lrreversible Enzyme Inhibitors. CLXXIV. Metabolisrii of 4-[p-(4,6-Diamino-l,2-dihydro-2,2-dimeth?-l-s-triazin-l-~ l)hvdrociniiaiiiitlo]-otoluenesulfonyl Fluoride (NSC-113423),an liclive- Site-Directed Irreversible Inhibitor of Dihj,drofolic Reductase
The IC-labeled title coinpound (1) was synthesized frum [1+CJcyaiioguaiiidine, acetolie, and p-(p-;triiiuohydliJcinnamido)-o-toluenesulfonyl fluoride (4). The sulfoiiic acid 2 corresponding to hydrolysis of the SOZFgroup W H Y the only radioactive excretion product, 20yc of the radioactivity appearing in the urine and 58Yc in the feces. Investigation of serum and liver extract, of the rat showed that the liver contained a "sulfonyl fluoridase" that rapidly converted 1 into 2 ; hydrolysis by serum was rniich slower, biit c*ornpletein 20 hr t % t37".
In the previous paper of this series,29 active-site-directed irreversible inhibitors of dihydrofolic reductase of the S02F type were tested against Walker 256 ascite. and Dunning leukemia ascites in the rat ; although cures could be achieved, no correlation between tissue specificity of irreversible inhibition of the enzyme and in vivo effectiveness was apparent. Furthermore, 5 reversible inhibitors-where the S0Jp group had been replaced ( 1 ) This work was generously supported by Grant S o . CA-08695 from t h e National Cancer Institute, U. S. Public Health Service. 12) For t h e previous paper in t,his series see B. R . Baker, N . M. J. Vermeillen, W.-1.-4shton. and .%. .J. Ryan. J . .\led. Chem.. 13, 1130 (1970). ,:$I On sabhaticsl leave from t h e University of Sydney, Australia. t $1 (a) N . 11. .J. Yermeulen wishes t o thank the Council of Scientific and Industrial Research, Republic of South .\frica, for a tuition fello\r.alli~~. ( I > ) TI, whorn correspondence should he addressed
1 ) ) H- -were ab effective 111 uivo ab the irreversible inhit)itors. These results indicated that other factors sucli transport and metabolism might be playing a r o l ( b
which negated correlation. Therefore one of the coiiipounds (1) wab labeled with I4C in the triazine ring :iiitl subjected t o a metabolic study in the rat. The rcsultc are the subject of this paper. Chemistry.-The *4C-ld~led1 I\ ab 73 Iithchized h i condensation of [14C]cysn~guanidlne, the arylamiiici precursor 4,J and acetone according to the general method of RIodest.6 Two obvious possibilities for metttbolic change of the d e chain of 1 were hydrolysis of ii) (
13 I< l$dhel a n d
