Cytotoxic heterodimers of meroterpene phenol from the fruits of Psoralea corylifolia

Abstract

Seventeen undescribed heterodimers of meroterpene phenol, psocorylins A–Q, were isolated from the fruits of Psoralea corylifolia. Their another monomeric unit derived from flavonone, chalcone, coumarin and isoflavone, respectively. Psocorylins A–E were rare natural spiroketals with the skeleton of 1,4,8-trioxaspiro[4.5]decane deriving from flavonone, and their plausible biosynthetic pathways were proposed. These structures were established by spectroscopic methods. Their absolute configurations were assigned via single-crystal X-ray diffraction, electronic circular dichroism (ECD) calculations and Rh2(OCOCF3)4-induced ECD spectra. Psocorylins B–E, F, M and Q exhibited potent cytotoxic activities against different kinds of tumor cells with IC50 values less than 10 μM.