[Nitroxyl derivatives of rubomycin]

The toxic and antitumor effects of new analogs of rubomycin were studied. It was shown that the spin-labeled derivatives had the lowest toxicity and highest antitumor activity. The diamagnetic analog was similar to rubomycin in its antitumor effect. It was demonstrated that ruboxyl-l had a lower cardiotoxicity than rubomycin and did not inhibit hemopoiesis at the maximum tolerated doses.