Water-Soluble Polysaccharides Extracted from Pueraria lobata Delay Aging of Caenorhabditis elegans under Heat Stress.

Pueraria lobata is a perennial legume, commonly used as a food source in China. The polysaccharides extracted from P. lobata have demonstrated various biological activities. However their anti-aging effects and the underline mechanisms are largely unknown. In this study, water-soluble polysaccharides (WSPS) from P. lobata were extracted and demonstrated antioxidant activity against DPPH radicals and hydroxyl radicals in vitro. Using nematode Caenorhabditis elegans as a model, we found that WSPS remarkably prolonged the survival, increased growth and locomotion under heat stress. To investigate the possible mechanism, the levels of reactive oxygen species (ROS) and lipid peroxidation product malondialdehyde (MDA) were determined. WSPS significantly decreased ROS and MDA levels which is consistent with increased activity of superoxide dismutase (SOD). Meanwhile, WSPS upregulated the expression of stress resistance genes sod-1, sod-5, hsf-1, hsp-12.6, hsp-16.2, skn-1 and gst-4. Together, these results suggest that the anti-aging activity of WSPS under heat stress was mediated most likely by activation of the target genes of heat-shock transcription factor (HSF)-1 and skinhead (SKN)-1, and thus inducing endogenous ROS scavenging response.