UPLC‐Q‐TOF‐MS/MS analysis of the guaiane sesquiterpenoids oxytropiols A–J and detection of undescribed analogues from the locoweed endophytic fungus Alternaria oxytropis (Pleosporaceae)

Abstract

Introduction: In addition to the mycotoxin swainsonine, the locoweed endophytic fungus Alternaria oxytropis (Pleosporaceae) also produces a series of rarely reported, highly oxygenated bicyclic guaiane sesquiterpenoids. Few investigations on the electrospray tandem mass fragmentation pattern of this sesquiterpenoid have been reported. Objectives: We aimed to analyze and detect new guaiane sesquiterpenoid analogues from crude extracts of the locoweed endophytic fungus A. oxytropis by UPLC-Q-TOF-MS/MS experiments. Materials and Methods: Oxytropiols A-J (1-10) and the extract of the locoweed endophytic fungus A. oxytropis were analyzed by UPLC-Q-TOF-MS/MS in positive mode. Results: Typical neutral losses, McLafferty rearrangement, 1,2-rearrangement, and 1,3-rearrangement were considered to be the main fragmentation patterns for the [M + H] + /[M + Na] + ions of 1-10 by UPLC-Q-TOF-MS/MS experiments, and possible fragmentation pathways of 1-10 were suggested. A unique and undescribed analogue named oxytropiol K (11) was found in the extract based on UPLC-Q-TOF-MS/MS analysis. Compound 11 was isolated and elucidated by NMR spectrometry, and its UPLC-Q-TOF-MS/MS analysis was consistent with the fragmentation pathways of 1-10. Conclusion:The results further support that UPLC-Q-TOF-MS/MS is a powerful and sensitive tool for the characterization of known compounds (dereplication) and the detection of new analogues from crude extracts and imply that the locoweed endophytic fungus A. oxytropis, with few chemical investigations, is an important resource for undescribed metabolites.

The Application of UHPLC-HRMS for Quality Control of Traditional Chinese Medicine

“…Meanwhile, a considerable amount of time is required to isolate and purify the compounds of TCMs. With the development of modern analytical techniques, a variety of high resolution mass spectrometry (HRMS) techniques, such as the quadrupole time-of-flight mass spectrometry (Q-TOF-MS) and Q-Exactive Orbitrap mass spectrometry (Q-Orbitrap-MS), have been widely used for the detection and identification of compounds in TCMs ( Wang L. et al, 2017 ; Liang et al, 2021 ; Tan et al, 2021 ). Mass spectrometers are more suitable for rapid and cost-efficient analysis and tentative identification of TCMs, and the types that have been used HRMS mass spectrometers ( Lv et al, 2018 ; Li et al, 2021 ).…”