Rapid analysis of diketopiperazines in Alternaria panax by UPLC-Q-TOF-MS/MS combined with fragmentation patterns

Abstract:

[Objective] To obtain the target compounds from the extract of Alternaria panax based on ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) combined with their fragmentation patterns. [Methods] A. panaxwas fermented in potato dextrose broth(PDB) for 14 days. The filtrate was extracted with ethyl acetate and concentrated under reduced pressure to obtain the crude extract. The chemical composition and fragmentation pattern of the crude extract of A. panax were analyzed by UPLC-Q-TOF-MS/MS (including high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), molecular formula, and fragment peak). Semi-preparative high-performance liquid chromatography (HPLC) was employed to further purify the target compounds. The structures of the compounds were identified by nuclear magnetic resonance (NMR), mass spectrometry (MS), and comparison with literature data. [Results] Nine diketopiperazines (1-9) were identified by UPLC-Q-TOF-MS/MS from the crude extract of A. panax and their fragmentation patterns were analyzed. To verify the correctness of these structures, we separated compounds 1-3 and determined their chemical structures. The obtained structures of compounds 1-3 were consistent with the results of UPLC-Q-TOF-MS/MS. [Conclusion] UPLC-Q-TOF-MS/MS combined with fragmentation patterns can rapidly and efficiently identify the target components in an unknown sample, which can guide the targeted isolation as well.

Key words:UPLC-Q-TOF-MS/MS;diketopiperazines;fragmentation pattern;targeted isolation