Steaming-associated physicochemical changes in Panax ginseng polysaccharides and their protective effects against...

Steaming converts Panax ginseng C. A. Meyer to red ginseng and alters its bioactivity, but the fraction-specific structural changes in ginseng polysaccharides and their relevance to oxidative senescence remain unclear. Four homogeneous polysaccharides (GPS-01-A, GPS-01-B, RGP-01-A and RGP-01-B) were structurally analyzed and evaluated in H₂O₂-induced injury of H9c2 rat cardiomyoblasts. Steaming altered the polysaccharide fractions differentially. The molecular weights were markedly altered by steaming, decreasing from 92.7 kDa to 82.9 kDa in RGP-01-A, while increasing from 6.9 kDa to 12.8 kDa in RGP-01-B. Steaming increased the relative proportion of AG-II polysaccharides in RGP-01-A compared with GPS-01-A. Steaming elevated the uronic acid content of RGP-01-B and disrupted the triple-helical structure of GPS-01-B. In addition, steaming treatment led to higher DM and lower DA in RGP-01-B. At 100 μg/mL, all polysaccharides improved cell viability and reduced Se-β-Gal positivity and intracellular ROS in cells exposed to 800 μM H₂O₂. Four homogeneous polysaccharides exerted anti-senescence effects by enhancing SOD activity, reducing MDA levels, decreasing the proportion of SA-β-Gal-positive cells, and alleviating H₂O₂-induced cellular apoptosis and nuclear damage. RGP-01-B exhibited superior biological activities to the other polysaccharides in multiple indexes. Treatment effects were associated with increased mRNA expression of Nrf2/HO-1, and decreased p53/p21/p16 mRNA expression. Compared with H₂O₂ treatment alone, RGP-01-B also increased total and nuclear Nrf2 and HO-1 protein levels and decreased p53 protein levels. These results indicate that steaming induces fraction-specific remodeling of ginseng polysaccharides that is associated with enhanced protection against oxidative senescence-like injury. RGP-01-B is a promising anti-aging active component in red ginseng polysaccharides and can be used as a candidate for further development.