Ultrasound assisted choline chloride-based deep eutectic solvent extraction of bioactive compounds from salsify (Tragopogon buphthalmoides (DC.) boiss. Var. Latifolius Boiss.): A Box–Behnken design approach for optimization

This study aimed to investigate the ultrasound-assisted extraction of bioactive compounds from salsify using deep eutectic solvents (DESs) with different molar ratios. For this reason, total phenolic (TPC), total flavonoid (TFC) compounds, and antioxidant activities (1,1-diphenyl-2-picrilhydrazyl radical scavenging activity (DPPH•), and ferric reducing antioxidant power (FRAP)) of extracts prepared with DES were investigated with an experimental design and optimization study conducted for this purpose. An extraction time of 40.15 min was determined as the optimal condition. Under these conditions, a molar ratio of 3:1 (acetic acid:choline chloride) and a water ratio of 42.17 % provided the highest phenolic/flavonoid compounds and antioxidant activity. Correlations between water ratio, molar ratio, and sonication extraction time were determined using principal component analysis (PCA). In conditions where TPC, FRAP, and DPPH• were high according to PCA, it can be concluded that the extraction time, water ratio, and molar ratio are at high levels; contrarily, TFC is at a low level. In conclusion, ultrasound-assisted extraction using DES proved effective for salsify. Therefore, choline chloride-based DESs, can be recommended as environmentally friendly green solvents and an alternative to organic solvents for the extraction of bioactive compounds from salsify.