Essential Oils Composition, Antibacterial Activity and Toxicity Study of Artemisia Species Growing in Ethiopia

Artemisia essential oils have been used in flavors, scents, mice repellents, cleansers, beauty care products, fragrances, and conventional pharmaceuticals. This work analyzed the phytoconstituents, in vitro antibacterial activity, and toxicity of essential oils of three Artemisia species growing in Wolaita, Ethiopia. GC-MS has been used to analyze chemical composition. In vitro antibacterial activity was assessed by disc diffusion and broth dilution techniques. The MTT assay was used to conduct toxicity studies. The main components of the essential oil extracted from Artemisia afra Jacq. ex Willd. were camphor (19.2%), followed by 1,8-cineole (17.8%), artemisia ketone (15.2%), artemisyl acetate (6.9%), and camphene (6.6%). In the Artemisia annua L. oil, the main constituents were camphor (21.8%), artemisia alcohol (18.1%), santolina triene (11.6%), -copaene (9.1%), sabinene (4.5%), and δ-cadinene (4.0%). In addition, the main phytochemicals of Artemisia abyssinica Sch.Bip. ex A.Rich. oil were yomogi alcohol (39.3%), followed by cis β-farnesene (10.9%), β-selinene (6.7%), β-copaene (5.2%), and nerolidol (5.1%). The essential oils of A. afra, A. annua, and A. abyssinica showed significant antibacterial activity at low molar concentrations, with MIC values of 0.31, 0.15, and 0.62 μL against Staphylococcus aureus and 0.62, 0.31, and 1.25 μL against E. coli, respectively, compared with standard broad-spectrum gentamicin (0.25 μL). A. afra, A. annua, and A. abyssinica oils were showed weak toxicity to Vero cell lines with IC50 values of 178.47 µg/mL, 183.86 µg/mL, and 187.46 µg/mL, respectively. This result suggests that EOs are promising antibacterial agents given their weak toxic effects on normal cell lines at low concentrations.