[On structure-activity relationships of N'methyl-N'-beta-chloroethyl-benzaldehyde hydrazones (author's transl)].

The inhibition of uridine and thymidine in Ehrlich ascites cells is a basic property of the methylhydrazone structure and is reinforced by introducing a beta-chloroethyl group. This was shown by variation of the substituents at the N'-nitrogen atom of N'-methyl-N'-beta-chloroethyl-benzaldehyde hydrazone. Probably this action is due to an ethylenimmonium intermediate. This is derived from the observation that substituents which increase the nucleophilic property of the N'-nitrogen atom show a greater inhibitory effect in vitro. The therapeutic effect, however, is not enhanced when tested on the solid Ehrlich ascites tumor of mice. A better therapeutic effect resulted from introduction of chlorine atoms in positions 3 and 4 of the ring which inhbiits as well a probable metabolic hydroxylation of the ring.