Sibiromycin, a glycosylated pyrrolobenzodiazepines (PBDs) compound, is a naturally occurring and potent antitumor antibiotic. It exerts its activity by covalently binding to DNA in the minor groove at the NH2 of guanine.
Rachelmycin (CC-1065; NSC 298223) is a potent naturally antibiotic isolated from Streptomyces zelensis . Rachelmycin binds non-covalently and covalently (N-3 adenine adduct) in the minor groove of B-form DNA. Rachelmycin has exceptionally potent antitumor activity.