

Cytochrome c was reduced when superoxide was generated from xanthine oxidase in the presence of alloxan, and by the reaction of alloxan and with reduced glutathione. In each case, most of the reduction was inhibited by superoxide dismutase, but considerably more enzyme was required than with superoxide alone. This indicates that the superoxide dismutase-inhibitible cytochrome c reduction was mainly due to a direct reaction with the alloxan radical, and implies that other reactions that are inhibited by superoxide dismutase could be due to either alloxan radicals or superoxide.

Effects of Greek legume plant extracts on xanthine oxidase, catalase and superoxide dismutase activities

2011 ◽  
Vol 68 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Chrysoula I. Spanou ◽  
Aristidis S. Veskoukis ◽  
Dimitrios Stagos ◽  
Kalliopi Liadaki ◽  
Nectarios Aligiannis ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Xanthine Oxidase ◽  
Plant Extracts ◽  
Legume Plant
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