Physicochemical and Anti–UVB–Induced Skin Inflammatory Properties of Lacticaseibacillus paracasei Subsp. paracasei SS–01 Strain Exopolysaccharide

Abstract

The exopolysaccharide secreted by Lacticaseibacillus paracasei subsp. paracasei SS–01 strain (LP–EPS) is isolated and purified from yogurt. It is a polysaccharide with a branched and multi– stranded structure, which exists in a smooth rod–like or cloud–like state, and possesses a good thermal stability and a molecular weight of 49.68 kDa (±4.436%). LP–EPS shows a high antioxidant capacity, anti–inflammatory and anti–sensitizing activity during in vitro experimental studies, with half clearance (IC50) rates of 0.449, 1.314, and 2.369 mg/mL for the ABTS, DPPH, and OH radicals, respectively, and a half inhibition rate (IC50) of hyaluronidase of 1.53 mg/mL. A cell–based assay, enzyme–linked immunosorbent assay (ELISA), and quantitative real–time fluorescence PCR (qRT– PCR) show that LP–EPS effectively treats or ameliorates the skin inflammatory responses triggered by UVB irradiation, as evidenced by a highly significant decrease in the secretion of inflammatory factors by human skin keratinocytes (HaCaT), and a highly significant downregulation of the mRNA expression of MAPK/AP–1 pathway cytokines.