56196-40-8Relevant academic research and scientific papers
Inhibition of the conversion of cholesterol to pregnenolone in bovine adrenocortical preparations
Burstein,Letourneux,Kimball,Gut
, p. 361 - 382 (1976)
The inhibition of the conversion of [4 14C] cholesterol to [4 14C]pregnenolone by a number of steroids has been studied in bovine adrenocortical mitochondrial acetone dried preparations. At equimolar substrate and inhibitor concentrations (3.3 μM) the most potent inhibitors were cholesterol derivatives containing a nitrogen function at C 22, followed by derivatives containing oxygen function at C 22 or C 20 or both. The presence of a hydroxyl group at C 17 or the replacement of the 3β hydroxyl group by fluorine reduced the inhibitory efficacy. In the presence of inhibitors that were also relatively good substrates of the cholesterol side chain cleavage system, such as some cholesterol derivatives hydroxylated in the side chain, the rate of [4 14C]pregnenolone formation increased with time as the inhibitor was consumed. (20S) 20,21 Dihydroxycholesterol exerted such an effect on the kinetics of [4 14C]pregnenolone formation, and yielded 21 hydroxypregnenolone which was identified by gas chromatography mass spectrometry. The synthesis of (20R) 22 ketocholesterol, of (20R, 22R) 22 hydroxycholesterol, (20R, 22S) hydroxycholesterol, and of (20S) desmosterol is described.
Steroids excreted in urine by neonates with 21-hydroxylase deficiency: Characterization, using GC-MS and GC-MS/MS, of the D-ring and side chain structure of pregnanes and pregnenes
Christakoudi, Sofia,Cowan, David A.,Taylor, Norman F.
experimental part, p. 34 - 52 (2010/09/20)
Steroid metabolites in urine from neonates with 21-hydroxylase deficiency are predominantly polyhydroxylated 17-hydroxyprogesterone and androgen metabolites, and most have incompletely defined structure. This study forms part of a comprehensive project to characterize and identify these in order to enhance diagnosis and to further elucidate neonatal types of steroid metabolism. Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra, obtained with constant excitation conditions, were used together to determine the structure of the D-ring and the side chain of 20-oxo and 20-hydroxy pregnane(ene)s without oxo groups on the A-, B-, and C-ring. All possible combinations of D-ring and side chain configuration were considered. Most fragmentations could be interpreted as partial or complete D-ring cleavages with loss of the side chain, aided by comparison with spectra of deuterated derivatives and of borohydride reduced metabolites. Possible rearrangement ions are also discussed. More than 140 endogenous metabolites were characterized. GC-MS/MS was especially beneficial for characterization of compounds with 16,17-dihydroxy-20-oxo structure, interpreted as markers of intra-uterine enzyme induction. It also assisted the differentiation of 16-hydroxy-20-oxo metabolites, present in urine of non-affected neonates, from the diagnostic 17-hydroxy-20-oxosteroids and enabled the detection of 15,17-dihydroxy-20-oxo compounds in low concentrations. The presence of 17,21-dihydroxylated pregnane(ene)s despite the deficit in CYP21A2 is discussed. We conclude that GC-MS combined with GC-MS/MS allows reliable identification of the structure of the D-ring and side chain of pregnane(ene)s without prior isolation, even when in low concentrations in urine.
