VitaMin D4

Description

Derived from cholesterol, vitamin D is biosynthesized from its prohormone cholecalciferol (D3), the product of solar ultraviolet irradiation of 7-dehydrocholesterol in the skin. In 1966, it was first recognized that vitamin D must undergo activation via two oxidative metabolic steps. The first oxidation to 25-hydroxycholecalciferol (25(OH)D3: calcifediol; Calderol) occurs in the endoplasmic reticulum of the liver and is catalyzed by vitamin D 25-hydroxylase. This activation step is not regulated by plasma calcium concentrations. The major circulating form (10–80 μg/mL) is 25(OH)D3, which also is the primary storage form of vitamin D.

Chemical properties

Pale Yellow Oil

The Uses of VitaMin D4

Vitamin D4 is the active analogue of Vitamin D.

Definition

ChEBI: Vitamin D4 is it is present in mushrooms. It has a role as a fungal metabolite. It is a vitamin D and a seco-ergostane.

Biological Functions

Sterol-specific cytoplasmic receptor proteins (vitamin D receptor) mediate the biological action of vitamin D. The active hormone is transported from the cytoplasm to the nucleus via the vitamin D receptor, and as a result of the interaction of the hormone with target genes, a variety of proteins are produced that stimulate the transport of calcium in each of the target tissues Active vitamin D works in concert with PTH to enhance active intestinal absorption of calcium, to stimulate bone resorption, and to prohibit renal excretion of calcium. If serum calcium or 1,25-calcitriol concentrations are elevated, then vitamin D 24-hydroxylase (in renal mitochondria) is activated to oxidize 25(OH)D3 to inactive 24,25-dihydroxy-cholecalciferol and to further oxidize active vitamin D to the inactive 1,24,25-trihydroxylated derivative. Both the 1,24,25-trihydroxylated and the 24,25-dihydroxylated products have been found to suppress PT H secretion as well. The biosynthesis of vitamin D is tightly regulated based on the serum concentrations of calcium, phosphate, PTH, and active vitamin D.