THE NEW CYTOTOXIC ANTIBIOTIC CYTORHODIN X, AN UNUSUAL ANTHRACYCLINONE-9α-GLYCOSIDE

From our screening program for novel antitumor antibiotics several anthracyclines (cytorhodins A similar to W) belonging to the rhodomycin-group have been isolated from the Streptomyces species HPL Y-11472 (DSM 2658). Very recently a new cytotoxic compound was isolated from this strain, which was found to have a new and unusual structure, and which we named cytorhodin X. Based on NMR, mass spectral analysis and chemical degradation cytorhodin X was identified as a heretofore unknown gamma -rhodomycinone glycoside containing a common trisaccharide chain at C-10 and an additional rhodosamine unit at C-9 (1). Compound 1 and its partial hydrolysis product 2 inhibited the growth of L1210 murine leukemia cells showing ED sub(50) values of 0.36 mu M and 0.51 mu M, respectively. Here, we report the isolation procedure and structure elucidation of this new 9 alpha -glycoside of the gamma -rhodomycin-group and its hydrolysis products.