Radical generation by the non-enzymatic reaction of methylglyoxal and hydrogen peroxide.
BACKGROUND
In various disorders, the reactive alpha-oxoaldehyde compounds methylglyoxal (MG) and glyoxal (GO) are thought to contribute to oxidative injury. However, the exact mechanism by which these molecules induce oxidative stress is unclear. We hypothesized that intermediate compounds, such as free radicals, are generated during the chemical reaction between H(2)O(2) and MG or GO.


METHODS
Chemiluminescence signals emitted from the 'test mixture' of MG/GO, luminol, and H(2)O(2) were measured. To confirm radical generation, the electron spin resonance (ESR) spectrum of MG/GO and H(2)O(2) was observed using the spin-trap method, in which 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 3,5-dibromo-4-nitrosobenzenesulfonic acid (DBNBS) were used as spin trap reagents for free radicals.


RESULTS
Luminol chemiluminescence as a function of MG concentration was increased by MG and partly decreased by DMPO. The MG increase was about 10 times that of GO. The free radicals generated by MG and H(2)O(2) included methyl and other carbon-centered radicals.


CONCLUSIONS
We demonstrated that free radicals are generated via a non-enzymatic reaction between MG and H(2)O(2) in vitro. The finding provides a novel perspective for understanding the toxicological aspects of MG and the pathophysiology of disorders associated with increased MG levels in vivo.
Nakayama
Masaaki
M
Tohoku University Graduate School of Medicine, Research Division of Dialysis and Chronic Kidney Disease, Sendai, Japan. mnakayama@mail.tains.tohoku.ac.jp
Saito
Keita
K
Sato
Emiko
E
Nakayama
Keisuke
K
Terawaki
Hiroyuki
H
Ito
Sadayoshi
S
Kohno
Masahiro
M
D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry*; D006037:Glyoxal / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007202:Indicators and Reagents / Q000378:metabolism; D008165:Luminol / Q000378:metabolism; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011765:Pyruvaldehyde / Q000737:chemistry*; D019097:Spin Trapping
D005609:Free Radicals; D007202:Indicators and Reagents; D016877:Oxidants; D006037:Glyoxal; D008165:Luminol; D011765:Pyruvaldehyde; D006861:Hydrogen Peroxide