Extraction of Seleno-Amino Acids from Cardamine Hupingshanensis by Ultrasonic Assisted Deep Eutectic Solvents Extraction

Abstract

In this work, deep eutectic solvent (DES) combined with ultrasonic-assisted extraction was proposed to extract free seleno-amino acids from Cardamine hupingshanensis. The contents of seleno-amino acids in the extract were determined by high-performance liquid chromatography with a fluorescence detector (HPLC-FLD). Response surface design was used to optimize the extraction conditions such as ultrasonic time, ultrasonic temperature, and liquid-solid ratio. The results showed that DES prepared by choline chloride and ethylene glycol had the highest extraction efficiency of seleno-amino acids. The main free seleno-amino acids in Cardamine hupingshanensis were selenocystine (SeCys₂) and selenomethylcysteine (SeMeCys). The optimal extraction conditions were as follows: liquid-solid ratio of 50 mL·g^–1; extraction temperature of 40 °C; and extraction time of 45 min. Under the optimal extraction conditions, the SeCys₂ and SeMeCys contents were 356 μg·g^–1 and 147 μg·g^–1, respectively. This study shows that DES has great potential in extraction and separation.