Effective extraction with deep eutectic solvents and enrichment by macroporous adsorption resin of flavonoids from Carthamus tinctorius L.

In the present study, deep eutectic solvents (DESs) were prepared and firstly applied to extract flavonoids from Safflower using ultrasonic-assisted extraction (UAE), and DES2-UAE was selected as a green and efficient extraction method. The effects of extraction parameters on extraction efficiency (EE) of flavonoids were investigated by single-factor experiments and optimized using a Box-Behnken design (BBD). The optimal results were 56.37 mL/g liquid-solid ratio, 55.85 min extraction time, 41.44 °C extraction temperature and 188.55 W ultrasonic power, respectively. Under optimal extraction conditions, the highest EE of flavonoids (55.41 mg/g) was obtained. The verification experimental results were in good correlation with the predicted results. The adsorption and desorption experiments of flavonoids on five types of macroporous resins (NKA-2, AB-8, HPD-100, D-101 and S-8) were carried out, NKA-2 and S-8 showed higher adsorption/desorption capacities, successively followed by AB-8, D-101 and HPD-100. The adsorption behaviors were better explained by Langmuir isotherm model according to correlation coefficient on the basis of static adsorption test at different temperature. In conclusion, the developed DES2-UAE combined with macroporous resin enrichment can be an alternative method for the green and efficient extraction of bioactive flavonoids from plant materials.