Antioxidant and Antiaging Effects and Mechanism of Action of <i>Gynura divaricata</i> (L.) DC Polysaccharides in <i>Caenorhabditis elegans</i>

With the increasing prominence of population aging, antiaging research has garnered significant attention. This study investigated the antioxidant and antiaging effects of a crude Gynura divaricata polysaccharide (GDP) and its purified fractions (GDP1, GDP3), prepared via a H₂O₂/Vc-assisted method. All GDPs exhibited potent radical-scavenging activity in vitro. In a Caenorhabditis elegans model, GDPs significantly extended lifespan (up to 19.17%), enhanced motility, and increased heat stress resistance. Treatment with 2 mg/mL GDP markedly reduced lipofuscin accumulation by 43.6% and elevated superoxide dismutase (SOD) and catalase (CAT) activities. GDP demonstrated the strongest effects. Mechanistic studies revealed GDP upregulates daf-16, sod-3, and skn-1 while downregulating daf-2 and age-1. Crucially, the lifespan-extending effect of GDP was abolished in daf-16 mutants, demonstrating that their antiaging action operates primarily via the insulin/IGF signaling (IIS) pathway.