Structural features and antioxidant activity of a new galactoglucan from edible mushroom Pleurotus djamor

A new water soluble galactoglucan with apparent molecular weight ~1.61 × 10⁵ Da, was isolated from the edible mushroom Pleurotus djamor by hot water extraction followed by purification through dialysis tubing cellulose membrane and sepharose 6B column chromatography. The sugar analysis showed the presence of glucose and galactose in a molar ratio of nearly 3:1 respectively. The structure of the repeating unit in the polysaccharide was determined through chemical and NMR experiments as: In vitro antioxidant studies showed that the PDPS exhibited hydroxyl radical scavenging activity (EC₅₀ = 1.681 ± 0.034 mg/mL), DPPH radical scavenging activity (EC₅₀ = 3.83 ± 0.427 mg/mL), reducing power (EC₅₀ = 4.258 ± 0.095 mg/mL), and ABTS radical quenching activity (EC₅₀ = 0.816 ± 0.077 mg/mL). So, PDPS should be explored as a natural antioxidant.