Viosterol

Template:Chembox ChEMBL
Ergosterol
Identifiers
CAS number 57-87-4 YesY
PubChem 444679
ChemSpider 392539 YesY
UNII Z30RAY509F YesY
EC number 200-352-7
MeSH Ergosterol
ChEBI CHEBI:16933 YesY
Jmol-3D images Image 1
Properties
Molecular formula C28H44O
Molar mass 396.65 g/mol
Melting point

160.0 °C

Boiling point

250.0 °C

 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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 cholesterol serves in animal cells.

Ergosterol is occasionally reported analytically to occur in grasses such as rye[1] and alfalfa (including alfalfa sprouts), and in plant flowers such as hops.[2] However, such detection is usually assumed to be detection of fungal growth upon (and sometimes contamination of) the plant, as fungi form an integral part of the grass decay system. This ergosterol assay technique may thus be used to assay grass, grain, and feed systems for fungal content.[3][4]

Since ergosterol is the provitamin of vitamin D2, the ultraviolet (UV) radiation of fungus-bearing grass materials can result in vitamin D2 production,[5] but this is production of a form of vitamin D from fungus ergosterol (much as in UV radiation of yeasts and mushrooms) and is not true vitamin D production by the plant itself from UV light, a process that cannot happen.

Vitamin D2 precursor

Ergosterol is a biological precursor (a provitamin) to vitamin D2. It is turned into viosterol by UV light, and is then converted into ergocalciferol, a form of vitamin D also known as D2 or D2.[6] For this reason, when yeast (such as brewer's yeast) and fungi (such as mushrooms), are exposed to UV light, significant amounts of vitamin D2 are produced. Such vitamin D2 serves as the only available dietary source of vitamin D for those who eat no animal products, although such persons can obtain ample vitamin D through exposure to sunlight.

A related process of producing food vitamin D from fungi (though not a process acceptable to vegans) occurs when milk-cows are fed diets of UV-irradiated yeast (which contains D2 produced from the ergosterol in the yeast). This form of the vitamin is eventually excreted as D2 in cow milk. However, this process for increasing vitamin D in milk was never as common as "supplementing" milk directly, by adding vitamin D3 to the milk. It was also not as common as the earlier Steenbock process, in which milk was exposed directly to ultraviolet light, which converts milk's natural 7-dehydrocholesterol content to vitamin D3.

Target for antifungal drugs

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.[7] This is the basis for the use of some antifungals against West African sleeping sickness.

Amphotericin B, an antifungal drug, targets ergosterol. It binds physically to ergosterol within the membrane, thus creating a polar pore in fungal membranes. This causes ions (predominantly potassium and protons) and other molecules to leak out, which will kill the cell.[8] 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 antifungal agents inhibit the enzyme that performs these demethylation steps in the biosynthetic pathway between lanosterol and ergosterol.

Other uses

Ergosterol is also used as an indicator of fungal biomass in soil. Though it 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 antitumor properties.[9][10]

Toxicity

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.[11]

See also

References

External links

  • Safety (MSDS) data for ergosterol Oxford University (2005)

Template:Vitamin

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.