| Ergosterol | |
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ergosta-5,7,22-trien-3β-ol |
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| Identifiers | |
| CAS number | 57-87-4 |
| PubChem | 444679 |
| ChemSpider | 392539 |
| UNII | Z30RAY509F |
| EC number | 200-352-7 |
| MeSH | Ergosterol |
| ChEBI | CHEBI:16933 |
| ChEMBL | CHEMBL1232562 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C28H44O |
| Molar mass | 396.65 g/mol |
| Exact mass | 396.339216 |
| Melting point |
160.0 °C |
| Boiling point |
250.0 °C |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Ergosterol (ergosta-5,7,22-trien-3β-ol) is a sterol found in fungi, and named for ergot, a common name for the members of the fungal genus Claviceps from which ergosterol was first isolated. Ergosterol does not occur in plant or animal cells. It is a component of yeast and fungal cell membranes, serving the same function that cholesterol serves in animal cells.
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Ergosterol is a biological precursor (a provitamin) to vitamin D2. It is turned into viosterol by ultraviolet light, and is then converted into ergocalciferol, a form of vitamin D also known as D2 or D2.[1] For this reason, when yeast (such as brewer's yeast) and fungi (such as mushrooms), are exposed to ultraviolet light, significant amounts of vitamin D2 are produced.
Such vitamin D2 serves as the only available dietary supplement of vitamin D for vegans, who avoid dietary intake of any animal product. A related indirect process of producing vitamin D from fungi (though not one that is acceptable to vegans) also occurs, when milk-cows are fed diets of UV-irradiated-yeast (producing D2 from the ergosterol in the yeast), which eventually was excreted as D2 in cow milk. (However, this process was never as common as "supplementing" milk directly by adding vitamin D, or in earlier Steenbock process, in which milk was exposed directly to ultraviolet light, which converts milk's natural 7-dehydrocholesterol content to vitamin D3).
Because ergosterol is present in cell membranes of fungi yet absent in those of animals, it is a useful target for antifungal drugs. Ergosterol is also present in the cell membranes of some protists, such as trypanosomes.[2] This is the basis for the use of some antifungals against West African sleeping sickness.
Amphotericin B is an antifungal drug that targets ergosterol. It binds physically to ergosterol within the membrane, and, thus, creates a polar pore in fungal membranes. This causes ions (predominantly potassium and protons) and other molecules to leak out, which will kill the cell.[3] Amphotericin B has been replaced by safer agents in most circumstances but is still used, despite its side-effects, for life-threatening fungal or protozoan infections.
Miconazole, itraconazole, and clotrimazole work in a different way, inhibiting synthesis of ergosterol from lanosterol. Ergosterol is a smaller molecule than lanosterol; it is synthesized by combining two molecules of farnesyl pyrophosphate, a 15-carbon-long terpenoid, into lanosterol, which has 30 carbons. Then, two methyl groups are removed, making ergosterol. The "azole" class of anti-fungal agents inhibit the enzyme that performs these demethylation steps in the biosynthetic pathway between lanosterol and ergosterol.
Ergosterol is also used as an indicator of fungal biomass in soil. Though ergosterol does degrade over time, if kept below freezing in a dark environment, this degradation can be slowed or even stopped completely.
Research has shown ergosterol may have anti-tumor properties.[4][5]
Ergosterol powder is an irritant to skin, eyes, and the respiratory tract. Ingestion of large amounts can cause hypercalcemia, which (if prolonged) can lead to calcium salt deposits in the soft tissues and, in particular, the kidneys.[6]
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