Anti-inflammatory activity of a novel lectin isolated from Pleurotus eryngii var. ferulae mushroom

Background and Aims: Pleurotus species are edible mushrooms with important economic and medicinal value. Many pharmacological properties of these species, such as anticancer, immunomodulating, and anti-inflammatory activities, have been attributed to lectin. The aim of this study was to purify a novel lectin from Pleurotus eryngii var. ferulae (PEFL) and investigate its anti-inflammatory activity. Methods: PEFL was purified by 80% ammonium sulphate fractionation, diethylaminoethyl (DEAE)-Sepharose-4B anion exchange, and Sephadex G-100 gel filtration chromatography. The molar mass of the purified lectin was determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) under denaturing conditions. Inhibition of lectin-induced haemagglutination by several carbohydrates and one glycoprotein (ovalbumin) was also performed using the haemagglutination inhibition activity test. The anti-inflammatory effect of PEFL was tested in a lipopolysaccharide (LPS)-induced inflammation model in mouse macrophage cells (RAW 264.7). The levels of prostaglandin (PG)-E2, tumour necrosis factor-alpha (TNF-alpha), interleukin1-beta (IL-1 beta), interleukin-6 (IL-6), interleukin-10 (IL-10), and interferon-gamma (IFN-gamma) were determined using enzyme-linked immunosorbent assay (ELISA) kits. Furthermore, the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was estimated by western blot analysis. Results: PEFL was obtained in 16% yield. The specific activity of PEFL was calculated as 1280 haemagglutinating units (HU)/mg protein and was inhibited only by D-galactose. The molecular weight was determined to be 46 kDa. PEFL showed an anti-inflammatory effect by reducing the production of pro-inflammatory PGs through COX-2 inhibition, as well as reducing iNOS expression. Furthermore, our findings reported that PEFL has a protective effect on inflammation by decreasing the production of pro-inflammatory cytokines and increasing the production of the anti-inflammatory cytokine (IL-10). Conclusion: The results suggest that PEFL can be considered as a potential therapeutic agent in the development of new therapeutic strategies for inflammatory diseases.