| Abstract [eng] |
Aurėja Kavaliauskaitė master’s thesis: Effect of dry methanol extracts of medicinal plant leaves accumulating tannins on microorganisms. The aim of the study: to compare the effects of dry methanolic extracts of leaves of Ericaceae and Rosaceae family members growing in Lithuania on microorganisms. Objectives: to evaluate the total amount of phenolic compounds and tannins in the dry methanolic extracts of leaves of Ericaceae (bog-rosemary, marsh Labrador tea, black crowberry, blueberry, lingonberry, mealy bearberry, Scotch heather) and Rosaceae (lady’s mantle, wild strawberry, common agrimony ir silverweed). To investigate the antimicrobial effect of members of the Ericaceae and Rosaceae family against Staphylococcus aureus, Streptoccocus mitis, Moraxella catarrhalis and Candida albicans. Methodology: dry methanolic extracts were prepared using a rotary evaporator and a lyophilizer. The total amount of phenolic compounds in dry methanolic extracts was determined by the Folin-Ciocalteu method. The total amount of tannins was determined using polyvinylpyrrolidone (PVPP) powder, which binds the tannins contained in the extracts. The antimicrobial activity of the extracts is determined by two methods: the Kirby-Bauer agar diffusion method and the microdilution method. Statistical data analysis was performed using Microsoft Office Excel 2016. Results and conclucions: the highest total amount of phenolic compounds was determined in the dry methanolic extract of the mealy bearberry (72.2 ± 2.3 %), the lowest in the common agrimony (16.2 ± 0.9 %). The highest total amount of tannins was determined in the dry methanolic extract of the marsh Labrador tea (48.4 ± 1.4 %), the lowest in the common agrimony (12.2 ± 1.3 %). The results of the Kirby-Bauer agar diffusion and microdilution methods showed that Candida albicans was the most resistant of all microorganisms tested. The growth of this fungus was affected only by the dry methanolic extracts of the leaves of black crowberry and marsh Labrador tea. Of all microorganisms tested, Staphylococcus aureus was the most sensitive. The methanolic extract of mealy bearberry had the strongest antimicrobial properties against Staphylococcus aureus, Moraxella catarrhalis and Streptococcus mitis of all the medicinal plants tested. The strongest antimicrobial effect against S. aureus was shown by the extracts of silverweed, mealy bearberry, bog-rosemary and black crowberry, against M. catarrhalis – by the extracts of wild strawberry and mealy bearberry, against S. mitis – by the extracts of silverweed, wild strawberry and common agrimony. |
