Chemical Composition, Enantiomeric Distribution, and Sensory Evaluation of the Essential Oils Distilled from the Ecuadorian Species (Kunth) Grifo and (Kunth) DC. (Myrtaceae).

The essential oils of and , belonging to the Myrtaceae family, were obtained by steam distillation. They were analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-flame ionization detector (GC-FID), enantioselective gas chromatography, and gas chromatography-olfactometry (GC-O). A total of 58 compounds for essential oil (EO) and 22 compounds for EO were identified and quantified by GC-MS with apolar and polar columns (including undetermined components). Major compounds (>5.0%) were limonene (5.3%-5.2%), 1,8-cineole (10.4%-11.6%), ()-caryophyllene (16.6%-16.8%), -calamenene (15.9%-14.6%), and spathulenol (6.2%-6.5%). The enantiomeric excess of eight chiral constituents was determined, being (+)-limonene and (+)-germacrene D enantiomerically pure. Eight components were identified as determinant in the aromatic profile: α-pinene, β-pinene, (+)-limonene, γ-terpinene, terpinolene, linalool, β-elemene and spathulenol. For , the major compounds (>5.0%) were α-pinene (29.2%-27.7%), β-pinene (31.3%-30.0%), myrcene (5.0%-5.2%), 1,8-cineole (8.5%-8.7%), and linalool (7.7%-8.2%). The enantiomeric excess of five chiral constituents was determined, with ()-α-pinene and (+)-germacrene D enantiomerically pure. The metabolites β-pinene, 1,8-cineole, γ-terpinene, terpinolene, linalool, and ()-β-caryophyllene were mainly responsible for the aroma of the EO. Finally, the essential oil has an inhibitory activity for cholinesterase enzymes (IC of 78.6 μg/ml and 18.4 μg/ml vs. acethylcholinesterase (AChE) and butyrylcholinesterase (BChE) respectively). This activity is of interest to treat Alzheimer's disease.