## 3 Results and Discussion
### Comparison of UAE, MAE, and ASE
(2017), oleuropein was found to be the most abundant compound in oleaster olive fruits, with a concentration of 61.93 mg/kg, applying maceration as the extraction method. However, there are no available literature data about the application of 'green' extraction methods of phenols from the wild olive fruit matrix in order to compare our data. Concerning olive leaves, [PERSON] et al. (2018) found that UAE was an extremely useful and important extraction method for extracting oleuropein. However, [PERSON] et al. (2019) reported that the oleuropein content in olive leaves for the MAE had a two-fold increase compared to the UAE. Oleoside and secologanoside derivative forms (A and B) were the second most represented group of secoriidoids and showed a higher content in the MAE extract (9.23 mg/kg dw) than that quantified in the UAE and ASE extracts (8.18 and 8.27 mg/kg dw, respectively). However, the third most abundant compounds, oleuropein aglycon derivatives, showed similar values in all extracts (4.61-4.93 mg/kg dw). Elenolic acid glucoside and lucidumoside C compounds appeared to be independent of the extraction method applied, while verbascoside, dimethyl ligroside, and ligtroside contents were highest in the UAE among the other extracts. Regarding simple phenols, hydroxytyrosol glucoside was the major constituent varying from 1.92 to 2.68 mg/kg dw in the WOF extracts, whereas hydroxytyrosol was quantified in traces. In the group of flavonoids, luteolin-7-glucoside was the most abundant compound in WOF, appearing to have the highest value in the MAE extract (18.35 mg/g dw), whereas no significant differences were observed in the UAE and ASE extracts. Among the other \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Phenolic Compound** & **UAE** & **MAE** & **ASE** \\ \hline  & \multicolumn{2}{c}{secoriidoids} & \\ \hline
**oleoside/secologanoside (A)** & 3.23 \(\pm\) 0.06 & 3.23 \(\pm\) 0.09 & 3.24 \(\pm\) 0.12 \\
**oleoside/secologanoside (B)** & 4.94 \(\pm\) 0.20 & 6.01 \(\pm\) 0.13 & 5.03 \(\pm\) 0.10 \\
**oleuropein aglycone (A)** & 0.40 \(\pm\) 0.01 & 0.64 \(\pm\) 0.02 & 0.71 \(\pm\) 0.01 \\
**oleuropein aglycone (B)** & 4.31 \(\pm\) 0.22 & 4.29 \(\pm\) 0.20 & 3.89 \(\pm\) 0.11 \\
**elenolic acid glucoside** & 1.12 \(\pm\) 0.07 & 1.08 \(\pm\) 0.05 & 1.08 \(\pm\) 0.04 \\
**verbaloscide** & 1.27 \(\pm\) 0.02 & 1.09 \(\pm\) 0.03 & 0.77 \(\pm\) 0.03 \\
**deuropein** & 72.03 \(\pm\) 0.71 & 52.68 \(\pm\) 0.93 & 44.49 \(\pm\) 1.05 \\
**dimethyl ligroside** & 1.63 \(\pm\) 0.07 & 1.36 \(\pm\) 0.12 & 0.62 \(\pm\) 0.01 \\
**ligtroside** & 1.14 \(\pm\) 0.03 & 0.56 \(\pm\) 0.03 & 0.53 \(\pm\) 0.01 \\
**lucidumoside C** & 0.39 \(\pm\) 0.01 & 0.40 \(\pm\) 0.02 & 0.24 \(\pm\) 0.01 \\ total secoriidoids & 89.83 \(\pm\) 0.51 \({}^{\text{a}}\) & 71.34 \(\pm\) 0.53 \({}^{\text{b}}\) & 61.89 \(\pm\) 0.93 \({}^{\text{c}}\) \\ \hline  & \multicolumn{2}{c}{flavonoids} & \\ \hline
**rutin** & 3.75 \(\pm\) 0.07 & 4.69 \(\pm\) 0.08 & 3.29 \(\pm\) 0.07 \\
**luteolin-7-glucoside** & 13.40 \(\pm\) 0.09 & 18.35 \(\pm\) 0.25 & 14.78 \(\pm\) 0.15 \\
**luteolin** & 0.11 \(\pm\) 0.00 & 0.05 \(\pm\) 0.00 & 0.07 \(\pm\) 0.00 \\ total flavonoids & 17.25 \(\pm\) 0.16 \({}^{\text{b}}\) & 23.08 \(\pm\) 0.17 \({}^{\text{a}}\) & 18.15 \(\pm\) 0.22 \({}^{\text{b}}\) \\ \hline  & \multicolumn{2}{c}{simple phenols} & \\ \hline
**hydroxytyrosol glucoside** & 1.92 \(\pm\) 0.06 & 2.34 \(\pm\) 0.08 & 2.68 \(\pm\) 0.05 \\ \hline  & \multicolumn{2}{c}{organic acids} & \\ \hline
**quinic acid** & 1.27 \(\pm\) 0.03 & 0.90 \(\pm\) 0.02 & 1.27 \(\pm\) 0.02 \\
**citric acid** & 0.08 \(\pm\) 0.01 & 0.11 \(\pm\) 0.01 & 0.15 \(\pm\) 0.02 \\ total organic acids & 1.35 \(\pm\) 0.02 & 1.01 \(\pm\) 0.01 & 1.42 \(\pm\) 0.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Phenolic compounds in wild olive fruit extracts obtained via ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and accelerated solvent extraction (ASE). Different letters in a line indicate a significant difference (\(p\leq 0.05\)).