Transformation of 16-dehydroprogesterone and 17α-hydroxyprogesterone by Mucor piriformis

Mucor piriformis was used to study the mode of transformation of 16-dehydroprogesterone (I, pregna-4, 16-diene-3, 20-dione) and 17-hydroxyprogesterone (II, 17-hydroxypregn-4-ene-3, 20-dione). Biotransformation products formed from I were 14-hydroxypregna-4, 16-diene-3, 20-dione (Ia), 7, 14-dihydroxypregna-4, 16-diene-3, 20-dione (Ib), 3, 7, 14-trihydroxy-5-pregn-16-en-20-one (Ic), and 3, 7, 14-trihydroxy-5-pregn-16-en-20-one (Id). Metabolites Ic and Id appear to be hitherto unknown. Time-course studies suggested that the transformation is initiated by hydroxylation at the 14-position (Ia) followed by hydroxylation at the 7-position (Ib). Microsomes (105,000 g sediment) prepared from 16-dehydroprogesterone-induced cells hydroxylate I to its 14-hydroxy derivative (Ia) in the presence of NADPH. Incubation of Ia with the organism resulted in the formation of Ib, Ic and Id. Biotransformation products formed from compound II were 17, 20-dihydroxypregn-4-en-3-one (IIa), 7, 17-dihydroxypregn-4-ene-3, 20-dione (IIb), 6, 17, 20-trihydroxypregn-4-en-3-one (IIc) and 11, 17, 20-trihydroxypregn-4-en-3-one (IId). Time-course studies indicated that IIa is the initial product formed, which is further hydroxylated either at the 6 or 11 position. Incubation of IIa with the organism resulted in the formation of IIc and IId. Reduction of the 4-en-3-one system and 20-keto group has not been observed before in organisms of the order Mucorales. In addition, M. piriformis has been shown to carry out hydroxylation at the C-6, C-7, C-11 and C-14 positions in the steroid molecules tested.     

Species and Tissue Distribution of Proteins Binding 16α,17α-Cycloalkanoprogesterone Derivatives

The binding of [³H]progesterone and [³H]16,17-cycloalkanoprogesterones to proteins from rat, rabbit, and human uteri and other organs was studied. We found that 16,17-cycloalkanoprogesterone derivatives display affinities for the uterine progesterone receptors comparable with that of the natural hormone and no substantial species differences in the affinity. Rabbit uterus was found to have no proteins distinct from the progesterone receptor that specifically bind [³H]16,17-cycloalkanoprogesterones. At the same time, in the human uterus, we found another protein that binds some of these progesterone derivatives; it turned out to be similar to the protein from rat uterus. A similar protein with the same selectivity and affinity for steroids was also found in rat and human kidneys. Blood serum, liver, lung, and a number of other tissues were found to contain a protein of the third type that binds the same 16,17-cycloalkanoprogesterones and exhibits submicromolar K _d values for these steroids and a very low affinity for progesterone. We speculated that the introduction of a bulky substituent adjacently to the 17-side chain of progesterone could result in a change in the general biodynamics of the derivative including its transport, uptake, and accumulation in tissues, which may determine the selectivity of its effect.     

Biotransformation of methyl ent-17-hydroxy-16β-kauran-19-oate by Rhizopus stolonifer

Methyl ent-17-hydroxy-16β-kauran-19-oate was fed to a 2-day-old culture of the fungus Rhizopus stolonifer, fermenting at room temperature (25 °C) in an orbital shaker (2 l). After 11 days, both broth and mycelia were extracted with ethyl acetate. Two novel compounds were isolated from this experiment: methyl ent-9α,17-dihydroxy-16β-kauran-19-oate and methyl ent-7α,17-dihydroxy-16β-kauran-19-oate. Their structures were fully confirmed by spectroscopic methods. Received: 22 July 1999 / Received revision: 2 November 1999 / Accepted: 12 November 1999     

Unusual oxidative transformations of a steroidal 16α,17α,22-triol

A number of unexpected reactions were observed during attempts to invert configuration at C16 in 16α,17α,22-triol 3a. The PDC oxidation of 3a produced the D-seco-aldehyde 4a. Analogous compound 4b was obtained by Swern oxidation of the 16α,17α-dihydroxy-22-O-TES-ether 3b in addition to the desired 16-ketone 7. The unprotected triol 3a yielded pentacyclic products 5 and 6 under similar conditions. The Mitsunobu reaction of the triol 3a afforded 16-ketone 8 with inverted configuration of the side chain. During heating of a solution of 3a in THF with NaH at reflux autoxidation to the 16-ketone cyclic hemiketal 5, identical to one of the Swern oxidation products, took place.     

The inhibition of gibberellic acid biosynthesis by ent-kauran-16β,17-epoxide

Ent-kauran-16β,17-epoxideinhibits the biosynthesis of ent-kaur-16-ene from mevalonate and its conversion to gibberellic acid. It binds to a kaurene carrier protein.     

Molecular docking and 3D-QSAR of 16α,17α-cycloalkanoprogesterone derivatives as ligands of the progesterone receptor

A series of 42 (pregna-D′-pentarane) steroid ligands was used to generate models predicting ligand affinity to the progesterone receptor. The best result (Q ² = 0.91) was obtained using a combination of molecular docking, molecular dynamics simulation and artificial neural networks. Good predictive power of the model was validated using a group of 8 pentaranes synthesized separately and tested in vitro (R _test ² = 0.77). This model can be used for determination of ligand-receptor binding affinity and accurate ranking of binding capacity of compounds tested.     

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.     

16α,17α-Cycloalkane Derivatives of Progesterone Intensively Bind to a Rat Serum Protein

The interaction of 6-methyl-[1,2-³H]16,17-cyclohexanoprogesterone with rat serum proteins has been studied. Specific binding of this ligand characterized by K _d = 0.36 ± 0.10 M and concentration of binding sites (B_max) of about 1 M (27.8 ± 12.5 pmol/mg total protein) was found. According to competitive analysis, the affinity of the studied progestins to a protein that differs from transcortin was to some extent correlated with their hydrophobicity. The dissociation kinetics of ³H-ligand–protein complexes were biphasic, the binding sites forming stable and labile complexes with ³H-ligand being eluted in the same region during ion-exchange chromatography. In overall properties, the serum protein differs from the progesterone receptor and the pregna-D"-pentarane-specific protein from rat uterus. It is suggested that the revealed protein may provide high progestagenic activity of 6-methyl-16,17-cyclohexanoprogesterone by prolonging its retention in the bloodstream.     

Synthesis of 16α-bromoacetoxy androgens and 17 β-bromoacetylamino-4-androsten-3-one: Potential affinity labels of human placental aromatase

A novel synthesis of 16α-hydroxy-4-androstene-3,17-dione ($\text{3}$), 16α-hydroxy-4-androstene-3, 6,17-trione ($\text{4}$), 17β-amino-5-androsten-3β-ol ($\text{10}$) and 17β-amino-4-androsten-3-one (14) is described. 16α-Bromoacetoxy-4-androstene-3, 17-dione ($\text{5}$), 16α-bromoacetoxy-4-androstene-3, 6,17-trione ($\text{6}$) and 17β-bromoacetylamino-4-androsten-3-one ($\text{15}$) were synthesized as potentially selective irreversible inhibitors of androgen aromatases. 16α-Bromo-4-androstene-3,17-dione ($\text{1}$) and 16α-bromo-4-androstene-3, 6,17-trione ($\text{2}$) were converted to compounds $\text{3}$ and $\text{4}$ in 80–90% yield by controlled stereospecific hydrolysis using sodium hydroxide in aqueous pyridine. Reductive amination of 3β-hydroxy-5-androsten-17-one and 3-methoxy-3,5-androstadien-17-one ($\text{11}$) using ammonium acetate and sodium cyanohydridoborate (NaBH₃CN) and a subsequent treatment with acid gave the amines $\text{10}$ and $\text{14}$ respectively, as a salt. The corresponding 17-imino compounds $\text{9}$ and $\text{13}$ were also isolated from the reaction mixtures when methanol was used as a solvent for the reaction. The 16α-hydroxyl compounds $\text{3}$ and $\text{4}$ and the 17β-amino compound $\text{14}$ were con- verted to the corresponding bromoacetyl derivatives, $\text{5}$, $\text{6}$, and $\text{15}$, with bromoacetic acid and N,N'-dicyclohexylcarbodiimide.     

Chemical synthesis of the 17-propanamide derivatives of stereoisomeric Δ14-17α- and 17β-estradiols: potential 17β-hydroxysteroid dehydrogenase inhibitors

The 17-propanamide derivatives of diastereomeric Δ¹⁴-17α- and 17β-estradiols, the potential candidates of a 17β-hydroxysteroid dehydrogenase (17β-HSD) inhibitor, were synthesized in 11 steps from estrone. The principal reactions employed involved in (1) conversion of estrone to the corresponding Δ¹⁴-estrone, (2) Grignard reaction of Δ¹⁴-estrone with allylmagnesium bromide followed by regioselective hydroboration of the resulting stereoisomeric 17ξ-allyl-Δ¹⁴-17ξ-ols with 9-borabicyclo[3.3.1]nonane (9-BBN), and (3) direct amidation of the 17ξ-O-/17ξ-C-spiro-γ-lactones with NH₃ under positive pressure of H₂.     

Contents of volume 16, 2006

EOITORIALA journey to a brighter futureGang Pei尺石功石的呀3 GATA·3PromotesTh2resPonsesthroughthreedifferentmeehanisms:inductionofThZeytokine Production,Selective growth of ThZ cells and inhibition of Thl eell·sPecific怕etors Jinfang Zhu,刀友论hiro Yamane,Javiel’ Cole一Sierra.Liying Guo,川llia脚E Paul1 1 The quantal theory of immunity 人治ndallA肠力ith20 Cytokines as critieal eo·stimulatory moleeules in modulating the immune resPonse of natural k川6F C6!!S Howa)汀A Young,…     

Preparation of 3β,16β-dihydroxyandrost-5-en-17-one: Stabilization of its α-ketolic group toward alkali by formation of a semicarbazone

Alkaline hydrolysis of a 16β-acetoxy-17-oxo steroid is accompanied by almost complete rearrangement of the product to a 16-oxo-17β-hydroxy steroid. Hydrolysis can be achieved without rearrangement by 1) formation of a C-17 semicarbazone, 2) alkaline removal of the acetate group, and 3) removal of the semicarbazone group in the presence of pyruvic acid-acetic acid. By employing this technique, the title compound was obtained from its diacetate in a yield of 65%.     

The Synthesis of O-Substituted 6-Oximes of 16α,17α-Cyclohexanopregn-4-ene-3,6,20-trione Labeled by Tritium in Position 1,2

6-O-(3-Methoxycarbonylpropyl)- and 6-O-(3-carboxypropyl)oximes of 16,17-cyclohexanopregn-4-ene-3,6,20-trione labeled by tritium in position 1,2 were synthesized. When using homogenous catalysts, the molar radioactivity of the resulting preparations was 1.5–1.7 PBq/mol.     

11α-Hydroxylation of 16α,17-epoxyprogesterone by Rhizopus nigricans in a biphasic ionic liquid aqueous system

11α-Hydroxylation of 16α,17-epoxyprogesterone (EP) by Rhizopus nigricans is an essential step in the synthesis of many steroidal drugs, while low conversion of the biohydroxylation is a tough problem to be solved urgently in industry. Two ionic liquids (ILs) of [BMIm][PF(6)] and [BMIm][NTf(2)] were used in the biotransformation of EP by R. nigricans. The results indicated that the conversion carried out in [BMIm][PF(6)]-aqueous biphasic system was greatly increased to above 90% at 18 g/L feeding concentration. A simplified mechanism was proposed to explain the improvement of the bioconversion in a biphasic ionic liquid aqueous system. Besides, successive three batches of bioconversion were carried out in the biphasic system with a total conversion of 87% at phase ratio 10 and 75% at phase ratio 5, respectively. Since recycling of the [BMIm][PF(6)] is quite easy, there is a great potential for the application of ILs in fungi biotransformation to implement green production.     

Solid-state NMR analysis of steroidal conformation of 17α- and 17β-estradiol in the absence and presence of lipid environment

Solid-state {(1)H}(13)C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy has been applied to 17β-estradiol (E2) and 17α-estradiol (E2α), to analyze the steroidal ring conformations of the two isomers in the absence and presence of lipids at the atomic level. In the absence of lipid, the high-resolution (13)C NMR signals of E2 in a powdered form show only singlet patterns, suggesting a single ring conformation. In contrast, the (13)C signals of E2α reveal multiplet patterns with splittings of 20-300Hz, implying multiple ring conformations. In the presence of a mimic of the lipid environment, made by mixing 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC) in a molar ratio 3:1, E2 and E2α revealed multiplet patterns different from those seen in the absence of lipids, indicating that the two isomers adopt multiple conformations in the lipid environment. In this work, on the basis of chemical shift isotropy and anisotropy analysis, we demonstrated that E2 and E2α prefer to adopt multiple steroidal ring conformations in the presence of a lipid environment, distinct from that observed in solution phase and powdered form.