## 3 Results and Discussion
### Optimal Green Solvent Design for Antioxidant Extraction from Lemon Balm
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1 & 0.5 (\(-\)1) & 20 (\(-\)1) & 10 (0) & 234.8 \(\pm\) 8.4 \({}^{\rm c}\) & 231.9 & 104.5 \(\pm\) 4.3 \({}^{\rm d,e}\) & 104.5 & 121.5 \(\pm\) 13.3 \({}^{\rm c}\) & 121.7 \\
2 & 1.5 (1) & 20 (\(-\)1) & 10 (0) & 159.5 \(\pm\) 10.3 \({}^{\rm a,b}\) & 162.4 & 73.8 \(\pm\) 3.8 \({}^{\rm b}\) & 73.7 & 102.1 \(\pm\) 6.8 \({}^{\rm b}\) & 101.9 \\
3 & 0.5 (\(-\)1) & 40 (1) & 10 (0) & 413.9 \(\pm\) 15.7 \({}^{\rm g}\) & 411.0 & 164.0 \(\pm\) 4.0 \({}^{\rm g}\) & 164.0 & 186.6 \(\pm\) 2.2 \({}^{\rm e}\) & 186.8 \\
4 & 1.5 (1) & 40 (1) & 10 (0) & 394.4 \(\pm\) 5.0 \({}^{\rm g}\) & 397.3 & 201.0 \(\pm\) 7.5 \({}^{\rm h}\) & 201.0 & 180.5 \(\pm\) 0.3 \({}^{\rm e}\) & 180.3 \\
5 & 0.5 (\(-\)1) & 30 (0) & 5 (\(-\)1) & 341.8 \(\pm\) 16.1 \({}^{\rm e}\) & 344.7 & 99.1 \(\pm\) 11.7 \({}^{\rm c,d}\) & 99.1 & 180.4 \(\pm\) 8.1 \({}^{\rm e}\) & 180.2 \\
6 & 1.5 (1) & 30 (0) & 5 (\(-\)1) & 291.6 \(\pm\) 22.3 \({}^{\rm d}\) & 288.7 & 115.4 \(\pm\) 5.4 \({}^{\rm e}\) & 115.4 & 155.1 \(\pm\) 10.4 \({}^{\rm d}\) & 155.2 \\
7 & 0.5 (\(-\)1) & 30 (0) & 15 (1) & 374.1 \(\pm\) 28.2 \({}^{\rm fg}\) & 377.1 & 168.1 \(\pm\) 5.7 \({}^{\rm g}\) & 168.0 & 184.4 \(\pm\) 4.7 \({}^{\rm e}\) & 184.3 \\
8 & 1.5 (1) & 30 (0) & 15 (1) & 352.8 \(\pm\) 14.6 \({}^{\rm fg}\) & 349.8 & 157.8 \(\pm\) 7.8 \({}^{\rm g}\) & 157.8 & 183.0 \(\pm\) 10.9 \({}^{\rm e}\) & 183.1 \\
9 & 1 (0) & 20 (\(-\)1) & 5 (\(-\)1) & 133.9 \(\pm\) 12.6 \({}^{\rm a,b}\) & 133.9 & 53.9 \(\pm\) 5.5 \({}^{\rm a}\) & 53.9 & 84.9 \(\pm\) 4.8 \({}^{\rm a}\) & 84.9 \\
10 & 1 (0) & 40 (1) & 5 (\(-\)1) & 349.0 \(\pm\) 9.9 \({}^{\rm fg}\) & 349.0 & 89.3 \(\pm\) 4.8 \({}^{\rm c}\) & 89.3 & 132.5 \(\pm\) 8.4 \({}^{\rm c}\) & 132.5 \\
11 & 1 (0) & 20 (\(-\)1) & 15 (1) & 168.0 \(\pm\) 5.1 \({}^{\rm b}\) & 168.0 & 72.7 \(\pm\) 9.3 \({}^{\rm b}\) & 72.7 & 96.1 \(\pm\) 8.2 \({}^{\rm a,b}\) & 96.1 \\
12 & 1 (0) & 40 (1) & 15 (1) & 493.7 \(\pm\) 29.7 \({}^{\rm h}\) & 493.7 & 273.5 \(\pm\) 6.9 \({}^{\rm f}\) & 273.5 & 209.5 \(\pm\) 3.1 \({}^{\rm f}\) & 209.5 \\
13 & 1 (0) & 30 (0) & 10 (0) & 284.2 \(\pm\) 0.6 \({}^{\rm d}\) & 278.4 & 140.9 \(\pm\) 7.6 \({}^{\rm f}\) & 124.0 & 152.9 \(\pm\) 0.6 \({}^{\rm d}\) & 141.4 \\
14 & 1 (0) & 30 (0) & 10 (0) & 274.5 \(\pm\) 2.8 \({}^{\rm d}\) & 278.4 & 139.6 \(\pm\) 10.3 \({}^{\rm f}\) & 124.0 & 149.9 \(\pm\) 6.5 \({}^{\rm d}\) & 141.4 \\
15 & 1 (0) & 30 (0) & 10 (0) & 276.4 \(\pm\) 6.9 \({}^{\rm d}\) & 278.4 & 91.5 \(\pm\) 3.2 \({}^{\rm c}\) & 124.0 &of water (WC = 20%) extracted during the shortest time (t = 5 min) the lowest amount of total antioxidants from LB (CUPRAC = 133.9 \(\upmu\)mol TE/g, ABTS = 53.9 \(\upmu\)mol TE/g, and DPPH = 84.9 \(\upmu\)mol TE/g). This suggests that the AC of the resulting extracts increased with an increase in WC in the utilized DES by prolonging the UAE time because the effect of acoustic cavitation can completely crack LB cells and prompt the release of antioxidant components from them into the green solvent. Furthermore, insignificant differences in AC results were observed between LB extracts obtained under the following conditions: ChCl:U = 1:2 and 3:2, WC = 40 and 30%, and t = 10 and 15 min, respectively (exps. 3, 4, 7, and 8) (Table 4, Figure 6, Duncan test). However, changing the ChCl:U ratio from 1:2 to 3:2, without changing the WC (20 and 30%) in DES and time (10 and 5 min, respectively), reduced the extraction of compounds with antioxidant features from LB (exps. 1, 2, 5, and 6). In these cases, the higher amount of ChCl in DES significantly decreased the binding of the chloride anion to the target antioxidant compounds, thereby hampering the extraction potency of this DES (Figure 6). It is noteworthy that WC in ChCl:U solvent and the extraction time (t) significantly affected the AC of LB (Table 4 and Figure 6). In this study, adding water to ChCl:U reduced the viscosity of this DES and increased its polarity, enhancing the extraction efficiency of antioxidants from LB.