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7/!-Hydroxycholesterol

The preparation of estranes via 19-hydroxy steroids has also been accompHshed microbially. 19-Hydroxycholesterol, prepared chemically (39), is incubated with JS icardia restrictus to provide estrone (20) direcdy (44). Similarly, 19-hydroxyandrost-4-en-3,17-dione is converted to estrone (20) (45). [Pg.210]

Koldamova, RP, Lefterov, IM, Ikonomovic, MD, Skoko, J, Lefterov, PI, Isanski, BA, DeKosky, ST, and Lazo, JS, 2003. 22R-hydroxycholesterol and 9-cw-retinoic acid induce ATP-binding cassette transporter A1 expression and cholesterol efflux in brain cells and decrease amyloid beta secretion. J Biol Chem 278, 13244-13256. [Pg.346]

Cholesterol transport and regulation in the central nervous system is distinct from that of peripheral tissues. Blood-borne cholesterol is excluded from the CNS by the blood-brain barrier. Neurons express a form of cytochrome P-450, 46A, that oxidizes cholesterol to 24(S)-hydroxycholesterol [11] and may oxidize it further to 24,25 and 24,27-dihydroxy products [12]. In other tissues hydroxylation of the alkyl side chain of cholesterol at C22 or C27 is known to produce products that diffuse out of cells into the plasma circulation. Although the rate of cholesterol turnover in mature brain is relatively low, 24-hydroxylation may be a principal efflux path to the liver because it is not further oxidized in the CNS [10]. [Pg.26]

The toxic effect of 7-oxysterols, 25- and 27-hydroxycholesterols and their involvement in LDL cytotoxicity have been extensively studied on the different vascular cell types (Lizard et al, 1999 Aupeix et al, 1995 Clare et al, 1995 Ramasamy et al, 1992). 7a and 7p-hydroxycholesterols, 7-ketocholesterol, 25 and 27-hydroxycholesterol induce apoptosis (Brown and Jessup, 1999 Lizard et al, 1999, 1998 Zhang et al, 1997 Hughes et al, 1994). 7p-hydroperoxycholesterol is one of the most toxic Oxysterols present in oxidized LDL (Brown and Jessup, 1999 Colles et al, 1996). 25-hydroxycholesterol, though less active (Aupeix et al 1995), is able to trigger a cytochrome c release and subsequent caspase activation in CHO cells, but also calcium inaease in relation with apoptosis (Rusinol et al, 2000). [Pg.130]

Ares, M.P., Pom-Ares, MI, Moses, S, Thyberg, J, Jrmtti-Berggren, L, Beiggien, P, Hultgardh-Nilsson, A, Kallin, B, Nilsson, J., 2000, Tbeta-hydroxycholesterol induces Ca(2-l-) oscillations, MAPK activation and apoptosis in human aortic smooth muscle cells, Atherosclerosis 153 2 3-35. [Pg.141]

Hughes, H., Mathews, B., Lenz, M.L., and Guyton, J.R., 1994, Cytotoxicity of oxidized LDL to porcine aortic smooth muscle cells is associated with the oxysterols 7-ketocholesterol and 7-hydroxycholesterol, Arteriosc/er. Thromb. 14 1177- 1185. [Pg.145]

Lizard, G., Monier, S., Cordelet, C., Gesquiere, L., Deckert, V., Gueldry, S., Lagrost, L., and Gambert, P., 1999, Characterization and comparison of the mode ofceU death, apoptosis versus necrosis, induced by 7beta-hydroxycholesterol and 7-ketocholesterol in the cells of the vascular wall, Arten oicZer. Thromb. Vase. Biol. 19 1190-1200. [Pg.146]

Bodin K, Andersson U, Rystedt E, Ellis E, Norlin M, et al. 2002. Metabolism of 4 beta -hydroxycholesterol in humans. J Biol Chem 277 31534-31540. [Pg.81]

Li-Hawkins J, Lund EG, Bronson AD, RusseU DW. 2000. Expression cloning of an oxysterol 7alpha-hydroxylase selective for 24-hydroxycholesterol. J Biol Chem 275 16543-16549. [Pg.86]

Martin C, Bean R, Rose K, Habib F, Seek J. 2001. cyp7bl catalyses the 7alpha-hydroxylation ofdehydroepiandroster-one and 25-hydroxycholesterol in rat prostate. Biochem J... [Pg.86]

Payne DW, Shackleton C, Toms H, Ben-Shlomo I, Kol S, et al. 1995. A novel nonhepatic hydroxycholesterol 7 alpha-hydroxylase that is markedly stimulated by interleukin-1 beta. Characterization in the immature rat ovary. J Biol... [Pg.88]

Another pathway of some importance occurs in the brain this is the cholesterol 24-hydroxylase pathway. About 25% of the body s cholesterol exists in the plasma membranes of myelin sheaths. Here, the blood-brain barrier prevents cholesterol exchanges with the circulating lipoproteins, which makes it difficult for cholesterol to leave the brain. The cytochrome P-450 enzymes (CYP 46), expressed almost exclusively in the endoplasmic reticula of the brain, allows formation of 24-hydroxycholesterol. [Pg.4]

Other precursors of alkaloids form intermedia as acids (e.g., capric acid in the coniine pathway, 26-hydroxycholesterol in the solasodine pathway and piperidine in the jervine pathway). Moreover, in the case of purine as an alkaloid precursor, the intermedia is inosine monophosphate (IMP). [Pg.93]

A full account of the syntheses of the four isomeric 20,22-epoxycholesterols is accompanied by two similar reports. Pregnenolone has been converted by two independent routes into 25-oxo-27-norcholesteryl acetate. Both routes employed the highly stereoselective platinium-catalysed hydrogenation of the 20,22-double bond which in one case was shown to have the E-configuration. Three additional syntheses of 25-hydroxycholesterol have been reported. The 6/3-methoxy-3a,5a-cyclo-20-carboxaldehyde (261), derived from stig-masterol, was converted into the diene (262) " or the dichloro-olefin (263) and thence into 25-hydroxycholesterol as indicated in Scheme 10. Alternatively the side-chain of the bromo-derivative (264) was extended as indicated in Scheme 2 2 186... [Pg.266]

In contrast to these results, 25-hydroxycholesterol (and also, 20-hy-droxycholesterol, 7-ketocholesterol, and diosgenin) in aortic, smooth-muscle cells effectively blocks the incorporation of acetate into lipid-linked oligosaccharides (and, also, into cholesterol7). Thus, less of the lipid-linked oligosaccharides were available for glycosylation of proteins. In harmony with the presumed, inhibitory mechanism was the observation that incorporation of mevalonate into lipid-linked oligosaccharides was not inhibited, and that mevalonate itself (the product formed by HMG-CoA reductase from HMG-CoA and NADPH) could reverse the inhibition of glycosylation of protein (see Scheme 1). [Pg.324]

In 3/i-hydroxysteroid-A5-oxidoreductase deficiency, 7a-hydroxycholesterol undergoes side-chain oxidation, producing 3/l,7a-dihydroxy-5-cholenoic acid and... [Pg.610]

This stereospecific rearrangement is a key step in a synthesis of optically active 26-hydroxycholesterol and 25,28-dihydroxy-7,8-dihydroergosterol. [Pg.151]

Formation of 7-hydroxycholesterol. The committed and rate-limiting reaction for bile acid synthesis is catalyzed by the endoplasmic reticulum enzyme 7c -hydroxylase. [Pg.473]

Purification of cholesterol through the dibromide completely eliminates cholestanol, 7-dehydrocholesterol, and latho-sterol (A7-cholestenol). The first crop of material from methanol-ether is also free from cerebrosterol (24-hydroxycholesterol) and 25-hydroxycholesterol, a product of autoxidation present in cholesterol that has been stored in the crystalline state for a few years with access to air. When material of highest purity is desired, only first-crop dibromide should be employed, since de-bromination of second-crop material gives sterol melting at 146-147° and giving a positive Beilstein test. [Pg.48]


See other pages where 7/!-Hydroxycholesterol is mentioned: [Pg.542]    [Pg.847]    [Pg.924]    [Pg.317]    [Pg.787]    [Pg.2281]    [Pg.2394]    [Pg.172]    [Pg.756]    [Pg.758]    [Pg.328]    [Pg.329]    [Pg.130]    [Pg.142]    [Pg.150]    [Pg.53]    [Pg.297]    [Pg.298]    [Pg.265]    [Pg.310]    [Pg.4]    [Pg.265]    [Pg.348]    [Pg.757]    [Pg.759]    [Pg.490]    [Pg.475]    [Pg.476]   
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20a-Hydroxycholesterol

24- Hydroxycholesterol 7-hydroxylation

24S-Hydroxycholesterol

24S-Hydroxycholesterol (cerebrosterol

25-Hydroxycholesterol cytotoxicity effect

25-Hydroxycholesterols

25-Hydroxycholesterols

25-Hydroxycholesterols acetate

7a-Hydroxycholesterol

7p-hydroxycholesterol

La-Hydroxycholesterol

Steroid 20-hydroxycholesterol

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