A novel radioimmunoassay of 7-oxo-DHEA and its physiological levels.

A novel radioimmunoassay (RIA) of unconjugated 7-oxo-dehydroepiandrosterone (7-oxo-DHEA) in human serum was developed for the first time. This steroid is an intermediate in the biosynthesis of immunomodulatory 7-hydroxylated DHEA metabolites, and has been shown to possess thermogenic properties. The method employs polyclonal rabbit antiserum to (19E)-3beta-hydroxy-7,17,19-trione-19-O-(carboxymethyloxime):BSA conjugate and a homologous radioiodinated derivative with tyrosine methyl ester. The cross reactivity of the antiserum with structurally closest 7-hydroxyepimers of DHEA was lower than 1.7%, with DHEA 0.4%, with all other related steroid less than 0.4%. The method includes ether extraction of serum (0.5 ml), followed by RIA. Its detection limit was 0.06 pmol (18 pg)/tube, the average intra- and inter-assay coefficients of variation were 4.1% and 8.3%, respectively. Mean recovery of serum spiked with 7-oxo-DHEA varied between 78.8% and 112%. Its levels in three serum pools were compared with a low-resolution gas chromatography-mass spectrometry method with satisfactory results. The method has been used for determination of 7-oxo-DHEA in serum samples of 215 subjects (91 males and 124 females) without overt endocrine disorders, aged 5-71 years. The over-all mean+/-S.D. was 0.280+/-0.227, the median 0.239 nmol/l. No significant sex differences were recorded. The only group which differed significantly from all other ones were males below 10 years, significantly lower values than in other age groups were found also in the first two age groups of females.

Pregnanolone isomers, pregnenolone and their polar conjugates around parturition.

The levels of four pregnanolone isomers and their polar conjugates and pregnenolone sulfate were measured in the plasma of 13 and 7 women at delivery with subarachnoidal and epidural analgesia, respectively, and in corresponding samples of umbilical plasma using a simple quadrupole GC/MS system with electron impact ionization (pregnenolone isomers), RIA following HPLC separation (pregnenolone) and specific RIA (pregnanolone sulfate). The concentration of epipregnanolone (3beta-hydroxy-5beta-pregnan-20-one) in both maternal and umbilical plasma was much lower than that of other pregnanolone isomers. The levels of 3beta-hydroxy-pregnanolone isomers were significantly higher in the umbilical plasma than in the maternal, while the differences in 3alpha-hydroxy-isomers were insignificant. The differences in conjugates were insignificant with the exception of allopregnanolone, the levels of which were lower in umbilical plasma. In all the pregnanolone isomers, a significantly lower conjugated/unconjugated steroid ratio was found in the umbilical plasma than in the maternal plasma. In addition, time profiles of the steroids were measured around parturition and in the postpartum period in the maternal serum. Similarly, the levels of polar conjugates of all pregnanolone isomers were followed during parturition. Changes in concentrations of free steroids exhibited a similar pattern, with a fall primarily within the first hour after delivery. The decrease in conjugated steroids was shifted to the interval within the first hour and first day after delivery, and the changes were more pronounced. The time profiles of the conjugated/free steroid ratio exhibited a significant decrease within the first hour and the first day after delivery in all of the isomers investigated. A decrease was also observed in the ratio of 3alpha/3beta-isomers and 5alpha/5beta-isomers around parturition. The possible physiological consequences of the findings are indicated.

Neuroactive steroids, their precursors and polar conjugates during parturition and postpartum in maternal and umbilical blood: 3.3beta-hydroxy-5-ene steroids.

Five 3beta-hydroxy-5-ene steroids involved in the metabolic route from pregnenolone sulfate to dehydroepiandrosterone and its sulfate, of which three are known allosteric modulators of neurotransmitter receptors, were monitored in the serum of 20 women around parturition. In addition, their levels in maternal and umbilical serum were compared at delivery. On the basis of these data, a scheme of steroid biosynthesis in maternal organism during the critical stages around parturition is proposed. In maternal serum, all the steroids except dehydroepiandrosterone sulfate decreased during labor and even first day after delivery, although their changes were less distinct the more distant from pregnenolone sulfate (PregS) in the metabolic pathway. Calculation of product/immediate precursor ratios in maternal serum over all stages around parturition enabled identification of the respective changes in the activities of the relevant enzymes. The ratio of 17-hydroxypregnenolone/pregnenolone did not change significantly, while that of dehydroepiandrosterone/17-hydroxypregnenolone grew, indicating increased C17,20 side chain cleavage on the account of C17-hydroxylation both catalyzed by C17-hydroxylase-C17,20-lyase. As was shown by factor analysis, the changes in the maternal steroids were associated with a single common factor, which strongly correlated with all the steroids except dehydroepiandrosterone sulfate. The lack of change in the pregnenolone sulfate/pregnenolone ratio and a marked increase of the ratio dehydroepiandrosterone sulfate to unconjugated dehydroepiandrosterone indicate a different means of formation of both steroid sulfates. On the basis of these data, a scheme of steroid biosynthesis in maternal organism during the critical stages around parturition is proposed.

Elimination of cross-reactivity by addition of an excess of cross-reactant for radioimmunoassay of 17alpha-hydroxypregnenolone.

Polyclonal antiserum against 3beta,17alpha-dihydroxypregn-5-en-20-one-19-O-(carboxymethyl )-oxime bovine serum albumin (17alpha-hydroxypregnenolone-19-CMO:BSA), was raised in rabbits. Its main structural determinants were the substituents on D-ring as demonstrated by its 107% cross-reaction with 17alpha-hydroxyprogesterone. This unspecificity was almost completely eliminated by addition of the excess of the cross-reactant directly to the analytical system. The contribution of the cross-reactant from the sample in such a system became negligible due to saturation of the populations of polyclonal antibodies recognizing the analyte as well as the cross-reactant. The possible interference of 17alpha-hydroxypregnenolone-3-sulfate was avoided by inserting ether extraction. The analytical system appeared to be stable to differences in cross-reactant concentrations even in samples from patients with pathologically elevated serum levels of 17alpha-hydroxyprogesterone. The radioimmunoassay was compared with the system using the unspecific antiserum alone, but after separation of the cross-reactants by HPLC. As demonstrated by parallel measurement of 125 samples of human plasma from both sexes and various ages either before and/or after adrenocorticotropin stimulation and 17 samples with elevated basal of human plasma 17alpha-hydroxyprogesterone levels, an excellent correlation was achieved between both methods. The method, based on a simple addition of the cross-reactant, avoids the time-consuming chromatographic separation and, in comparison with the other approaches for improving the specificity of polyclonal antisera, is efficient and rapid. Mathematical analysis of the relations in equilibrium demonstrates that such a simple approach is an efficient way for improvement of immunoassay specificity using some polyclonal antisera.

Age relationships and sex differences in serum levels of pregnenolone and 17-hydroxypregnenolone in healthy subjects.

17-Hydroxypregnenolone (3beta,17alpha-dihydroxypregn-5-en-20-one) and pregnenolone (3beta-hydroxypregn-5-en-20-one) were determined by radioimmunoassay following HPLC separation in serum of healthy subjects of both sexes from 2 to 66 years old (29 girls, 85 women, 30 boys, 89 men). The effects of age and sex on the levels of both steroids were investigated and the upper limits of normal in age groups were determined. The 17-hydroxypregnenolone levels as a function of age were characterized by a statistically significant maximum at the age of 18 and 20 years followed by a local minimum at the age of 39 and 37 years and by a statistically insignificant local maximum at the age of 55 and 49 years in men and women, respectively. Pregnenolone age-dependence was similar and the statistically significant maximum was reached at the age of 17 and 16 years, the local minimum occurred at the age of 37 and 38 years and the second, statistically insignificant, local maximum at the age of 48 and 47 years in men and women, respectively. Both 17-hydroxypregnenolone and pregnenolone in both sexes exhibited similarly shaped peaks with age. Both peaks of the polynomial fit in 17-hydroxypregnenolone were more pronounced in men than in women (13.0 and 9.20 nmol/l in the first peak; 7.72 and 4.78 in the second peak respectively). The situation with pregnenolone was the opposite. Both peaks of the polynomial fit in pregnenolone were lower in men than in women (2.29 and 3.21 nmol/l in the first peak; 0.92 and 1.78 in the second peak, respectively). The higher serum levels of pregnenolone at puberty and during fertile age and their wider variance in comparison with men could, be explained by the different gonadal steroidogenesis depending on the menstrual cycle, where the pregnenolone serves as a substrate for progesterone formation. The age dependencies of 17-hydroxypregnenolone and pregnenolone in women resembled that of unconjugated dehydroepiandrosterone. These results indicate that the increased metabolic activity in gonads in adolescence concerns not only dehydroepiandrosterone as the product of the 5-ene metabolic pathway but also its precursors.

Synthesis of (19E)-3 beta,7 alpha-dihydroxy-17-oxoandrost-5-en-19-al 19-(O-carboxymethyl)oxime, a new hapten for 7 alpha-hydroxydehydroepiandrosterone (3 beta,7 alpha-dihydroxyandrost-5-en-17-one).

The title compound was prepared in 11 steps from 17,17-ethylenedioxy-19-hydroxyandrost-5-en-3 beta-yl acetate. After tert-butyldimethylsilyl protection of the 19-hydroxyl group, a 7-oxo group was introduced by oxidation with 3,5-dimethylpyrazole-chromium trioxide complex, and then selectively reduced with L-Selectride to give a 7 alpha-hydroxy derivative. This partially protected triol was acetylated and desilylated to 3,7-diacetate. Subsequent oxidation with pyridine-chromium trioxide complex gave 19-aldehyde, which was transformed into the corresponding protected 19-(O-carboxymethyl)oxime. Successive ketal cleavage, deacetylation, and methyl ester splitting gave the final (19E)-3 beta,7 alpha-dihydroxy-17-oxoandrost-5-en-19-al 19-(O-carboxymethyl)oxime, designed as a hapten for 7 alpha-hydroxydehydroepiandrosterone immunoassays.

Synthesis of (15E)-17 beta-hydroxyandrost-4-en-3,15-dione 15-(O-carboxymethyl)oxime, a potential hapten for testosterone immunoassays.

The key intermediate, 15-oxandrost-5-en-3 beta, 17 beta-diyl 3-acetate 17-benzoate (10), was prepared by a five-step procedure based on the addition of 4-methoxybenzyl alcohol to 3 beta-hydroxyandrosta-5, 15-dien-17-one (1). The resulting C-15 isomers were separated as acetates. In both series, the 17-ketones were reduced to 17 beta-hydroxy derivatives, and after benzoylation, the protecting methoxyphenylmethyl group at position 15 was removed with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, leaving 15 beta-hydroxyandrost-5-ene-3 beta, 17 beta-diyl 3-acetate 17-benzoate (6) and its 15 alpha-isomer 9. After Jones oxidation, both benzoates afforded the identical ketone 10. The reaction of 10 with (O-carboxymethyl)hydroxylamine in pyridine followed by diazomethane esterification gave (15E)-15-oxandrost-5-ene-3 beta, 17 beta-diyl 3-acetate 17-benzoate 15-(O-carboxymethyl)oxine methyl ester (11). Methyl ester 11 was successively submitted to acidic deacetylation, Oppenauer oxidation, potassium hydroxide treatment and reesterification with diazomethane to give (15E)-17 beta-hydroxyandrost-4-ene-3,15-dione 15-(O-carboxymethyl) oxine methyl ester (14). After purification, ester 14 was hydrolyzed with potassium hydrogen carbonate in aqueous methanol at elevated temperature into fee testosterone 15-(O-carboxymethyl)oxine (15).

Chemical synthesis of 15 beta-hydroxytestosterone and its derivatives using a (4-methoxyphenyl)methyl protecting group.

Reaction of 3 beta-hydroxyandrosta-5,15-dien-17-one with 4-methoxybenzyl alcohol followed by acetylation gave mainly 15 beta-[(4-methoxyphenyl)methoxy]-17-oxoandrost-5-en-3 beta-yl acetate. This product was transformed by borohydride reduction and organosilyl derivatization into the orthogonally protected 17 beta-(dimethylthexylsiloxy)-15 beta-[(4-methoxyphenyl)methoxy]androst-5-en-3 beta-yl acetate and 17 beta-(dimethylisopropylsiloxy)-15 beta-[4-methoxyphenyl)methoxy]androst-5-en-3 beta-yl acetate. After deacetylation, these intermediates were submitted to Oppenauer oxidation and both yielded testosterone derivatives 17 beta-(dimethylthexylsiloxy)-15 beta-[(4-methoxyphenyl)methoxy]androst-4- en-3-one and 17 beta-(dimethylisopropylsiloxy)-15 beta-[(4-methoxyphenyl)- methoxy]androst-4-en-3-one. Removal of the (4-methoxyphenyl)methyl group from position 15 by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone treatment gave the partially protected derivatives 17 beta-(dimethylthexylsiloxy)-15 beta-hydroxyandrost-4-en-3-one and 17 beta-(dimethylisopropylsiloxy)-15 beta-hydroxyandrost-4-en-3-one. After acidic deprotection, the dimethylthexylsilyl derivative yielded 15 beta-hydroxytestosterone (15 beta,17 beta-dihydroxyandrost-4-en-3-one). Dimethylisopropylsilyl derivative was converted to the corresponding 15-hemisuccinate and 15-hemiglutarate (17 beta-hydroxy-3-oxoandrost-4-en-15 beta-yl 15-hemisuccinate and 15-hemiglutarate, respectively), which were designed as model haptens for immunoassay studies.

Preparation and properties of 3-(O-(2-carboxyethyl)oxime derivatives of steroid hormones.

Mixtures of 3E and 3Z isomers of 3-(O-(2-carboxyethyl)oxime (CEO) derivatives of testosterone and 17 alpha-methyltestosterone were prepared by reaction with (O-(2-carboxyethyl))hydroxylamine. These isomers were separated after conversion into methyl esters, and mild alkaline hydrolysis recovered pure E/Z-isomers of 3-CEO derivatives of testosterone and 17 alpha-methyltestosterone. By the same method, after oximation, methylation, and separation, (20R)-20-hydroxypregn-4-en-3-one gave (3E,2OR)-20-hydroxypregn-4-en-3-one 3(O-(2-carboxyethyl)oxime and (3Z,20R)-20-hydroxypregn-4-en-3-one 3-(O-(2-carboxyethyl))oxime methyl esters. The oxidation and subsequent hydrolysis of these compounds produced 3E and 3Z isomers of the 3-CEO derivative of progesterone. Pure E/Z-isomers of 3-CEO derivatives are designed for the development of immunoanalytical systems, which make use of the bridge heterology based on the geometric isomerism.

Synthesis of (19E)-3 beta,17-dihydroxy-20-oxopregn-5-en-19-al 19-(O-carboxymethyl)oxime, new steroidal hapten for 17-hydroxypregnenolone.

A synthesis of (19E)-3 beta,17-dihydroxy-20-oxopregn-5-en-19-al 19-(O-carboxymethyl)oxime (15), is reported. Hydride reduction of ketone 1 gave the (20R)-hydroxy derivative 2 as the main product. Formylation of 2 followed by cleavage of the epoxide ring and mild Jones oxidation afforded aldehyde 6. Oximation with (O-carboxymethyl)hydroxylamine and subsequent methylation yielded methyl ester 8 which was selectively hydrolyzed to alcohol 9 and oxidized to ketone 10. Enolacetylation, epoxidation, and hydrolysis led to the desired 19-(O-carboxymethyl)oxime derivative of 17-hydroxypregnenolone 15.

Synthesis of the sulfates derived from 5 alpha-cholestane-3 beta,6 alpha-diol.

Three new steroid sulfates--3 beta-hydroxy-5 alpha-cholestan-6 alpha-yl sulfate, 6 alpha-hydroxy-5 alpha-cholestan-3 beta-yl sulfate, and 5 alpha-cholestan-3 beta,6 alpha-diyl disulfate--were synthesized. For the syntheses of the key intermediates, 3 beta-hydroxy-5 alpha-cholestan-6 alpha-yl acetate and 6 alpha-hydroxy-5 alpha-cholestan-3 beta-yl acetate, selective protection of hydroxy groups in 5 alpha-cholestane-3 beta,6 alpha-diol was necessary. This problem was solved by using a combination of acetyl, tetrahydropyranyl, and methoxymethyl protective groups, which represents a new approach leading to these hydroxy acetates. Sulfated derivatives of 5 alpha-cholestane-3 beta,6 alpha-diol are present in marine invertebrates and were synthesized for the purposes of biologic testing.

Reversed phase high performance liquid chromatographic separation of hydroxy steroidal unsaturated esters and their hemisuccinates.

The high performance liquid chromatographic (HPLC) separation and identification of 12 isomeric and/or highly chemically related steroids with an unsaturated ester moiety at position 17 beta has been achieved. The main stereochemical features of the steroid skeleton cover 3 alpha/beta, 5 alpha/beta or delta, and 20 E/Z, bearing the alcohol or hemisuccinate group at the 3 position. The isocratic reversed phase C18 HPLC separation employed ethanol, methanol and its mixtures with water or 0.01 M phosphoric acid as the mobile phase. The best separation of the respective alcohols from their hemisuccinates has been achieved with 20% of aqueous phase content. The best separation among isomeric or related steroids has been achieved with methanol:water 8:2 and 85:15 and similar systems containing phosphoric acid.

Synthetic approach to analogues of 19-norsteroids with an acyclic side chain.

Racemic 14 beta-hydroxy-3-methoxy-8 alpha,9 alpha-1,3,5(10)-estratriene-17-one (I), obtained by total synthesis, was converted into a derivative with alkoxycarbonyl-ethylenic side chain, rac-(20E)-21-methoxycarbonyl-19-nor-8 alpha,9 alpha-pregna- 1,3,5(10),20-tetraene-3,14 beta-diol 3-methyl ether (XII) using two Wittig reactions. Analogous derivatives of 5 alpha-androstane were prepared as synthetic models. In the estrane series the stereochemistry of attachement of the side chain in position 17, biological activity of some compounds, and their chromatographic properties were investigated.

Reversed-phase high-performance liquid chromatographic separation of steroids with the beta-crotonate side chain.

An isocratic high-performance liquid chromatographic separation of some ethyl 3-stereoidyl crotonates [ethyl-24-nor-20(22)-cholen-23-oate derivatives] was developed. The separations were achieved by reversed-phase chromatography (Separon Si C18) using methanol, methanol-water, methanol-0.1 M formic acid and ethanol-0.01 M aqueous phosphoric acid mixtures as mobile phases. The steroidal crotonates were detected at 230 and 240 nm.