Agaricus blazei (Himematsutake)

Agaricus blazei Murrill, commonly called Himematsutake or “Brazilian mushroom,” is an edible basidiomycete native to Brazil but cultivated worldwide for its medicinal properties. The fruiting body and mycelial extracts are marketed as dietary supplements intended to modulate immune function and support overall health.

The principal bioactive is a β‑1,3/1,6‑glucan polymer (C₆₆H₁₁₀O₅₆, MW ≈ 10–15 kDa). Its repeating unit is (β‑D‑glucose)ₙ linked by β‑1,3 backbone with β‑1,6 side‑chains. Phenolic constituents include gallic acid (C₇H₆O₅) and catechin (C₁₅H₁₄O₆) with typical flavonoid structures (C‑6′‑hydroxyl, C‑3′‑O‑glucoside). The mushroom also contains ergosterol (C₂₈H₄₄O) and small amounts of vitamin D₂. The polysaccharide is water‑soluble, forms viscous gels at 1–3 % w/v, and is resistant to gastric acid but hydrolyzed by intestinal β‑glucanases, allowing systemic immune activation via gut‑associated lymphoid tissue (GALT).

Commercial A. blazei is cultivated in Brazil, Japan, and China using controlled substrate (sawdust‑based) and sterile fermentation for mycelial extracts. The most consistent products are mycelial‑culture powders produced by submerged fermentation, which yields higher β‑glucan content (30–40 % w/w) than fruiting‑body powders. Quality indicators include: (i) ≥30 % β‑glucan (measured by enzymatic assay), (ii) absence of heavy metals (<5 ppm Pb, As, Cd), (iii) microbial limits (<10⁴ CFU/g total aerobic count). Standardization to a specific β‑glucan content is essential; third‑party certifications (e.g., GMP, ISO 22000) provide assurance. Wild‑harvested fruiting bodies are rare and may contain variable polysaccharide levels and higher contaminant risk, thus are less recommended for supplements.