A Novel Low-Molecular-Weight Glucomannogalactan from Phyllanthus emblica L.: Structural Characterization and Multitarget Effect in Regulating Glycolipid Metabolism Disorder

Abstract

While pectin from Phyllanthus emblica L. has already been studied, the nonpectic polysaccharides remain largely unexplored. Here, a novel low-molecular-weight glucomannogalactan (PEP) was isolated and structurally characterized as a backbone of 1,4-linked Galp and Manp residues, with a postulated branching architecture involving 1,6-Manp side chains and 1,3-/1,6-Glcp branches. Bioactivity assessment demonstrated that PEP inhibited α-amylase and promoted the growth of glycolipid metabolism-associated beneficial bacteria. Its fermentation metabolites from Bacteroides significantly ameliorated insulin resistance-HepG2 cells. In vivo, PEP attenuated postprandial glycemic excursion in mice, reducing the area under the curve by 37.19%. Collectively, PEP exhibits integrated effects, potentially linking the inhibition of upper gastrointestinal glycolipid absorption, promotion of the growth of beneficial bacteria, and improvement of hepatic insulin sensitivity. While further in vivo mechanistic investigations are warranted to validate these hypotheses, PEP highlights its potential as a promising multifunctional polysaccharide ingredient for managing postprandial glucose homeostasis.