Abstract: Anthraquinone is one of the major functional components in Cassia obtusifolia L. seeds. Response surface methodology was employed to optimize the ultrasonic-assisted extraction of free anthraquinone from Semen Cassiae. The extraction efficiency of free anthraquinone was investigated with respect to four process conditions including ethanol concentration, extraction temperature, ultrasonic treatment time and material-to-liquid ratio. The optimal conditions for anthraquinone extraction were 80% aqueous ethanol as the extraction solvent, material-to-liquid ratio of 15:1 (mL/g), extraction temperature of 65 ℃, ultrasonic treatment time of 30 min and ultrasonic power of 100 W. Under the optimal extraction conditions, the extraction rate of free anthraquinone from Semen Cassiae. was 28.32%.

Key words: Cassia obtusifolia L., ultrasonic, anthraquinone, response surface methodology