ABSTRACT This paper describes the chemical composition and the enantiomer content of the volatile oil hydrodistilled from Clinopodium brownei (Sw.) Kuntze, Lamiaceae. The plant was collected in the South of Ecuador. Thirty one components were identified by GC-MS, which accounted for the 96.15% of the volatile oil. The major components were pulegone (48.44%), menthone (34.55%) and β-acorenol (3.41%). Oxygenated monoterpenes (86.06%), followed by oxygenated sesquiterpenes (5.36%) constituted the most abundant fractions. The enantiomeric compositions of β-pinene, sabinene, 3-octanol, menthone, pulegone and menthyl acetate were determined by enantioselective GC-MS. (-)-Menthone showed the highest enantiomeric excess (ee = 83.4%). In in vitro tests, the volatile oil showed high selective inhibitory activity for butyrylcholinesterase with an IC50, 13.4 ± 1.8 µg/ml. In contrast, it was weakly active against acetylcholinesterase with an IC50 >250 µg/ml.

Abstract Lepechinia mutica (Benth.) Epling, Lamiaceae, and Vallea stipularis L.f., Elaeocarpaceae, are the object of the present study. These plants are endemic to the Andean region and have attracted our attention on the basis of interesting results obtained in a preliminary anticholinesterase screening. Actually, carnosol and tiliroside, isolated from L. mutica and V. stipularis, respectively, have shown a promising selective inhibitory activity against butyrylcholinesterase. Specifically, the anti-butyrylcholinesterase activity of carnosol was 5.15 µM and that of tiliroside was 52.9 µM, compared to 8.568 ± 0.570 µM of the positive control Donepezil. Carnosol and tiliroside were purified chromatographically from the ethyl acetate extract of L. mutica and V. stipularis, respectively. Spectrophotometric methods were used for enzymatic studies.