Response surface methodology( RSM) was used to optimize the extraction condition of crude polysaccharides( WJc) from Brassica rapa L.. Three independent variables of extraction temperature( ℃),extraction time( h),and ratio of water to raw material( mL/g) were investigated. The experimental levels were determined by singlefactor tests. The optimum conditions were as follows: extraction temperature 80℃,extraction time 2. 5 h,liquid /solid ratio 30 mL /g. Under these conditions,the experimental value was 8. 858%,which was very closed with the predicted valuel. In vitro,free radical scavenging activities results indicated that WJc were found to be effective in scavenging hydroxyl radicals. Overall,WJc may have potential applications in the medical and health food.

The extraction of Illicium micrantbum polysaccharide and its scavenging capacity of free radical were studied in this paper. Through single factor experiment and orthogonal experiment,the optimum extracting conditions were investigated through that the temperature was 75℃,material to water 1 ∶ 14,extracting time 2h,ultrasonic power 300 W.The polysaccharide yield was up to 0.83%.Meanwhile,the polysaccharide of Illicium micrantbum had strong scavenging effect on free radical.

Brassica rapa L. is widely used by the Uygur as herbs. Recently more research concentrates on its chemical constituents. The chemical constituents and biological activity of Brassica rapa L. were summarized so as to provide theoretical basis for its further development and utilization.