Species and strain comparison of the metabolism of gentian violet by liver microsomes

Comparative metabolism of hexamethylpararosaniline chloride, a poultry feed additive known as gentian violet, was examined in vitro in the presence of uninduced liver microsomes prepared from both sexes of four mouse strains, three rat strains, hamster, guinea pig, and chicken. Metabolites, isolated by solvent extraction and HPLC, were identified by comparison of reverse-phase HPLC retention times and electron impact mass spectral fragmentation patterns with those of standards prepared by unambiguous synthetic routes. The major metabolites were pentamethylpararosaniline and the isomeric N,N,N',N'- and N,-N,N',N"-tetramethylpararosanilines. The pattern of demethylated metabolites was found to be comparable among the species with little difference between the sexes.