Catalytic inhibition of topoisomerase IIalpha by demethylzeylasterone, a 6-oxophenolic triterpenoid from Kokoona zeylanica.
Furbacher TR, Gunatilaka AA.
In a study to evaluate celastroloids as potential anticancer agents, demethylzeylasterone (5), a 6-oxophenolic triterpenoid from Kokoona zeylanica, was found to be an inhibitor of the enzyme topoisomerase IIalpha (IC(50) = 17.6 microM). Studies of the relationship of this inhibitor to both DNA and the enzyme resulted in 5 being classified as a 'catalytic inhibitor' of topoisomerase II. Demethylzeylasterone selectively inhibits the growth of the breast cancer cell line MCF-7 (IC(50) = 12.5 microM) without inhibiting the growth of non-small cell lung cancer (NCI-H460) and CNS glioma (SF-268) cell lines. This is the first report of topoisomerase II inhibitory activity in a celastroloid.