Structural characteristics and antioxidant activity in vivo of a polysaccharide isolated from Phellinus linteus mycelia

In this study, a water-soluble polysaccharide (PLP1-I) was purified from Phellinus linteus mycelia through hot water extraction, ethanol precipitation, and chromatography on DEAE Sepharose Fast Flow and Sephacryl S-400 HR columns. PLP1-I was characterized as a neutral heteropolysaccharide composed of glucose and galactose at a molar ratio of 8.9:1.0, with an average molecular weight (Mw) of ∼290,000 kDa. The structure of PLP1-I consists of a (1→4)-α-D-glucopyranose backbone, whereas the (1→3)-α-D-galactopyranosyl residues formed branches at the O-6 position with 1-linked-α-d-glucopyranosyl terminal residues. Evaluation of the antioxidant activity in vivo showed that PLP1-I administration significantly increased the activity of antioxidant enzymes and reduced the levels of malondialdehyde in the serum and liver of aging mice induced with D-galactose. PLP1-I also effectively stimulated the immune system of aging mice. This study demonstrated that PLP1-I exhibited strong antioxidant activities in vivo and could be explored as a potential antioxidant for functional food and medicine.