Study of the antitumoral activity of S-carbamoyl-L-cysteine derivatives in animal experiments.

: The antitumoral activity of three amino acid derivatives, S-carbamoyl-L-cysteine, S-ethyl-carbamoyl-L-cysteine, and S-chloroethyl-carbamoyl-L-cysteine, was studied. The ethyl and chloroethyl derivatives had a pronounced curative effect on certain animal tumors. It is interesting in the case of S-carbamoyl-L-cysteine that N-ethylization of the substance resulted in increased chemotherapeutic effectivity with no simultaneous change of the toxicity. According to various studies this effect is different in many respects from that of the known cytostatics, and a possibility of a specific selective or surface activity is raised.