A Polysaccharide PEPP-1-A from Passiflora edulis Sims Peel: Structural Characterization and Its Mechanism of Action in Alleviating Insulin Resistance.

Diabetes mellitus (DM) is a chronic metabolic disease whose primary manifestations include persistent hyperglycemia and insulin resistance. Given this pathological context, polysaccharides are increasingly recognized as promising candidates derived from natural sources for DM management and therapeutic intervention. In this study, Passiflora edulis Sims peel polysaccharides (PEPP) extracted with hot-water was purified to obtain PEPP-1-A using DEAE-52 ion-exchange and Sepharose CL-6B gel chromatography. Subsequently, we investigated the physicochemical and structural characteristics, as well as the hypoglycemic effects of PEPP-1-A. The results indicated that PEPP-1-A, a molecular weight of 20.74 kDa, composed of Fuc, GalN, Rha, Ara, GlcN, Gal, Glc, Xyl, Man, Fru, and GalA with molar percentages of 0.90, 0.40, 2.40, 8.60, 4.30, 6.10, 35.20, 1.70, 4.80, 26.70, and 8.80, respectively. PEPP-1-A effectively alleviates oxidative stress in the IR-HepG2 cell model. Thereby, it relieves lipid metabolism disorders, ameliorates insulin resistance, and enhances glucose uptake. Further analysis using proteomics and western blotting revealed PEPP-1-A may potentially ameliorate insulin resistance, with its effects associated with the modulation of the JNK/p38 MAPK pathway. These results provide preliminary insights into the potential mechanism by which PEPP-1-A may improve insulin resistance, suggesting a link to the alleviation of oxidative stress. and lay a theoretical foundation for its development in functional foods.