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.

Keywords: Cytotoxicity; Heterodimer; Leguminosae; Meroterpene phenol; Psoralea corylifolia; Spiroketal.