Reassignment of the structure for the antitumor agent RR-150

7-Cysteaminomitosane (RR-150) has been reported to be superior to mitomycin C against P388 leukemia and B-16 melanoma in mice and is less leukopenic. Studies reported here indicated the absence of a free thiol group in RR-150 and therefore the structure was incorrectly assigned. Reaction of mitomycin A. with either 2-aminoethanethiol or cystamine gave the same disulfide, 7-N, 7'-N'-dithiodiethylenedimitomycin C, which is the newly proposed structure for RR-150. Attempts to produce 7-cysteaminomitosane by reduction of the disulfide have not succeeded because of its apparent instability.