Objective  The pine needles of Pinus massoniana are rich in polyphenols and flavonoids with multiple active functions. In this paper, the preparation and antioxidant activity of the deep eutectic solvents (DES) extract of pine needles of P. massoniana were studied to deepen the exploitation of the undergrowth resources under tree crowns and to provide a more environmentally-friendly extraction method of active ingredients with more activities and higher efficiencies compared with traditional ways.

  Method  Active ingredients were extracted from P. massoniana needles by ultrasonic technology under the assistance of DES. Firstly, three kinds of DES were screened by comparing the extraction effect. Then, based on the selected DES-choline chloride/glucose, a single factor test was conducted on the effect of liquid-solid ratio, ultrasonic temperature, ultrasonic time and ultrasonic power on the extraction effect. Based on single factor experiments, different capacities between DES extract and conventional ethanol extract to scavenge and reduce DPPH·, ABTS⁺· was compared with the yield of polyphenols and flavonoids taken as indexes and response surface method as the optimization of main process parameter.

  Result  The optimal process to produce P. massoniana needle extract was: ratio of liquid to solid 10 mL/g, ultrasonic temperature 48 ℃, ultrasonic time 60 min, ultrasonic power 300 W, yield of polyphenol in the above condition 7.387%, yield of flavonoids in the above condition 10.377%, regression model fits well. The antioxidant activity of DES extract was overall better than that of the conventional ethanol extract.

  Conclusion  Ultrasonic technology under the assistance of DES has higher yield of the P. massoniana needles extract compared with conventional extraction methods, and it has significant effect on the antioxidant activity compared with ethanol extraction method. So this method can provide efficient extraction of P. massoniana needles ingredients while fully maintaining the biological activity. So this method can provide efficient extraction of P. massoniana needles ingredients while fully maintaining the biological activity. It will be significant in the resource utilization of the P. massoniana.