## 4 Discussion
vulgare_ samples had various polyphenic profiles [38]. Similarly, when comparing leaves and discs of flower polyphenol types, it was reported that the disc contained apigenin, luteolin, and chrysoeriol, but leaves, on the other hand, had 6-hydroxyluteolin derivatives [39]. Antibacterial effects could depend on the part of the plant used in the extract, and also the solvent type used. In our study, there were no significant differences between the solvent type and the amount of TPC extracted; correlation between the amount of TPC and the antibacterial effects could not be calculated. Although 30% acetone extracts of _T. vulgare_ flowers had the highest TPC, they did not have an antibacterial effect on bacteria. The dried flowers of _T. vulgare_ contain less tannins than the leaves of _T. vulgare_ (they contain 2.01% and 2.45%, respectively) [40]. Possibly, the combination of specific phenolic compounds could also influence the antibacterial activity. Distinctive phenolic compounds have been reported to have a different effect on Gram-negative or Gram-positive bacteria [41], because they have differing mechanisms of action against bacteria. The antibacterial mechanism of phenolic compounds is mainly attributed to their ability to generate hydrogen peroxide, which, when coupled with the metal ion complexation capacity, results in the inhibition of the activity of essential enzymes and their ability to destabilize bacterial membranes, causing an increase in their permeability [42]. Differing mechanisms of action of polyphenol groups are provided by [PERSON] [43]. Flavonols had antibacterial effects against both Gram-positive and Gram-negative bacteria, possibly because of their aggregatory effect on all bacterial cells. Condensed tannins (proanthocyanidins) inhibit the growth of several pathogenic bacteria through several mechanisms, such as permeabilization of the cell membrane, destabilization of the cytoplasmic membrane, inhibition of extracellular microbial enzymes, direct actions on microbial metabolism, or deprivation of the substrates required for microbial growth (because proanthocyanidins chelate metals such as iron and zinc). Ellagitannins inhibited the growth of some Gram-negative intestinal bacteria, but gallotannins showed better activity against Gram-positive bacteria. Antibacterial effects are primarily due to the affinity of gallotannins for iron and the inactivation of membrane-bound proteins [43]. Other phytochemicals with antibacterial properties, such essential oils and their isolated components, could have affected the results. It was reported that the essential oil of _T. vulgare_ flowers has antibacterial effects against _E. coli_, _S. aureus_, _Enterobacter aerogenes_, _Sarcina lutea_, _Bacillus cereus_, and _Candida albicans_. This effect varied depending on strains of the same species. It must be noted that the clinical isolates of bacteria are usually more resistant. In addition, the effect with this essential oil was found to be weaker than with the isolated \(\alpha\)- and \(\beta\)-thujone mixture. However, authors of the study could not directly link the effect to \(\alpha\)- and/or \(\beta\)-thujone alone. They noted possible antibacterial propertiesof other components of the essential oil and their synergism. Further, they explained that the composition of the essential oil of _T. vulgare_ flowers varied in other studies (lower concentrations of \(\beta\)-thujone or lack of it) [44]. Varying chemotypes of _T. vulgare_ were reported in Finland in 1987 [45], and it was observed that, based on the location, the main essential oil components (thujone, camphor, sabinene, umbellulone, bornyl acetone, 1,8-cineol, \(\alpha\)-pinene, germacrene D) and their combinations changed. In a later study in Finland from 2001 [15], different chemotypes were reported, and they found 15 chemotypes with main components such as camphor, trans thujone, artemisinin ketone, 1,8-cineole, and davadone-D. The composition of the essential oil of _T.