Potentiation of iron-induced lipid peroxidation by a series of bipyridyls in relation to their ability to reduce iron.
We determine the relative abilities of three bipyridyls (Paraquat P + +, Benzylviologen B + + and Diquat D + +) to stimulate iron-induced lipid peroxidation in relation to their ability to redox cycle and to reduce iron. The ability to redox cycle increases with the redox potential, in the order: P + + < B + + < D + +. The initial rates of Fe3+ reduction increased from P + + to D + + and B + +. NADPH-dependent microsomal lipid peroxidation was measured in different conditions (1) increasing incubation time, 100 microM bipyridyl, 10 microM FeCl3; (2) increasing concentrations of bipyridyls, 10 microM FeCl3, 10 min incubation time; (3) increasing concentrations of FeCl3, 100 microM bipyridyl, 10 min incubation time. Bipyridyls potentiated the production of malondialdehyde (MDA), particularly with the shortest incubation times and the lowest concentrations of FeCl3, in the order of activity P + + < D + + < B + +. The strong correlation between the initial rate of lipid peroxidation and Fe3+ reduction indicates that the rate of Fe3+ reduction determines the intensity of the potentiation effect of bipyridyls on lipid peroxidation--on the condition that the amount of peroxidizable substrate is not the limiting factor.
Fernandez
Y
Y
INRA, Laboratoire des Xénobiotiques, Toulouse, France.
Anglade
F
F
Mitjavila
S
S
D000818:Animals; D001594:Benzyl Viologen / Q000633:toxicity*; D004178:Diquat / Q000633:toxicity*; D004357:Drug Synergism; D006540:Herbicides / Q000633:toxicity*; D007501:Iron / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010269:Paraquat / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar
D006540:Herbicides; D001594:Benzyl Viologen; D009249:NADP; D004178:Diquat; D007501:Iron; D010269:Paraquat; D010100:Oxygen