Structural characterization of a polysaccharide from Suillellus luridus and its antidiabetic activity via Nrf2/HO-1 and NF-κB pathways.

A heteropolysaccharide designated SLPC-1S with the Mw of 9.4 kDa was purified from the caps of Suillellus luridus. Monosaccharide composition analysis revealed that SLPC-1S was composed of galactose, glucose, arabinose and mannose in a molar ratio of 44.9:27.6:14.7:12.8. Structural characterization indicated that SLPC-1S had a backbone principally composed of 1,3 linked α-D-Galp, 1,3 linked β-D-Glcp and 1,6 linked β-D-Glcp with the branches mainly composed of 1,3 linked β-D-Glcp, 1,3 linked α-L-Arap, 1,3 linked α-D-Manp and T-linked α-D-Galp. Furthermore, SLPC-1S exhibited excellent antidiabetic activities in the streptozotocin-induced diabetic mice. Protein expression and mRNA levels in NF-kB and Nrf2/HO-1 signaling pathways were detected by western blots and real-time polymerase chain reaction (RT-PCR), respectively. The results strongly proved that SLPC-1S can be treated as a potential agent for preventing and treating diabetes via regulating Nrf2-mediated oxidative stress and NF-κB-mediated inflammatory responses.