Previtamin D3 is an intermediate in the production of cholecalciferol (vitamin D3).

Previtamin D3
Stereo skeletal formula of previtamin D3 ((1R)-1-ol, (Z)-en, (1R,3aR,7aR)-7a-meth,-1-hept,-3a-hydro, (2R)-2-yl)
Names
IUPAC name
(3S,6Z)-9,10-Secocholesta-5(10),6,8-trien-3-ol
Systematic IUPAC name
(1S)-4-Methyl-3-[(Z)-2-{(1R,3aR,7aR)-7a-methyl-1-[(2R)-6-methylheptan-2-yl]-2,3,3a,6,7,7a-hexahydro-1H-inden-4-yl}ethen-1-yl]cyclohex-3-en-1-ol
Other names
Previtamin D3
Identifiers
3D model (JSmol)
ChemSpider
  • 78098 checkY
  • 4832524 (E)-en checkY
  • 9660762 (1S)-1-ol, (E)-en, (1R,7aR)-7a-meth,-1-hept, (2R)-2-yl checkY
  • 9375051 (1S)-1-ol, (Z)-en, (1R,7aR)-7a-meth,-1-hept, (2R)-2-yl checkY
ECHA InfoCard 100.013.304 Edit this at Wikidata
EC Number
  • 241-561-3
MeSH Previtamin+D(3)
  • 86590
  • 6178113 (E)-en
  • 25245851 (1S)-1-ol, (Z)-en, (2R)-2-yl
  • 11485943 (1S)-1-ol, (E)-en, (1R,7aR)-7a-meth,-1-hept, (2R)-2-yl
  • 11199982 (1S)-1-ol, (Z)-en, (1R,7aR)-7a-meth,-1-hept, (2R)-2-yl
UNII
  • InChI=1S/C27H44O/c1-19(2)8-6-9-21(4)25-15-16-26-22(10-7-17-27(25,26)5)12-13-23-18-24(28)14-11-20(23)3/h10,12-13,19,21,24-26,28H,6-9,11,14-18H2,1-5H3 checkY
    Key: YUGCAAVRZWBXEQ-UHFFFAOYSA-N checkY
  • CC(C)CCCC(C)C1CCC2C(C=CC3=C(C)CCC(O)C3)=CCCC12C
Properties
C27H44O
Molar mass 384.648 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

It is formed by the action of UV light, most specifically UVB light of wavelengths between 295 and 300 nm, acting on 7-dehydrocholesterol in the epidermal layers of the skin.[1][2][3]

The B ring of the steroid nucleus structure is broken open, making a secosteroid. This then undergoes spontaneous isomerization into cholecalciferol, the prohormone of the active form of vitamin D, calcitriol.

The synthesis of previtamin D3 is blocked effectively by sunscreens.[4]

Interactive pathway map

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Click on genes, proteins and metabolites below to link to respective articles. [§ 1]

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|alt=Vitamin D Synthesis Pathway (view / edit)]]
Vitamin D Synthesis Pathway (view / edit)
  1. ^ The interactive pathway map can be edited at WikiPathways: "VitaminDSynthesis_WP1531".

References

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  1. ^ MacLaughlin JA, Anderson RR, Holick MF (May 1982). "Spectral character of sunlight modulates photosynthesis of previtamin D3 and its photoisomers in human skin". Science. 216 (4549): 1001–3. Bibcode:1982Sci...216.1001M. doi:10.1126/science.6281884. PMID 6281884.
  2. ^ Webb AR (September 2006). "Who, what, where and when-influences on cutaneous vitamin D synthesis". Progress in Biophysics and Molecular Biology. 92 (1): 17–25. doi:10.1016/j.pbiomolbio.2006.02.004. PMID 16766240.
  3. ^ Pope SJ, Holick MF, Mackin S, Godar DE (2008). "Action spectrum conversion factors that change erythemally weighted to previtamin D3-weighted UV doses". Photochemistry and Photobiology. 84 (5): 1277–83. doi:10.1111/j.1751-1097.2008.00373.x. PMID 18513232. S2CID 23246616.
  4. ^ Sayre RM, Dowdy JC (2007). "Darkness at noon: sunscreens and vitamin D3". Photochemistry and Photobiology. 83 (2): 459–63. doi:10.1562/2006-06-29-RC-956. PMID 17115796. S2CID 23767593.