Abstract: Ultrasonic-assisted flash extraction (UFE) was employed to extract anthocyanins from blueberry fruit. The effects of ultrasonic power, flash extraction speed, extraction time, solid-to-liquid ratio and ethanol concentration on the yield of anthocyanins were investigated. A combination of one-factor-at-a-time method and genetic algorithm was used to optimize the extraction parameters. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Annexin V-FITC/PI double label staining were employed to investigate the effects of the anthocyanin extract at different concentrations on proliferation and apoptosis of S180 cells. Its in vivo antitumor activity was tested using an S180 tumor-bearing mice model and enzyme-linked immunosorbent assay (ELISA). The results showed that the optimum extraction conditions that provided the highest yield of anthocyanins of (2.71 ± 0.08) mg/g were obtained as follows: extraction time 10 min, ultrasonic power 450 W, flash extraction speed 8 400 r/min, solid-to-liquid ratio 1:30 (g/mL) and ethanol concentration 68%. The content of anthocyanins in the resulting extract was (31.79 ± 0.53)%. In vitro tests showed that the anthocyanin extract could remarkably inhibit proliferation, induce apoptosis of S180 cells, and block the cells in S phase. In vivo anti-tumor tests showed that the masses of tumors treated with the anthocyanin extract at low, medium and high doses were significantly lower than that of the model control group (P < 0.05) and the anti-tumor rates were 26.36%, 33.33% and 46.51%, respectively. The levels of IL-12 and TNF-α in the serum of tumor-bearing mice treated with the anthocyanins at the three doses were significantly higher than those of the model control group (P < 0.05), while the serum level of IL-10 was significantly lower than that of the model control group (P < 0.05). In conclusion, UFE is an efficient method for anthocyanins extraction, and the anthocyanin extract can inhibit the growth of tumors by inducing apoptosis and enhancing immunity.

Key words: ultrasonic-assisted flash extraction, blueberry, anthocyanins, process, anti-tumor activity