High-Resolution Liquid Chromatography–Mass Spectrometry-Based Metabolomic Discrimination of <i>Citrus</i>-Type Crude Drugs and Comparison with Nuclear Magnetic Resonance Spectroscopy-Based Metabolomics

Abstract

Five <i>Citrus</i>-type crude drugs (40 samples) were classified using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. The following six flavonoid derivatives were identified as contributors from the loading plots of multivariate analysis: naringin (<b>1</b>), neohesperidin (<b>2</b>), neoeriocitrin (<b>3</b>), narirutin (<b>9</b>), hesperidin (<b>10</b>), and 3,5,6,7,8,3',4'-heptamethoxyflavone (<b>12</b>). Three coumarin derivatives, namely, meranzin (<b>6</b>), meranzin hydrate (<b>7</b>), and meranzin glucoside (<b>8</b>), were also identified as contributors. Furthermore, compared with our previous studies on proton (¹H) and ¹³C NMR spectroscopy-based metabolomics, the present study revealed that the <i>Citrus</i>-type crude drugs were distinguished with the same pattern; however, the contributors differed between the ¹H and ¹³C NMR spectroscopy-based metabolomics. The high dynamic range of NMR spectroscopy provided broad coverage of the metabolomes including the primary and secondary metabolites. However, LC-MS appeared to be superior in detecting secondary metabolites with high sensitivity, some of which occurred in quantities that were undetectable using NMR spectroscopy.