Background: Essential oils, obtained by hydro distillation of plant parts, are important
products in the world and have been traditionally used for treatment of infections and diseases. Due
to their significant impact from an environmental point of view, there has been extensive research to
explore and determine the antimicrobial activity of the plant essential oils.
Methods: The chemical composition of the hydro distilled essential oils obtained from leaves of Cupressus
sempervirens L. and Juniperus phoenicea L., collected from three different altitudes (125,
391, and 851 m high of sea level) at Al-Jabel Al-Akhdar area, Libya were analyzed by GC/MS, and
higher than 30 compounds were determined in total. The impact of the altitude on the quantity and
chemical constituents of the essential oils was studied.
Results: The yield of the essential oils significantly depends on the species of the trees and the highest
yield (0.29%) was obtained with C. sempervirens of altitude I (125 m) while the lowest (0.05%)
was found with that obtained from altitude III (851 m). The chemical composition confirmed that the
oils were rich in essential phytochemicals including monoterpenes, monoterpenes hydrocarbons,
sesquiterpenes and diterpenes. These constituents revealed some variability among the oils displaying
interesting chemotypes, 1R-α-pinene (15.06-27.33%), α-myrcene (3.89-7.94%), 3-carene (3.31-
19.63%), limonene (3.93-19.39%), terpinolene (1.91-6.62%), α -terpinyl acetate (5.45-12.98%), β -
caryophyllene (1.17-23.92%), and (E)-germacrene D (2.08-4.43%) which were the main constituents
of the oils isolated from three altitudes. The oils were tested in vitro for antifungal activity against
Botrytis cinerea (Pers.) as plant pathogen. In general, the oils exhibited an inhibition of the mycelia
growth and the most significant result was obtained with J. phoenicea oils with EC50 111.73, 195.21
and 210.19 µg/ml at altitudes I, II and III, respectively.
Conclusion: The results of this work points out the importance of the environmental conditions
which are in direct relation with the altitude could affect significantly the oil composition both in
qualitative and quantitative. Consequently, their biological activities are considerably influenced.
Moreover, the obtained data offer the opportunity to choose essential oils with preferential compounds
for pharmaceutical, antimicrobial, and food industries in such important region in Libya.