## 4 Conclusions  
Tannins belong to plant polyphenols and have strong antibacterial activity. In this study, it was demonstrated that C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) has strong antibacterial properties against _P. aeruginosa_. Observed antibacterial activity is the result of influence on the various structural components of the bacteria, including membrane proteins and phospholipids. Specifically, C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) reduces bacterial cell viability and disturbs the membrane's hydrophilic and hydrophobic sections, potentially leading to increased permeability and compromised cellular integrity. Additionally, the compound has been shown to interact with membrane proteins through a static mechanism, forming tannin-protein complexes. This interaction can modify the structure and function of the proteins, ultimately contributing to the inhibition of bacterial resistance mechanisms such as efflux pumps. The study highlights that C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) can form stable complexes with _P. aeruginosa_ membrane proteins via spontaneous hydrophobic interactions between the compound and bacterial proteins. Furthermore, C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) induces changes in the Zeta potential of _P. aeruginosa_ cells. Our highly innovative studies demonstrate that 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-\(\beta\)-D-glucose possesses strong antibacterial activity against _P. aeruginosa_. According to the obtained results, it can be concluded that C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) possesses strong antibacterial activity against _P. aeruginosa_ with application potential in treating infections caused by _P. aeruginosa_, especially in the context of multidrug resistance. Also, it can be assumed that one of the possible modes of C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) antibacterial action is connected with _P. aeruginosa_ membrane lipids and proteins, but further studies are needed to verify if C\({}_{55}\)H\({}_{40}\)O\({}_{34}\) activity can occur via other mechanisms, e.g., like inhibition of electron transport, cell wall synthesis or ribosomal function.  
Conceptualization, M.L., E.O.-G. and S.S.; methodology, M.L. and E.O.-G.; formal analysis, M.L. and E.O.-G.; investigation, M.L., K.C. and E.O.-G.; chemical isolation of used tannins, N.A.; writing--original draft preparation, M.L., E.O.-G. and S.S.; writing--review and editing, E.O.-G. and S.S.; supervision, E.O.-G. and S.S. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Concentration** & & & & & & \\
[\(\mu\)M] & **0** & **2** & **4** & **6** & **8** & **10** \\ \hline Zeta potential & \(-14.75\pm 1.26\) & \(-16.36\pm 1.55\) & \(-16.44\pm 1.61\) & \(-17.31\pm 1.57\) & \(-16.58\pm 1.42\) & \(-16.62\pm 1.56\) \\ Cell size [nm] & \(1192.30\pm 139.09\) & \(1134.85\pm 173.89\) & \(1220.99\pm 185.52\) & \(1298.66\pm 191.28\) & \(1305.81\pm 227.61\) & \(1237.64\pm 126.68\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Zeta potential and particle size changes in _P. aeruginosa_ membrane proteins in the presence of C\({}_{55}\)H\({}_{40}\)O\({}_{34}\). Data represented as mean \(\pm\) SD, \(n\) = 6.