Rapid analysis of the chemical composition of the Equiseti hiemalis herba based on UHPLC-Q-Exactive Orbitrap MS with parallel reaction monitoring

Abstract: Background: Equiseti hiemalis herba (EH) is traditionally used for heat-clearing, promoting diuresis, resolving phlegm, relieving cough, improving vision and reducing ocular opacity. Previous phytochemical studies on EH have mainly focused on flavonoids and organic acids, whereas a comprehensive characterization of its chemical constituents remains lacking. Objectives: This study aimed to establish a rapid and systematic analytical strategy for the comprehensive characterization of chemical constituents in EH. Methods: In this work, a UHPLC-Q-Exactive Orbitrap MS system was employed for compound identification, utilizing full MS scan with subsequent data-dependent MS2 acquisition or parallel reaction monitoring incorporating an inclusion ion list. Results: A total of 82 compounds were identified or tentatively characterized from EH, including 34 organic acids, 22 flavonoids, 10 terpenes, 3 nucleotides, 3 amino acids, 3 coumarins, 2 alkaloids and 5 other compounds. Among them, 71 compounds were reported in EH for the first time. Organic acids and flavonoids were the predominant constituents, while the identification of terpenes further revealed the chemical diversity of EH. Conclusion: The established analytical strategy provides an effective approach for the rapid characterization of chemical constituents in EH and offers a theoretical basis for further studies on its pharmacodynamic material basis and pharmacological mechanisms.