Alternative Methods for the Extraction of Phenolic Compounds from Chicory (Cichorium intybus) Using Glycerol-Based Natural Deep Eutectic Solvents

Abstract

 Introduction: Chicory (Cichorium intybus L.) exhibits antioxidant, antibacterial, antidiabetic, and anti-inflammatory properties, owing to its bioactive components, with flavonoids and phenolic acids being the most significant. Natural Deep Eutectic Solvents (NADES) are increasingly used as an alternative to conventional solvents in the extraction of active compounds, thanks to their non-toxicity. 

Aim: To investigate the efficiency of flavonoid and phenolic acid ultrasound extraction from chicory herb using NADES and to compare the results with extracts obtained using conventional solvents. 

Materials and Methods: A total of six samples of chicory herb were examined. Extraction was performed using three different NADES: 70% ethanol, methanol, and water. The solvents based on glycerol were used: glycerol citric acid (2:1), glycerol–urea (1:1), glycerol–glucose (2:1). NADES were prepared by mixing and heating. The content of phenolic acids and flavonoids was determined using high-performance liquid chromatography. 

Results: Ten bioactive compounds were identified and quantified in the analyzed extracts: phenolic acids gallic acid, chlorogenic acid, para-hydroxybenzoic acid, caffeic acid, coumaric acid, ferulic acid, rosmarinic acid and epicatechin quercetin, and naringenin from flavonoids. In eight out of ten extracts obtained using NADES, the content of bioactive compounds was significantly higher compared to extracts obtained using conventional solvents—70% ethanol, methanol, and water. 

Conclusion: In this study, the efficiency of extracting phenolic acids and flavonoids from the herb of chicory using natural deep eutectic solvents was analysed and confirmed. The use of novel green solvents resulted in significantly higher yields of phenolic compounds compared to conventional solvents.