Extraction technology of flavonoids from pine shell and its antioxidant activity

  Objective  Pinus koraiensis is an important economic tree species in northeastern China. The chemical components in its pine shell have many biological activities, especially the content of flavonoids is very rich. It is a kind of natural antioxidant, and the pine shell is regarded as the waste, which is sent to the landfill or burned, resulting in the waste of resources. Therefore, in-depth study on flavonoids in pine shell has practical significance for the development and utilization of Korean pine.

  Method  Response surface methodology was used to optimize the extraction process of flavonoids from Korean pine shell by ultrasonic assisted deep eutectic solvents, and the antioxidant activity of the extract was studied.

  Result  The best extraction parameters of flavonoids were: the moisture content of DES was 40%, ultrasonic power was 200 W, extraction time was 30 min, extraction temperature was 60 ℃, solid liquid ratio (w/v) was 1∶55. Under these conditions, the yield of flavonoids was (9.838 ± 0.211)%, 69% higher than that of alcohol extraction. The IC50 of DPPH•, ABTS+• and •OH scavenging rate of flavone extracted by DES were(5.195 ± 0.039) μg/mL, (9.528 ± 0.132) μg/mL, (151.860 ± 0.238) μg/mL, respectively, which were 40.98%, 52.94% and 11.59% lower than those of flavone extracted by alcohol extraction. When the concentration of flavone was in the range of 0.1−0.5 mg/ml, it had a protective effect on HepG2 damaged cells, and the protective effect of flavone extracted by DES was better than that extracted by alcohol.

  Conclusion  The green and environment-friendly DES can be used to extract flavonoids from pine shell, and the extract can maintain good antioxidant activity.