An efficient approach for the extraction of orientin and vitexin from Trollius chinensis flowers using ultrasonic circulating technique

•Ultrasonic circulating extraction was firstly used to obtain orientin and vitexin.•Factors were evaluated by single factor, Plackett–Burman and Box-Behnken design.•The proposed method was compared with other heat or ultrasonic extraction methods.•UCE mechanism was discussed in detail to illustrate its advantage in extraction.•The developed method with high efficiency can be applied in industrial scale-up. Ultrasonic circulating extraction (UCE) approach was developed for effective extraction of orientin and vitexin from the flowers of Trollius chinensis successfully. In this study, some parameters potentially influencing the yields of orientin and vitexin were systematically investigated and optimized by Plackett–Burman and Box-Behnken design, and the optimum operational conditions obtained were 60% ethanol volume fraction, 1000r/min stirring speed, 30°C temperature, 28min ultrasonic irradiation time, 10mL/g liquid-solid ratio and 738W ultrasonic irradiation power. Satisfactory yields of orientin (6.05±0.19mg/g) and vitexin (0.96±0.03mg/g) were obtained in a relatively shorter extraction time under the derived optimum conditions, compared to other ultrasonic extraction methods and heat extraction methods. The mechanism of UCE procedure was discussed in detail, to illustrate the advantage of UCE in the extraction process. In addition, no degradation of orientin and vitexin and high reproducibility of the developed UCE method were observed under the optimum conditions. The proposed UCE technique with high-capacity and circulation function is a rapid and efficient sample extraction technique, and performs promising in large-scale sample preparation.