Extraction Et Analyse De La Composition Chimique De Plantes Sahariennes D’intérêt Médicinal

Résumé: This work is part of a research program that focuses on the phytochemical study of medicinal plants in the Algerian Sahara, which are known for their richness in secondary metabolites and their therapeutic properties. The research through this thesis concerns this framework and is particularly interested in the phytochemical study of two species Brocchia cinerea (Vis.) and Matricaria pubescens (Desf.) which are widely used in traditional medicine in the Saharian regions. The aim of this study is the structural characterization of isolated constituents from these two plants. For that various extraction methods such as hydrodistillation, maceration were used and a variety of chromatographic techniques: CC, CCM and HPLC have been very useful for the purification of constituents. The phytochemical investigation of Brocchia cinerea chloroformic extract resulted in the isolation of six sesquiterpene lactones, the structures of three germacranolids, two guaianolids and one eudesmanolide were established by spectral methods (MS, IR, NMR1H, NMR13C, DEPT, COSY, HSQC, HMBC, NOESY, XRD and VCD). While, it’s essential oil analyzed by GC-MS was very rich in terpenic compounds, the main constituents were: thujone (47.72 - 55.4%), camphor (10.54 - 11.28%) and santolinatriene (5.8-8.00%). The study of Matricaria pubescens volatile composition analyzed by GC-FID and GC-MS on apolar column (HP1) and polar one (Innowax) identified a varied composition in which the herniarin (16.92%) was the main compound. Moreover, the evaluation of the antioxidant activity by DPPH method for the two studied plants through a variety of their extracts, showed the strongest PI% (more than 90%) for Matricaria pubescens AcOEt and butanolic extracts.

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