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].