title: Desulfonation of a colitis inducer 2,4,6-trinitrobenzene sulfonic acid produces sulfite radical.
abstract: 2,4,6-Trinitrobenzene sulfonic acid (TNBS) has been used in vivo to induce colitis. With the nitroreductase of intestinal cells, TNBS underwent redox cycling to produce TNBS-nitro and superoxide radical anions which are thought to be involved in initial oxidative reactions that lead to colonic injury. In this study, we demonstrated that the TNBS desulfonative reaction with tissue amino acids produces sulfite which is subsequently oxidized to sulfite radical. Sulfite radical was measured using a spin trapping methodology. Sulfite radical adducts of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) or 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO) were detected in a mixture of TNBS and lysine, xanthine oxidase, red blood cells, colonic mucosal or submucosal muscle tissues. TNBS alone did not produce sulfite radical, indicating that its formation required the presence of amino acids. Because sulfite radical is the precursor of highly reactive sulfiteperoxyl and sulfate radicals, our data imply that these sulfite-derived free radicals may also contribute to oxidative reactions leading to colonic injury in TNBS-induced colitis.
authors.affiliation: Department of Physiology, Louisiana State University Medical Center, New Orleans 70112-1393, USA. wchamu@lsumc.edu
authors.forename: W
authors.initials: W
authors.lastname: Chamulitrat
mesh_terms: D000818:Animals; D003092:Colitis / Q000139:chemically induced*; D003106:Colon / Q000187:drug effects / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004912:Erythrocytes / Q000378:metabolism; D005609:Free Radicals; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013447:Sulfites / Q000378:metabolism*; D013450:Sulfones / Q000378:metabolism*; D014302:Trinitrobenzenesulfonic Acid / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity
chemical_list: D005609:Free Radicals; D013447:Sulfites; D013450:Sulfones; D014302:Trinitrobenzenesulfonic Acid