A comparison study between different molecular weight polysaccharides derived from Lentinus edodes and their antioxidant activities in vivo

Context: Polysaccharide purified Lentinus edodes (Berk.) Sing (Tricholomataceae) has been reported to attenuate oxidative stress in vitro. Objective: This study investigated whether polysaccharides from L. edodes with different molecular weight have protective effects against oxidative stress induced by D-galactose (D-gal) in vivo, and determined the specific relationship between molecular weight and antioxidant activity. Materials and methods: In the present study, we successfully obtained three purified polysaccharides, coded as LT1, LT2, and LT3, and their molecular weights were 25.5, 306.2, and 605.4 kDa, respectively. The D-gal-treated mice received three polysaccharides once daily for 60 days. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), the content of malondialdehyde (MDA), and erythrocyte membrane fluidity were measured to evaluate the changes of the antioxidant ability. Results: It was demonstrated that the administration of LT1, LT2, and LT3 could improve the antioxidant status to different levels. Furthermore, LT2 exhibited the highest antioxidant ability among these samples in vivo. Indeed, LT2 significantly decreased the content of MDA in liver (15.91 +/- 0.31 versus 23.79 +/- 1.18 nmol/mg protein for the model group, p < 0.05), enhanced the fluidity of erythrocyte membrane (2.458 +/- 0.023 versus 2.167 +/- 0.024 for the model group, p < 0.05), and increased the activities of SOD (147.19 +/- 4.90 versus 82.26 +/- 5.55 units/mg protein for the model group, p < 0.05) and GSH-Px (310.91 +/- 6.24 versus 243.64 +/- 6.77 units/mg protein for the model group, p < 0.05) in liver. Discussion and conclusion: The LT2 had a potential to be used as a novel natural antioxidant.