The change in structure and improvement of anti-aging effects of polysaccharides in Polygonati Rhizoma after the traditional "Nine Steaming-Nine Sun-Drying".

Abstract

Plant-derived polysaccharides are increasingly recognized as promising anti-aging agents due to their potent bioactivities and low toxicity. As the principal bioactive constituents of Polygonati Rhizoma (PR), polysaccharides undergo defined structural transformations during the traditional "Nine Steaming-Nine Sun-Drying" processing. This study first reveals two novel polysaccharides: RPR-N2 (5.5 kDa) from raw PR, featuring a unique fructan backbone [→1)-β-D-Fruf-(2→] anchored to a →6)-α-D-Glcp-(1→ core with →1,6)-β-D-Fruf-(2→ branches, and PPR-N2 (10.5 kDa) from processed PR, which evolves into a branched galactan with →4)-β-D-Galp-(1→ main chains, →4,6)-β-D-Galp-(1→ linkages, and side chains. A β-fructan (RPR-N2) from raw PR was transformed into a branched β-galactan (PPRN2) after processing. Both polysaccharides significantly attenuated H₂O₂-induced senescence in MRC-5 fibroblasts through multiple mechanisms: (1) reducing senescence-associated β-galactosidase (SA-β-Gal) activity; (2) enhancing proliferation and antioxidant defenses; (3) mitigating G₁-phase cell cycle arrest; (4) restoration of mitochondrial membrane potential; and (5) suppressing senescence-associated secretory phenotype (SASP) factor secretion. This study investigated the structural evolution of PR polysaccharides during processing and established their potential as nutraceutical agents for aging modulation. The results provide a scientific foundation for the optimization of traditional processing methods.