Synthesis of 3α,7α-dihydroxy-5β-androstan-17-one

A short and efficient method for the stereospecific synthesis of 3α,7α-dihydroxy-5β-androstan-17-one was accomplished from the readily available 4-androstene-3,17-dione. Key steps are the stereospecific and selective epoxidation of 4,6-androstadiene-3,17-dione, followed by hydrogenations with carefully selected reagents, solvents and reaction conditions.     

C-19-steroid 7α-hydroxylation by rat testes. isolation and identification of: 7α, 17β-dihydroxy-5α-androstan-3-one, 5α-androstan-3α,7α,17β-triol and 5α-androstane-3β,7α, 17β-triol

From incubations of testosterone with rat testicular homogenates in the presence of a NADPH-generating system, the following 7α-hydroxylated metabolites could be isolated and identified: 7α,17β-dihydroxy-4-androsten-3-one (7α-hydroxy-testosterone), 7α-17β-dihydroxy-5α-androstan-3-one (7α-hydroxy-Dht), 5α-androstan-3α,7α,17β-triol (7α-hydroxy-3α-A'DIOL) and 5α-androstane-3β,7α,l7β-triol (7α-hydroxy-3β-A'DIOL). To our knowledge this is the first demonstration of the formation of 5α-reduced-7α-hydroxylated metabolites of testosterone in the male gonad. These 5α-reduced-7α-hydroxylated metabolites could also be isolated after incubations of 5α-androstane-3α,17β-diol (3α-A'D10L) with testicular homogenates in the presence of a NADPH-generating system.Measured as the sum of 7α-hydroxy-testosterone, 7α-hydroxy-Dht. 7α-hydroxy-3α-A'DIOL and 7α-hydroxy-3β-A'DIOL formed using testosterone as substrate, total 7α-hydroxylase activity was six times higher in testes of mature rats than in testes from animals 23 days old. With 3α-A'DIOL as substrate total 7α-hydroxylase in the mature testis was about three times greater than in the sexually immature testis.     

Synthesis of (4-C)-labeled and non-labeled 3β,15α-dihydroxy-5-pregnen-20-one and 3β,15α-dihydroxy-5-androsten-17-one

The synthesis of labeled and non-labeled 3β,15α-dihydroxy-5-pregnen-20-one (V) and 3β, 15α-dihydroxy-5-androsten-17-one (XI) is described. Treatment of 15α-hydroxy-4-pregnene-3,20-dione (I) with acetic anhydride and acetyl chloride gave 3,15α-diacetoxy-3,5-pregnadien-20-one (II). The enol acetate (II) was ketalized by a modification of the general procedure to yield 3,15α-diacetoxy-3,5-pregnadien-20-one cyclic ethylene ketal (III) which was then reduced with NaBH₄ and LiAlH₄ to give 3β, 15α-dihydroxy-5-pregnen-20-one cyclic ethylene ketal (IV). Cleavage of the ketal group of IV gave V. Similarly, XI was prepared by starting with 15α-hydroxy-4-androstene-3,17-dione (VII). The (4-¹⁴C)-3β,15α-dihydroxy-5-pregnen-20-one was prepared by a modification of the above procedure in that the enol acetate (II)was directly reduced with NaBH₄ and LiAlH₄ to yield 5-pregnene-3β,15α,20β-triol (XIII) which was then oxidized enzymatically with 20β-hydroxysteroid dehydrogenase to V.     

Metabolism of 17β-hydroxy-2-hydroxymethylene-5α-androstan-3-one in the rabbit

An acidic metabolite, 2α-carboxy-5α-androstane-3α, 16α, 17αtriol and two neutral metabolites, 2α-hydroxymethyl-5α-androstane-3α, 17α-diol, and 2α-hydroxymethyl-5α-androstane-3α, 16α, 17α-triol have been identified in the urine of rabbits orally dosed with 17β-hydroxy-2-hydroxymethylene-5α-androstan-3-one. 2α-Hydroxymethyl-5α-androstane-3α, 16α, 17α-triol was previously obtained from the urine of rabbits dosed with 17β-hydroxy-2α-methyl-5α-androstan-3-one. The acidic metabolite was the major urinary excretion product.     

5α,6α- AND 5β,6β-dichloromethylene adducts of 3β-acetoxy-5-androsten-17-one

Both the 5α, 6α- and 5β, 6β-dichloromethylene adducts ($\text{2a}$ and $\text{2b}$) of 3β-acetoxy-5-androsten-17-one ($\text{1}$) are produced when the latter is exposed to dichlorocarbene generated from chloroform and base by Phase Transfer Catalysis using ultrasound as a means of agitation. The ¹H NMR substituent effects of 5α, 6α- and 5β, 6β-dichloromethylene on the angular methyl groups (Zürcher values) are given. The ¹³C NMR spectra for both compounds are presented and discussed.     

Synthesis of 5α-Androstane-3α,16α,17β-triol from 3β-hydroxy-5-androsten-17-one

5α-Androstane-3α, 16α 17β-triol was synthesized from 3β-hy-droxy-5-androsten-17-one. The procedure Involved catalytic hydrogenation of 3β-hydroxy-5-androsten-17-one to 3β-hydroxy-5α-androstan-17-one. This was followed by conversion of the 3β-hydroxy group to 3α-benzoyloxy group by the Mitsunobu reaction. Further treatment with isopropenyl acetate yielded 5α-androsten-16-ene-3α, 17-diol 3-benzoate 17-acetate. This was then converted to 3α, 17-dihydroxy-5α-androstan-16-one 3-benzoate 17-acetate via the unstable epoxide intermediate after treatment with $\text{m}$-cloroperoxybenzoic acid. LiAlH₄ reduction of this compound formed 5α-androstane-3α, 16α, 17β-trlol. ¹H and ¹³C NMR of various steroids are presented to confirm the structure of this compound.     

Metabolism of 3α, 7α-dihydrexy-7β-methyl-5β-cholanoic acid and 3α,7β-dihydroxy-7α-methyi-5β-cholanoic acid in hamsters

The metabolic fate of the bile add analogs, 3α,7α-dihydroxy-7β-methyl-5β-cholanoic acid and 3α,7β-dihydroxy-7α-methyl-5β-cholanoic acid, was investigated and compared with that of chenodeoxycholic acid in hamsters. Both bile acid analogs were absorbed rapidly from the intestine and excreted into bile at similar to that of chenodeoxycholic acid. In the strain of hamster studied, the biliary bile were conjugated with both glycine and taurine. After continuous intravenous infusion, chenodeoxycholic acid the analogs became the major bile acid constituents in bile. After oral administration of a single dose of these compounds, fecal analysis revealed the existence of unchanged material (25–35%) as well as considerable amounts of metabolites (65–75%). The major metabolites excreted into feces were more polar than the starting material and were tentatively identified as trifaydroxy-7-methyl compounds by radioactive thin-layer chromatography. However, monohydroxy compounds were also found in the fecal extracts. These results show that chenodeoxycholic acid and ursodeoxycholic acid with a methyl group at the 7-position are resistant to bacterial 7-dehydroxylation than the normally occurring bile acids and that a certain proportion of these analogs is hydroxylated to give the corespondiag trihydroxy compound(s), In a control experiment, about 5% of administered chenodeoxychoulic acid was metabolized to a trihydroxy feile acid, but most of the compound (95%) was transformed into lithocholic acid.     

Synthesis of 3β-hydroxy-androsta-5,7-dien-17-one from 3β-hydroxyandrost-5-en-17-one via microbial 7α-hydroxylation

The synthesis of 3β-hydroxy-androsta-5,7-dien-17-one from 3β-hydroxy-androst-5-en-17-one (dehydroepiandrosterone, DHEA) via microbial 7α-hydroxylation has been accomplished. At the first stage, 3β,7α-dihydroxy-androst-5-en-17-one was obtained in high yield (71.2%) using a strain of Gibberella zeae VKM F-2600, which was first applied for DHEA conversion. The further route included the substitution of 7α-hydroxyl group with chlorine followed by a dehydrochlorination stage, and required minimal purifications of the intermediate products. The steroids obtained at every step were characterized by TLC_,¹H NMR, MS, UV- and IR-spectrometry.The combination of microbial and chemical steps ensured 54.6% yield of the target 3β-hydroxy-androsta-5,7-dien-17-one from DHEA and can be applied for obtaining novel vitamin D derivatives.     

Quantification of urinary 3α,21-dihydroxy-5β-pregnan-20-one and 5-pregnene-3β, 20α-diol by mass fragmentography

A sensitive and accurate method is described for measuring urinary corticosteroids by gas chromatography-mass spectroscopy (GC-MS). Using single peak monitoring (mass fragmentography) and electron impact ionization, the acetates of 3α,21-dihydroxy-5β-pregnan-20-one (tetrahydrodeoxycorticoster-one) and 5-pregnene-3β,20α-diol were estimated with deuterio-acetate carriers as recovery markers. With this technique, the coefficient of variation did not exceed 3% for GC-MS analyses of the urinary corticosteroid samples by single peak monitoring. An evaluation of the trimethylsilyl ether derivatives of the two steroids by chemical ionization was also made. Secretion rates determined for deoxycorticos-terone derived from specific activities of urinary tetrahydrodeoxycorticosterone and excretion levels of 5-pregnene-3β,20α-diol were slightly lower than those obtained by other methods.     

Synthesis and acetylcholinesterase inhibitory activity of 2β,3α-disulfoxy-5α-cholestan-6-one

Disodium 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (8) has been synthesized using cholesterol (1) as starting material. Sulfation was performed using trimethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. The acetylcholinesterase inhibitory activity of compound 8 was evaluated and compared to that of disodium 2β,3α-dihydroxy-5α-cholestane disulfate (10) and diols 7 and 9. Compounds 8 and 10 were active with IC(50) values of 14.59 and 59.65 μM, respectively. Diols 7 and 9 showed no inhibitory activity (IC(50)>500 μM).     

Metabolism of (24R and 24S)-27-nor-24-methyl-3α,7α-dihydroxy-5β-cholestan-26-oic acids and 27-nor-3α,7α-dihydroxy-5β-cholestan-26-oic acid in guinea pigs

[7β-³H]-(24R and 24S)-27-nor-24-methyl-3α,7α-dihydroxy-5β-cholestan-26-oic acids and [7β-³H]-27-nor-3α,7α-dihydroxy-5β-cholestan-26-oic acid (C₂₇ and C₂₆ bile acids having the same nuclear configuration as cheno-deoxycholic acid and its precursor, 3α,7α-dihydroxy-5β-cholestan-26-oic-acid) were synthesized and administered intraperitoneally to bile fistula guinea pigs. The biliary bile acids formed were hydrolyzed and analyzed by thin layer chromatography, and the metabolites were identified by the inverse isotope dilution method. The results showed that both (24R and 24S)-27-nor-24-methyl-3α,7α-dihydroxy-5β-cholestan-26-oic acids were not metabolized by the liver and were excreted unchanged as their taurine and glycine conjugates whereas 27-nor-3α,7α-dihydroxy-5β-cholestan-26-oic acid was converted to chenodeoxycholic acid.     

Radioimmunoassay of 17β-hydroxy-5α-androstan-3-one, 4-androstene-3,17-dione,dehydroepiandrosterone, 17-hydroxyprogesterone and progesterone and its application to human male plasma

RIA methods for the measurement of 5α-dihydrotestosterone (DHT), androstenedione (Δ4), dehydro-epiandrosterone (DHEA), 17-hydroxyprogesterone (17-OHP) and progesterone (P) have been developed and applied to the study of factors determining the levels of these steroids in males.It has been shown that DHT, 17-OHP and DHEA levels are lower in elderly males than in young (<50 years) subjects, Δ4 and P levels remaining constant. All steroids, with the exception of DHT, show significant nyctohemeral variations: upon ACTH stimulation T levels decrease, whereas Δ4 and DHEA, 17-OHP and P increase significantly. Dexamethasone has the reverse effect, although T levels do not decrease. HCG stimulation results in a significant increase of T, DHT, 17-OHP and Δ4 levels, whereas DHEA and P levels are hardly influenced. In a small group of orchidectomized males, all steroids studied, with the exception of P were significantly lower than in normal males of similar age.It is concluded that in males T, DHT and 17-OHP have an almost exclusive testicular origin; Δ4 has a mixed testicular and adrenal origin, whereas DHEA has a predominant and P an exclusive adrenal origin in males.     

Concentrations of unconjugated 5α-androstan-3β,17β-diol in human peripheral plasma as measured by radioimmunoassay

5α-androstane-3β,17β-diol was measured in human peripheral plasma using a specific antibody generated against a carboxymethyloxime BSA conjugate linked at position 7. Concentrations were significantly higher in normal men than women. Preliminary results suggest that plasma 5α-androstane-3β,17β-diol concentrations might be a useful clinical parameter in cases of hirsutism and male infertility.     

The identification and characterization of the c19o3 steroid metabolites of 5α-androstane-3β, 17β-diol produced by the canine prostate: 5α-androstane-3β, 6α, 17β-triol and 5α-androstane-3β, 7α, 17β-triol

This study has identified the polar metabolites of 5α-androstane-3β, 17β-diol(3β-diol) produced by the canine prostate. The major metabolite is 5α-androstane-3β, 7α, 17β-triol (7α-triol) accounting for approximately 80% of the total polar metabolites of 3β-diol. The remaining 20% is accounted for exclusively by another triol, 5α-androstane-3β, 6α, 17β-triol(6α-triol). This study has also characterized two enzymatic hydroxylases responsible for respective triol formation: 5α-androstane-3β, 17β-diol 6α-hydroxylase (6α-hydroxylase) and 5α-androstane-3β, 17β-diol 7α-hydroxylase (7α-hydroxylase). Both of these irreversible hydroxylases are located in the particulate fraction of the prostate and can utilize either NADH or NADPH as cofactor. Several $\text{in vitro}$ steroid inhibitors of these hydroxylases were identified including cholesterol, estradiol and diethylstilbestrol. Neither of the hydroxylases were found to be decreased by castration (3 months) when expressed as activity/DNA. Using a variety of C₁₉ androstane substrates, 6α- and 7α-triol were found to be major components of the total 3β-hydroxy-5α-androstane metabolites produced by the canine prostate.     

Enhanced biotransformation of dehydroepiandrosterone to 3β,7α,15α-trihydroxy-5-androsten-17-one with Gibberella intermedia CA3-1 by natural oils addition

Dihydroxylation of dehydroepiandrosterone (DHEA) is an essential step in the synthesis of many important pharmaceutical intermediates. However, the solution to the problem of low biohydroxylation conversion in the biotransformation of DHEA has yet to be found. The effects of natural oils on the course of dihydroxylation of DHEA to 3β,7α,15α-trihydroxy-5-androsten-17-one (7α,15α-diOH-DHEA) were studied. With rapeseed oil (2 %, v/v) addition, the bioconversion efficiency was improved, and the 7α,15α-diOH-DHEA yield was increased by 40.8 % compared with that of the control at DHEA concentration of 8.0 g/L. Meantime, the ratio of 7α,15α-diOH-DHEA to 7α-OH-DHEA was also increased by 4.5 times in the rapeseed oil-containing system. To explain the mechanism underlying the increase of 7α,15α-diOH-DHEA yield, the effects of rapeseed oil on the pH of the bioconversion system, the cell growth and integrity of Gibberella intermedia CA3-1, as well as the membrane composition were systematically studied. The addition of rapeseed oil enhanced the substrate dispersion and maintained the pH of the system during bioconversion. Cells grew better with favorable integrity. The fatty acid profile of G. intermedia cells revealed that rapeseed oil changed the cell membrane composition and improved cell membrane permeability for lipophilic substrates.     

Extending SAR of bile acids as FXR ligands: discovery of 23-N-(carbocinnamyloxy)-3α,7α-dihydroxy-6α-ethyl-24-nor-5β-cholan-23-amine

Within our efforts in the discovery of novel potent and selective ligands for the FXR receptor, 23-N-(carbocinnamyloxy)-3α,7α-dihydroxy-6α-ethyl-24-nor-5β-cholan-23-amine was synthesized and evaluated for its ability to activate and modulate the biological response of the receptor. Alphascreen and RT-PCR revealed that the 6α-ethyl-24-norcholanyl-23-amine derivate behaves as full FXR agonist endowed with high binding affinity and efficacy, representing a promising lead candidate for further optimization. In addition, docking studies provide new insights into the molecular basis governing the partial and full agonist activity at FXR.     

A direct radioiodination technique for the radioimmunoassay of 17α-ethynyl, 17β-hydroxy-4-estren-3-one

A new technique is described for the direct labelling of norethisterone with¹²⁵I for use in radioimmunoassay. This method allows the preparation of tracers possessing both high specific activity and unaltered immunological properties. The steroid is radioiodinated in the presence of H₂O₂ using acetic acid as the solvent, in a sealed vial heated at 100°C. The reaction mixture is then chromatographed on bidimensional t.l.c. and six major radioactive spots are separated; only one of these fractions possess immunoreactivity. When submitted to repeated t.l.c. it behaves as a single compound, possibly a monoiodinated derivative, substituted in Ring A.The new tracer was compared in RIA with both the tyrosine-iodinated and the tritiated tracers. The standard inhibition curve obtained with the new labelled ligand had the same slope as that obtained using the tritiated one; on the other hand the slope of the curve obtained with the tyrosine iodinated derivative was slightly higher than that of the directly iodinated one.The results obtained indicate that the possibility exists of radioiodinating steroids without losing their immunoreactivity.