Abstract: Using a single factor experiment to determine the ultrasonic extraction of total flavonoids from Pileostegia tomentella,three-level Box-Behnken response surface methodology was used to optimize the extraction process with three factors of extraction temperature, ethanol volume fraction, and solid-liquid ratio, and the scavenging rate of DPPH free radicals and reducing ability were calculated. The results showed that the condition for the optimal extraction process of total flavonoids from Pileostegia tomentella was extraction temperature of 49 ℃, ethanol volume fraction of 46%, and solid-liquid ratio of 1∶66 g/mL. The total flavonoids yield from Pileostegia tomentella under the condition was 27.01 mg/g. There were significant differences in the total flavonoids content of Pileostegia tomentella in different origins. In the measured mass concentration, the total flavonoids from Pileostegia tomentella had a good scavenging ability to DPPH free radicals, and its reducing ability increased with the increase of total flavonoids concentration. The extraction process of the total flavonoids from Pileostegia tomentella was stable, the operation was simple, and the methodology was good, which could be used for its large-scale industrial production.

Key words: Pileostegia tomentella, total flavonoids, response surface methodology, antioxidant