Ergosterol (redirected from viosterol)

ergosterol [ər′gäs·tə‚rȯl]

(biochemistry)

C₂₈H₄₄O A crystalline, water-insoluble, unsaturated sterol found in ergot, yeast, and other fungi, and which may be converted to vitamin D₂on irradiation with ultraviolet light or activation with electrons. Also known as ergosterin.

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Ergosterol 

(also provitamin D₂), C₂₈H₄₄O, a natural compound of the sterol group with the structural formula

Ergosterol is formed in yeast, molds, and other fungi. The crystals have a melting point of 165°C. Insoluble in water, they are soluble in organic solvents. Ergosterol is optically active, with a specific rotation of [α]_D = –129°. The compound is highly reactive because of conjugate double bonds in the B ring of the system. Like cholesterol, it can form molecular complexes and inclusion complexes in cells. When irradiated with ultraviolet light, the B ring breaks, and ergosterol forms precalciferol, which is easily isomerized by heating to yield vitamin D₂ (ergocalciferol).

In the pharmaceutical industry, ergosterol is used in the preparation of vitamin D₂ and the hormone progesterone. Ergosterol is extracted from the alkaline hydrolyzates of baker’s yeast or the mycelial by-products from the manufacture of antibiotics.