Exploration Phytochimique Des Extraits Anti-nosocomiaux De Quelques Asteraceae Medicinales Du Sahara Algerien

Résumé: The objective of this study is to evaluate the antimicrobial effects of medicinal plant extracts belonging to the pharmacopoeia of southwestern Algeria on bacterial and fungal nosocomial strains and to chemically characterize the most active fractions in order to identify their bioactive molecules. The survey was carried out among five hospital structures in South-West Algeria located in four wilayas concerning the methods of disinfection, preparation, and treatment of waste and linen as well as the evaluation of the microbiological quality of the hospital environment; Air, surfaces, medical devices revealed that all the investigated hospital structures have very low levels of target levels whose values put almost all services in a state of action and alertness, a fact that imperatively requires implementation of corrective actions that we have established and proposed in this study. We found a set of microbial groups with the highest rates being Gram positive cocci with 59% and mold with 85.72%. Exploration of the carriage of Pseudomonas sp and Staphylococcus aureus strains among hospital staff and of agr complex dysfunction in isolated S. aureus strains revealed predictive markers of methicillin resistance. The ethnopharmacological investigation revealed the considerable use of species belonging to the families Asteraceae and Lamiaceae, hence the choice to use the aerial parts of five species belonging to the Asteraceae family:, B. graveolens, C. cinerea, L. arboresence, L. nudicaulis, and W. saharae. C. cinerea showed the highest activity rate of 50.25%. The HCl and aqueous extracts of the species studied gave the most important results, with values of 84.8% and 45.6% respectively. These extracts showed a markedly greater antibacterial effect than the antifungal effect. The aqueous extract of C. cinerea was very active on nosocomial fungal strains. The minimum inhibitory mass evaluated for C. albicans ranged from 0.65 mg / disc for C. cinerea to 1.5 mg / disc for L. nudicaulis and L. arboresens. The average fungal inhibition rates are between 21.27% and 73.53% respectively for L. naudicaulis and C. cinerea against strains of Aspergilus flavus and between 13.71% and 73.63% for L. arboresens and C. cinerea against strains of Aspergilus niger.The minimum inhibitory mass obtained for nosocomial strains of S. aureus between 1.10-3g and 5.10-4 g. The fractions purified from the aqueous extracts of the five plant species investigated were subjected to a chemical characterization performed by thin layer chromatography, high performance liquid chromatography, infrared spectral analysis and magnetic resonance spectral analyzes NMR proton 1H and NMR carbon 13C which has highlighted the richness of the plant species studied in polar bioactive molecules with variable λ max between 280 and 350 and retention times between 6.100 min and 7.691 min. The chemical characterization of a bioactive fraction obtained revealed the presence of a pyrrolisidine alkaloid to which we have assigned five structures presenting similarities relative to the results obtained for the analyzes of magnetic reasoning 1 H NMR and 13 H NMR; This molecule was isolated from the aqueous extract of L. arborescens and has been shown to be bioactive on S. aureus ATCC 25923 and C. albicans ATCC 10231. The results obtained reveal a large nosocomial flora within the sites and materials investigated, requiring rapid and effective intervention at different levels. The use of aqueous extracts of the selected spontaneous plant species may be a good alternative for control in order to avoid excessive use of antimicrobial products that can lead to the appearance of multi-resistance.

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