Chemical composition, antioxidant activity and in vitro antibacterial activity of Achillea wilhelmsii C. Koch essential oil on methicillin-susceptible and methicillin-resistant Staphylococcus aureus spp.

The present study investigated the chemical composition of the essential oil (EO) from aerial parts (flowering stage) of Achillea wilhelmsii C. Koch by GC-MS. In addition, the antioxidant activity of the EO as well as its antimicrobial activity against methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MRSA) strains was tested. Antioxidant activity was measured by the ability of the EO to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals while the antimicrobial activity was assessed by the disc-diffusion method. In total, 52 compounds were recognized, accounting for 97.33 % of the EO. The main compounds in the EO were carvacrol (22.49 %), dihydrocarvone (13.23 %), linalool (12 %), 1,8-cineol (11.42 %), camphene (8.31 %), thymol (5.28 %), camphor (3.71 %), pulegone (2.82 %) alpha-terpineol (2.11 %), bornyl acetate (1.14 %), and farganol (1.01 %). The EC50 value of the EO was 0.01 and 0.08 mg/mL for the antioxidant and DPPH-scavenging ability, respectively. A. wilhelmsii EO affected methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA, but the impact was more effective on MSSA.