Structure characterization and anti-infection activity of a homogeneous heteropolysaccharide COP-60a from Cornus...

Cornus officinalis, a plant used in traditional medicine and as a food, has anti-inflammatory and immune-enhancing properties. This study investigated the structure and anti-infection capabilities of a polysaccharide (COP-60a) from its leaves under microgravity stress. COP-60a was a homogeneous heteropolysaccharide (13,774 Da) composed of arabinose, galactose, xylose, and glucose. Its backbone structure included α-Araf-(1→, →4,6)-β-Galp-(1→, →5)-β-Araf-(1→, →3,6)-α-Galp-(1→, →6)-β-Glcp-(1→ with branches at specific C4/C3 positions. Functionally, COP-60a activated the p38 MAPK pathway (nsy-1, sek-1, pmk-1) and the mitochondrial unfolded protein response (UPR^mt), upregulated immune genes (irg-1, hsf-1, lys-1, spp-1, abf-1), and repaired mitochondrial dysfunction, enhancing C. elegans' anti-infection capacity under microgravity. Additionally, microgravity weakens lung immunity and disrupts lung microbiota homeostasis in mice, but COP-60a restored these imbalances. These findings provided valuable insights into the structure-activity relationship of COP-60a and highlighted its potential as a protective strategy against infection risks in microgravity environments.