Constituents promoting osteogenesis from the fruits of Psoralea corylifolia and their structure-activity relationship study

The mature fruit of Psoralea corylifolia L. is a common traditional Chinese medicine used to tonify the kidney and yang, and as well as to treat osteoporosis. Systematic phytochemical investigations have established the most comprehensive constituent library to date, covering over 180 compounds. In this study, 109 chemical constituents containing 37 undescribed compounds were reported and incorrect structures of four known coumarins were corrected. The structures of these undescribed compounds were elucidated using spectroscopic methods, single-crystal X-ray diffraction, Rh2(OCOCF3)4 and Mo2(OAc)4-induced circular dichroism spectra. To identify potentially active compounds and investigate their structure-activity relationship (SAR), 89 constituents in the library were evaluated for their osteogenic differentiation and mineralisation activities in MC3T3-E1 cells. We found that coumarins, isoflavones, flavonones, and meroterpenoids were the material basis for Psoralea corylifolia-based treatment of osteoporosis, with some compounds exhibiting excellent activities. These compounds function via the estrogen receptor (ER) pathway and were natural phytoestrogen. Further SAR analysis showed that compounds with an intact isopentenyl replacement possessed superior activities, which was explained by their improved affinity with the ER.