前维生素D3

維生素D₃原（又稱：前維生素D₃，英語：Previtamin D₃）是膽鈣化醇（維生素D₃）合成的中間產物，由皮膚表皮中的7-脫氫膽固醇在紫外線（主要是295nm - 300nm 的UV-B）照射下開環生成^[1][2][3][4]。

Previtamin D3
IUPAC名 Previtamin D3
識別
CAS號	1173-13-3  Y 17592-07-3  Y
PubChem	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）
ChemSpider	78098, 4832524 (E)-en, 9660762 (1S)-1-ol, (E)-en, (1R,7aR)-7a-meth,-1-hept, (2R)-2-yl, 9375051 (1S)-1-ol, (Z)-en, (1R,7aR)-7a-meth,-1-hept, (2R)-2-yl
SMILES	CC(C)CCCC(C)C1CCC2C(C=CC3=C(C)CCC(O)C3)=CCCC12C
EINECS	241-561-3
MeSH	Previtamin+D(3)
性質
化學式	C27H44O
摩爾質量	384.64 g·mol−1
若非註明，所有數據均出自標準狀態（25 ℃，100 kPa）下。

參考文獻

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