A chromenone analog as an ATP-competitive, DNA non-intercalative topoisomerase II catalytic inhibitor with preferences toward the alpha isoform.

5-Hydroxy-2-phenyl-7-(thiiran-2-ylmethoxy)-4H-chromen-4-one (compound 52) was found as a DNA non-intercalative topo II specific catalytic inhibitor by targeting its ATP-binding domain. Showing changes in interaction with Mg2+, it exhibited highly selective properties against the α-isoform with less toxicity, unlike other topo II poisons, such as etoposide.