Cholesterol deuteration

The earliest attempts to prepare deuterated steroids were carried out by exchange reactions of aliphatic hydrogens with deuterium in the presence of a surface catalyst. Cholesterol, for example, has been treated with platinum in a mixture of deuterium oxide and acetic acid-OD, and was found to yield... 

The preparation of 7,7-d2-cholesterol in 1950 was the first example of deuterium incorporation into steroids via desulfurization of mercaptals with deuterated Raney nickel. A substantially modified version of this reaction subsequently became the first widely used method for site-specific insertion of two deuteriums in place of a carbonyl oxygen. This conversion consists of the preparation of a mercapto derivative (84 85), which usually... 

In 1933, Schoenheimer, who was medically qualified and had been working with Aschoff in the Pathology Institute in Freiburg, moved to Columbia University, New York, and was joined the next year by David Rittenberg. Rittenberg had just spent some time in Urey s laboratory in the Rockefeller Institute learning techniques for handling deuterium. Their first experiments concerned the metabolism of deuterated fatty acids in rats and the demonstration (see below) that 2H from heavy water was incorporated by the animals into fatty acids and cholesterol. 

Deuterium NMR studies of chain and headgroup deuterated phospholipid bilayers and phospholipid—cholesterol mixtures... 

An LC-MS method for quantification has been available for many years [79] using 13C2 cholesterol sulfate as an internal standard. The deuterated material is now commercially available (CDN or ISOTEC). Negative-ion ESI-MS is used for quantitation and m/z 365 (M-II, analyte) and 367 (M-H", internal standard) are monitored. The mean cholesterol sulfate level in 166 cases of RXLI was 4859 1589 pg/dl and for normal individuals 186 112 pg/dl (n = 109). 

Another example of selective deuteration in homogeneous solution is saturation of the sterically more accessible A5-double bond in ergosterol acetate (142 - 143).22 The a-configuration of the incorporated deuteriums is established from the NMR spectrum of the corresponding 22-dihydro derivative.21 The unconjugated C-5 double bond in cholesterol does not react under these conditions.22... 

A D20/lipid ratio of 2 1 (v w) led to easily handled samples and consistent spectroscopic results. Typically, 10 mg of specifically deuterated phospholipid and 20wl D2O were added to a culture tube, which was then sealed and incubated at 55°C for at least 1 hr, with periodic agitation to ensure complete dispersal and hydration. Similar procedures were followed for cholesterol and Gramicidin D-containing samples. Samples were placed between two AgCl windows, and sealed with a 6 pM, spacer. The assembly was wrapped with Teflon tape, as a further seal against dehydration, and inserted into a Harrick cell. Temperature was controlled to + 0.1 C with a Haake circulating water bath and monitored with a thermocouple placed as close as feasible to the point where the IR radiation was focused. 

The molecular mechanism of local anesthesia, the location of the local anesthetic dibucaine in model membranes, and the interaction of dibucaine with a Na+-channel inactivation gate peptide have been studied in detail by 2H- and 1H-NMR spectroscopy [24]. Model membranes consisted of PC, PS, and PE. Dibucaine was deuterated at H9 and H3 of the butoxy group and at the 3-position of the quinoline ring. 2H-NMR spectra of the multilamellar dispersions of the lipid mixtures were obtained. In addition, spectra of deuterated palmitic acids incorporated into mixtures containing cholesterol were obtained and the order parameter, SCD, for each carbon... 

Stockton, G. W. and Smith, I. C. P. (1976). A deuterium NMR smdy of the condensing effect of cholesterol on egg phosphatidylcholine bilayer membranes. 1. Per-deuterated fatty acid probes. Chem. Phys. Lipids 77 251. 

Figure 3.18 (a) Plot of RQ versus Q for a bilayer ofa 1.3 mixture of deuterated DMPC and cholesterol in 50mM NaF in H2O at = -800 mV. Points with associated error bars show the experimental data. Solid curve... 

A recent application [34] of deuterated hydroxyacids in NMR spectroscopy has been the study of lipid rafts in membranes. It is thought that sphingomielin and cholesterol are basilar for forming lipid rafts. 

The calculation of selectivity values showed that there was discrimination against the incorporation of the deuterated CLA isomers into TAG and CE and a preferential incorporation into PC and phosphatidyl ethanolamine (PE) relative to 9-18 1- /8 and 9, l2-18 2- Q. Comparison of selectivity values for the CLA isomers to r9, l2-18 2- 2 values and values previously reported for c- and r-18 1 positional isomers and 18 0 (17-22) showed that the incorporation of cS,t - and rlO,rl2-CLA matches the r-18 l isomers more than 18 0, 9-18 1, or 9, 12-18 2. This observation is an interesting anomaly since several positive health benefits have been reported for CLA (4), but tram fatty acids (TEA) are considered to have a negative effect on serum cholesterol. Epidemiological studies found a relationship between coronary heart disease risk and dietary intake of TEA from partially hydrated vegetable oils, which mainly contain the t9-, rlO-, and rl 1-18 1 isomers, but no such relationship was found for TEA intake from animal derived foods, whose major TEA isomer is t9-18 1 (vaccenic acid, VA) (19,23,24). 

Man Conversion of deuterated cholesterol to urinary pregnanediol in an 8 months pregnant woman (Bloch, 1945) conversion of tritiated and C-cholesterol to urinary tetrahydrocortisol in man (Werbin and LeRoy, 1954) conversion of blood cholesteroM- K] to cortisol in vivo indicating that about 80% of the latter is derived from blood cholesterol (Borkowski et al., 1967). Cow conversion of cholesterol-3- C to cortisol and corticosterone in the isolated perfused adrenal (Zaffaroni et al., 1951). Hog conversion of cholesteroW- C to cortisol and corticosterone in adrenal homogenates (Heard et al., 1956). 

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