Seasonal variation in <italic>Juniperus polycarpos</italic> var. <italic>turcomanica</italic> essential oil from northeast of Iran.

The composition of hydro-distilled essential oils from fresh leaves of wild growing <italic>Juniperus polycarpos</italic> var. <italic>turcomanica</italic>, collected from northeaste of Iran, were investigated by GC and GC-MS analysis during growing season 2012-2013. The oil yields depend on the month of collecting and ranged between 1.5 and 2.1% (v/w). Analysis of the essential oil identified 49 components that representing 89.7-94.6% of the total oil. Results indicated that the predominant presence of monoterpene constituents, representing 56.9-85.6% of the essential oil. The main constituent was α-pinene (41.8-75.4%), followed by germacrene B (1-5.8%), camphor (0.7-4.5%) and α-cadinol (0.4-4.8%). Regarding essential oil composition, quantitative and qualitative variations were recorded for 12 different collection periods. The best time for harvesting juniper leaves seems to be from mid-autumn to mid-winter. [ABSTRACT FROM AUTHOR]