An extracellular polysaccharide from Aspergillus versicolor ameliorates palmitate-induced insulin resistance in HepG2...

The distinct conditions of the marine habitat drive microorganisms to synthesize exopolysaccharides possessing unique structural features and a broad spectrum of bioactive properties. An extracellular polysaccharide (AVP1) was obtained from the fermented liquid of a marine Aspergillus versicolor CS13 from the Yellow River Delta sediment. AVP1 was characterized as a mannogalactan with a molecular weight of approximately 16.2 kDa and a mannose-to-galactose molar ratio of 1.0: 2.4. The polysaccharide AVP1 was constituted by a backbone of →2)-α-D-Manp-(1→ and →5)-β-D-Galf-(1→ units, and branch at C-6 of →5)-β-D-Galf-(1→ units. The side chains contained →6)-α-D-Manp-(1→ and α-D-Manp-(1→ units. AVP1 possessed an obvious α‑amylase inhibitory activity in vitro. AVP1 significantly enhanced insulin sensitivity and glucose consumption in insulin-resistant (IR)-HepG2 cells, and alleviated sodium palmitate (PA)-induced insulin resistance. Moreover, AVP1 effectively reduced total cholesterol (TC) and triglyceride (TG) levels, while increased the activities of superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH). It also decreased malondialdehyde (MDA) content and reactive oxygen species (ROS) levels, thereby improved lipid metabolism and mitigated oxidative stress in IR-HepG2 cells. These results demonstrated that AVP1 exhibited notable restorative effects in IR-HepG2 cells and possessed strong activity to alleviate insulin resistance in vitro. This study provides a basis for the development of novel marine-derived hypoglycemic agents.