Abstract: In order to determine the optimum conditions for extraction of polysaccharides from fermented mycelia of Lentinus edodes by ultrasonic cell disruption and subsequent hot water extraction, a L9(34) orthogonal array design was employed to investigate the effects of the operating parameters material-to-solvent ratio, temperature, ultrasound intensity and extraction time on polysaccharide extraction. The optimum conditions for extracting polysaccharides from fermented mycelia of Lentinus edodes were material-to-solvent ratio1:15, extraction temperature 90 ℃, ultrasound intensity 400 W and extraction time 3 h. Under the optimum conditions, the extraction yield of polysaccharides was 3.38‰. Further, the obtained extract was purified/fractionated sequentially by DEAE-52 ion exchange column and Sephadex G-100 gel permeation column and as a result, a polysaccharide having DPPH free radical scavenging ability was obtained and named as LMP Ⅱ. UV spectral scanning and cellulose acetate membrane electrophoresis demonstrated the high purity of LMP Ⅱ. The fraction had the capability of scavenging superoxide anion and hydroxyl free radicals, and could inhibit the production of MAD in plasma and hydrogen peroxide-induced erythrocyte hemolysis in a dose-dependent fashion. Thus, LMP Ⅱ has a strong antioxidant potential.

Key words: Lentinus edodes mycelium, polysaccharides, purification, antioxidation