Preparation and determination of phenolic compounds from Pyrola incarnata Fisch. with a green polyols based-deep eutectic solvent

A group of green solvent named polyols-based deep eutectic solvents (PDES) combined with microwave assisted extraction (MAE) was first successfully applied in extracting phenolic compounds from pyrola. A series of PDES with mixing different ratios choline chloride (ChCl) to different polyols were investigated for extraction, and ChCl/1,4-Butanediol (1/4) was found to be the suitable extraction solvent. MAE was more effective than heat-stirring extraction and ultrasonic assisted extraction with PDES. The extraction parameters were optimized by BBD test combined with response surface methodology. The optimal extraction conditions were 30% of water in ChCl/1,4-Butanediol (1/4) at 70   °C for 20   min and liquid/solid ratio 10   mL/g. Moreover, RP-HPLC-UV was developed for the determination of five main active components in pyrola. This method exhibited satisfactory linearity ( R 2   >   0.999), precision (RSD   <   4.03%) and recovery (96.17–103.25%). Sample analysis showed that the contents of hyperin, 2′-O-galloylhyperin, quercitrin, quercetin-O-rhamnoside and chimaphilin in pyrola were 1.627, 4.958, 0.041, 0.089 and 0.349   mg/g, respectively. These results revealed that PDES would be promising green solvents for analytical sample preparation from plant herbs.