AskDefine | Define ergosterol

Dictionary Definition

ergosterol n : a plant sterol that is converted into vitamin D by ultraviolet radiation

User Contributed Dictionary



  1. In the context of "steroid hormone|mycology": The steroid precursor of vitamin D2. It is found in cell membranes of fungi, and is their functional equivalent of cholesterol. It is also found in the membranes of some protists.

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Extensive Definition

Ergosterol (ergosta-5,7,22-trien-3β-ol), a sterol, is a biological precursor to Vitamin D2. It is turned into viosterol by ultraviolet light, and is then converted into ergocalciferol, which is a form of Vitamin D.
Ergosterol is a component of fungal cell membranes, serving the same function that cholesterol serves in animal cells. The presence of ergosterol in fungal cell membranes coupled with its absence in animal cell membranes makes it a useful target for antifungal drugs. Ergosterol is also used as a fluidizer in the cell membranes of some protists, such as trypanosomes. 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 to ergosterol and creates a polar pore in fungal membranes. This causes ions (predominantly K+ and H+) and other molecules to leak out of the cell, killing it. Amphotericin B has been replaced by safer agents in most circumstances but is still used, despite its side effects, for life-threatening fungal infections. Miconazole,Clotrimazole also inhibit synthesis of 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.


External links

Safety (MSDS) data for ergosterol Oxford University (2005)
ergosterol in German: Ergosterin
ergosterol in Esperanto: Ergosterolo
ergosterol in French: Ergostérol
ergosterol in Italian: Ergosterolo
ergosterol in Dutch: Ergosterol
ergosterol in Japanese: エルゴステロール
ergosterol in Portuguese: Ergosterol
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