Abstract: Objective: To study the polysaccharides extraction technology and antioxidant activity from Gymnema sylvestre. Methods: The content of polysaccharides of Gymnema sylvestre was determined by the method of phenol-sulphate acid. On the basis of single factors tests, the four factors including temperature, time, solid-liquid ratio and the extraction times on the yield of the polysaccharides were studied by orthogonal test design. The salicylic acid method was used to inspect the capability to scavenge hydroxyl radicals of the polysaccharides from Gymnema sylvestre. Results: The results showed that temperature is the most important factor for the extraction percentage of the polysaccharides, and the time unit is the second. The optimal extraction technology conditions are: temperature 100 ℃, extraction time 3 h, solid-liquid ratio 1:15 and extraction times 2 times. The yield of the polysaccharides is 2.21%, and the content of polysaccharides 25.57%. The polysaccharides have good capability to scavenge the hydroxyl radicals, and the scavenging capability is obviously related to the concentrations. The scavenging rate is 50% at the concentration of 3.5 mg/ml, while the scavenging rate is 94.42% at the concentration of 12 mg/ml. Conclusion: This extraction technology can be used for the extraction of the polysaccharides from Gymnema sylvestre. The polysaccharides have good antioxidant activity at a high concentration.

Key words: Gymnema sylvestre, polysaccharide, extraction technology, antioxidant activity, hydroxyl radicals