Simultaneous analysis of coumarin derivatives in extracts of Radix Angelicae pubescentis (Duhuo) by HPLC-DAD-ESI-MSⁿ technique

Radix Angelicae pubescentis (Duhuo) is a traditional Chinese herbal medicine (TCM) used for the treatment of rheumatic diseases. The coumarin derivatives in the Duhuo extracts are important bioactive compounds. In this work, a high performance liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MSⁿ) method was established for the rapid separation and characterization of coumarin compounds from the Duhuo extracts. A total of 24 coumarin compounds were detected, of which 7 compounds were unambiguously characterized by comparing their retention time (t_R), UV and MS spectra with those of the reference standards, and the others were tentatively identified based on their tandem mass spectrometry fragmentation data obtained in the positive ion mode on line. Importantly, five of these characterized coumarin compounds were reported from this plant for the first time.