Quenching-free chemiluminescence method for ranking the antioxidants and inhibition of AAPH-induced membrane peroxidation of red blood cells using new aminophenol derivative

Abstract

In this work, a quenching-free peroxyoxalate chemiluminescence method for ranking the antioxidant activity and determination of both hydrophobic and hydrophilic antioxidants is introduced. A highly fluorescent furan derivative, diethyl-2-(cyclohexylamino)-5-(E)-2-phenyl-1-etheny1-3,4-furandicarboxylate, (L-2), with protected functional groups is used as fluorophore to prevent the interaction between excited fluorophore and antioxidant molecule and hence, removing the quenching effect in the calculated antioxidant capacities. In addition, new aminophenol derivative, 4-(((2-amino-5-nitrophenyeimino)methyl)-2-methoxy phenol, (MNMP), with strong antioxidant activity is introduced for inhibition of AAPH-induced membrane peroxidation of the red blood cells and determination of H2O2 in aqueous solutions. Based on the proposed method the ascorbic equivalent antioxidant capacity (AEAC) values for ascorbic acid, MNMP, BHT and caffeine were found to be 1, 7.19, 23.10 and 30.54, respectively. The IC50 values for ascorbic acid, MNMP, BHT and caffeine were obtained as 2.96 x 10(-5) M, 2.13 x 10(-4) M, 6.86 x 10(-4) M and 9.04 x 10(-4) M, respectively. The obtained antioxidant activity order is in agreement with the structural interpretation of the interaction between antioxidants and dioxetanedione intermediates. The detection limits for determination of ascorbic acid, BHT, caffeine and H2O2 were 1.38 x 10(-6) M, 1.25 x 10(-6) M, 1.30 x 10(-6) M and 1.32 x 10(-5) M, respectively. The cytotoxicity experiments performed on the human fibroblast skin cells showed that MNMP has no toxic effects on the tested cells.