Anti-estrogenic activity of mansorins and mansonones from the heartwood of Mansonia gagei DRUMM.

Through an anti-estrogenic bioassay-guided fractionation of the methanol extract of Mansonia gagei, three new coumarins, called mansorins I (1), II (2) and III (3) and a new naphthoquinone, mansonone I (4), were isolated. Their structures were determined based on their NMR data and CD spectroscopy. The anti-estrogenic activity of the fractions and the isolated compounds were investigated using a yeast two-hybrid assay method expressing estrogen receptors alpha (ERalpha) and beta (ERbeta). In addition, an ERalpha competitor screening system (ligand binding screen) was used to verify the binding affinities of the isolated compounds to the estrogen receptor. 1,2-Naphthoquinones (mansonones) showed more binding affinities to ER in both assay systems. All the tested compounds showed higher binding affinities to ERbeta than to ERalpha in the yeast two-hybrid assay. Mansonones F and S showed the most potent estrogen binding and estrogen antagonistic effects.