¹H nuclear magnetic resonance based-metabolomic characterization of Peucedani Radix and simultaneous determination of praeruptorin A and praeruptorin B

As a widely used traditional herbal medicine, it is crucial to characterize the holistic metabolic profile of Peucedani Radix (Chinese name: Qian-hu). However, it is quite arduous to obtain the whole picture of chemical constituents appropriately with the existing analytical techniques that were based on HPLC-UV or LC-MS/MS system. In present investigation, nuclear magnetic resonance (NMR) spectroscopy coupled with principal components analysis (PCA) was introduced to metabolomic characterization of Qian-hu crude extracts without any chromatographic separation. In addition, the contents of praeruptorin A (PA) and proaeruptorin B (PB) in Qian-hu were simultaneously determined using quantitative ¹H NMR (q¹H NMR) spectroscopy. Eighteen reference compounds (1-18), which were purified from this herbal drug extract previously, were recruited for the assignment of the protonic signals in the ¹H NMR spectra. Following PCA, 15 batches of Peucedani Radix were divided into two groups (I and II), and angular-type pyranocoumarins, in particular PA and PB, as well as 5-methoxycoumarin were demonstrated as the predominant markers being responsible for the distinguishment of Qian-hu from different districts. The contents of the two analytes (PA & PB) were calculated by the relative ratio of the integral values of the target peak for each compound to the known amount of the internal standard, formononetin (IS). The lower limits of quantitation were determined as 19.5μg/mL for both PA and PB. The quantitative results indicated that the contents of PA and PB showed quite variable qualities among different extract samples. Above all, ¹H NMR spectroscopy, that could not only provide comprehensive profiles of the metabolites but also achieve convenient determination of praeruptorin A and praeruptorin B, is a promising means for evaluating the medicinal samples of Peucedani Radix.