Steffimycin B is an anthracycline metabolite isolated from a Streptomyces sp., with antibacterial and antineoplastic properties. Crystallographic studies of binding to DNA suggest that it has a higher CpG base sequence specificity over the TpA step, similar to that of daunorubicin and nogalamycin. A close analogue was shown to be active against ras oncogene-expressed cells.
