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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/12/21 09:13:32」(JST)

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The epidermal strata of the skin.

7-Dehydrocholesterol is a zoosterol that functions in the serum as a cholesterol precursor, and is converted to vitamin D₃ in the skin, therefore functioning as provitamin-D₃. The presence of this compound in human skin enables humans to manufacture vitamin D₃ from ultraviolet rays in the sun light, via an intermediate isomer pre-vitamin D₃. It is also found in the milk of several mammalian species.^[1] In insects it is a precursor for the hormone ecdysone, required for reaching adulthood.^[2] It was discovered by Nobel-laureate organic chemist Adolf Windaus.

Location

The skin consists of two primary layers: an inner layer, the dermis, comprising largely connective tissue, and an outer, thinner epidermis. The thickness of the epidermis ranges from 0.08 mm to greater than 0.6 mm (from 0.003 to 0.024 inches).^[3] The epidermis comprises five strata; from outer to inner, they are the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. The highest concentrations of 7-dehydrocholesterol are found in the epidermal layer of skin—specifically in the stratum basale and stratum spinosum.^[4] The production of pre-vitamin D₃ is, therefore, greatest in these two layers.

Radiation

Synthesis of pre-vitamin D₃ in the skin involves UVB radiation, which effectively penetrates only the epidermal layers of skin. 7-Dehydrocholesterol absorbs UV light most effectively at wavelengths between 290 and 320 nm and, thus, the production of vitamin D₃ will occur primarily at those wavelengths. The two most important factors that govern the generation of pre-vitamin D₃ are the quantity (intensity) and quality (appropriate wavelength) of the UVB irradiation reaching the 7-dehydrocholesterol deep in the stratum basale and stratum spinosum.^[4] Another important consideration is the quantity of 7-dehydrocholesterol present in the skin. Under normal circumstances, ample quantities of 7-dehydrocholesterol (about 25–50 mg/cm² of skin) are available in the stratum spinosum and stratum basale of human skin to meet the body's vitamin D requirements.

Interactive pathway map

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

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|{{{bSize}}}px|alt=Vitamin D Synthesis Pathway edit|]]

File:VitaminDSynthesis WP1531.png

Vitamin D Synthesis Pathway edit

^ The interactive pathway map can be edited at WikiPathways: "VitaminDSynthesis_WP1531".

References

^ "7-dehydrocholesterol." The American Heritage Stedman's Medical Dictionary. Houghton Mifflin Company, 2002. 21 Jan. 2007. Answers.com.
^ Ed Yong (2012), Thanks to one gene, this fly needs a cactus to escape Neverland Not Exactly Rocket Science
^ Frediric Martini et al. (2006). Human Anatomy. Pearson/Benjamin-Cummings Publishers, p. 89. ISBN 0-8053-7211-3.
^ ^a ^b Norman, Anthony W. (1998) Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D:integral components of the vitamin D endocrine system. Am J Clin Nutr;67:1108–10.

English Journal

UV-irradiated 7-dehydrocholesterol coating on polystyrene surfaces is converted to active vitamin D by osteoblastic MC3T3-E1 cells.

Satué M, Córdoba A, Ramis JM, Monjo M.SourceDepartment of Fundamental Biology and Health Sciences, Research Institute on Health Sciences (IUNICS), University of Balearic Islands, Spain. marta.monjo@uib.es.
Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology.Photochem Photobiol Sci.2013 Jun 21;12(6):1025-35. doi: 10.1039/c3pp50025j. Epub 2013 Mar 28.
The aim of the present study was to determine the effects of UV irradiation on the conversion of 7-dehydrocholesterol (7-DHC), which has been coated onto a polystyrene surface, to cholecalciferol (D3), and the resulting effect on the formation of vitamin D (1,25-D3) by MC3T3-E1 cells. The changes in
PMID 23538933

The Sterol-C7 Desaturase from the Ciliate Tetrahymena thermophila Is a Rieske Oxygenase, Which Is Highly Conserved in Animals.

Najle SR, Nusblat AD, Nudel CB, Uttaro AD.SourceInstituto de Biología Molecular y Celular de Rosario, CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
Molecular biology and evolution.Mol Biol Evol.2013 May 15. [Epub ahead of print]
The ciliate Tetrahymena thermophila incorporates sterols from its environment that desaturates at positions C5(6), C7(8), and C22(23). Phytosterols are additionally modified by removal of the ethyl group at carbon 24 (C24). The enzymes involved are oxygen-, NAD(P)H-, and cytochrome b5 dependent, rea
PMID 23603937

Japanese Journal

Prevention of Prion Propagation by Dehydrocholesterol Reductase Inhibitors in Cultured Cells and a Therapeutic Trial in Mice(Biopharmacy)

HAGIWARA Ken'ichi,NAKAMURA Yuko,NISHIJIMA Masahiro,YAMAKAWA Yoshio
Biological & pharmaceutical bulletin 30(4), 835-838, 2007-04-01
… We here show that AY-9944 (a 7-dehydrocholesterol reductase inhibitor) and U18666A (a 24-dehydrocholesterol reductase inhibitor) prevent PrP^<Sc> …
NAID 110006271236

Stimulative Effects of (22E,24R)-Ergosta-7,22-diene-3β,5α,6β-triol from Fruiting Bodies of Tricholoma auratum, on a Mouse Osteoblastic Cell Line, MC3T3-E1

HATA Keishi,SUGAWARA Fuyuki,OHISA Naganori,TAKAHASHI Saori,HORI Kazuyuki
Biological & pharmaceutical bulletin 25(8), 1040-1044, 2002-08-01
… Physical data for the isolated active compound were identical to those for (22E,24R)-ergosta-7,22-diene-3β,5α,6β-triol (1). … To investigate the relationships between the chemical structure and differentiation-inducing activity of the compound, ALP-inducing activities of MC3T3-E1 cells by 1, ergosterol (2), ergocalciferol (3), cholesta-3β,5α,6β-triol (4), 7-dehydrocholesterol (5) and cholecalciferol (6) were tested. …
NAID 110003638871

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関連記事	「dehydrocholesterol」

「dehydrocholesterol」

7-Dehydrocholesterol
Identifiers
CAS number	434-16-2
PubChem	172
ChemSpider	388534
UNII	BK1IU07GKF
MeSH	7-dehydrocholesterol
ChEBI	CHEBI:17759
Jmol-3D images	Image 1
	SMILES O[C@@H]4C/C3=C/C=C1\[C@H](CC[C@]2([C@H]1CC[C@@H]2[C@H](C)CCCC(C)C)C)[C@@]3(C)CC4 ;
	InChI InChI=1S/C27H44O/c1-18(2)7-6-8-19(3)23-11-12-24-22-10-9-20-17-21(28)13-15-26(20,4)25(22)14-16-27(23,24)5/h9-10,18-19,21,23-25,28H,6-8,11-17H2,1-5H3/t19-,21+,23-,24+,25+,26+,27-/m1/s1-dehydrocholesterol ; Key: UCTLRSWJYQTBFZ-DDPQNLDTSA-N InChI=1/C27H44O/c1-18(2)7-6-8-19(3)23-11-12-24-22-10-9-20-17-21(28)13-15-26(20,4)25(22)14-16-27(23,24)5/h9-10,18-19,21,23-25,28H,6-8,11-17H2,1-5H3/t19-,21+,23-,24+,25+,26+,27-/m1/s1; Key: UCTLRSWJYQTBFZ-DDPQNLDTBZ ;
Properties
Molecular formula	C27H44O
Molar mass	384.638
	Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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	Infobox references

　　[★] デヒドロコレステロール

[WikiPathways-5] The interactive pathway map can be edited at WikiPathways: "VitaminDSynthesis_WP1531".

[1] "7-dehydrocholesterol." The American Heritage Stedman's Medical Dictionary. Houghton Mifflin Company, 2002. 21 Jan. 2007. Answers.com.

[2] Ed Yong (2012), Thanks to one gene, this fly needs a cactus to escape Neverland Not Exactly Rocket Science

[3] Frediric Martini et al. (2006). Human Anatomy. Pearson/Benjamin-Cummings Publishers, p. 89. ISBN 0-8053-7211-3.

[Norman-4] Norman, Anthony W. (1998) Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D:integral components of the vitamin D endocrine system. Am J Clin Nutr;67:1108–10.

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7-dehydrocholesterol