Table 3.
Application of DES/NADES in improving stability of plant metabolites.
| Plants | Bioactive Compounds | Selected DES/NADES (Molar Ratio in mol/mol) and Optimal Condition |
Conventional Solvents for Comparison | Results | Refs. |
|---|---|---|---|---|---|
| Safflower (Carthamus tinctorius L.) | Carthamin | NADES that contain sugar, such as glucose-choline chloride, sucrose-choline chloride, xylitol-choline chloride; heating and stirring at 40 °C for 30 min. | Water and 40% ethanol | Natural safflower pigment was more stable in NADES that contained sugar than in water or 40% ethanol solution under various conditions (high temperature, light, storage time). | [40] |
| Flower petals of Catharanthus roseus (L.) G.Don | Cyanidin (anthocyanins) | Lactic acid-glucose (5:1) using UAE for 30 min. | 3% formic acid in methanol | The extraction capacity of the selected NADES for anthocyanins was equal to that of the conventional solvent, but it had at least three times the stabilizing capacity for cyanidins. | [39] |
| Roselle (Hibiscus sabdariffa L.) | Anthocyanins | Sodium acetate-formic acid (molarity ratio of 1:2); UAE at room temperature for 20 min. | Distilled water, 70% ethanol, and 80% methanol | Anthocyanins were more stable in the selected NADES with 0% additional water. | [45] |
| Curcuma longa L. | Curcuminoids | Citric acid-glucose (1:1) and 15% water content; matrix/solvent ratio was 0.1/10 g/mL; 50 °C and 30-min extraction time with constant stirring. | Ethanol and methanol | At 80 °C, curcuminoids were more stable in NADES than in ethanol and methanol. The stability of curcuminoids test suggest that 4 °C, rather than 25 °C, is the best temperature for storing curcuminoids in NADES. | [28] |
| Choline chloride-glycerol (1:1), mechanical stirrer for 24 h. | Methanol | Curcumin is more stable in NADES solution than in methanol. | [29] | ||
| Rosemary (Rosmarinus officinalis L.) | Phenolics | Choline chloride-lactic acid (3:1) and 10% water; at 40 °C, 50–60 Hz, for 120 min using UAE. | Pure ethanol | Ethanolic extracts had a lower kinetic constant (kα) and half-life (t1/2) than NADES extracts, indicating that the NADES has a higher stabilizing capability than ethanol. | [43] |
| Mulberry | Anthocyanins (Cyanidin-3-glucoside) | Choline chloride-lactic acid (1:2) with 20% water; using UAE for 10 min at 40 °C in the absence of light. |
80% ethanol and 0.4% HCl, lactic acid | Anthocyanin stability enhancement occurred in NADES solution compared to the tested acidified ethanol at 80 °C. If stored at −20 °C, only about 7% anthocyanins were lost in NADES, while in acidified ethanol, up to 20% were lost. After 3 months of storage at 4 °C and 25 °C, the anthocyanin concentration in NADES was 1.2- and 1.7-fold greater than that in acidified ethanol. | [46] |
| Green tea (Camellia sinensis (L.) Kuntze) | Catechins (epigallocatechin-3-gallate (EGCG)) | Betaine-glycerol-glucose (4:20:1) and 30% water; using UAE for 45 min at ambient temperature. | Water, methanol, 70% methanol, and 70% ethanol | NADES is more efficient in EGCG extraction than 70% ethanol. The decrease in EGCG levels in NADES was smaller than in the comparison conventional solvent. | [44] |