AlertsSign in
Back to Compound Explorer

PSK (Polysaccharide-K / Krestin)

Strong
Protein-bound beta-glucan (β-1,3/1,4-glucan with fucose side chains)

Mechanism of Action

PSK is a protein-bound polysaccharide (~62 kDa) consisting of β-1,3-glucan backbone with β-1,4 and β-1,6 side chains and approximately 38% protein content. It acts as a selective TLR-2 (Toll-like receptor 2) agonist, activating dendritic cells and triggering downstream NF-κB signaling. This stimulates CD8+ cytotoxic T-cell proliferation and NK cell cytotoxicity while enhancing antigen presentation. PSK also directly inhibits tumor cell metalloproteinase expression (MMP-2, MMP-9), reducing metastatic potential. Additionally, it acts as a biological response modifier (BRM), restoring immune competence in cancer patients whose immunity is suppressed by chemotherapy or radiation.

Research Notes

Turkey TailMushroom

PSK is the most clinically validated mushroom-derived compound in oncology. It was approved by Japan's Ministry of Health in 1977 and has been used in >40 randomized controlled trials involving >12,000 patients. A landmark meta-analysis (Oba et al., 2007, Cancer Science, 8 RCTs, n=8,009) demonstrated that PSK as adjunct to chemotherapy significantly improved 5-year disease-free and overall survival in gastric cancer patients after curative resection. An RCT (Nakazato et al., 1994, The Lancet) showed PSK + chemotherapy improved 5-year survival from 64% to 73% in stage III colorectal cancer. Derived from FRUITING BODY mycelium (Kureha pharmaceutical extraction process).

Found In 1 Herb

Turkey Tail

Turkey Tail

Mushroom

3D Molecular Structure

Protein-bound beta-glucan (β-1,3/1,4-glucan with fucose side chains)
Drag to rotate · Click atoms to explore

PSK (Polysaccharide-K / Krestin)

Protein-bound beta-glucan (β-1,3/1,4-glucan with fucose side chains)Immunomodulatory polysaccharides found in fungi and grains

Representative pattern: (C₆H₁₀O₅)ₙ

Atoms
Carbon
Oxygen

Live Research

Open on PubMed

This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare practitioner before using any herbal product.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This content is for educational purposes only and is not a substitute for professional medical advice.