Abstract: Total flavonoids were extracted from Sedum sarmentosum Bunge using ethanol as extraction solvent with the aid of ultrasonic treatment. The effects of the extraction parameters material-to-liquid ratio (g/mL), ethanol concentration, ultrasonic treatment time and extraction temperature on extraction efficiency were explored by one-factor-at-a-time and orthogonal array design methods. The lipid peroxidation inhibitory activity and hydroxyl free radical scavenging activity of total flavonoids extract were evaluated and compared with those of several natural antioxidants. The extraction rate of total flavonoids was up to 1.968% after 40 min of ultrasonic treatment for extraction with 40% ethanol at 80 ℃ and a material-to-liquid ratio of 1:25. The resulting extract revealed obvious scavenging activity on hydroxyl free radicals and antioxidant effect on oil and fat. Under the same conditions, it was superior to citric acid but inferior to vitamin C in terms of antioxidant effect on oil and fat.

Key words: Sedum sarmentosum Bunge, total flavonoids, extraction, fat and oil, hydroxyl free radicals, antioxidation