Chemical composition of the essential oil of five Iranian Nepeta species (N. crispa, N. mahanensis, N. ispahanica, N. eremophila and N. rivularis)

Essential oils from aerial parts of Nepeta crispa Willd., Nepeta mahanensis Jamzad & Simmonds, Nepeta ispahanica Boiss., Nepeta eremophila Hausskn. & Bornm. and Nepeta rivularis Bornm. were obtained by hydro‐distillation. The oils were analyzed by capillary gas chromatography, using flame ionization and mass spectrometric detection. Twenty‐eight components were identified in the oil of Nepeta crispa with 1,8‐cineole (62.8%), 4aα‐7α‐7aα‐nepetalactone (10.3%) and 4aβ‐7α‐7aβ‐nepetalactone (9.2%) as main constituents. Eighteen compounds were identified in the oil of Nepeta mahanensis with nepetalactone (37.6%), 1,8‐cineole (27.2%) and germacrene D (6.5%) as the main components. Twenty‐seven compounds were characterized in the oil of Nepeta ispahanica with 1,8‐cineole (71.7%) as the main constituent. Twenty‐six compounds were characterized in the oil of Nepeta eremophila with 4aβ‐7α‐7aβ‐nepetalactone (73.3%) and 1,8‐cineole (13.1%) as the main constituents. Twenty‐two components were identified in the oil of Nepeta rivularis with 1,8‐cineole (38.5%), sabinene (14.8%), β‐pinene (10.7%) and γ‐terpinene (5.1%) as the main constituents. The results showed that, although the nepetalactone isomers are the main components of the essential oils of N. mahanensis and N. eremophila, the oil of N. crispa consists of about 20% nepetalactone and the oils of other species have different compositions. 1,8‐Cineole was present in all oils at percentages of 13.1% (the lowest amount in N. eremophila) to 71.7% (the highest amount in N. ispahanica). Copyright © 2006 John Wiley & Sons, Ltd.