Chemical composition, antioxidant capacity, toxicity and antibacterial activity of the essential oils from Acantholippia deserticola (Phil.) Moldenke (Rica rica) and Artemisia copa Phil. (Copa copa) extracted by microwave-assisted hydrodistillation

Acantholippia deserticola (Rica rica; RR) and Artemisia copa (Copa copa; CC) are herbs native to the Chilean highlands and have historically been used for medicinal purposes by the Atacameños people. The essential oils were analized by GC/MS, the principal compounds found in RR essential oil (RR_EO) were β-thujone (45%), β-linalool (16%), and eucalyptol (9%) and were butyric acid (38%), γ-terpinene (16%), and cis-2-menthenol (12%) in CC essential oil (CC_EO). The total polyphenol content (TPC) and the antioxidant capacity (AC) were evaluated. The TPC was 25 and 20 mg/mL for CC_EO and RR_EO, respectively, and the respective AC values were 740 and 320 μg eq Trolox/mL by the ferric reducing antioxidant power (FRAP) method. The IC50 (1,1-diphenyl-2-picrylhydrazyl; DPPH) values were 316.9 and 485.8 μg/mL for CC_EO and RR_EO, respectively. Antimicrobial activity was evaluated against 32 bacteria using the agar disc diffusion method. CC_EO exerted a significant inhibitory effect (>20 mm) against 9 bacteria, including Listeria monocytogenes and Staphylococcus aureus, and RR_EO significantly inhibited Escherichia coli. The CC_EO MIC values were 0.39 μg/mL for Corynebacterium. The RR_EO MIC value was 6.25 μg/mL for S. viridans. Neither EO showed toxicity against the nematode C. elegans at 2.5 mg/mL. The essential oils of RR and CC, extracted by MAHD have important bioactive potential and low toxicity, which would allow their use of active ingredients that could potentially be used in areas such as the clinic, food, cosmetics, sanitizers, and detergents, among others.