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Caractérisation chimique d’huiles essentielles de conifères introduits en Corse et de plantes endémiques de Madagascar

Gabriel Garcia 1
1 SPE Université de Corse Pasquale Paoli
SPE - Sciences pour l'environnement
Abstract : The MAP sector (Medicinal and Aromatic Plants) is a booming sector. The demand for essential oil is constantly increasing, and in addition to the historical purchasers such perfumers, there is an increasing demand from the general public, especially since the advent of the "organic" trend. Their fields of application are multiple, from aromatherapy to cosmetics or perfumery or agri-food. In this context, this work had two main objectives. Initially, the study of the essential oils of several coniferous species introduced in Corsica (Larix decidua, Pseudotsuga menziesii, Pinus ponderosa, Sequoiadendron giganteum, Cryptomeria japonica and Calocedrus decurrens), which could contribute to a broader range of the essential oils produced on the island. In the second phase, we focused on the essential oils of various endemic species to Madagascar (Melicope belahe, Vepris unifoliolata, Cinnamosma madagascariensis and Elionurus tristis), which are widely used in traditional medicine. Analysis of all essential oils was carried out by combination of GC(RI), GC-MS and 13C-NMR.The first part of this thesis concerns the analysis of the oils of six coniferous species introduced in Corsica. Among them, the oils of L. decidua, P. menziesii, P. ponderosa, S. giganteum and C. japonica are dominated by a high content of monoterpenes. Those of L. decidua, P. menziesii and C. japonica also contain a few sesqui- and diterpenes at appreciable contents, while those of P. ponderosa and S. giganteum are rich in phenylpropanoids. On the other hand, C. decurrens oils are more complex and required several fractionation steps to identify four unknown molecules in our databases: pin-2-en-8-ol, pin-2-en-8-yl acetate, methyl pin-2-en-8-oate, and pin-2-en-8-al. The last two are new molecules.The second part was devoted to the analysis of the essential oils of endemic Madagascar species. The leaves essential oil of M. belahe led to the identification of 56 constituents, majors of which are: α-pinene (42.6%), linalool (6.2%), (E)-β-caryophyllene (5.2%) and β-elemene (4.4%). V. unifoliolata exhibited a bark essential oil with high amounts of thermosensitive molecules: isofuranodiene (43.9%), germacrone (17.1%), curzerene (9.6%) and germacrene B (5.3%). 13C-NMR allowed the identification and quantification of these compounds. In addition to β-pinene (49.9%) and α-pinene (19.5%) as major constituents, the bark oil of C. madagascariensis contains cyclolocopacamphene (2.0%), an epimer of cyclosativene. We report for the first time its 13C-NMR chemical shifts. The essential oils of E. tristis are characterized by great chemical complexity. We have identified several oxygenated sesquiterpenes that are rarely encountered and four unknown compounds: (i) 7-epi-khusian-2-ol and 4,8-di-epi-acorone (respectively two new epimers of khusian-2-ol and acorone); (ii) 2-epi-ziza-5-en-2-ol; and (iii) elionurone, which is so far the one and only molecule with the new terpenic skeleton that we have named elionurane. We suggest a biosynthesis pathway for this molecule, which seems to be directly linked to that of the zizaane skeleton.
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Gabriel Garcia. Caractérisation chimique d’huiles essentielles de conifères introduits en Corse et de plantes endémiques de Madagascar. Chimie. Université Pascal Paoli, 2017. Français. ⟨NNT : 2017CORT0012⟩. ⟨tel-02529789v2⟩

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