Effect of pumpkin polysaccharide-milk combinations on oxidative stress resistance of Caenorhabditis elegans based on Chou-Talalay model

This study investigated the synergistic antioxidant effects between pumpkin polysaccharide (PPe) and milk to overcome the limitations of single-component efficacy. PPe was prepared via radical-mediated extraction, precipitation, and deproteinization. Combinations of PPe (1.6, 3.2, 4.8 mg·mL-1) with five commercial milk samples (A-E) were screened using the Chou-Talalay combination index (CI) and DPPH/·OH radical assays. The combination of 1.6 mg mL-1 PPe with milk A or B exhibited the strongest synergy, with low Cm (median-effect dose) and CI values. In C. elegans under oxidative stress, these optimal combinations significantly extended mean survival time (by 62.85% and 52.34%, respectively) and enhanced endogenous antioxidant defenses (SOD, CAT, GSH). This protective effect was associated with the synergistic upregulation of key antioxidant-related genes, including daf-16, sod-3 (insulin/IGF-1 signaling pathway), sir-2.1, and skn-1 (Nrf2/KEAP1 pathway). These findings highlight the synergistic antioxidant potential of PPe-milk combinations and provide a theoretical basis for developing functional dairy products.