Abstract: Ethanol reflux extraction was selected for the extraction of total flavonoids from Fructus Polygoni Orientalis due to its advantages such as high yield, simplicity and low cost over other three extraction techniques, Soxhlet extraction, ultrasonic-assisted extraction and aqueous extraction. In order to achieve maximum extraction efficiency, the ethanol reflux extraction process was optimized using an orthogonal array design. The optimal extraction conditions were determined as two extraction cycle with 55% ethanol at a solid-to-solvent ratio of 1:24 (g/mL) and 90 ℃ for 4 h. Under these conditions, the extraction yield of total flavonoids was 7.06%.

Key words: Fructus Polygoni Orientalis, total flavonoids, extraction process, optimization