Grape seed extract (GSE), rich in polyphenolic compounds such as catechins and proanthocyanidins, exhibits strong antioxidant potential. This study explored the protective effects of GSE on oxidative stress resistance and longevity in Caenorhabditis elegans. Worms were treated with 100 and 500 μg/mL GSE from L1 to adulthood. In vitro assays confirmed enhanced DPPH and ABTS radical scavenging. In vivo, 500 μg/mL of GSE significantly increased median lifespan by 16.67%, improved thermotolerance by 17.65%, and promoted body growth and motor activity. Fertility remained unaffected, suggesting non-toxic longevity benefits. Biochemical assays showed elevated SOD, CAT, and GSH-Px activities, with reduced MDA levels, indicating enhanced antioxidant defenses. RT-qPCR revealed upregulation of skn-1, daf-16, sod-3, gst-4, and hsp-16.2, pointing to the activation of stress response pathways. Notably, GSE also increased the expression of set-2, suggesting epigenetic regulation via H3K4 methylation. GC-MS-based metabolomics revealed that GSE-treated worms exhibited altered amino acid metabolism, including elevated levels of glutamine, glutamate, and glycine—precursors for glutathione synthesis—alongside reduced pyruvate and succinate, indicating improved mitochondrial function and reduced metabolic stress. Increased norvaline and phenylalanine levels further suggested modulation of nitrogen metabolism and antioxidant pathways.

Collectively, these findings demonstrate that GSE confers significant anti-aging effects in C. elegans through coordinated activation of antioxidant enzyme systems, transcriptional upregulation of stress-responsive genes, epigenetic modulation, and metabolic reprogramming. This study provides mechanistic insights into GSE’s bioactivity and supports its potential as a dietary polyphenol for managing oxidative stress-related aging and metabolic decline.