Sunfo leaf essential oil (Clinopodium nubigenum [Kunth] Kuntze) from Ecuador: Yield optimization, chemical composition and biological properties

Abstract

The objective of the study was to optimize the obtaining of essential oil (EO) by water-steam distillation from sunfo leaves (Clinopodium nubigenum [Kunth] Kuntze) from Ecuador, as well as to characterize its composition and biological properties. The distillation time was analyzed, between 60 and 150 min, as well as the ratio between plant material/water, which ranged between 1:3 and 1:5. By increasing both factors the EO oil yield increased. The EO obtained with the optimized parameters presented a yield of 1.51%. Pulegone (43.30%), menthone (23.00%) and thymol (14.28%) were the major compounds. The antioxidant capacity of the EO was evidenced by the ferric reducing antioxidant power, where 190.83 μmol Fe²⁺/g was obtained, and ABTS radical elimination assays, with a IC₅₀ of 0.10 mg/mL. In addition, the antimicrobial activity was evaluated based on the minimum inhibitory concentration, where effectiveness against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella enterica, with MICs of 0.5-2.0 mg/L.