High throughput identification of pentacyclic triterpenes in Hippophae rhamnoides using multiple neutral loss markers scanning combined with substructure recognition (MNLSR).

A fast and simple analytical method was developed to fully understand the chemical diversity of pentacyclic triterpenes: lupane, oleanane and ursane type, using multiple neutral loss markers scanning combined with substructure recognition (MNLSR). This procedure was performed on ultra-high performance liquid chromatography coupled to electrospray ionization quadrupole Orbitrap high resolution mass spectrometry (UHPLC/ESI Q-Orbitrap). Hippophae rhamnoides was used as an example. This approach includes three systematic workflows: (i) targeted identification of 25 reference standards in order to deduce the mechanism of fragmentation in both positive and negative modes. (ii) statistical analysis for neutral loss markers and structural fragment markers of pentacyclic triterpenes by fragmentation mechanism information. (iii) untargeted identification using multiple neutral loss markers scanning technique to discover new compounds and then confirming structural characterization by structural fragment markers. This mass spectra data analysis approach was successful to identify and confirm 15 new compounds from Hippophae rhamnoides samples. This study extended the application of mass spectrometry to satisfy the requirements of high-throughput identification for pentacyclic triterpenes in new medicine or food resources and could help chemists rapidly discover novel similar substructure compounds from a complex matrix.