Activité antibactérienne et inhibitrice de β-lactamases des huiles essentielles des graines de Nigella sativa L.

Abstract

Essential oils obtained from two types of fixed commercials oils of Nigella sativa (Abou el Kacem and Miracle) were obtained by water-distillation. Chemical analysis of essential oils extracts performed by Thin Layer Chromatography (TLC) showed the presence of compounds with known antimicrobial activity, including thymoquinone, carvacrol and/or thymol. Thus, a study of the evaluation of antibacterial activity of essential oils and the majors compounds (thymoquinone, carvacrol and thymol) were screened against 12 different isolates of clinical bacteria which was identified as resistant to β-lactams and 3 other are reference bacteria (E. coli ATCC25922, P. aeruginosa ATCC 25927 and S. aureus ATCC 25923). A visible antibacterial activity is made in vitro with three techniques, the agar diffusion test or aromatogram, the micro atmosphere method which is used to prove the antibacterial effect of the volatiles phase of theses essential oils and by microdilution method. The results gotten from these works showed that the major’s compounds which tested separately exhibited a broad inhibition spectrum, presenting strong activity and also shows good potential to kill these isolates, exceptionally against the isolates of P. aeruginosa. However, the essentials oils showed antibacterial properties with inability to exercise an antibacterial power on most tested bacteria, moderate to strong inhibition, with a more restricted action against studied. The activity depends on the concentration, microbial species and the method used. Finally, the susceptibility of inhibition of β-lactamase type penicillinase from Bacillus cereus by essentials oils extracts and their major’s compounds was assessed. The kinetic method is realised with these agents showed their inability to exercise any inhibitors effect against these enzyme. The positive or negative results found, are interesting for complementary studies, more deepened and more detailed.