关键词: 杜仲多糖, DPPH自由基的清除能力, 铁还原能力, 维生素C

Abstract: Ultrasonic-assisted extraction was used for the extraction of polysaccharide from Eucommia ulmoides bark. The effects of the pre-soaking time, the ultrasonic power, the extracting time, the ultrasonic temperature, the ratio of liquid to solid and the extraction times were examined. The optimal conditions for ultrasound extraction were obtained as following: pre-soaking time 2 h, extraction power 250 W, extracting time 30 min, ultrasonic temperature 40℃， liquid to solid ratio 1∶12 g·mL^-1, and extraction 2 times. The highest polysaccharide yield (1.94%) was obtained under the optimal extraction condition. In addition, the antioxidant activity of polysaccharide from E.ulmoides was analyzed and evaluated. The results showed that the DPPH free-radical scavenging ability of polysaccharide is much higher than that of vitamin C at the same concentration. While compared with vitamin C, it exhibited a moderate and concentration-dependent ferric-reducing power.

Key words: Eucommia ulmoides polysaccharide, DPPH free-radical scavenging ability, ferric-reducing power, vitamin C