3/?-Hydroxysteroid

Cortisol-Cortisone Conversion. Under normal conditions, this equilibrium slightly favors the oxidized compound. Similarly, the conversion of corticosterone to 11-deoxycorticosterone is also mediated by the liP-hydroxysteroid dehydrogenase enzyme system and requites NAD(P) /NAD(P)H. This conversion is especially important both in the protection of the human fetus from excessive glucocorticoid exposure, and in the protection of distal nephron mineral ocorticoid receptors from glucocorticoid exposure (14). The impairment of this conversion is thought to result in hypertension associated with renal insufficiency (15). 

A.- ng deduction. This is an irreversible reaction which is a foremost determinant of the secretion rate of cortisol (double bonds and C-3 carbonyl). Catalyzed predominantiy by cortisone P-reductase and 3a-hydroxysteroid dehydrogenases, SP sterols result, although 5a sterols are more prevalent in the case of other glucocorticoids. Urocortisol and urocortisone result from the metabohsm of cortisol and cortisone, respectively. Compounds can be complexed to glucuronic acid at this point. 

C-20 deduction. Two stereoisomers can result from this transformation, although cortisol is thought to act primarily with (R)20P-hydroxysteroid dehydrogenase. This is a first step in the metabohsm of corticosterone. 

Dehydration to olefins, which sometimes accompanies the reaction of alcohols with DAST [95, 108], is seldom as extensive as with a-fluoroamines (FAR and 1,1,2,3,3,3 hexafluoropropyldiethylamine) but occurs in a few cases to the exclusion of fluonnation, thus, 9a-fluoro-11-hydroxysteroids give 9a fluoro-A -steroids [127, 128] Dehydration accompanied by Wagner-Meerwein rearrangement occurs during the fluonnation of testosterone [129] Intermolecular dehydration to form ethers in addition to fluorides is observed in the reaction of benzhydryl alcohols [104] (Table 6)... 

Testosterone, the principal male sex steroid hormone, is synthesized in five steps from cholesterol, as shown below. In the last step, five isozymes catalyze the 17/3-hydroxysteroid dehydrogenase reactions that interconvert 4-androstenedione and testosterone. Defects in the synthesis or action of testosterone can impair the development of the male phenotype during embryogenesis and cause the disorders of human sexuality termed male pseudohermaphroditism. Specifically, mutations in isozyme 3 of the 17/3-hydroxysteroid dehydrogenase in the fetal testis impair the for-... 

Another version of the double [2,3]-sigmatropic rearrangement, involving the sequence sulfenate - sulfoxide - sulfenate, has also been observed. For example, an effective one-pot epimerization procedure of 17a-vinyl-l 7/i-hydroxysteroids to the rather inaccessible 17-epimers has been achieved by the use of such a rearrangement (equation 35)137. Thus treatment of alcohol 76a with benzenesulfenyl chloride afforded the sulfoxide 77 as a single isomer and E-geometry of the olefinic double bond. Exposure of 77 to trimethyl phosphite in refluxing methanol produced a mixture of 76b and 76a in a 73 27 ratio. 

Van t Hoff t-factors 565 Vinylallenes rearrangement of 748 synthesis of 737 Vinyl carbonium ions 620 17a-Vinyl-17/f-hydroxysteroids, epimerization of 735 Vinyl sulphides, as alkyl sulphoxide reduction products 930, 932 Vinyl sulphones - see also Alkenyl... 

An impressive indication of the high regioselectivity of hydroxysteroid dehydrogenases (HSHDs) was reported for the oxidation of various hydroxyl groups at the steroid core ofbile acids [26] (Scheme 9.1). The hydroxy-substituents at positions 3, 7, and 12 could be selectively addressed depending on the hydroxysteroid... 

CLIP Corticotropin-hke intermediate lobe peptide OHSD Hydroxysteroid dehydrogenase PNMT Phenylethanolamine-W-methyltransferase ... 

The 17P-hydroxysteroid oxidoreductase enzymes (HSOR) occur as two distinct isoforms (I and II). They are involved in the conversion of estrone to estradiol. The type I enzyme converts estrone to estradiol (also androstenedione to testosterone) and the type II catalyses the reverse reaction. Phytoestrogens have been shown to inhibit both HSOR enzymes in vitro. 

Lanthier A. and Patwardhan V.V. (1987). Effect of heterosexual olfactory and visual stimulation on 5a-en-3P hydroxysteroids and progesterone in the male rat brain. J Steroid Biochem 28, 697-701. 

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