Schimmelpilze / Mykotoxine: the pathway in the body

Schimmelpilze / Mykotoxine is part of the pathway “Mycotoxins”. This page shows the whole pathway; the station of Schimmelpilze / Mykotoxine is highlighted.

Where this laboratory value sits: Moulds — Aspergillus, Penicillium. Some moulds growing on grain, nuts, coffee or dried fruit produce substances they do not need for their own growth. Such substances are called mycotoxins. Source 1

In brief

Mycotoxins are substances that some moulds form on foods, such as aflatoxin B1 and ochratoxin A. In the body, liver enzymes convert them; the products are bound to glutathione and leave with urine and stool.

The pathway step by step

1. Moulds → Aflatoxin B1 Fungal enzymes Aflatoxin B1 is made by a long chain of fungal enzymes. It largely withstands heat and is absorbed into the blood in the small intestine. Source 1, 2
2. Aflatoxin B1 → Aflatoxin epoxide CYP1A2, CYP3A4 · NADPH, oxygen In the liver, the enzymes CYP1A2 and CYP3A4 attach an oxygen atom as a ring. This form is highly reactive and readily combines with proteins and genetic material. Source 2, 3
3. Aflatoxin epoxide → Glutathione conjugate Glutathione S-transf. · glutathione (GSH) Glutathione S-transferases attach glutathione to the epoxide. This neutralises its reactive site and makes it water-soluble. Source 3, 2
4. Glutathione conjugate → Mercapturic acid γ-GT, N-acetyltransf. Further enzymes shorten the conjugate and add an acetyl group. The resulting mercapturic acid leaves the body in the urine. Source 3
5. Ochratoxin A → Bound to albumin · albumin In the blood, ochratoxin A is almost entirely bound to albumin. It is excreted in bile, reabsorbed in the gut and therefore stays in circulation for a long time. Source 4
6. Bound to albumin → Ochratoxin α Carboxypeptidase A Carboxypeptidase A from the pancreas and enzymes of gut bacteria cleave off the phenylalanine. What remains is ochratoxin α. Source 4, 5
7. Ochratoxin α → Excretion Ochratoxin α and a smaller share of unchanged ochratoxin A leave the body in urine and stool. Both can be detected there. Source 5

Cofactors in this pathway

• Glutathione — Glutathione S-transferases attach it to the aflatoxin epoxide and make it water-soluble Source 3, 2In the ORY catalogue as a laboratory value: Glutathion (GSH)
• NADPH — Electron donor of the cytochrome P450 enzymes CYP1A2 and CYP3A4 Source 2, 6
• Oxygen — Provides the oxygen atom that the P450 enzymes attach as an epoxide or OH group Source 2, 3
• Iron — Central atom in the haem of the cytochrome P450 enzymes Source 6In the ORY catalogue as a laboratory value: Eisen
• Vitamin B2 (FAD, FMN) — Flavin cofactors of P450 reductase, which passes electrons from NADPH to the P450 enzymes Source 6
• Zinc — Metal in the active site of carboxypeptidase A, which separates ochratoxin A into two parts Source 7, 4In the ORY catalogue as a laboratory value: Zink
• Acetyl-CoA — Donor of the acetyl group in the last step towards the mercapturic acid Source 3

Sources

1. Sweeney MJ, Dobson AD. Molecular biology of mycotoxin biosynthesis. FEMS Microbiol Lett 1999 · PubMed 10386364
2. Dohnal V, Wu Q, Kuča K. Metabolism of aflatoxins: key enzymes and interindividual as well as interspecies differences. Arch Toxicol 2014 · PubMed 25027283
3. Deng J, Zhao L, Zhang NY et al. Aflatoxin B(1) metabolism: Regulation by phase I and II metabolizing enzymes and chemoprotective agents. Mutat Res Rev Mutat Res 2018 · PubMed 30454686
4. Ringot D, Chango A, Schneider YJ, Larondelle Y. Toxicokinetics and toxicodynamics of ochratoxin A, an update. Chem Biol Interact 2006 · PubMed 16293235
5. Duarte SC, Pena A, Lino CM. Human ochratoxin a biomarkers--from exposure to effect. Crit Rev Toxicol 2011 · PubMed 21401326
6. Iyanagi T, Xia C, Kim JJ. NADPH-cytochrome P450 oxidoreductase: prototypic member of the diflavin reductase family. Arch Biochem Biophys 2012 · PubMed 22982532
7. Kim DH. Chemistry-based design of inhibitors for carboxypeptidase A. Curr Top Med Chem 2004 · PubMed 15320722

Whole pathway: Mycotoxins

Related pathways

• Glutathione — mercapturic acid
• 8-OHdG — Glutathion (GSH), Eisen
• Copper — Glutathion (GSH), Eisen
• Borrelia — Eisen, Zink
• Calprotectin — Eisen, Zink

As of 2026-09-16. Draft written by Claude to schema v2; sources checked in PubMed; expert approval pending
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