Structural elucidation of three antioxidative polysaccharides from Tricholoma lobayense

Tricholoma lobayense is a nutritious mushroom with great health benefits. Three polysaccharides with purity higher than 99% were successfully extracted from Tricholoma lobayense. The molecular weights of TLH-1, TLH-2 and TLH-3 were determined to be 8.43×10⁵，5.36×10⁵ and 4.53×10³Da, respectively. The backbones of TLH-1 and TLH-2 were mainly composed of 1,4-linked α-d-glucopyranosyl. However, polysaccharide TLH-3 was found to be a highly branched glucogalactan, which is made up of 1,3-linked α-d-glucopyranosyl branched at C-6 and 1,3-linked β-d-galactopyranosyl. In vitro antioxidant activity assays revealed that TLH-3 exhibited highest antioxidant activities among the polysaccharides from Tricholoma lobayense, which were comparable to those of ascorbic acid. The results suggested that the outstanding antioxidant activities of TLH-3 might depend on its low molecular weight, high branch degree, versatile linkage types and complex conformation. These characteristics make TLH-3 an attractive natural antioxidant for food and pharmaceutical applications.