## 3 Results
### Cell Membrane Interactions with Cyprodini and Cyprodini Penetration into Cells  
The graphs show the results obtained during microelectrophoretic experiments, showing the dependence of the zeta potential on the pH of the electrolyte for A-375 and DLD-1 cancer cell lines exposed to cyprodini for 24 h (Figure 4). Based on the presented graphs, it can be concluded that the course of the obtained curves has a similar shape for both the control cells not treated with the fungicide, and the cells incubated with cyprodini. At low pH values, there is an increase in the zeta potential of the cells, whereas at high pH values, the zeta potential decreases, reaching a plateau. It can also be noted that cyprodini  
Figure 3: Bar graphs presenting the percentage of apoptotic and necrotic cells under the influence of cyprodini in selected concentrations (**A–D**); the influence of cyprodini on apoptosis and necrosis in the A-375 and DLD-1 cell line estimated using fluorescence microscope assay (200\(\times\) magnification) (**E,F**). The cells were cultured with cyprodini for 24 h and stained with Calcein-AM and propidium iodide. Three independent experiments were conducted, and representative images are depicted. Caspase 3/7 activity in A-375 (**G**) and DLD-1 (**H**) cells under the influence of selected concentrations of cyprodini. Each value on the graph is the mean of three independent experiments, and error bars show the standard deviation (SD). * \(p<\) 0.05, ** \(p<\) 0.01, and *** \(p<\) 0.001 represent significant effects between treatments and controls followed by a Dunnett’s test.  
applied at lower concentrations does not cause statistically significant changes in the zeta potential values of either the A-375 or DLD-1 cell lines. However, higher concentrations of this fungicide result in an increase in the zeta potential of both cancer cell lines, shifting toward more positive values in the pH range of 2-4 and less negative values for pH above 4, compared to the control cells.  
As indicated in Table 1, which shows the amount of cyprodinil that entered the cells of both tested cell lines (A-375 and DLD-1), statistically significant amounts of compounds entered the cells. In the case of cyprodinil at a concentration of 0.05 \(\upmu\)M, more than 70% of the compound entered the cells of the A-375 line, and more than 49% of cyprodinil at a concentration of 0.2 \(\upmu\)M entered the cells of the same line. In the case of the DLD-1 cell line, in the case of cyprodinil at a concentration of 0.025 \(\upmu\)M, 83% of the compound was identified in the cells, while in the concentration of 0.2 \(\upmu\)M, 47% of cyprodinil entered the cells. We therefore conclude that the tested pesticide enters the cells in larger amounts when it is used at a lower concentration. This confirms the results of the cell proliferation assays, which show the highest increase in proliferation at the lowest concentrations tested. This applies to both cell lines tested.  
Figure 4: The membrane surface charge of A375 cells (**A**) and DLD1 cells (**B**) versus different pH values. Control cells are represented by green and cyprodinil treated cells by red and dark blue markings.