Elsamitrucin
Elsamitrucin is an heterocyclic antineoplastic antibiotic isolated from the bacterium Actinomycete strain J907-21.  Elsamitrucin intercalates into DNA at guanine-cytosine (G-C)-rich sequences and inhibits topoisomerase I and II, resulting in single-strand breaks and inhibition of DNA replication. (NCI04)