Identification of ring oxidized metabolites of 1-nitropyrene in the feces and urine of germfree f344 rats

1-Nitro[U-4,5,9,10-¹⁴C]pyrene in trioctanoin was administered by gavage to male germfree F344 rats. Extracts of the 120 h feces and urine were analyzed by h.p.l.c., with or without acetylation. 4,5-Dihydro-4,5-dihydroxy-1-nitropyrene, 1-nitro-3-hydroxypyrene, 1-nitro-6-hydroxypyrene and 1-nitro-8-hydroxypyrene but not 1-aminopyrene, 1-amino-6-hydroxypyrene or 1-amino-8-hydroxypyrene were identified by co-chromatography with standards. These results are in contrast to those obtained in the conventional F344 rat in which 1-aminopyrene, 1-amino-6-hydroxypyrene, and 1-amino-8-Miydroxypyrene were fecal and urinary metabolites, indicating that intestinal microflora are involved in their formation.