Application of choline chloride-based deep eutectic solvents for the extraction of dopamine from purslane (Portulaca oleracea L.)

Abstract

Deep eutectic solvents (DESs) are a recently developed class of green, efficient, and versatile alternatives to traditional organic solvents in natural product extractions. Inspired by the emergence of natural DESs and their green nature, we herein optimized the experimental variables for the extraction of dopamine from purslane (Portulaca oleracea L., POL) using DESs. Nine choline chloride (ChCl)-based DESs were tested to select the optimum solvent for ultrasound-assisted extraction (UAE), and the combination of ChCl:glycerol (1:2) with 30% water extracted more dopamine from POL than ethanol. The amount of dopamine in the extracts was quantified by HPLC equipped with a fluorescence detector. The influence of UAE treatment on the morphology of plant material was studied by SEM. Based on single-factor experiments, the UAE conditions were optimized by response surface methodology using the Box-Behnken design. The optimum conditions were: extraction time of 30 min, water content in DESs of 32%, temperature of 58 °C, and plant material-liquid ratio of 40 mg/mL, which resulted in 2.96 mg of dopamine per 1 g of POL. The percentage of water in DESs and the extraction temperature were the most significant factors influencing the extraction efficiency of dopamine from POL. The results of this study promote the application of DESs for green and efficient extractions of bioactive alkaloids and other target molecules from plant materials.