Corsica is a Mediterranean mountain island which displays many aromatic and medicinal plants liable to produce essential oils potentially used in different domains. For their valorization, the knowledge of the oil chemical compositions is an essential challenge. This thesis deals with the chemical compositions of the essential oils and the volatile fractions of three coastal plants from Corsica and Sardinia: Chamaemelum mixtum, Anthemis maritima and Erygium maritimum. There are two aims: (i) The fundamental aim consists in characterizing the chemical compositions of essential oils and volatile fractions of the three species evaluated, using and improving our laboratory analytical methodology which involves integrated techniques, such as CC, GC/FID, GC/MS-EI, GC/MS-CI, NMR 1D and NMR 2D. (ii) The applied aim consists in assessing the commercial potential of these essential oils studying their chemical variability and their biological activities. The study of Chamaemelum mixtum essential oil allowed us to describe a Corsican original chemical oil composition (relative to those from Morocco previously reported in the literature) and a new linear ketone: (Z)-9,16-heptadecadien-7-one, never reported in the literature. The chemical composition of Anthemis maritima essential oils rich in chrysanthenyl esters was reported here for the first time. The use of an original analytic strategy allowed us to describe 14 esters of cis- and trans-chrysanthenol. A lot of them were never been described by NMR. Eryngium maritimum essential oil was described completely for the first time. We reported here for the first time, the isolation and the identification of three new natural compounds: 4-muurol-9-en-15-ol, 4-cadin-9-en-15-ol and 4-cadin-9-en-15-al. Moreover 13C-NMR shifts of 4-muurol-9-en-15-al were reported for the first time. The antibacterial potential of the three essential oils was investigated and Chamaemelum mixtum oil showed a good activity against germs involved in nosocomial and food borne illness. The study of the oil chemical variability showed some statistic groups for each plant linked to their geographic origin. More precisely, Anthemis maritima essential oil exhibits two chemical profiles clearly different. Chemical compositions of essential oils and volatile fractions sampled by SPME of the different parts of the plant have been investigated. Our results, confirms the SPME as an analytical tool, fast and reliable for the acquisition of the chemical profile of a volatile fraction.
