Four new homoisoflavonoids from <i>Caesalpinia pulcherrima</i>

Four new homoisoflavonoids, 7-hydroxy-3-[hydroxy(4'-methoxyphenyl)methyl]-benzopyran-4-one (<b>1</b>), (3<i>R</i>)<b><i>-</i></b>7, 8-dihydroxy-3-(4'-methoxybenzyl)-chroman-4-one (<b>2</b>), 7-hydroxy-3-(2'-hydroxy-4'-methoxybenzyl)-chroman-4-one (<b>3</b>), and 7-hydroxy-3-(2'-hydroxy-4'-methoxybenzyl)-benzopyran-4-one (<b>4</b>), were isolated from the seeds of <i>Caesalpinia pulcherrima</i>. The structures of new compounds were elucidated by MS and NMR spectra. Their absolute configurations were assigned using electronic circular dichroism spectrum. Compounds <b>2</b> and <b>4</b> exhibited cytotoxic effects on MCF-7/TAM cells with the IC₅₀ values of 101.4 ± 0.03 and 93.02 ± 0.03 <i>μ</i>M, respectively.