Structural elucidation and anti-inflammatory activity of a proteoglycan from spent substrate of Lentinula edodes

A proteoglycan LEPS1 was firstly isolated and purified from the spent substrate of Lentinula edodes, an agricultural waste that may cause environmental pollution. The average molecular weight of LEPS1 was 1.18 × 10⁴ g/mol, and carbohydrate moiety (88.9 %) was composed of glucose, arabinose, galactose, xylose and mannose at a molar ratio of 1.2:1.2:1.0:2.3:1.1. The protein moiety (8.5 %) of LEPS1 was bonded to the polysaccharide chain via O-glycosidic linkage. LEPS1 could significantly improve the inflammatory injury of LPS stimulated RAW264.7 macrophages by inhibiting the secretion of NO and decreasing the levels of pro-inflammatory factors (TNF-α, IL-1β and IL-6). LEPS1 inhibited JAK-STAT1 and p38 MAPK signaling pathway via modulating JAK expression, phosphorylation of STAT1 and phosphorylation of p38, respectively. Moreover, LEPS1 could promote the expression of CD 206 and IL-10 which were the markers for repairing macrophages. Overall, LEPS1 had anti-inflammatory activity and can potentially treat as a novel anti-inflammation agent. This work could provide scientific basis and valuable information for the highly efficient utilization of spent L. edodes substrates as the by-product in mushroom industries.