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Effect of antioxidants on induction time of luminol luminescence elicited by 3-morpholinosydnonimine (SIN-1)

1999; Wiley; Volume: 14; Issue: 2 Linguagem: Inglês

10.1002/(sici)1522-7243(199903/04)14

1522-7243

Carlos Pascual, Konrad Reinhart,

Vitamin C and Antioxidants Research

The reaction between luminol as a chemiluminescence probe and 3-morpholinosydnonimine (SIN-1) as a peroxynitrite donor was evaluated in order to determine the action of several antioxidants. Several well-known antioxidants found in biological fluids or cells modify the light profile of the reaction between SIN-1 and luminol. One main modification was characterized by a transient suppression of the light signal, thus permitting evaluation of an induction time (σ) which is linearly related to the concentration of the additive. From induction time measurements and using Trolox as a reference antioxidant, the trapping ability of a compound against oxidants and radicals produced in the luminol–SIN-1 reaction at pH 7.4 was determined. Uric acid showed higher antioxidant capacity than Trolox, while bilirubin and ascorbic acid, in decreasing order, were slightly less efficient. On the other hand the main modification of the light signal produced by superoxide dismutase, desferrioxamine and myoglobin was characterized by a decrease of the luminescence during the course of the reaction. The reaction luminol–SIN-1 was compared with the known luminol–ABAP (2,2′-azo-bis-2-amidinopropane) method for evaluation of antioxidant capacity in human plasma, since this biological fluid modifies the luminol–SIN-1 reaction with well-defined induction times. Samples were obtained from patients with sepsis, a condition where it has been postulated that excess oxygen radicals including peroxynitrite are produced. Using Trolox as reference, the results (mean ± standard error of mean) of both assays showed that the patients (SIN-1, 263 ± 16; ABAP, 218 ± 13; n = 19) have significantly (SIN-1, p < 0.02; ABAP, p < 0.001) lower values in comparison to non-septic controls (SIN-1, 330 ± 16; ABAP, 398 ± 16; n = 20). SIN-1 could be useful as a source of oxidant for the characterization of antioxidant behaviour in a system where superoxide and nitric oxide are simultaneously generated. Copyright © 1999 John Wiley & Sons, Ltd.