20.500.12556/DKUM-87982 Vpliv kovin na protibakterijsko učinkovitost taninov magistrsko delo Effect of metals on the antibacterial properties of tannins Tanini so sekundarni metaboliti višjih rastlin. Pri rasti in razvoju rastlin ne sodelujejo, pač pa je njihova glavna naloga varovanje rastlin pred rastlinojedci in drugimi napadalci iz okolja. Po svoji strukturi in lastnostih so si zelo različni, kar jim omogoča tvorbo koordinacijskih spojin z raznimi kovinskimi ioni, kompleksacijo s proteini, obenem pa kažejo tudi dobre protimikrobne lastnosti. Ravno zaradi slednjih se danes vse pogosteje uporabljajo kot potencialne protimikrobne učinkovine. Eksperimentalno delo je zajemalo karakterizacijo izbranega seva Escherichia coli, čemur je sledilo določanje minimalne inhibitorne koncentracije (MIC) čistih taninov (veskalagin, kastalagin, veskalin, kastalin in galna kislina) ter vodnega kostanjevega ekstrakta Farmatan. Nato smo preučevanim taninom in ekstraktu dodali še kovinske ione različnih koncentracij in spremljali njihov vpliv na vrednost MIC. V obeh postopkih smo določili vrednosti MIC z metodama turbidimetrije in dodajanjem jodonitrotetrazolijevega klorida (INT barvilo). Na začetku smo okarakterizirali izbran sev E. coli tako, da smo izrisali umeritveno in rastno krivuljo. Z umeritveno krivuljo smo določili enačbo premice, katero smo uporabili v vseh nadaljnjih korakih dela. Rastno krivuljo pa smo izrisali ob pripravi primerne redčine bakterijske kulture. Za to smo morali pomerjati optično gostoto (OD) skozi daljši čas (3 dni). Čiste tanine in kostanjev ekstrakt smo pripravili v različnih koncentracijah in določili vrednosti MIC posameznih učinkovin potrebne za zaviranje rasti E. coli. Dobljene vrednosti MIC po metodi turbidimetrije so bile za veskalagin: 0,112 ± 0,074 g/L; kastalagin: 0,217 ± 0,093 g/L; veskalin: 0,145 ± 0,034 g/L; kastalin: 0,078 ± 0,022 g/L; galna kislina: 4,200 ± 0,748 g/L; in Farmatan: 0,794 ± 0,213 g/L. Z dodatkom INT barvila, pa so bile za veskalagin: 0,138 ± 0,070 g/L; kastalagin: 0,171 ± 0,019 g/L; veskalin: 0,145 ± 0,034 g/L; kastalin: 0,078 ± 0,022 g/L; galna kislina: 4,333 ± 0,745 g/L; in Farmatan 0,481 ± 0,030 g/L. V nadaljevanju smo uporabljenim taninom in ekstraktu dodali različne koncentracije kovinskih ionov Fe(II), Fe(III), Cu(II), Mn(II), Zn(II) in Ni(II) in z enakima metodama spremljali vpliv na MIC vrednosti. Iz dobljenih rezultatov je bilo razvidno, da so se vrednosti MIC večine vzorcev ob dodatku kovinskih ionov dvignile. To nakazuje na interakcije med kovinskimi ioni ter tanini, saj pride do nastanka koordinacijskih spojin, kar vpliva na protibakterijsko aktivnost taninov. Tannins are secondary metabolites of higher plants. They are not involved in plant growth and development, but their main function is to protect plants from herbivores and other invaders from the environment. They are very versatile in structure and properties, which allows them to form coordination compounds with various metal ions, complex with proteins, and also exibit good antimicrobial properties. It is for the latter reason that they are now increasingly used as potential antimicrobial agents. The experimental work consisted of the characterisation of a selected strain of Escherichia coli, followed by the determination of the minimum inhibitory concentration (MIC) with purified tannins (vescalagin, castalagin, vescalin, castalin and gallic acid) as well as with aqueous chestnut extract Farmatan. Finally, metal ions of different concentrations were added to the tannins and extract studied and their effect on the MIC value was monitored. In both procedures, the MIC values were determined by turbidimetry and by the addition of iodonitrotetrazolium chloride (INT dye). At the outset, we characterised the selected E. coli strain by plotting calibration and growth curves. The calibration curve was used to determine the equation, which was applied in all subsequent steps of the work. The growth curve was then determined with a suitably prepared inoculum dilution. This required the measuring of the optical density (OD) over a longer period of time (3 days). Subsequently, purified tannins and chestnut extract were used, at different concentrations and the MICs required to inhibit E. coli growth were determined. The values obtained by turbidimetry were for vescalagin: 0,112 ± 0,074 g/L; castalagin: 0,217 ± 0,093 g/L; vescalin: 0,145 ± 0,034 g/L; castalin: 0,078 ± 0,022 g/L; gallic acid: 4,200 ± 0,748 g/L; and Farmatan: 0,794 ± 0,213 g/L. With the addition of INT dye, the values were for vescalagin: 0,138 ± 0,070 g/L; castalagin: 0,171 ± 0,019 g/L; vescalin: 0,145 ± 0,034 g/L; castalin: 0,078 ± 0,022 g/L; gallic acid: 4,333 ± 0,745 g/L; and Farmatan: 0,481 ± 0,030 g/L. Moreover, different concentrations of metal ions Fe(II), Fe(III), Cu(II), Mn(II), Zn(II) and Ni(II) were added to the tannins and extract used and the differences in the MIC values obtained were monitored, by turbidimetry and by the INT dye addition methods. From the results obtained, it was evident that the MIC values mostly increased, but not everywhere. This is because of interactions between metal ions and tannins, which lead to the formation of coordination compounds and, therefore, affects the antibacterial activity of tannins. tanini hidrolizirajoči tanini protibakterijske lastnosti kovinski ioni minimalna inhibitorna koncentracija Escherichia coli tannins hydrolyzable tannins antibacterial properties metal ions minimal inhibitory concentration Escherichia coli true true false [M. Fermišek] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2024-04-04 11:27:11 2024-04-18 11:15:20 2024-05-16 03:11:42 0000-00-00 00:00:00 2024 0 Maribor 0 Maribor 1 spletni vir (1 datoteka PDF (XI, 50 f.)) 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 547.98:[604.4:615.281.9](043.2) 195533827 MAG_Fermisek_Miha_2024.pdf MAG_Fermisek_Miha_2024.pdf 1 DE2B594963B7AB0044441B5EF2AF2148 bedb6806d8400de1b7b2c701960c68740b5f1870b8af4a9c10907af8c47b8e40 0731ae58-fd57-11ee-bd4d-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=178694 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0