7-dehydrocholesterol Research Articles

Enzymatic stereospecificity in the conversion of Δ 7-cholesten-3β-OL to 7-dehydrocholesterol

Enzymatic stereospecificity in the conversion of Δ 7-cholesten-3β-OL to 7-dehydrocholesterol

Steroid requirements of trichomonads.

SYNOPSIS. The steroid requirement of a Trypticase‐requiring strain, SLT, of Trichomonas gallinae on the Shorb‐Lund synthetic basal medium minus ribonucleic acid was fulfilled by cholesterol, 7‐dehydrocholesterol(provitamin D3), cholestanol (dihydrocholesterol), and to a lesser degree, by ergosterol (provitamin D2), β‐sitosterol and zymosterol acetate. Cholestanol was inhibitory at certain concentrations. All steroids were subsequently checked by gas chromatography. Only cholesterol and zymosterol acetate showed one peak, the others containing 2 to 4 peaks. Repurified cholestanol was active and showed no inhibition of growth, but repurified β‐sitosterol was inactive. The following were also inactive: diethylstilbestrol, estrone, dehydroepiandrosterone, progesterone, testosterone, desoxycorticosterone acetate, cortisone acetate, compound A, 5,6‐dihydro‐ergosterol, dihydroergosterol acetate, stigmasterol, sodium taurocholate, cholic acid, methyl desoxycholate, desoxycholic acid and methyl cholate. Precursors in cholesterol synthesis, acetate, mevalonic acid, mevalonic acid plus a liver extract and squalene were inactive in replacing cholesterol, although acetate is required for growth in the presence of cholesterol. Crystalline fat soluble vitamins, carotene, calciferol (vitamin D2), activated 7‐dehydrocholesterol (vitamin D3), menadione (vitamin K3) and tocopheryl acetate (vitamin E acetate) were inactive in replacing cholesterol.Trichomonas species PN from the pig's nose utilized cholesterol, 7‐dehydrocholesterol and the impure β‐sitosterol sample in a modified SL medium with acetate omitted. A reinvestigation of steroid requirements seems to be indicated when a completely synthetic medium and pure steroids are available.

Provitamin D3 in tissues and the conversion of cholesterol to 7-dehydrocholesterol in vivo.

Research Article| April 01 1952 Provitamin D3 in tissues and the conversion of cholesterol to 7-dehydrocholesterol in vivo Mary Glover; Mary Glover 1Department of Biochemistry, The University of Liverpool Search for other works by this author on: This Site PubMed Google Scholar J. Glover; J. Glover 1Department of Biochemistry, The University of Liverpool Search for other works by this author on: This Site PubMed Google Scholar R. A. Morton R. A. Morton 1Department of Biochemistry, The University of Liverpool Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1952) 51 (1): 1–9. https://doi.org/10.1042/bj0510001 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share MailTo Twitter LinkedIn Cite Icon Cite Get Permissions Citation Mary Glover, J. Glover, R. A. Morton; Provitamin D3 in tissues and the conversion of cholesterol to 7-dehydrocholesterol in vivo. Biochem J 1 April 1952; 51 (1): 1–9. doi: https://doi.org/10.1042/bj0510001 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1952 CAMBRIDGE UNIVERSITY PRESS1952 Article PDF first page preview Close Modal You do not currently have access to this content.

Investigations on sterols. V. Thio‐derivatives of provitamins D

AbstractA description is given of the synthesis of the thio‐analogues of ergosterol and 7‐dehydrocholesterol from these two compounds.

Compounds related to provitamin D3 (II). The sulphur analogue of provitamin D3

AbstractThe preparation of the sulphur analogue of provitamin D3 is described. Bromination of S‐acetyl‐cholestene‐5‐thiol‐3, followed by elimination of hydrogen bromide, did not give good results.The synthesis has been realised by applying these reactions to cholesteryl rhodanide; 7‐dehydrocholesteryl rhodanide so obtained submitted to selective reduction by means of LiAlH4 afforded cholestadiene‐5,7‐thiol‐3.Bis‐(7‐dehydrocholesteryl‐3)‐disulphide, which may be prepared from 7‐dehydrocholesteryl rhodanide, could also be reduced by means of LiAlH4 to the same sulphur analogue of provitamin D3.

Conversion of Cholesterol to Provitamin D3 in vivo

THERE is now evidence in the literature that steroid hormones1 and bile acids2 are formed from cholesterol. A similar origin for provitamin D3 (7-dehydrocholesterol) in the animal body, certainly of Herbivora, is now accepted; but there is little or no conclusive evidence as to the site or mode of formation of the provitamin. The part of the body richest in 7-dehydrocholesterol is generally thought to be the skin3. Recently, however, we have detected a sterol showing the ultra-violet absorption (max. 271·5 mμ, 281·5 mμ and 292 mμ inflexion 260–265 mμ and min. 276 mμ) characteristic of the provitamins D, and thought to be provitamin D3, in the lining of the small intestine of the guinea pig, rat and ox. It is most concentrated in the duodenum and is associated largely with the mucosa and lamina propria. In the guinea pig, the concentration of the '7-dehydrocholesterol' in the non-saponifiable matter of the whole of the small intestine is c. 3·6 per cent and is very much greater than the 0·5 per cent observed in the skin; whereas in the rat both organs contain about 0·5 per cent.

Investigations on sterols.): IV. The configuration of the junction between rings C and D in cholesterol

AbstractThe ketone C18H32O, obtained by the oxidation of vitamin‐D3 and which still contains the rings C and D of the original sterol, appears to be readily converted into an isomer and the same holds for its semicarbazone. This isomerisation is to be explained by the conversion of the trans‐hydrindane into the cis‐hydrindane configuration. From this it is concluded that the junction between the rings C and D in vitamin‐D3, 7‐dehydrocholesterol and cholesterol very probably has the trans‐configuration.

Studies in the sterol group; a new route to 7-dehydrocholesterol (provitamin D3) and its derivatives.

Studies in the sterol group; a new route to 7-dehydrocholesterol (provitamin D3) and its derivatives.

Investigations on sterols: I. A new synthesis of 7‐dehydrocholesterol (provitamin D)

AbstractA new synthesis of 7‐dehydrocholesterol (provitamin D3) from cholesterol is described, which gives a higher yield than the well known Windaus synthesis. The synthesis is carried out via a 7‐bromocholesteryl ester, from which hydrogen bromide is eliminated to give an ester of 7‐dehydrocholesterol.Careful hydrolysis of the impure 7‐bromocholesteryl benzoate affords either 7‐α‐ or 7‐β‐hydroxycholesteryl‐3 benzoate depending on the reagent. The two epimeric 7‐bromocholesteryl benzoates are prepared from the hydroxy‐compounds by interaction with phosphorus tribromide; the two hydroxy‐compounds are regenerated by hydrolysis.

A New Route to 7-Dehydrocholesterol, Provitamin D3

IN 1935, Windaus, Lettre and Schenck1 described the preparation from cholesterol (I) of 7-dehydrocholesterol (III), which on irradiation gave a highly antirachitic product (vitamin D3), later2 shown to be identical with the naturally occurring vitamin D isolated from tunny liver oil. The original route to provitamin D3, giving an overall conversion from cholesterol of about 4 per cent, has since been employed for the synthesis of several related dehydrosteroids3, but it has not been materially improved, although some useful minor modifications have been described4. Claims5 have been made for alternative and improved methods, but, so far as we are aware, none of these has proved entirely satisfactory.

Activation of Pro-Vitamin D3 in the Rat

The experiments of Boer et al.,1 who isolated 7-dehydro-cholesterol from cholesterol of animal origin were followed by the discoveries of Brockman, Drummond, Simons et al.,234 who identified activated 7-dehydrocholesterol as the main constituent of the natural Vitamin D in fish liver oils, indicating that the Vitamin D found in the animal organism is Vitamin D3 in contra-distinction to Vitamin D2 which is formed by activation of ergosterol.In view of the ability of the animal organism to form biologically highly active sterol derivatives of a hormone nature, it was considered of importance to determine whether the animal organism, per se, possesses the means of transforming cholesterol or cholesterol-derivatives into Vitamin D3. Several of these compounds are now being investigated, namely, 7-keto-cholesterol, 7-hydroxy-cholesterol and 7-dehydro-cholesterol. This report concerns the fate of 7-dehydro-cholesterol in the rat.A sample of 7-dehydro-cholesterol was prepared from cholesterol by the method of Wi...