Study of properties and effect of some natural antimicrobial substances

This bachelor thesis is focused on the testing of natural antimicrobial substances of plant origin, dealing with their characterisation, their effect against the microorganisms, optimization of antimicrobial testing and increasing of efficiency of their active compounds. Theoretical part of this thesis describes a characterisation of used natural species, their important properties, spectrophotometrical methods applied in determination of active compounds, opportunities of stabilization of natural substances and various techniques of antimicrobial testing. In experimental part 8 kinds of tea and non-tea plants (Pai Mu Tan, Formosa Gunpowder, Gunpowder Black, Honeybush, Lapacho, Aspalathus linearis and Paullinia cupana) were used and combined with 6 herbal species (Syzygium aromaticum, Urtica dioica, Hippophae rhamnoides, Matricaria recutita, Plantago lanceolata and cinnamon), extracted by different solvents (water, ethanol and dimethyl sulfoxide). In these extracts amount of antioxidants and effect to three bacterial cultures (Escherichia coli, Micrococcus luteus and Serratia marcescens) were determined. To improve antimicrobial, antioxidant activity and stability aqueous tea extracts were encapsulated into liposomal particles