Participation of metabolic activation of 2,4,6-trinitrotoluene to 4-hydroxylamino-2,6-dinitrotoluene in hematotoxicity.
Exposure to 2,4,6-trinitrotoluene (TNT) causes methemoglobin (metHb) formation, hemolysis and negative heme balance in vivo, but the mechanistic details are poorly understood. In the present study, we examined the participation of metabolic activation in TNT-mediated hematotoxicity. Exposure of rats with TNT (300 mg/kg, i.p.) for 4 days resulted in a decrease of hematocrit value coupled to an increase in metHb formation. The red blood cells treated with 4-hydroxylamino-2,6-dinitrotoluene (HADNT), a metabolite of TNT, underwent readily hemolysis in vitro, whereas such a phenomenon was not seen with TNT. Consistent with this, HADNT is active toward metHb formation and the decrease in thiol content of the globin moiety compared with TNT and its metabolites 4-amino-2,6-dinitrotoluene (ADNT) and 4-acetylamino-2,6-dinitrotoluene (AADNT). Furthermore, interaction of purified rat oxyhemoglobin (oxyHb) with HADNT, but not TNT, ADNT, and AADNT, caused a concentration-dependent production of H2O2 and ferrylhemoglobin (ferrylHb) which is a highly oxidizing state formed by reaction of oxyHb with H2O2. Notably, hemin was released during interaction of oxyHb with HADNT. Taken together, these findings suggest that HADNT is an active metabolite that mediates TNT-induced hematotoxicity via formation of prooxidants such as H2O2 and ferrylHb.
Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba.
Yasuhiro
Y
Shinkai
Song
S
Li
Tomohiro
T
Kikuchi
Yoshito
Y
Kumagai
D000814:Aniline Compounds / Q000633:toxicity*; D000818:Animals; D002478:Cells, Cultured; D004136:Dinitrobenzenes / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism*; D006400:Hematocrit; D006427:Hemin / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D008706:Methemoglobin / Q000378:metabolism; D009574:Nitro Compounds / Q000378:metabolism* / Q000633:toxicity*; D010108:Oxyhemoglobins; D011916:Rats, Inbred F344; D014050:Toluene / Q000031:analogs & derivatives* / Q000378:metabolism / Q000633:toxicity
C545368:2,4,6-trinitrenotoluene; D000814:Aniline Compounds; D004136:Dinitrobenzenes; D006454:Hemoglobins; D009574:Nitro Compounds; D010108:Oxyhemoglobins; C517773:ferrylhemoglobin; D014050:Toluene; C085951:4-hydroxylamino-2,6-dinitrotoluene; D006427:Hemin; D008706:Methemoglobin; D006861:Hydrogen Peroxide