Characterization of Volatile Organic Compounds and Essential Oil Profile of Pittosporum tobira (Thunb.) W.T. Aiton Cultivated in Tunisia.

Abstract

The chemical compositions of the essential oils (EOs) of roots, young and old leaves and stems, and flowers of Pittosporum tobira (Thunb.) W.T. Aiton cultivated in Tunisia and of the volatile organic compounds (VOCs) emitted by the powder of each organ were identified. The EOs are extracted from fresh material by hydrodistillation, whereas the VOCs are obtained by head space solid-phase microextraction (HS-SPME) from the powdered dry tissues. Fifty-eight VOCs are identified, while, 105 components are detected for the EOs. The main EOs compounds are α-neoclovene, β-caryophyllene and limonene in roots (22.56, 12.52, and 8.59 %, respectively), viridiflorol in young stems, flowers and young leaves (34.90, 31.60, and 24.60 %, respectively), α-cadinol in young stems and leaves, and flowers (13.80, 10.40, and 9.10 %, respectively), (E)-nerolidol in flowers (13.30 %), and germacrene D in old stems (9.06 %). The major detected VOCs are n-undecane, mainly in young and old leaves (71.40 and 40.90 %, respectively), n-nonane in young leaves and flowers (31.80 and 27.10 %, respectively), α-cubebene in old stems and flowers (22.60 and 15.50 %, respectively), and α-gurjunene and β-gurjunene in roots (14.20 and 12.20 %, respectively). Principal Component Analysis (PCA) carried out on the 26 main volatile compounds (relative content exceeding 6 %) identified both by HS and in the EOs allowed their classification into two groups; compounds specific to roots and those specific to aerial parts. The later are subdivided in to two subgroups; old leaves and stems compounds subgroup, and young leaves and stems, and flowers one. We can notice that the two methods used to extract P. tobira volatile compounds and identify them are complementary. This study defines and differentiates, for the first time, the specific aroma profile of P. tobira from Tunisia. In addition to its ornamental value, all the organs of this species, could be valued as a source of volatile compounds useful in perfume, cosmetics and as food flavoring products.