General survey of Fructus Psoraleae from the different origins and chemical identification of the roasted from raw Fructus Psoraleae

Fructus Psoraleae, a traditional Chinese medicine, is widely used for preventing and treating various diseases such as vitiligo, osteoporosis and psoriasis. Coumarin, such as psoralenoside, isopsoralenoside, psoralen and isopsoralen, are important compounds in Fructus Psoraleae. In our study, ultra performance liquid chromatography coupled with diode array detector was employed for an excellent method validation for simultaneous quantification of psoralenoside, isopsoralenoside, psoralen and isopsoralen, which was further applied in performing general survey of Fructus Psoraleae from the different origins and chemical identification of the roasted from raw Fructus Psoraleae in the light of illuminating the transformed rule of psoralenoside and isopsoralenoside. There is a reciprocal relationship between (iso)psoralenoside and (iso)psoralen, and the total content remains balance in Fructus Psoraleae from the different origins. In addition, we found that (iso)psoralenoside in the powder of the raw Fructus Psoraleae could be easily transformed into (iso)psoralen in methanol aqueous solution, especially above 50% water, rather than the roasted one. Thus, we proposed a hypothesis that transformation between (iso)psoralenoside and (iso)psoralen was hindered by inactivation of β-glucosidase in the process of roasting Fructus Psoraleae, which was further verified by observing transformation of (iso)psoralenoside under the different conditions, such as temperature, pH and β-glucosidase. Therefore, we developed a feasible method to distinguish the roasted from raw Fructus Psoraleae by observing conversion from (iso)psoralenoside to (iso)psoralen in 50% methanol aqueous solution. In summary, these results pave the way for elevating quality standard for Fructus Psoraleae and distinguishing the salt-processed from raw Fructus Psoraleae.