## 3 Results and Discussion
### Biological Activities of Sea Fennel Leaf, Flower, and Fruit EOs and Hydrolates
The EOs from flowers and leaves exerted better inhibition against AChE rather than BuChE [15]. The results for the AChE and BuChE inhibitory activity of hydrolates are presented in Table 3, and they also indicate better activity of the flower hydrolate against AChE than BuChE (two-fold lower inhibition). This sample was recognized for the highest content of teripinen-4-ol, which could be the reason for its inhibition activity, as previously reported. The activity of the hydrolates on the inhibition of AChE and BuChe could be explained by terpinene-4-ol, 1,8-cineole, and linalool. In the case of the leaf hydrolate, activity only against BuChE was recorded (3.31% inhibition). The cytotoxic effects of sea fennel EOs from the leaves, flowers, and fruits at different concentrations, along with the hydrolates, were tested against three human cancer cell lines \begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multirow{2}{*}{**Plant Part**} & \multicolumn{3}{c}{**Antioxidant Activity**} & \multicolumn{3}{c}{**Enzyme Inhibition**} \\ \cline{2-6}  & **FRAP** & **DPPH** & **ORAC** & **AChE** & **BuChE** \\  & **(mM Fe\({}^{2+}\)/L)** & **(Inhibition \%)** & **(\(\upmu\)mTE/L)** & **(Inhibition \%)** & **(Inhibition \%)** \\ \hline
**Leaves** & n.a. & 6.30 \(\pm\) 1.48 & 122.98 \(\pm\) 0.50 & n.a. & 4.59 \(\pm\) 2.56 \\ \hline
**Flowers** & n.a. & 6.11 \(\pm\) 1.68 & 103.22 \(\pm\) 0.44 & 5.05 \(\pm\) 0.75 & 3.04 \(\pm\) 1.73 \\ \hline
**Fruits** & n.a. & 5.67 \(\pm\) 0.38 & 98.88 \(\pm\) 1.00 & n.a. & n.a. \\ \hline \hline \end{tabular}  
* n.a.—not active, detected. All results are expressed as mean \(\pm\) SD.  
\end{table} 
Table 3: Antioxidant activity and inhibition of acetyl- (AChE) and butyl- (BuChE) cholinesterase by hydrolates from different sea fennel plant parts. (MDA-MB-231, MCF-7, and OVCAR-3) after 4, 24, 48, and 72 h of incubation. The IC\({}_{50}\) values are presented in Figure 2. Additionally, healthy human embryonic kidney HEK-293 cells were treated with fruit and flower EOs, and the results are shown in Figure S3. Of the three tested cell lines, cytotoxic activity was observed against two, namely MDA-MB-231 and MCF-7, while none of the EOs or hydrolases reached the IC\({}_{50}\) value for any tested concentration on the OVCAR-3 cell line (Figure 2). The human breast adenocarcinoma MDA-MB-231 cell line was the most sensitive to the sea fennel flower EO at concentrations of 200 and 250 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, with 28.25 and 27.36% cell survival after 48 h and 26.46% and 25.71% cell survival after 72 h, respectively. The fruit EO reached the IC\({}_{50}\) (250 \(\mathrm{\SIUnitSymbolMicro g}\)/mL) after 48 h with 43.39% cell survival. The flower hydrolate reached the IC\({}_{50}\) after 48 h (with 37.42% cell survival) and after 72 h (with 26.75% cell survival), while the leaf hydrolate reached the IC\({}_{50}\) (with 41.92% cell survival) only after 72 h. The human breast metastatic adenocarcinoma MCF-7 cell line was sensitive to flower and fruit EOs for all the tested times, but the best results were observed after 72 h of incubation (IC\({}_{50}\) = 250 \(\mathrm{\SIUnitSymbolMicro g}\)/mL), with 31.97% and 34.22% cell survival. No reduction in the amount of healthy human embryonic kidney HEK-293 cells (Figure S3) was observed when they were treated with different concentrations of fruit and flower essential oils (the EOs that had the highest cytotoxic activity on cancer cell lines). Interestingly, at concentrations <200 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, the cell count doubled after 48 and 72 h, while at a concentration of 250 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, some cytotoxic effects were observed, but the IC\({}_{50}\) was not reached. These results suggest the need for further research on sea fennel EOs regarding the potential mechanism of their healing properties [49].