The stereoisomers are interchangeable in aqueous solution and the antibiotic, Neothramycin, contains both in approximately equal amounts.[1] They belong to the pyrrolo(1,4)benzodiazepine, or anthramycin, group which includes other antibiotics such as anthramycin, tomaymycin, and sibiromycin. Neothramycin was originally isolated from Streptomyces No.