The biological activity of compounds contained in plants XVIII. Antimicrobial activity of some secondary metabolites 2.

Váňová, J.: Biological Activity of Plant Metabolites XVII. Antimicrobial Activity of Some Secondary Metabolites 2. Rigorous Thesis, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany and Ecology, Hradec Králové 2009, 106 pp. The antibacterial activity of 4 selected plant extracts was evaluated against E. coli O157:H7 and Staphylococcus aureus. Extracts were prepared by extraction in 80% ethanol and subsequent percolation. Two methods were used for determination of minimal inhibitory concentration (MIC). In the first case the values of MIC expected for E .coli on the basis of the other literature studies were not reached. All samples within the concentration range of 5 - 0,005 ppm which were prepared in two series were negative even after 48 hours exposition. In the second case better results were reached for E. coli and S. aureus. Two series of serial twofold dilutions within the concentration range of 25 %-0.02 % were prepared. The lowest values of MIC were exhibited by Thymus vulgaris extract, especially against Gram-positive indicator strain. Nevertheless the values of MIC remain very high (3.13 % for E. coli, 0.2 % for S. aureus). For determination of minimal bactericidal concentration (MBC) in E. coli O157:H7 and E. coli O55 seven essential..