Abstract: The millet bran was used as raw material to explore the optimal extraction process parameters of flavone by ultrasonic/microwave assisted extraction technology.The optimal extraction process conditions were explored through Box-Benhnken central composite design.At the same time,the purified samples were characterized by IR spectra.The anti-inflammatory activity of total flavonoids of millet bran was evaluated by measuring the cell proliferation,cell morphology and proinflammatory cytokine secretion of RAW264.7 macrophages induced by LPS.The results showed that the optimal condition was as follows∶Ultrasonic microwave time of 0.87 h,ethanol concentration of 77%,material-liquid ratio of 1∶48 (g/mL) and microwave power of 486 W.Under these conditions,the extraction yield of total flavonoids was 31.26 mg/g.This method was 21.01 mg/g higher than the traditional ethanol reflux method.The structure of total flavonoids in millet bran was the same as that of rutin.The concentration of total flavonoids in millet bran was 50-200 μg/mL,which can significantly reduce the inhibitory effect of LPS on macrophage proliferation and repair cellular morphological changes and decrease the secretion of proinflammatory cytokines in a dose-dependent manner.The total flavonoids of millet bran were a potential immunomodulator with a certain anti-inflammatory effect.

Key words: ultrasonic-microwave synergistic extraction, total flavones from millet bran, extraction process, anti-inflammatory activity, proinflammatory cytokine