Intestinal transformation of 2,6-dinitrotoluene in male Wistar rats

1. Metabolites formed by anaerobic incubation of 2,6-dinitrotoluene (2,6-DNT) with intestinal microflora of male Wistar rats were examined. Intestinal transformation of 2,4-dinitrotoluene (2,4-DNT) was also studied to determine whether azoxy compounds are produced in the anaerobic incubation. 2. 2,6-DNT was transformed by the intestinal microflora into 2-nitroso-, 2-hydroxylamino- and 2-amino-6-nitrotoluene, and 2,6-diaminotoluene. A time course study showed that 2-nitroso-, 2-hydroxylamino-, and 2-amino-6-nitrotoluene reached peaks at 2, 5 and 6 h of the anaerobic incubation; 2,6-diaminotoluene appeared at 12 h of the incubation. The formation of 2,6-diaminotoluene from 2-amino-6-nitrotoluene in the incubation was confirmed. 3. Two nitroazoxy compounds, namely, 2,2'-dimethyl-5,5'-dinitroazoxybenzene and 4,4'-dimethyl-3,3'-dinitroazoxybenzene, in addition to known metabolites (nitrosonitrotoluenes, hydroxylaminonitrotoluenes, aminonitrotoluenes and diaminotoluene), were detected in the incubation of 2,4-DNT with intestinal microflora. The formation of the two nitroazoxy compounds (2% dose in 24 h) was non-enzymic and merely involved mixing 2-hydroxylamino-4-nitrotoluene with 2-nitroso-4-nitrotoluene or 4-hydroxylamino-2-nitrotoluene with 4-nitroso-2-nitrotoluene in methanol, respectively.