Polyphenol content and bioactivity of Achillea moschata from the Italian and Swiss Alps

Achillea moschata Wulfen, which grows in the Alps, is extensively used by local people for its medicinal properties. Two studied samples were collected, at the flowering stage, in Val Mustair (Switzerland) and Valchiavenna (Italy), respectively. The aerial parts were defatted with petroleum ether (PET) and successively extracted with dichloromethane (DCM) and methanol (MeOH). High-performance liquid chromatography and electrospray ionization-tandem mass spectrometry analyses of the methanolic extracts evidenced that flavonoids were the predominant compounds compared to phenolic acids in both samples (89.5 vs. 33.0 μg/mg DW in A. moschata Valchiavenna and 82.5 vs. 40.0 μg/mg DW in A. moschata Val Mustair). Among flavonoid derivatives, luteolin and apigenin were the predominant aglycones, free and glycosilated. The A. moschata Valchiavenna extract was characterized by apigenin as the main compound (60.4 μg/mg DW), while A. moschata Val Mustair was characterized by its derivative apigenin 7-O-glucoside (44.7 μg/mg DW). The antioxidant activity of all the obtained extracts was tested by the DPPH (2,2-diphenyl-picryl hydrazyl) and ABTS (2,21-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) methods, which showed their increasing scavenger capacity in relation to extract polarity (PET extract < DCM extract < MeOH extract). The extracts were also investigated against three Gram-positive (Bacillus cereus, Enterococcus faecalis and Staphylococcus aureus) and three Gram-negative (Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa) bacterial species using the disc diffusion assay. DMC and PET were the most active extracts (inhibition diameter: ≥12 mm).