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.

Pyrrolobenzodiazepines (PBDs) are sequence selective DNA alkylating agents with remarkable antineoplastic activity[1]. Alkylation of DNA by anthramycin, sibiromycin and tomaymycin is sequence specific with the following trend for binding preference 5′-Pu-G-Pu>5′-Py-G-Pu>5′-Pu-G-Py>5′-Py-G-Py[1]. Sibiromycin shows cytotoxicity against L1210 (leukemia), ADJ/PC6 (plasmacytoma) and CH1 (ovarian) cells with IC50s of ranging 0.000017 ~0.0029 μM[1].