Metabolic profile of and antimicrobial activity in the aerial part of leonurus turkestanicus V.I. Krecz. et Kuprian. from Kazakhstan

An HPLC quadrupole time-of-flight (Q-TOF) MS method was developed for the identification of secondary metabolites in Leonurus turkestanicus V.I. Krecz. et Kuprian. Ethanolic and chloroform extracts from the plant’s aerial parts were tested. A total of 16 compounds (iridoid glycosides, phenylpropanoids, flavonoids, and nitrogen-containing compounds, as well as diterpene acetate derivatives) were identified and tentatively characterized based on (or using) their retention times and UV and Q-TOF-MS data. Previously reported aucubin (1), 6-deoxy-8-acetylharpagid (2), and stachydrine (13, 15) and homostachydrine isomers (14, 16) were identified, along with a lavandulifolioside isomer (3), verbascoside (4), rutin (5), 3-O-kaempferol rutinoside (6), and an unknown diterpene acetate (8). Compounds 3–6 were detected for the first time in this plant. Additionally. antimicrobial activity was evaluated. No significant differences were found between ethanolic and chloroform extracts of L. turkestanicus; however, the alcoholic extract showed stronger antifungal activity [minimal inhibitory concentration (MIC) of 2.5–5 mg/mL], whereas the chloroform extract showed stronger activity against the tested spore-forming Bacillus species (MIC 1.25–2.5 mg/mL).