Maitake Mushroom (Grifola frondosa)

Maitake (Grifola frondosa) is a large, polyporous fungus native to temperate forests of East Asia, North America, and Europe. It is used as a dietary supplement due to its high concentration of bioactive polysaccharides (especially β‑glucans), proteins, and triterpenoids that modulate immune and metabolic pathways.

• Active component: The hallmark bioactive component is β‑(1→3),(1→6)‑D‑glucan, a polysaccharide with repeating units of C₆H₁₀O₅ (molecular weight ≈ 150 kDa for the polymer).
• Monomer: A representative monomer has the IUPAC name: (4‑O‑β‑D‑glucopyranosyl)-(1→3)-β-D‑glucopyranose.
• Triterpenoids: Triterpenoids such as grifolin (C₁₇H₂₄O₅; 2‑(4‑hydroxy‑3‑methoxy‑phenyl)‑4‑methyl‑3‑hydroxy‑5‑methyl‑2‑penten-1‑one) and erogosterol (C₂₈H₄₄O; 5α‑ergosta-7,22-diene‑3β,5α,6β‑triol) are also isolated.
• Function: The β‑glucan’s high solubility in hot water and resistance to gastrointestinal enzymes allow it to reach intestinal immune tissue intact, where it interacts with pattern‑recognition receptors.

• Wild Harvesting: Wild‑harvested Maitake grows on the roots of oak and beech trees in Japan, Korea, and the northern United States.
• Commercial supplements:
  • Typically use cultivated mycelium grown in sterile, submerged fermentation systems to ensure constant β‑glucan content; this method yields a cleaner, contaminant‑free product compared to wild collection.
  • Extraction methods include hot-water extraction followed by ethanol precipitation to isolate the β‑glucan fraction, and supercritical CO₂ extraction for triterpenoids.
• Quality control: Quality‑focused manufacturers test for:
  • (i) β‑glucan content (≥30 % w/w)
  • (ii) absence of heavy metals
  • (iii) microbial limits (E. coli, Salmonella <10 CFU/g)
  • (iv) DNA barcoding (ITS region) for species verification.
• Recommendations: Look for third‑party certifications (e.g., USP, NSF) to ensure product integrity.