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  • Title: Comparison of antioxidant activities of aminoguanidine, methylguanidine and guanidine by luminol-enhanced chemiluminescence.
    Author: Yildiz G, Demiryürek AT, Sahin-Erdemli I, Kanzik I.
    Journal: Br J Pharmacol; 1998 Jul; 124(5):905-10. PubMed ID: 9692775.
    Abstract:
    1. The objective of this study was to investigate the ability of aminoguanidine, methylguanidine and guanidine to inhibit free radicals or metabolites generated by either stimulated human leucocytes or cell-free systems using luminol-enhanced chemiluminescence (CL). 2. Aminoguanidine (0.1 microM-10 mM), methylguanidine (10 microM-10 mM) and guanidine (10 microM-10 mM) produced concentration-dependent inhibition (96+/-0.1%, n=7, 59+/-1.3%, n=6, and 62+/-3%, n=6, P<0.05 at 10 mM, respectively) in FMLP-stimulated leucocytes CL. 3. In cell-free experiments, hydrogen peroxide (H2O2), hypochlorous acid (HOCl), hydroxyl radical and peroxynitrite-induced CL responses were initiated by hydrogen peroxide (3.5 mM), NaOCl (50 microM), FeSO4 (40 nM) and peroxynitrite (20 nM), respectively. Aminoguanidine, methylguanidine and guanidine produced concentration-dependent inhibition in H2O2-(69+/-0.7%, n=7, 26+/-1%, n=6, and 15+/-0.5%, n=6, at 1 mM, respectively) and HOCl-(84+/-0.3%, n=6, 50+/-1%, n=6, and 29+/-1%, n=7, at 1 mM, respectively) induced luminol CL. Peroxynitrite-induced CL was markedly attenuated in a concentration-dependent manner by aminoguanidine (99+/-0.1%, n=6, at 10 mM), methylguanidine (5+/-0.2%, n=6, at 10 mM) and guanidine (27+/-0.4%, n=7, at 10 mM). However, inhibition with aminoguanidine was found to be more marked than with methylguanidine and guanidine. Aminoguanidine (95+/-0.5%, n=6, at 1 mM) and methylguanidine (25+/-1%, n=6, at 1 mM), but not guanidine (2+/-1%, n=6, at 1 mM), significantly decreased ferrous iron-induced CL. 4. Collectively, these data suggest that aminoguanidine and a high concentration (> or = 0.1 mM) of methylguanidine have direct scavenging activities against H2O2, HOCl, hydroxyl radical and peroxynitrite. Guanidine, at a high concentration (> or = 0.1 mM), scavenges H2O2, HOCl and peroxynitrite, but not the hydroxyl radical. These direct scavenging properties may contribute to inhibitory effects of these compounds on human leucocyte CL.
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