Isolation and LC-QToF Characterization of Secondary Metabolites from an Endemic Plant Artemisia heptapotamica Poljak

Abstract

Phytochemical investigation of the aerial parts of Artemisia heptapotamica Poljak led to the isolation of ten known compounds, including four alkyl p-coumarates: octadecyl trans-p-coumarate (1), icosy trans-p-coumarate (2), docosyl trans-p-coumarate (3), and tetracosyl trans-p-coumarate (4), one sesquiterpene lactone: santonin (5), four flavonoids; axillarin (6), quercetin 3-O-methyl ether (7), luteolin (8), and quercetin (9), and one phenolic acid derivative: p-coumaric acid (10). The structures of the isolated compounds were identified by various spectroscopic analyses. Additionally, the antimicrobial activity of the total extract and different fractions was screened, and they exhibited no inhibition of the growth of Candida albicans, C. neoformans, Aspergillus fumigatus, methicillin-resistant Staphylococcus aureus (MRS), E. coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Vancomycin-resistant Enterococci (VRE) at the tested concentrations ranging from 8 to 200 μg/mL. The identification and tentative characterization of the secondary metabolites were conducted using LC-QToF analysis. This method helps in the putative characterization of sesquiterpene lactones, flavonoids, coumarate derivatives, and aliphatic compounds. The developed method identified 43 compounds, of which the majority were sesquiterpene lactones, such as eudesmanolides, germacranolides, and guaianolide derivatives, followed by flavonoids. The proposed LC-QToF method helps develop dereplication strategies and understand the major class of chemicals before proceeding with the isolation of compounds.