Clinopodium nubigenum (Kunth) Kuntze essential oil: Chemical composition, antioxidant activity, and antimicrobial test against respiratory pathogens

Abstract

The essential oil of leaves and flowers of Clinopodium nubigenum (Kunth.) Kuntze (Lamiaceae) collected in the province of Pichincha-Ecuador was steam distilled and analyzed by gas chromatography mass spectrometry (GC/MS) to determine its chemical composition. The majority of the compounds identified were carvacrol acetate (42.1%), carvacrol (20.6%), pulegone (6.3%) and thymol (5.5%). Antioxidant activity was assessed by the assays of diphenylpicrylhydrazyl (DPPH) (IC50: 1.8 μl / ml), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) (IC50: 0.3 μl / ml) and β-carotene (IC50: 0.031 μl / ml) compared to Thymus vulgaris and butylated hydroxyanisole (BHA) as referents. The specie also shows a promising medicinal potential exhibiting significant antibacterial activity at different concentrations against Staphylococcus aureus (2.5% v/v), Streptococcus pyogenes (0.6% v/v), Streptococcus pneumoniae (0.6% v/v) and Streptococcus mutans (0.6% v/v), suggesting an interesting natural alternative in the fight against bacteria that generate resistance to other antibiotics. Key words: Clinopodium nubigenum, gas chromatography mass spectrometry (GC/MS), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), diphenylpicrylhydrazyl (DPPH), antimicrobial test.