Structural characterization and potential antitumor and immunostimulatory activities of mycelial polysaccharides from Ophiocordyceps gracilis

Abstract

Ophiocordyceps gracilis (O. gracilis), the same genus as Ophiocordyceps sinensis, has been used as an edible medicinal fungus for many years. However, the active ingredients of O. gracilis polysaccharides remain relatively unknown. To address this, a 310.1 kDa novel polysaccharide (PDP-1a) was isolated from O. gracilis. The structural characteristics of PDP-1a were determined by different spectroscopy analyses, revealing that PDP-1a was α-glucan homologs with →4)-α-Glcp(1→ as the main chain. Furthermore, PDP-1a inhibited tumor cell proliferation, particularly in the A549 cell line, with a cell death mechanism involving cell cycle blockage, mitochondrial membrane potential reduction, and increased reactive oxygen species, thereby leading to apoptosis. Importantly, PDP-1a promotes antitumor cytokine secretion and enhances macrophage phagocytosis concentration-dependently. These findings provide a theoretical foundation for the use of O. gracilis and emphasize the potential application of PDP-1a in antitumor immunomodulatory therapy.