About Zearalenone
Zearalenone (ZEN) is a macrocyclic β-resorcylic acid lactone produced principally by Fusarium graminearum and F. culmorum on cool-temperate cereal grains. Despite chemistry that bears no resemblance to steroid hormones, the molecule binds vertebrate estrogen receptors (ERα and ERβ) and acts as a mycoestrogen, a non-steroidal compound with estrogenic biological activity.
Chemistry
ZEN is a 14-membered macrocyclic lactone built around a resorcinol moiety. The flat geometry of the macrocyclic ring positions the resorcinol hydroxyls in a spacing that mimics the 17β-estradiol A-ring pharmacophore, which is how a fungal polyketide ends up activating vertebrate estrogen receptors. Two principal mammalian metabolites (α-zearalenol and β-zearalenol) have differing receptor affinities; α-zearalenol is the more potent estrogen.
Mechanism
ZEN and its metabolites bind ERα and ERβ at concentrations comparable to weak estrogens. The receptor-binding mechanism is the same as endogenous estradiol but with reduced potency and altered ER-α/ER-β selectivity. Mechanism description is cellular only.
Producing organisms
| Species | Panel | Notes |
|---|---|---|
| Fusarium spp. | Extended | F. graminearum, F. culmorum, F. cerealis, F. equiseti |
Conditions of production
ZEN production requires high water activity, Aw ≥ 0.95, and cool-temperate temperatures (12–25 °C optimum)[1]. The combination of high moisture and cool temperatures is characteristic of late-season cereal field conditions in temperate climates and of cool-storage periods. Substrates are corn, wheat, barley, sorghum, oats.
Natural occurrence
Cereal grains in temperate climates: primarily corn, wheat, and barley. Both pre-harvest (field) and post-harvest (storage) contamination occur. Indoor relevance is low for residential ERMI scenarios; ZEN appears in indoor environments via grain-handling routes (storage, pet food, livestock feed) rather than via building water damage.
Regulatory references
IARC carcinogen classification: Group 3 (not classifiable as to human carcinogenicity)[3].
Related mycotoxins
The α- and β-zearalenol metabolites have varying estrogenic potency. ZEN-glucuronide conjugates are urinary metabolites used in biomonitoring research. ZEN is not biosynthetically related to other indoor mycotoxin families at this level.
References
- Zinedine A, Soriano JM, Moltó JC, Mañes J. Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: an oestrogenic mycotoxin. Food Chem Toxicol. 2007;45:1–18.
- EFSA Panel on Contaminants in the Food Chain. Scientific opinion on the risks for public health related to the presence of zearalenone in food. EFSA Journal. 2011;9(6):2197.
- International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 56: Some Naturally Occurring Substances. Lyon: IARC; 1993.