The evaluation of five bioactive compounds content and in vitro antioxidant of Caryophylli Flos extracts obtained by natural deep eutectic solvents

In this study, a simple, green and efficient method based on ultrasound-assisted NADESs was used to extract ellagic acid, isoquercitrin, myricetin, luteolin and eugenol from Caryophylli Flos. Nine different NADESs were synthesized and screened, and 1,3-butanediol-levulinic acid (molar ratio 1: 3) was selected as the topgallant solvent for maximizing target compounds extraction yields. Single factor experiments combined with response surface methodology and genetic algorithm were applied for efficient optimization of the main variables in the extraction procedure. The optimum experimental conditions were as follows: water content in NADES 29%, liquid-solid ratio 21 mL/g and extraction time 30 min. After the optimization of several main variables, an extract obtained showed higher extraction yields and DPPH and ABTS radical scavenging rate than conventional organic solvents extracts which were used for comparison. Consequently, this study provides a suitable strategy for efficiently extracting bioactive compounds from Caryophylli Flos, and NADESs can be employed as green extraction media for obtaining other natural products.