## 3 Results and Discussion
### Comparative Performance of Different DESs for Antioxidant Extraction
However, LB extract obtained by ChCl:CitA-UAE exhibited approximately 7.2, 4.7, and 5.2 times lower CUPRAC, ABTS, and DPPH results, respectively, than those achieved using B:U. As shown in Figure 1, M extracts obtained with all six DESs had somewhat lower antioxidant properties (CUPRAC = 60.2-358.2 umol TE/g, ABTS = 21.3-136.8 umol TE/g, and DPPH = 29.6-162.8 umol TE/g) than the LB extracts (CUPRAC = 59.3-429.9 umol TE/g, ABTS = 30.7-144.3 umol TE/g, and DPPH = 32.6-170.3 umol TE/g). Importantly, insignificant differences in ABTS results for LB, N, and ChoP extracts obtained by the Gu:U-30-UAE procedure were observed (Figure 1b, Duncan test). The Duncan test also indicated that the effectiveness of Gu:U-50 in extracting bioactive compounds from Cha, N, and BH, which can neutralize DPPH**+** radicals, did not differ significantly (Figure 1c). Similarly, [PERSON] et al. [6] reported that among five studied ethanolic extracts of post-distillation solid residues, lemon balm presented the highest antioxidant activity determined using ABTS, DPPH, and FRAP assays, followed by spearmint, Greek oregano, Greek sage, and rosmary, respectively. On the other hand, the selected ChCl-based DES, Gu-based DESs, and B-based DESs affected the AC of plant extracts (Figure 2). Various DES types have shown differences in the extractability of antioxidants from four herbs and two by-products. This can be explained by the disparate hydrogen bonding and \(\pi\)-\(\pi\) interactions of target antioxidant molecules with particular DESs [32]. Among six prepared DESs, DES6 composed of B and U (1:1) demonstrated the highest extraction efficiency for antioxidants from LB, M, and ChoP, whereas the Gu-based DESs (DES3 and DES4) were the best green solvents for the recovery of antioxidants from Cha, N, and BH (Figure 2). Although, Gu:U (1:1) with a lower water amount of 30% (DES3) can be deemed the most effective extraction solvent for compounds having antioxidant potential from N and BH (Figure 2d,e). However, increasing the WC to 50% in this green solvent (DES4) increased extraction effects on antioxidants in Cha (Figure 2a). In contrast, Figure 2 shows that two DESs (DES1 and DES5) containing CitA (ChClCiAtA and B:CiAtA) had the lowest extraction efficiency for antioxidant compounds from the studied samples. Figure 1: CUPRAC (**a**), ABTS (**b**), and DPPH (**c**) results for four herbs and two agro-food wastes extracts prepared by six various DESs. Bars with different letters indicate significant differences (one-way ANOVA and Duncan test, \(p<0.05\)). Moreover, among five lactic acid-based DESs, lactic acid/glycine/water (3:1:3) was found to be significantly more potent in extracting antioxidants from dittany, marjoram, mint, and sage with the highest ability to scavenge DPPH\({}^{\bullet}\) radicals. The highest antiradical activity (above 2000 \(\upmu\)mol DPPH/g dw) had sage and mint extracts [24]. In addition, higher amounts of total phenolics extracted from chokeberry pomace were achieved using green solvents such as 50% glycerol + 1% formic acid or 50% ethanol + 1% citric acid (TPC = 8676-11,036 mg gallic acid (GA)/100 g) compared to water and ethanol acidified with 1% of these two acids (TPC = 2712-9268 mg GA/100 g dw) [11]. The solvent type (methanol, ethanol, and water) used for the extraction of total antioxidants from nettle by three different techniques (UAE, without stirring extraction, and stirring extraction) affected the DPPH and ABTS values of the obtained extracts [25]. The highest DPPH values had nettle extracts prepared using water as a solvent and traditional extraction without stirring (DPPH = 87.7%) and with stirring (DPPH = 91.1%), as well as methanol and UAE (DPPH = 90.2%). In contrast, water extracts prepared by UAE and traditional extraction without stirring revealed the highest ABTS results (91.8% and 90.8%), whereas methanol was the most effective solvent for the stirring method to isolate the antioxidants with a high ability to ABTS\({}^{\bullet+}\) cation radical scavenging (86.6%).