Biological activity of plant metabolites IX. Antimicrobial activity of some secondary metabolites

Váňová, J.: Biological Activity of Plant Metabolites IX. Antimicrobial Activity of Some Secondary Metabolites. Diploma Thesis, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany and Ecology, Hradec Králové 2008, 62 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 they were not reached the values of MIC expected for E .coli on the basis of the other literature studies. 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 it was reached better results 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..