The enzymatic reduction of the N-hydroxy derivatives of 2-acetylaminofluorene and related carcinogens by tissue preparations.

cause the hydroxamic acid is readily reduced both in vivo and in vitro (9, 13, 16, 22), the balance of the N-hydroxyla tion and reduction reactions is of considerable importance in determining the carcinogenic dose applied to the tissues. Studies on the microsomal system which N-hydroxylates AAF have been reported by Irving (13) and are in progress in this laboratory (17). The present paper reports on the distribution and characteristics of an enzyme system that reduces N-hydroxy-AAF and related hydroxamic acids to their respective arnides and on the reduction of N-hydroxy Extensive metabolic studies have shown that 2-acetyl aminofluorene (AAF)' is subject to deacetylation (26, 29, 35) and to oxidative attack on the various ring positions (35, 38) and on the nitrogen atom (2, 5—7, i2, 13, 16, 17,