A Novel Chemical Profile of a Selective In Vitro Cholinergic Essential Oil from Clinopodium taxifolium (Kunth) Govaerts (Lamiaceae), a Native Andean Species of Ecuador

Resumen

A novel chemical profile essential oil, distilled from the aerial parts of <i>Clinopodium taxifolium</i> (Kunth) Govaerts (Lamiaceae), was analysed by Gas Chromatography-Mass Spectrometry (GC-MS, qualitative analysis) and Gas Chromatography with Flame Ionization Detector (GC-FID, quantitative analysis), with both polar and non-polar stationary phase columns. The chemical composition mostly consisted of sesquiterpenes and sesquiterpenoids (>70%), the main ones being (<i>E</i>)-<i>β</i>-caryophyllene (17.8%), <i>α</i>-copaene (10.5%), <i>β</i>-bourbonene (9.9%), <i>δ</i>-cadinene (6.6%), <i>cis</i>-cadina-1(6),4-diene (6.4%) and germacrene D (4.9%), with the non-polar column. The essential oil was then submitted to enantioselective GC analysis, with a diethyl-<i>tert</i>-butyldimethylsilyl-<i>β</i>-cyclodextrin diluted in PS-086 chiral selector, resulting in the following enantiomeric excesses for the chiral components: (1<i>R</i>,5<i>S</i>)-(-)-<i>α</i>-thujene (67.8%), (1<i>R</i>,5<i>R</i>)-(+)-<i>α</i>-pinene (85.5%), (1<i>S</i>,5<i>S</i>)-(-)-<i>β</i>-pinene (90.0%), (1<i>S</i>,5<i>S</i>)-(-)-sabinene (12.3%), (<i>S</i>)-(-)-limonene (88.1%), (<i>S</i>)-(+)-linalool (32.7%), (<i>R</i>)-(-)-terpinen-4-ol (9.3%), (<i>S</i>)-(-)-<i>α</i>-terpineol (71.2%) and (<i>S</i>)-(-)-germacrene D (89.0%). The inhibition activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) of <i>C. taxifolium</i> essential oil was then tested, resulting in selective activity against BChE with an IC₅₀ value of 31.3 ± 3.0 μg/mL (positive control: donepezil, IC₅₀ = 3.6 μg/mL).