A New Galactoglucomannan from the Mycelium of the Medicinal Parasitic Fungus Cordyceps cicadae and Its Immunomodulatory Activity In Vitro and In Vivo

Abstract

A new galactoglucomannan (C-0-1) was purified from the medicinal parasitic fungus of Cordyceps cicadae using an anion-exchange column and gel permeation column. The results of high-performance liquid chromatography and high-performance gel permeation chromatography indicated that C-0-1 consists of galactose, glucose, and mannose in a ratio of 5:1:4 and has a molecular weight of 23.3 kDa. The combined structural elucidation analysis methods including partial acid hydrolysis, methylation analysis, and NMR experiments revealed that C-0-1 was a comb-like polysaccharide with a core structure including (1→2)-α-D-Manp residues in the backbone and branches at O-6 of the main chain. (1→4)-α-D-Glcp, (1→2)-β-D-Galf, (1→2,6)-β-D-Galf, and terminal β-Galf were located at the side chains. An in vitro experiment using RAW 264.7 cells indicated that C-0-1 exhibits good immunomodulatory activity by enhancing inducible nitric oxide synthase secretion and the production of some major inflammatory cytokines. On inhibiting the cytokine production using anti-pattern recognition receptors antibodies, it was revealed that the activation of macrophages is mainly carried out by C-0-1 through the mannose receptor. Toll-like receptor 4 and Toll-like receptor 2 were also involved in this identification process. An in vivo experiment on immunosuppressive mice treated with cyclophosphamide indicated that C-0-1 improves the secretion of serum-related cytokines (IFN-γ, TNF-α, IL-2, IL-4, and IL-10) and affects the balance of T helper cells Th1/Th2. Given the structural and bioactivity similarity between Cordyceps cicadae and Cordyceps sinensis, we can conclude that Cordyceps cicadae could be used as an important medicinal fungus like Cordyceps sinensis.

Bioactive Compounds Produced by Macromycetes for Application in the Pharmaceutical Sector: Patents and Products

“…Its central structure is α-(1,2)-D-Manp and O-6 branches. The polysaccharide contains α-(1,4)-D-Glcp, β-(1,2)-D-Galf, β-(1,2,6)-D-Galf, and β-Galf terminal in the side chains [46]. Additionally, it exhibits immunomodulatory activity, enhancing the production of nitric oxide synthase and several crucial inflammatory cytokines.…”