Chromomycin A3 is an anthraquinone that exhibits antibacterial and anticancer chemotherapeutic activity. Chromomycin A3 binds Mg2+ and Zn2+ ions, and these complexes bind GC sequences in nucleosomal DNA; this inhibits DNA gyrase, RNA polymerase, and DNA transcription. Chromomycin inhibits growth of bacteria such as Bacillus, inhibits alcohol dehydrogenase, and suppresses tumor growth of breast cancer xenografts in animal models.