Rapid separation, identification, and quantification of coumarins in Peucedanum ostruthium by high-performance liquid chromatography with diode-array detection and mass spectrometry

Abstract

The genus Peucedanum (Apiaceae) contains over 120 species. Various coumarins are typical for its family and, therefore, can be used to distinguish between closely related species [1]. As the rhizomes of Peucedanum ostruthium are traditionally used in the alpine region as herbal drug and as ingredient of liqueurs and bitters [2], there is a need for quality control of this drug (“Radix Imperatoriae“). A high performance liquid chromatography-diode array detector-mass spectrometry (HPLC-DAD-MS) method has been developed for the simultaneous separation and identification of the six main coumarins, Oxypeucedanin-hydrate, Oxypeucedanin, Ostruthol, Imperatorin, Isoimperatorin, and Ostruthin, in the dichloromethane extract of the dried rhizomes of Peucedanum ostruthium. Fast HPLC separation of the (furano)coumarins could be achieved on a Aquasil C18 column (150×2,1, particle size: 3µm) using a mobile phase gradient of acetonitrile-water modified with 0,01% acetic acid. Peak assignment and purity control were obtained by multistage LC-MS using a 3D quadrupole ion trap instrument equipped with an orthogonal electrospray ionisation source. The identity of the main compounds was confirmed either by comparison with reference compounds (Oxypeucedanin, Imperatorin and Isoimperatorin), or by isolation (Oxypeucedaninhydrate, Ostruthol and Ostruthin) and structural characterization by NMR and MS. Moreover, the content of the main coumarins was quantified in various batches of commercial and field-collected rhizomes of Peucedanum ostruthium by this newly established HPLC-DAD method. Hence, it can be used for performing a fast profiling and quantification of the main coumarins in samples of “Radix Imperatoriae“.