Protective effect of Inonotus obliquus polysaccharide on fibroblasts after MGO-induced nonenzymatic glycation

Abstract Background Nonenzymatic glycation of fibroblasts causes functional downregulation and behavioral disorders in skin. Methods To investigate the effect of Inonotus obliquus on the nonenzymatic glycation of skin, we examined advanced glycation end product (AGE) inhibition by four extract fractions: n-butanol, ethyl acetate, n-hexane and aqueous alcoholic precipitation. The physical properties and chemical structure of the most effective, purified, crude I. obliquus polysaccharide (IOP) were examined. The effects of IOP on carboxymethyl lysine (CML) accumulation, inflammatory factor release, reactive oxygen species (ROS) production, key extracellular matrix (ECM) protein (MMPs 1, 2 and 9, FN-1, LM-5 and COL-1) mRNA expression and cell survival, migration and adhesion were examined by cellular assays. Results The results showed that IOP is a polysaccharide with a molecular weight Mw of 2.396×104 (± 6.626%), which is mainly composed of glucose, galactose, xylose, mannose and arabinose (29.094:21.705:14.857:9.375:7.709). In addition, the results of cellular anti-glycation assay showed that IOP had strong anti-glycation activity in the range of 6–24 µg/mL, which could promote ECMs by inhibiting the accumulation of CML, inhibit the release of inflammatory factors (IL-1β, IL-6, and TNF-α), inhibit the production of reactive oxygen species (ROS), and inhibit the expression of matrix metalloproteinase (MMP-1\-2\-9), and promote the ECMs (COL1, FN1, LM5) protein synthesis, and improve cellular dysfunction. Conclusion The IOPs effectively reduced the levels of inflammatory factors and reactive oxygen species caused by AGEs, further prevented the impairment of cell behaviour (decreased migration levels, reduced cell adhesion) and prevented the downregulation of expression of key extracellular matrix proteins due to AGEs. The results indicate the potential application of IOPs as AGE inhibitors in skin care.