UHPLC-ESI-Orbitrap-MS/MS Untargeted Metabolomic Profiling and In Vitro Antioxidant and Antibacterial Activity of Different Achillea clypeolata Sibth. & Sm. Extracts.

Achillea clypeolata Sibth. & Sm. is an endemic Balkan species traditionally used in Bulgarian folk medicine. The present study aimed to conduct untargeted metabolomic profiling and characterization of 70% methanol, 70% ethanol, and water A. clypeolata extracts via the UHPLC-ESI-Orbitrap-MS/MS method. Furthermore, the in vitro antioxidant and antibacterial activities were determined. The putative analysis led to the identification of 62 compounds: 41 in positive and 21 in negative ionization mode. Predominant classes included flavonoids, organic acids, terpenes, fatty acids, sugars, and amino acids. The antiradical tests revealed the greatest antioxidant potential for the methanol extract, followed by the ethanol one, consistent with the findings for the total polyphenol and flavonoid contents. The antibacterial assays revealed the lowest minimum inhibitory concentration against the studied Gram-positive bacteria for the methanol extract, while the ethanol one better suppressed the Gram-negative ones' growth. Additionally, the ethanol extract had the lowest minimum bactericidal concentration (MBC) against S. aureus while the hydroalcoholic extracts's MBC was equal for the rest of the studied bacterial strains. The present findings provide additional insights into the phytochemical contents and in vitro biological activity of Achillea clypeolata, and serve as a basis for future investigations associated with its pharmacological application.