Novel vitamin D photoproducts and their precursors in the skin.
Level 5 - mechanism / opinion, no new human data
Narrative review of bench chemical and biochemical characterization studies without clinical human data.
PubMed 24494038 · doi:10.4161/derm.23938
What was done
The authors reviewed the characterization of novel metabolic pathways initiated by CYP11A1 action on 7-dehydrocholesterol (7DHC), ergosterol, and vitamins D3 and D2, analyzed using chemical synthesis, ultraviolet spectroscopy, mass spectrometry, and nuclear magnetic resonance (NMR) techniques.
What was found
The abstract reports no quantitative numbers. CYP11A1 converted 7DHC sequentially to 22(OH)7DHC, 20,22(OH)27DHC, and 7-dehydropregnenolone, yielding 5,7-dienes that transform into active secosteroids under UVB exposure. CYP11A1 also hydroxylated vitamins D3 and D2 at positions C17, C20, C22, C23, and C24; the resulting derivatives were biologically active, non-toxic, non-calcemic at relatively high doses, and acted as partial agonists at the vitamin D receptor.
Why it matters
Identifying non-calcemic vitamin D derivatives expands therapeutic possibilities for hyperproliferative and inflammatory conditions, such as psoriasis and cancers, where standard vitamin D therapy is limited by hypercalcemia risks.
Limits
The abstract provides no quantitative experimental values, concentrations, or sample sizes. Evidence is entirely preclinical and biochemical, lacking in vivo pharmacokinetic and human clinical trial validation.
Cited by
- supports When UVB light strikes cholesterol in the skin, 15 to 20 other photoproduct chemicals are synthesized alongside vitamin D3.