Precursor Ion-Scan Mode-Based Screening Strategy for New Amorfrutin Derivatives from Amorpha fruticosa by UPLC–QqQ–MS and UPLC–Q-TOF–MS

Abstract

This study presents a screening strategy for unknown compounds by coupling UPLC–QqQ–MS and UPLC–Q-TOF–MS analyses. Amorfrutins, potential PPARγ agonists in Amorpha fruticosa, were selected as the research target. First, MS/MS analysis of three amorfrutin references (AA, AB, and AC) by Q-TOF revealed the mass-spectrometric fragmentation patterns of amorfrutins, and m/z 225 was recognized as a characteristic and common fragment ion of amorfrutins. Then, unknown amorfrutins were screened in the fruits of A. fruticosa by UPLC–QqQ–MS operating in precursor ion-scan mode, and the product ion was set as m/z 225 for screening potential amorfrutins. According to the high-resolution MS–MS spectral data provided by UPLC–Q-TOF–MS, the molecular formula of potential amorfrutins and their respective characteristic fragments were calculated. Finally, three unknown amorfrutins, namely, amorfrutin D and two new amorfrutins, were identified. As far as we know, this is the first study to rapidly identify unknown compounds by combined application of QqQ–MS precursor ion scan and Q-TOF–MS formula calculation. This research strategy will also be effective for the discovery of other trace natural products and metabolites.