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Identification of the Primary Structure of Selenium-Containing Polysaccharides Selectively Inhibiting T-Cell Proliferation

Summary

This research identified specific polysaccharides from shiitake mushroom that can selectively suppress certain immune system responses. When enriched with selenium, these compounds showed potential as targeted immunosuppressive agents. This is significant because most mushroom compounds typically stimulate rather than suppress immune responses. Impacts on everyday life: – Could lead to new treatments for autoimmune diseases with fewer side effects – Demonstrates how growing conditions can dramatically change beneficial compounds in mushrooms – Shows potential for developing new pharmaceutical products from common food mushrooms – Highlights the importance of selenium in biological processes – May influence how medicinal mushroom supplements are produced and standardized

Background

Mushroom-derived polysaccharides, particularly β-D-glucans, are known for their immune-modulating properties. Previous research isolated a selenium-containing polysaccharide fraction from Lentinula edodes mycelial culture that showed unexpected immunosuppressive activity, rather than the typical immunostimulatory effects of fungal polysaccharides. The fraction was found to be a protein-containing mixture of high molar mass polysaccharides, but the specific components responsible for the immunosuppressive activity remained unknown.

Objective

To separate and identify the pure polysaccharides from the selenium-containing polysaccharide fraction isolated from L. edodes mycelium, determine their primary structures, and investigate which components were responsible for inhibiting T-cell proliferation.

Results

Four polysaccharide components were identified: α-1,4-glucan (Mw 2.25 × 106 g/mol), unbranched β-1,6-D-glucan, unbranched β-1,3-D-glucan and β-1,3-branched β-1,6-D-glucan (Mw 1.10 × 105 g/mol). All components showed biological activity, with selective inhibition of T-cell proliferation. The effect was weaker but more selective than the crude fraction. The selenium content significantly impacted activity, with higher selenium concentrations correlating with stronger immunosuppressive effects.

Conclusion

The isolated selenium-containing polysaccharides demonstrated unique selective immunosuppressive activity via CD3 receptors, which is atypical for fungal polysaccharides. The biological effects appear to depend on both selenium incorporation and the distinct structural features of the isolated fractions. These findings reveal that L. edodes can biosynthesize polysaccharides with completely different structures and biological activities than previously described when grown under specific culture conditions.
  • Published in:Molecules,
  • Study Type:Laboratory Research,
  • Source: 10.3390/molecules26175404
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