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With an aim to understand the toxicity mechanisms of the explosive 4,6-dinitro- benzofuroxan (DNBF), we studied its single-electron reduction by NADPH:cytochrome P450 reductase and ferredoxin:NADP(+) reductase, and two- electron reduction by DT-diaphorase and Enterobacter cloacae nitroreductase. The enzymatic reactivities of DNBF and another explosive(More)
We have examined the structure-activity relationships in methemoglobin (MetHb) formation by high explosives 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenyl-N-nitramine (tetryl) and 2,4,6-trinitrophenyl-N-nitraminoethylnitrate (pentryl), and a number of model nitrobenzenes. In lysed human erythrocytes the rate constants of oxyhemoglobin (OxyHb) oxidation(More)
In spite of well-known ability of lipoamide/dihydrolipoamide (LipS2NH2/Lip(SH)2NH2) and oxidized/reduced glutathione (GSSG/GSH) couples to scavenge singlet oxygen (1O2), the possible protective effects of these compounds against photodynamical damage by Alphtalocyanine tetrasulfonate (Al-PcS4) were examined. Using erythrocyte glutathione reductase, pig(More)
Polyphenolic antioxidants protected against Al-phthalocyanine tetrasulfonate-sensitized photohemolysis of human erythrocytes. A quantitative structure-activity relationship has been obtained to describe the protective effects of di- and trihydroxybenzenes: log cI(50) (microM)=(1.8620+/-1.5565)+(3.6366+/-2.8245) E(1)(7) (V)-(0. 4034+/-0.0765) log P(More)
Flavonoids exhibit prooxidant cytotoxicity in mammalian cells due to the formation of free radicals and oxidation products possessing quinone or quinomethide structure. However, it is unclear how the cytotoxicity of flavonoids depends on the ease of their single-electron oxidation in aqueous medium, i.e., the redox potential of the phenoxyl radical/phenol(More)
The toxicity of conventional nitroaromatic explosives like 2,4,6-trinitrotoluene (TNT) is caused by their enzymatic free radical formation with the subsequent oxidative stress, the formation of alkylating nitroso and/or hydroxylamino metabolites, and oxyhemoglobin oxidation into methemoglobin. In order to get an insight into the mechanisms of toxicity of(More)
Strong radical-scavenging activity of Geranium macrorrhizum extracts isolated by using various solvent systems has been reported previously. This study aimed at expanding the knowledge on the bioactivities of antioxidatively active G. macrorrhizum butanol fraction, which was isolated from ethanolic extract (EB), and water fraction, which was isolated from(More)
Prooxidant nitroaromatic and quinoidal compounds possess antimalarial activity, which might be attributed either to their formation of reactive oxygen species or to their inhibition of antioxidant enzyme glutathione reductase (GR, EC 1.6.4.2). We have examined the activity in vitro against Plasmodium falciparum of 24 prooxidant compounds of different(More)
The irradiation of Trypanosoma congolense trypanothione reductase (TR), human erythrocyte (HGR) and yeast glutathione reductase (YGR) with visible light in the presence of Al-phthalocyanine tetrasulfonate (A1PcS4) or hematoporphyrine (Hp) caused a time-dependent inactivation of these enzymes. TR was inactivated more rapidly than either HGR or YGR.(More)
Although quinones have been the subject of great interest as possible antimalarial agents, the mechanism of their antimalarial activity is poorly understood. Flavoenzyme electrontransferase-catalyzed redox cycling of quinones, and their inhibition of the antioxidant flavoenzyme glutathione reductase (GR, EC 1.8.1.7) have been proposed as possible(More)