Pancreatic lipase-inhibiting polysaccharide from Stropharia rugosoannulata: Structural characterization and interaction mechanisms.

Obesity as a global epidemic concern is often considered as a risk factor for multiple metabolic syndrome. Exploring safe and effective natural ingredients exhibiting excellent pancreatic lipase (PL) inhibition has become a promising way to overcome this issue. This study aimed to investigate the structural characterization of Stropharia rugosoannulata polysaccharide (STR-II*) as well as its inhibition effect and mechanism on PL. The results showed that STR-II* with an average M of 8.5 kDa was composed of Gal, Glu, Man and GlcA at the molar ratio of 3.3: 82.6: 7.9: 6.2. Its backbone was probably composed of →6)-β-Glcp(1→, →3,6)-β-Glcp(1→, →β-1,6-Man-(1→, and →4)-β-Galp(1→, with branches of →1,3-Glc-(1→ and β-t-Glc-(1→. STR-II* exhibited a concentration-dependent inhibition against PL within the tested concentrations (0-3.75 mg/mL), showing higher than 60 % inhibition at 2.5 mg/mL. Kinetics studies suggested that STR-II* interacted with PL by a reversible mixed-type manner. Multi-spectroscopic results revealed that STR-II* could interact with PL through hydrogen bonds and van der Waals forces, leading to changes in the secondary structure and microenvironment of the Trp residue in PL. These results suggested that STR-II* has potential as an obesity prevention agent for applications in functional food and medicine industries.