Attenuation of luminol-amplified chemiluminescent intensity and lipid peroxidation in the livers of quercetin-fed mice

We assessed the antioxidative effects of quercetin-feeding on ddY strain ma le mice by measuring luminol-amplified chemiluminescence that was enhanced by a hydrophilic free radical initiator 2,2'-azobis(2-amidinopropane) dihyd rochloride. Quercetin suppressed chemiluminescent intensity in a dose-depen dent manner in vitro with a half-inhibition concentration (IC50) of 3 x 10( -8) M, which was lower than the value of synthetic antioxidant 2,6-di-tert- butyl-p-cresol (IC50: 7 x 10(-7) M). Lysosomal (12 000 x g pellet) and supe rnatant fractions obtained from the livers of mice fed a diet containing 0. 2% quercetin for 7 days showed more inhibition of chemiluminescent intensit y than those from non-treated mice. Quercetin feeding also resulted in the inhibition of lipid peroxidation as determined by a thiobarbituric acid rea ctive substance test which detected suppression of the release of lysosomal enzymes induced by lipophilic free radical initiator 2,2'-azobis(2,4-dimet hylvaleronitrile). These results probably reflect radical quenching activit y of quercetin, indicating that the measurement of chemiluminescence is a u seful tool for the assessment of total antioxidant activity in biological s ystems. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.