Comparison on characterization and antioxidant activity of polysaccharides from Ganoderma lucidum by ultrasound and conventional extraction

The polysaccharides of Ganoderma lucidum (GLP) extracted by the methods of ultrasound assisted extraction (UAE) and hot water extraction (HWE) were characterized and the antioxidant activities of GLPUAE and GLPHWE were compared. High performance gel permeation chromatography (HPGPC) showed that the average molecular weight of GLPUAE and GLPHWE were 465.65 kDa and 703.45 kDa, respectively. GLPUAE was composed of mannose, rhamnose, glucose, galactose and arabinose in the molar ratio of 2.58:1.25:11.17:2.5:1, while GLPHWE was composed of the same monosaccharide in the ratio of 3.11:1.11:19.44:2.33:1. GLPHWE showed a relatively higher antioxidant activity than GLPUAE by testing the reducing power, the scavenging ability on 1.1‑diphenyl‑2‑picryl‑hydrazyl (DPPH), hydroxyl radical and cellular protective effect on yeast cells from ultraviolet radiation (UV) damage. GLPUAE and GLPHWE were purified by chromatographic column of DEAE-52 cellulose. GLPUAE, GLPHWE and the purified components could be novel antioxidants for functional food.