Enantiomeric composition of α-pinene in essential oils of leaves and unripe cones of Juniperus communis L

The leaves and unripe cones of common juniper (Juniperus communis L.) were sampled from 11 habitats across Lithuania. The essential oils of leaves and cones from 110 samples (=trees) each were isolated by hydrodistillation in a European Pharmacopoeia apparatus during two hours. The enantiomers of α-pinene were separated by the chiral-phase capillary GC and identified by matching their retention times to the optically pure analytical standards. The average content, the min-max values and the variation coefficient of (1R)-(+)-α-pinene were 74±1%, 7–92% and 16.4% in leaves and 69±2%, 0–96% and 24.9% in unripe cones, respectively; the average content, the min-max values and the variation coefficient of (1S)-(-)-α-pinene were 26±1%, 8–93% and 45.8% in leaves and 31±2%, 4–100% and 55.7% in unripe cones, respectively. It was established that the most of samples of leaves and unripe cones of the studied J. communis individuals were rich in (1R)-(+)-α-pinene, while (1S)-(-)-α-pinene dominated in 2.7% samples of leaves and 10.9% those of unripe cones only. However, the (1S)-(-)-α-pinene absolutely predominated in leaves of two J. communis individuals. The absolute predomination of the (1R)-(+)-α-pinene was not detected neither in leaves nor in unripe cones.

Acknowledgement: This research was funded by a grant (No. MIP-56/2010) from the Research Council of Lithuania.