Chartreusin,an antitumor glycoside antibiotic,induces DNA strand scission

The interaction of chartreusin with covalently closed circular PM2 phage DNA was studied. The antibiotic caused a single strand scission in the presence of reducing agents, such as dithiothreitol, ascorbic acid or NaBH₄. The degree of DNA breakage was dependent upon the drug concentration. The DNA-cleaving activity was enhanced by ferrous ion; but was completely blocked by catalase and partially by superoxide dismutase. The results suggest that reduction, chelate formation and auto-oxidation of the antibiotic, presumably the 5,12-dione moiety, produce free radicals, including $\text{O}{}_2{}^{\mathrm{<mtext>?</mtext>}}$ and ^?OH, which are capable of inducing DNA strand scission.