Comparison of antioxidant activities of aminoguanidine, methylguanidine and guanidine by luminol-enhanced chemiluminescence.
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.
Yildiz
G
G
Department of Pharmacology, Faculty of Pharmacy, Gazi, Turkey.
Demiryürek
A T
AT
Sahin-Erdemli
I
I
Kanzik
I
I
D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D005296:Ferrous Compounds / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology*; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry / Q000494:pharmacology*; D006146:Guanidines / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006997:Hypochlorous Acid / Q000737:chemistry; D066298:In Vitro Techniques; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D008163:Luminescent Measurements; D008165:Luminol; D008760:Methylguanidine / Q000737:chemistry / Q000494:pharmacology*; D009566:Nitrates / Q000737:chemistry
D000975:Antioxidants; D005296:Ferrous Compounds; D016166:Free Radical Scavengers; D005609:Free Radicals; D006146:Guanidines; D009566:Nitrates; C039642:peroxynitric acid; C020748:ferrous sulfate; D008165:Luminol; D008760:Methylguanidine; D006997:Hypochlorous Acid; D006861:Hydrogen Peroxide; D019791:Guanidine; C004479:pimagedine