"Etude phytochimique et activités antioxydante, antiproliférative, antibactérienne et antivirale d’extraits et d’huiles essentielles de quatre espèces endémiques du genre Thymus."

Abstract

"The antioxidant and antiproliferative activities investigation of the extracts of Thymus guyonii De Noe, Thymus ciliatus Desf. and Thymus numidicus (Poiret) , shows that this latter species presents the best biological potential : the most polar extracts are the most antioxidant while the least polar extracts are the most antiproliferative. The rosmarinic acid (10.61%) and the methyl rosmarinate (44.02%) were purified from the T. numidicus methanol extract. The fractionnation of the T. numidicus hydro-ethanolic extract, by increasing polarity solvents, allowed to concentrate the main compounds responsible of the antioxidant activity in the ethyl acetate fraction. A flavone (luteolin, 4.54 %), a flavanol (quercetin, 0.64 %) and two phenolic acids (rosmarinic acid, 25.12 % and methyl rosmarinate, 15.53 %) were isolated from the ethyl acetate fraction. All these isolated molecules are very active, with a CI50 in approximately of 10 μg/mL. The T. numidicus dichloromethane fraction presents the best bactericidal potential towards the eight studied bacterial strains. The T. numidicus aqueous fraction is the only one to be antiviral towards the coxsackievirus B3 strain. The phytochemical investigation of the T. numidicus dichloromethane extract (antiproliferative one), led to the obtaining of a cold precipitate similar to the ursolic acid and containing 3 predominant products. The GC and GC/MS analysis of T. guyonii essential oil showed that it is mainly composed of : o-cymene (9,69 %), δ-terpinene (5,73 %), thymol (21,18 %) and carvacrol (55,60 %). The GC and GC/MS analysis of Thymus hirtus Willd. essential oil showed that it is mainly composed of : α-pinene (9,46 %), camphene (5,38 %), eucalyptol (1,8-cineole) (34,62 %) and 2-bornanone (18,55 %). The GC and GC/MS analysis of T. numidicus essential oil showed that it is mainly composed of: thymol (23,92%), linalool (17,20%), o-cymene (11,41%), γ-terpinene (10,84%), thymol methyl ether (6,73%) and carvacrol (6,02%). The T. guyonii essential oil showed the better bactericidal activity towards the eight studied bacterial strains, especially Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853."