Natural Deep Eutectic Solvents for Enhanced Extraction of Chicoric Acid from Chicory (Cichorium intybus L.) Herb

Introduction: Chicory (Cichorium intybus L.) is a rich source of bioactive phenolic compounds, among which chicoric acid, is recognized for its pronounced antioxidant, anti-inflammatory, and metabolic regulatory properties. Natural deep eutectic solvents (NADES) represent a sustainable and non-toxic alternative to conventional organic solvents for the extraction of such bioactive compounds from plant matrices.

Methods: Ten NADES formulations based on choline chloride, glycerol, urea, glucose, erythritol, lactic acid, malic acid, and citric acid were prepared and applied for ultrasound-assisted extraction of chicoric acid from chicory herb. Water and ethanol were used as conventional reference solvents. Quantification was performed by HPLC-DAD.

Results and Discussion: Chicoric acid content in herb extracts ranged from 0.54 ± 0.05 to 3.31 ± 0.26 mg/g dry weight. The highest yield was obtained with the urea/glucose NADES (3.31 ± 0.26 mg/g), followed by glycerol/malic acid (2.70 ± 0.24 mg/g) and glycerol/citric acid (2.62 ± 0.15 mg/g). NADES formulations significantly outperformed water and ethanol (p < 0.05), with the lowest yields observed for aqueous infusion (0.54 ± 0.05 mg/g) and water extraction (0.55 ± 0.04 mg/g). The glycerol/urea system failed to yield detectable chicoric acid, likely due to excessive solvent viscosity limiting analyte diffusion. NADES containing organic acids provided significantly higher chicoric acid content compared to acid-free formulations (p < 0.01), consistent with enhanced hydrogen-bonding interactions with the polar hydroxyl and carboxyl groups of chicoric acid.

Conclusions: NADES formulations, particularly those combining urea or organic acids with sugars or polyols, represent efficient and environmentally friendly alternatives to conventional solvents for chicoric acid extraction from chicory herb, supporting their potential application in sustainable food and nutraceutical processing.

Acknowledgments: This work is supported by Provincial Secretariat for Higher Education and Scientific Research, Province of Vojvodina (Grant No. 003874431 2025 09418 003 000 000 001).