Chemical Composition of the Essential Oils of Some Central Asian Nepeta Species (Lamiaceae) by GLC-MS.

The chemical composition of the essential oils obtained from aerial parts of Nepeta alatavica Lipsky, N. nuda L, and N. olgae Regel (Lamiaceae), growing wild in Central Asia (Tajikistan and Uzbekistan), were analyzed by GLC and GLC-MS. The main constituents of the essential oil from N. nuda were 1,8-cineole (24.6%), 4a-α,7-β,7a-α-nepetalactone (21.0%), germacrene D (13.5%), and β-caryophyllene (12.7%), whereas those of N. alatavica were thymol (48.5%) verbenone (7.7%), and carvacrol (7.5%). In the essential oil of N. olgae the most abundant compounds were acetylcyclohexene (31.5%), 4-tridecyne (13.2%), 2-methyl cyclopentanone (6.8%) and 1,8-cineole (6.0%). The potential antioxidant activity of these essential oils was studied by using DPPH, ABTS and FRAP assays. The essential oil of N. alatavica showed the highest in vitro free radical scavenging activity, probably due to its high thymol and carvacrol content.