Fructan PKP-1b from Polygonatum kingianum attenuates aging and neurodegeneration by inhibiting insulin/IGF-1 signaling

Polygonatum kingianum is a known tonic herb of Traditional Chinese Medicine, extensively consumed in China, but the structure and activity of its polysaccharides remain to be clarified. In this study, a homogeneous fructan fraction, designated PKP-1b, was isolated and purified from this plant and structurally identified as an agavin-type fructan. In both Caenorhabditis elegans and a D-galactose-induced aging mouse model, PKP-1b exhibited significant anti-aging effects, including lifespan extension, improved motor function, reduced lipofuscin accumulation, and mitigation of neurodegenerative changes. Mechanistic investigations revealed that PKP-1b exerts its anti-aging effects by inhibiting the insulin/IGF-1 signaling (IIS) pathway, which in turn promotes nuclear translocation of the transcription factor DAF-16/FOXO, upregulates expression of the antioxidant gene sod-3, thereby enhancing overall antioxidant capacity and reducing oxidative damage. These findings elucidate the anti-aging mechanism of PKP-1b from P. kingianum and provide a theoretical foundation for its application in developing anti-aging products.