Investigation of the Ability of Natural Deep Eutectic Solvents to Act as Efficient Extraction Media for Chamomille (Matricaria chamomilla L.)

Chamomile (Matricaria chamomilla L.) is a significant medicinal herb across Europe, rich in bioactive compounds with numerous medicinal and cosmetic properties. In this work, a methodology for the extraction of bioactive molecules from chamomile using natural deep eutectic solvents (NADES) is presented. Six NADES were synthesized and their pH and polarity, important factors in extraction efficiency, were determined. All the NADES were used as extraction media under mild temperature conditions (40℃). The total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of the NADES-extracts was determined. The NADES containing glucose and lactic acid proved to be the most effective solvent. The process optimization was achieved using Box-Behnken experimental design and indicated the optimum conditions: 5.8 h, 20 mg_chamomile/g_solvent, 34% w/w water as co-solvent. The results for the NADES-water extract obtained using the optimum conditions, revealed TPC and TFC values of 43.29 mg_GAE/g_chamomile and 9.10 mg_CAE/g_chamomile respectively, while for the antioxidant activity evaluated using the DPPH ((2,2-diphenyl-1-picrylhydrazyl) free radical scavenging assay, an IC₅₀ of 9.26 μL of NADEs-water extract/mL was calculated. In addition, the HPLC analysis performed in the NADES-extract obtained using the optimum conditions and an extract obtained using hydroethanolic solvent revealed that the NADES was able to extract higher amounts of phenolic acids and their derivatives (e.g. chlorogenic acid: 282.3 ppm, benzoic acid: 109.8 ppm, rosmarinic acid: 100.8 ppm) than the hydroethanolic solvent (e.g. chlorogenic acid: 235.5 ppm, benzoic acid: 93.3 ppm, rosmarinic acid: 83.8 ppm).