“Vitamin D₃ Cholecalciferol”  

Cholecalciferol as Vitamin D₃ (Calciol)

  In our body, Cholecalciferol (Vitamin D₃) is a naturally occurring form of the sterol vitamin D, produced in the epidermis by ultraviolet radiation (290-315 nm) of 7-dehydrocholesterol. 25-hydroxyvitamin D [25(OH)D], and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] are the major circulating metabolites. Vitamin D₃ is made in large quantities in the skin when sunlight strikes the bare skin, also obtained from food and food supplements, and as a fat-soluble vitamin has a long half-life of approximately 2 months.

7-dehydroxycholesterol Derivative

  Cholecalciferol (Vitamin D₃) is a derivative of 7-dehydroxycholesterol formed by ultraviolet rays breaking of the C9-C10 bond. Cholecalciferol (Vitamin D₃) differs from Ergocalciferol in having a single bond between C22 and C23 and lacking a methyl group at C24.

Cholecalciferols

  Examples of cholecalciferols include:

• hydroxycholecalciferols
  • calcifediol (25-hydroxyvitamin D)
  • dihydroxycholecalciferols
    • calcitriol (1,25-dihydroxyvitamin D)
    • 24,25-dihydroxycholecalciferol

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“Hydroxycholecalciferols”  

Hydroxycholecalciferol

  In lipid science, Hydroxycholecalciferols are hydroxy analogs of cholecalciferols.
  Examples of hydroxycholecalciferols include:

• calcifediol (25-hydroxyvitamin D)
• dihydroxycholecalciferols
  • calcitriol (1,25-dihydroxyvitamin D)
  • 24,25-dihydroxycholecalciferol

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“25-hydroxyvitamin D (Calcifediol)”  

Calcifediol (25-hydroxyvitamin D)

  In our body, the Calcifediol (25-hydroxyvitamin D), (abbreviated 25(OH)D), as a major circulating metabolite of cholecalciferol (vitamin D₃) , is a prehormone produced in the liver by hydroxylation of liver by the enzyme cholecalciferol 25-hydroxylase.
  In our body, the Calcifediol is then converted in the kidneys (by the enzyme 25(OH)D-1α-hydroxylase) into calcitriol (1,25-(OH)₂D₃), a secosteroid hormone that is the active form of vitamin D. In our body, the Calcifediol can be converted into 24-hydroxycalcidiol in the kidneys via 24-hydroxylation. **

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“Dihydroxycholecalciferols”  

Dihydroxycholecalciferol (Dihydroxyvitamin D)

  Dihydroxycholecalciferol (Dihydroxyvitamin D) are cholecalciferol (vitamin D₃) substituted with two hydroxy groups in any position.
  As a form of cholecalciferols, Dihydroxycholecalciferols are hydroxycholecalciferols that specically refer to; calcitriol (1,25-dihydroxyvitamin D) and 24,25-Dihydroxyvitamin D 3.
  Examples of dihydroxycholecalciferols include:

• calcitriol (1,25-dihydroxyvitamin D)
• 24,25-dihydroxycholecalciferol

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“Calcitriol (1,25-dihydroxyvitamin D)”  

Calcitriol

  In our body, Calcitriol (1,25-dihydroxyvitamin D) is made from calcidiol (25-hydroxyvitamin D) in both the kidneys and monocyte-macrophages in the immune system.

  Calcitriol is the most physiologically active form of this potent steroid hormone, derived from cholecalciferol (vitamin D₃) in the body.
  In our body, Calcitriol when synthesized by monocyte-macrophages, calcitriol acts locally as a cytokine, defending the body against microbial invaders. **

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“24,25-Dihydroxyvitamin D 3 (24,25-Dihydroxycholecalciferol)”  

24,25-Dihydroxycholecalciferol

  In our body, 24,25-Dihydroxyvitamin D 3 is a physiologically active metabolite of vitamin D, formed from 25-hydroxyvitamin D3 by the action of P450cc24 encoded by the CYP24A1 gene for the (25-hydroxyvitamin D3-24-hydroxylase) involved in the regulation of calcium metabolism. **

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