Reconstruction of the macromolecular antitumor antibiotic SN-07 from SN-07 chromophore and DNA.

Abstract

To characterize the novel macromolecular antitumor antibiotic SN-07 and the role of DNA in SN-07, we reconstructed SN-07 in vitro from SN-07 chromophore and calf thymus DNA. Reconstructed SN-07 was identical with the native SN-07 in the ultraviolet absorption spectrum, nuclease-resistance characteristics, and biological activities (antibacterial activity and cytotoxicity). The DNA moiety promoted the cytotoxic activity of SN-07 chromophore against KB and HeLa cells, but suppressed the activity against some bacteria and L1210 cells. DNA containing guanine suppressed the activity more strongly than DNA not containing guanine against some bacteria and L1210 cells. The antibacterial activity of SN-07 chromophore was affected by dosage only when DNA was supplied, but not RNA or BSA. Thus the DNA composition of the SN-07 chromophore-DNA complex affected the activity of SN-07 chromophore and guanine had an important role of the binding of SN-07 chromophore to DNA.