Mother liquors from steffimycin B crystallizations have been processed to yield steffimycin C, a new member of the steffimycin family of anthracyclines. It has been identified, using spectroscopic methods, as 10-deoxysteffimycin B. Steffimycin C has antibacterial activity only against Streptococcus pneumoniae. Whether steffimycin C is a precursor of steffimycin B or a metabolic reduction product is unknown at this time.
