Lack of release from hepatocytes in vitro or excretion in vivo of mutagenic chrysoidine metabolites

Rat liver postmitochondrial supernatant (S9) converted the azo dyes chrysoidine Y and R to products that were mutagenic towards Salmonella typhimurium strain TA100. No such release of mutagens was demonstrated using intact rat hepatocytes as an activation system despite the fact that chrysoidine dyes cause unscheduled DNA synthesis in these cells. It appears that genotoxic products produced within hepatocytes either react within the cell or are detoxified prior to release. Following intraperitoneal administration of chrysoidine Y to rats (100 mg/kg i.p.) there was also no evidence of mutagenic or por-mutagenic products excreted in bile or urine. The S9-derived mutagens appear to be largely independent of bacterial acetylation since they were active in the acetylation-deficient strain TA98/1,8-DNP6 in addition to strain TA98. The ultimate mutagenic form(s) are therefore unlikely to be acetoxyarylamines.