7-Dehydrocholesterol: Difference between revisions
imported>OAbot m Open access bot: doi updated in citation with #oabot. |
imported>Fabvill Alter: last3, title. Add: bibcode, pmid, authors 1-1. Removed URL that duplicated identifier. Removed parameters. Some additions/deletions were parameter name changes. | Use this tool. Report bugs. | #UCB_Gadget |
||
| Line 45: | Line 45: | ||
==Location == | ==Location == | ||
The skin consists of two primary layers: an inner layer, the [[dermis]], comprising largely [[connective tissue]], and an outer, thinner [[Epidermis (skin)|epidermis]]. The thickness of the epidermis ranges from 0.04 mm to greater than 0.6 mm.<ref>{{Cite journal | | The skin consists of two primary layers: an inner layer, the [[dermis]], comprising largely [[connective tissue]], and an outer, thinner [[Epidermis (skin)|epidermis]]. The thickness of the epidermis ranges from 0.04 mm to greater than 0.6 mm.<ref>{{Cite journal |last1=Lintzeri |first1=D.A. |last2=Karimian |first2=N. |last3=Blume-Peytavi |first3=U. |last4=Kottner |first4=J. |date=2022 |title=Epidermal thickness in healthy humans: a systematic review and meta-analysis |journal=Journal of the European Academy of Dermatology and Venereology |language=en |volume=36 |issue=8 |pages=1191–1200 |doi=10.1111/jdv.18123 |issn=0926-9959|doi-access=free |pmid=35366353 }}</ref> 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.<ref name="Norman_1998">{{cite journal | vauthors = Norman AW | title = Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D: integral components of the vitamin D endocrine system | journal = The American Journal of Clinical Nutrition | volume = 67 | issue = 6 | pages = 1108–1110 | date = June 1998 | pmid = 9625080 | doi = 10.1093/ajcn/67.6.1108 | doi-access = free }}</ref> The production of pre-vitamin D<sub>3</sub> is, therefore, greatest in these two layers. | ||
==Radiation== | ==Radiation== | ||
| Line 53: | Line 53: | ||
== Sources == | == Sources == | ||
7-DHC can be produced by animals and plants via different pathways. It is not produced by fungi in significant amounts. It is made by some [[algae]], but the pathway is poorly understood.<ref>{{cite journal | vauthors = Jäpelt RB, Jakobsen J | title = Vitamin D in plants: a review of occurrence, analysis, and biosynthesis | journal = Frontiers in Plant Science | volume = 4 | pages = 136 | date = 2013 | pmid = 23717318 | pmc = 3651966 | doi = 10.3389/fpls.2013.00136 | doi-access = free}}</ref> | 7-DHC can be produced by animals and plants via different pathways. It is not produced by fungi in significant amounts. It is made by some [[algae]], but the pathway is poorly understood.<ref>{{cite journal | vauthors = Jäpelt RB, Jakobsen J | title = Vitamin D in plants: a review of occurrence, analysis, and biosynthesis | journal = Frontiers in Plant Science | volume = 4 | pages = 136 | date = 2013 | pmid = 23717318 | pmc = 3651966 | doi = 10.3389/fpls.2013.00136 | doi-access = free| bibcode = 2013FrPS....4..136J }}</ref> | ||
Industrially, 7-DHC generally comes from [[lanolin]], and is used to produce vitamin D3 by UV exposure.<ref name="Holick05">{{cite journal | vauthors = Holick MF | title = The vitamin D epidemic and its health consequences | journal = The Journal of Nutrition | volume = 135 | issue = 11 | pages = 2739S–2748S | date = November 2005 | pmid = 16251641 | doi = 10.1093/jn/135.11.2739S | quote = [Vitamin D3] is produced commercially by extracting 7-dehydrocholesterol from wool fat, followed by UVB irradiation and purification [...] [Vitamin D2] is commercially made by irradiating and then purifying the ergosterol extracted from yeast | doi-access = free }}</ref> [[Lichen]] ([[Cladonia rangiferina]]) is used to produce [[vegan]] D3.<ref>{{cite web |title=Vitamin D |url=https://www.vegansociety.com/resources/nutrition-and-health/nutrients/vitamin-d |website=The Vegan Society |language=en}}</ref><ref>{{cite journal |last1=Gangwar |first1=Gourvendra |title=Formulation of Lichen Based Pill a Natural Source of Vitamin D3 with a High Absorption Rate by Ambrosiya Neo-Medicine Pvt. Ltd |journal=International Journal of Biomedical Investigation |date=1 July 2023 |page=1 |url=https://openj.edwiserinternational.com/index.php/ijbi/article/download/102/101}}</ref> | Industrially, 7-DHC generally comes from [[lanolin]], and is used to produce vitamin D3 by UV exposure.<ref name="Holick05">{{cite journal | vauthors = Holick MF | title = The vitamin D epidemic and its health consequences | journal = The Journal of Nutrition | volume = 135 | issue = 11 | pages = 2739S–2748S | date = November 2005 | pmid = 16251641 | doi = 10.1093/jn/135.11.2739S | quote = [Vitamin D3] is produced commercially by extracting 7-dehydrocholesterol from wool fat, followed by UVB irradiation and purification [...] [Vitamin D2] is commercially made by irradiating and then purifying the ergosterol extracted from yeast | doi-access = free }}</ref> [[Lichen]] ([[Cladonia rangiferina]]) is used to produce [[vegan]] D3.<ref>{{cite web |title=Vitamin D |url=https://www.vegansociety.com/resources/nutrition-and-health/nutrients/vitamin-d |website=The Vegan Society |language=en}}</ref><ref>{{cite journal |last1=Gangwar |first1=Gourvendra |title=Formulation of Lichen Based Pill a Natural Source of Vitamin D3 with a High Absorption Rate by Ambrosiya Neo-Medicine Pvt. Ltd |journal=International Journal of Biomedical Investigation |date=1 July 2023 |page=1 |url=https://openj.edwiserinternational.com/index.php/ijbi/article/download/102/101}}</ref> | ||
Revision as of 13:46, 23 June 2025
Script error: No such module "redirect hatnote". Template:Chembox
7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically 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 (cholecalciferol). Upon exposure to ultraviolet UV-B rays in the sun light, 7-DHC is converted into vitamin D3 via previtamin D3 as an intermediate isomer. It is also found in the milk of several mammalian species.[1][2] Lanolin, a waxy substance that is naturally secreted by wool-bearing mammals, contains 7-DHC which is converted into vitamin D by sunlight and then ingested during grooming as a nutrient. In insects 7-dehydrocholesterol is a precursor for the hormone ecdysone, required for reaching adulthood.[3] 7-DHC was discovered by Nobel-laureate organic chemist Adolf Windaus.
Biosynthesis
It is synthesized from lathosterol by the enzyme lathosterol oxidase (lathosterol 5-desaturase). This is the next-to-last step of cholesterol biosynthesis.[4] Defective synthesis results in the human inherited disorder lathosterolosis resembling Smith–Lemli–Opitz syndrome.[4] Mice where this gene has been deleted lose the ability to increase vitamin D3 in the blood following UV exposure of the skin.[5]
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 0.04 mm to greater than 0.6 mm.[6] 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.[7] 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 295 and 300 nm and, thus, the production of vitamin D3 will occur primarily at those wavelengths.[8] 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.[7] Light-emitting diodes (LEDs) can be used to produce the radiation.[9]
Another important consideration is the quantity of 7-dehydrocholesterol present in the skin. Under normal circumstances, ample quantities of 7-dehydrocholesterol (about 25–50 μg/cm2 of skin) are available in the stratum spinosum and stratum basale of human skin to meet the body's vitamin D requirements. 7-DHC insufficiency has been proposed as an alternate cause for Vitamin D deficiency.[10]
Sources
7-DHC can be produced by animals and plants via different pathways. It is not produced by fungi in significant amounts. It is made by some algae, but the pathway is poorly understood.[11]
Industrially, 7-DHC generally comes from lanolin, and is used to produce vitamin D3 by UV exposure.[12] Lichen (Cladonia rangiferina) is used to produce vegan D3.[13][14]
7-DHC is used for vitamin D3 synthesis via lanosterol in land animals, via cycloartenol in plants, and in algae together with another provitamin D ergosterol for D2. In fungi solely ergosterol is used for synthesis of D2 via lanosterol.[15]
Interactive pathway map
Template:VitaminDSynthesis WP1531
See also
References
Template:Vitamin Template:Cholesterol metabolism intermediates Template:Vitamin D receptor modulators
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".