Abstract:Objective To extract and purify extracellular polysaccharides (EPS) from Sphingomonas echinoides 1K04342 and investigate the ameliorating effects and mechanisms of the purified EPS on glucose and lipid metabolism disorders induced by oleic acid (OA) in human hepatoma cells (HepG2).Methods A response surface methodology was employed to optimize the ultrasound power, ultrasound time, and incubation time for maximizing the EPS yield of S. echinoides 1K04342 from ultrasound-assisted extraction. The crude EPS underwent deproteinization and was further purified through a DEAE-Sepharose Fast Flow anion exchange column. The effects of the purified EPS on the proliferation, glucose uptake, and α-glucosidase inhibition and pancreatic lipase inhibition rates in HepG2 cells were evaluated. The most effective EPS component for mitigating OA-induced glucose and lipid metabolism disorders in IR-HepG2 cells was selected for in-depth physicochemical and bioactivity analyses.Results The optimal EPS extraction parameters were as follows: ultrasound power at 59.39 W, extraction for 42.08 s, and incubation for 9.24 h, under which the estimated yield of EPS reached 2.13 g/L. Under the adjusted parameters (60 W, 42 s, and 9.2 h), the EPS yield was 2.10 g/L, which was statistically consistent with the theoretical value (2.13 g/L). The optimal component for ameliorating glucose and lipid metabolism disorders in IR-HepG2 cells was EPS-2, which showed the total sugar content of 74.3%, with a monosaccharide profile comprising fucose, rhamnose, arabinose, galactose, glucose, and mannose. EPS-2 alleviated OA-induced glucose and lipid metabolic disorders in IR-HepG2 cells. EPS-2 reversed OA-induced decreases in cell viability. EPS-2 may activate the IRS-1/PI3K/AKT pathway, up-regulating the protein levels of GSK3β and FoxO1 and down-regulating the mRNA and protein levels of PEPCK and G6Pase, thereby mitigating glucose metabolism disorders. EPS-2 may regulate OA-induced lipid metabolism disorders by activating the AMPK/ACC1/SREBP-1C pathway, lowering the triacylglycerol (TG), total cholesterol (TC), and low-density lipoprotein (LDL) levels, and increasing the high-density lipoprotein (HDL) level.Conclusion EPS-2 derived from S. echinoides 1K04342 could effectively ameliorate glucose and lipid metabolism disorders in IR-HepG2 cells.