Novel selective inhibitors for human topoisomerase I, BM2419-1 and -2 derived from saintopin

Compounds BM2419-1 and -2 were isolated from a culture broth of a fungus Pa ecilomyces sp. BM2419. It was shown that these novel compounds were artifac ts derived from saintopin, a dual inhibitor of topoisomerase I and II by in dependent processes. In the human topoisomerase I inhibition assay using th e recombinant Saccharomyces cerevisiae, BM2419-1 and -2 inhibited selective ly the yeast growth dependent on human topoisomerase I induction with IC50 values of 0.3 ng/ml and 6.0 ng/ml, respectively.