Optimization of enzyme assisted extraction of polysaccharides from Astragalus membranaceus.

Astragalus polysaccharide (APS) is known to have a variety of pharmacological activities. In the present study, enzyme assisted extraction of APS from Astragalus mongholicus using various enzymes were examined. Research found that glucose oxidase offered a better performance in enhancement of extraction yields of APS than other ones. Glucose oxidase assisted extraction process was further optimized by using response surface method (RSM) to obtain maximum yield of crude APS. The optimized extraction conditions were as follows: enzyme amount of 3.0%, enzyme treated time of 3.44 d, enzyme treated temperature of 56.9 °C and extraction solvent pH of 7.8. Under these conditions, the experimental yield was 29.96 ± 0.14%, which was well in close agreement with the value (30.19%) predicted by RSM model and increased more than 250% compared with none enzyme treated ones. Pharmacological test showed that enzyme assisted APS had a better antioxidant activity (about 2 times higher) than none enzyme treated ones.