Design, synthesis, and biological evaluation of novel androst-17ß-amide structurally related compounds as dual 5α-reductase inhibitors and androgen receptor antagonists.

Prostate cancer (PCa) is the second leading cause of death in men. Apart from androgen receptor, 5α-reductase has also been recognized as a potential target. In this study, a series of androst-17ß-amide compounds have been designed and synthesized targeting both AR and 5α-reductase. Their anti-proliferation activities were evaluated in AR + cell line 22RV1 and AR - cell line PC-3. The results indicated that most of the synthesized compounds inhibited the testosterone-stimulated cell proliferation with good selectivity and safety. Among all the compounds, androst[3,2-c]pyrazole derivatives (9a-9d) displayed the best inhibition activity comparable with flutamide. Moreover, most of the synthesized compounds displayed good 5α-reductase inhibitory activities with IC50 lower than 1 µM. The docking result of 9d-AR indicated that AR was forced to expands its binding cavity and maintain an antagonistic conformation since the steric hindrance of 9d impeded H12 transposition. Overall, compound 9d can be identified as a potential dual 5α-reductase inhibitor and AR antagonist, which might be of therapeutic importance for PCa treatment.

Synthesis of a dansyl-labeled inhibitor of 17ß-hydroxysteroid dehydrogenase type 3 for optical imaging.

The steroidogenic enzyme 17ß-hydroxysteroid dehydrogenase type 3 (17ß-HSD3) is a therapeutic target in the management of androgen-sensitive diseases such as prostate cancer and benign prostate hyperplasia. In this Letter, we designed and synthesized the first fluorescent inhibitor of this enzyme by combining a fluorogenic dansyl moiety to the chemical structure of a known inhibitor of 17ß-HSD3. The synthesized compound 3 is a potent fluorogenic compound (λex=348 nm and λ em=498 nm). It crosses the cell membrane, keeps its fluorescent properties and is distributed inside the LNCaP cells overexpressing 17ß-HSD3, where it inhibits the transformation of 4-androstene-3,17-dione into the androgen testosterone (IC50=262 nM).

Synthesis and biological evaluation of 3-tetrazolo steroidal analogs: Novel class of 5α-reductase inhibitors.

In the present study, a series of steroidal tetrazole derivatives of androstane and pregnane have been prepared in which the tetrazole moiety was appended at C-3 and 17a-aza locations. 3-Tetrazolo-3,5-androstadien-17-one (6), 3-tetrazolo-19-nor-3,5-androstadien-17-one (10), 3-tetrazolo-3,5-pregnadien-20-one (14), 17a-substituted 3-tetrazolo-17a-aza-D-homo-3,5-androstadien-17-one (26-31) and 3-(2-acetyltetrazolo)-17a-aza-d-homo-3,5-androstadien-17-one (32) were synthesized from dehydroepiandrosterone acetate (1) through multiple synthetic steps. Some of the synthesized compounds were evaluated for their in vitro 5α-reductase (5AR) inhibitory activity by measuring the conversion of [(3)H] androstenedione in human embryonic kidney (HEK) cells. In vivo 5α-reductase inhibitory activity also showed a significant reduction (p <0.05) in rat prostate weight. The most potent compound 14 showed 5AR-2 inhibition with IC50 being 15.6nM as compared to clinically used drug finasteride (40nM). There was also a significant inhibition of 5AR-1 with IC50 547nM compared to finasteride (453nM).

A Geomimetic Approach to the Formation and Identification of Fossil Sterane Biomarkers in Crude Oil: 18-nor-D-homo-Androstane and 5α,14ß-Androstane.

A diazonium ion derived from 18-aminoandrostane rearranged upon decomposition by a carbonium and a carbenium ion to furnish a mixture of a cyclopropanated compound and two D-homo-androstenes. Hydrogenation of this mixture gave the saturated hydrocarbons, 18-nor-D-homo-androstane and 5α,14ß-androstane, which are both fossil sterane biomarkers in Neoproterozoic crude oil. The so far unknown constitution and configuration as well as the geochemical genesis were established by this experiment. The starting material for this investigation, 18-aminoandrostane, was prepared in twelve steps from androstan-17-one (12.5% overall yield) with a Barton reaction as the key step.

Synthesis, structural analysis and antitumor activity of novel 17α-picolyl and 17(E)-picolinylidene A-modified androstane derivatives.

The heterocyclic ring at C-17 position of the androstane compounds plays an important role in biological activity. The aim of the present study was to synthesize and evaluate potential antitumor activity of different A-modified 17α-picolyl and 17(E)-picolinylidene androstane derivatives. In several synthetic steps, novel derivatives bearing the hydroximino, nitrile or lactame functions in A-ring were synthesized and characterized according to the spectral data, by mass analysis as well as XRD analysis (compounds 6, 13 and 15). The structurally most promising compounds 6, 11-17 were investigated as antitumor agents. The in vitro antiproliferative activity was evaluated against six human cancer cell lines: estrogen receptor negative (ER-) breast adenocarcinoma (MDA-MB-231); estrogen receptor positive (ER+) breast adenocarcinoma (MCF-7); prostate cancer (PC-3); human cervical carcinoma (HeLa); lung adenocarcinoma (A549) and colon adenocarcinoma (HT-29) using MTT assay. The results of the 48h incubation time in vitro tests showed that compound 15 was the most effective against PC-3 (IC50 6.6µM), compound 17 against MCF-7 (IC50 7.9µM) cells, while compound 16 exhibited strong antiproliferative effect against both, MCF-7 (IC50 1.7µM) and PC-3 (IC50 8.7µM) cancer cells. It was also found that compounds 16 and 17 induced apoptosis in MCF-7 cells (dicyano derivative 17 stronger then dioxime 16 and reference formestane), with no distinct changes in the cell cycle of MCF-7 cells.

Synthesis of novel 1,2,3-triazolyl derivatives of pregnane, androstane and D-homoandrostane. Tandem "click" reaction/Cu-catalyzed D-homo rearrangement.

Copper-catalyzed 1,3-dipolar cycloaddition has been employed in the reaction of steroidal azides with various terminal alkynes. A number of novel 1,2,3-triazolyl derivatives of pregnane, androstane and D-homoandrostane were obtained in high yield (70-98%). The developed synthetic protocols allowed us to attach the triazolyl moiety to both the side chain and the steroidal backbone directly, despite the steric hindrance exerted by the polycyclic system. The presence of Cu(II) was shown to evoke d-homo rearrangement under mild conditions. A rational choice of the copper precatalyst permitted us to carry out the "click" reaction either along with tandem d-homo rearrangement or in the absence of this process. The tendency of 16-heterosubstituted steroids to undergo D-homo rearrangement under Cu(II) catalysis was studied.

Synthesis of 5α-androstane-17-spiro-δ-lactones with a 3-keto, 3-hydroxy, 3-spirocarbamate or 3-spiromorpholinone as inhibitors of 17ß-hydroxysteroid dehydrogenases.

We synthesized two series of androstane derivatives as inhibitors of type 3 and type 5 17ß-hydroxysteroid dehydrogenases (17ß-HSDs). In the first series, four monospiro derivatives at position C17 were prepared from androsterone (ADT) or epi-ADT. After the protection of the alcohol at C3, the C17-ketone was alkylated with the lithium acetylide of tetrahydro-2-(but-3-ynyl)-2-H-pyran, the triple bond was hydrogenated, the protecting groups hydrolysed and the alcohols oxidized to give the corresponding 3-keto-17-spiro-lactone derivative. The other three compounds were generated from this keto-lactone by reducing the ketone at C3, or by introducing one or two methyl groups. In the second series, two dispiro derivatives at C3 and C17 were prepared from epi-ADT. After introducing a spiro-δ-lactone at C17 and an oxirane at C3, an aminolysis of the oxirane with L-isoleucine methyl ester provided an amino alcohol, which was treated with triphosgene or sodium methylate to afford a carbamate- or a morpholinone-androstane derivative, respectively. These steroid derivatives inhibited 17ß-HSD3 (14-88% at 1 µM; 46-94% at 10 µM) and 17ß-HSD5 (54-73% at 0.3 µM; 91-92% at 3 µM). They did not produce any androgenic activity and did not bind steroid (androgen, estrogen, glucocorticoid and progestin) receptors, suggesting a good profile for prostate cancer therapy.

A facile 'click' approach to novel 15ß-triazolyl-5α-androstane derivatives, and an evaluation of their antiproliferative activities in vitro.

Intermolecular Cu(I)-catalyzed azide-alkyne cycloadditions of 15ß-azido-17ß-hydroxy-5α-androstan-3ß-yl acetate with different terminal alkynes under optimized reaction conditions were carried out to furnish 15ß-triazolyl derivatives in good yields. Subsequent oxidation of the 'click' products with the Jones reagent afforded the corresponding 17-ketones. All the synthetized compounds were tested on three malignant human cell lines (HeLa, MCF7 and A431) in order to investigate their antiproliferative activities in vitro. Evidence of cell cycle blockade and apoptosis induction was obtained for the most effective five selected compounds by means of flow cytometry and microscopic techniques. The 15ß-triazolyl-5α-androstane framework may be considered an appropriate base for the design of steroidal antiproliferative agents.

From an ent-Estrane, through a nat-Androstane, to the Total Synthesis of the Marine-Derived Δ8,9-Pregnene (+)-03219A.

The total synthesis of (+)-03219A, a rare Δ8,9-pregnene isolated from the marine-derived Streptomyces sp. SCSIO 03219, is described that is based on a series of transformations that enable progression from epichlorohydrin to an ent-estrane, then conversion to a nat-androstane, and finally establishment of the natural product target. Key to the success of these studies was implementation of two rearrangement processes to formally invert the quaternary center at C13 and establish the C10 quaternary center.

Novel and efficient synthesis and antifungal evaluation of 2,3-functionalized cholestane and androstane derivatives.

Synthetic modifications of cholesterol and other traditional steroid molecules have become a promising area for the exploration and development of novel antifungal agents, especially with respect to the development of fatty-acid esters of steroids. In addition, 2,3-functionalized steroids are also compounds with potentially interesting biological properties and proper functionalization of 2,3-steroids can lead to the development of efficient syntheses of building blocks for novel fatty-acid esters of steroids. In this Letter, we outline a novel and efficient approach to the synthesis of 2,3-functionalized cholestane and androstane derivatives and present their promising preliminary antifungal activities against a number of fungal species.

Significant steroids: effective and general synthesis of 4alpha- and 4beta-amino-5alpha-androstanes.

4alpha-Aminosteroids were synthesized by the substitution of a 2alpha-bromo ketone using K(2)CO(3) as an activator; 4beta-aminosteroids were synthesized in excellent yields by a highly regioselective and trans-stereospecific ring opening of a steroidal 3,4alpha-epoxide using ZnCl(2)-H(2)O as a catalyst.

Molecular rearrangements of poststerone derivative steroid core with formation of unique D-homostructures of pregnane and androstane series.

20R-Hydroxy short-chain ecdysteroids were synthesized by chemo- and stereoselective reduction of poststerone acetonide with L-Selectride or LiAlH4. The same reaction with the excess of L- Selectride followed by the treatment of the reaction mixture with hydrochloric acid is accompanied by (8R)-13(14 → 8)abeo- rearrangements, which resulted in the contraction/expansion of C/D pregnane rings. The reaction of 20R-hydroxy poststerone analogs with (diethylamino)sulfur trifluoride (DAST) proceeds through intramolecular rearrangements and provides D-homo- or 13,14-seco- androstane structures.

Synthesis of (+)-cortistatin A.

Cortistatin A is a marine steroid with highly selective and perhaps mechanistically unique antiangiogenic activity. Herein we report a synthesis of this natural product by way of "cortistatinone", an intermediate ideally suited for investigating the key pharmacophore of the cortistatin family. The synthesis begins with a terrestrial steroid and traverses a route to cortistatin A through the discovery of unique chemical reactivity. Specifically, we demonstrate the first example of a directed, geminal C-H bisoxidation, a new fragmentation cascade to access expanded B-ring steroid systems, a chemoselective cyclization to install the hallmark oxabicycle of the cortistatin family, and a remarkably selective hydrogenation reaction, which should find extensive use in future syntheses of the cortistatins and designed analogues. The synthesis displays a level of brevity, efficiency, and practicality that will be crucial in evaluating the medicinal potential of this fascinating class of marine steroids.

Synthesis of novel steroidal D-ring substituted isoxazoline derivatives of 17-oxoandrostanes.

A facile synthesis of isoxazoline derivatives of 17-oxoandrostane at the side chain of D-ring is reported. The scheme involves the transformation of the starting dehydroepiandrosterone acetate (ketone) to the Knoevenegel product, reduction to the nitrile, and elimination to the carboxaldehyde. Cycloaddition of nitrileoxides across olefinic aldehyde intermediate led to the synthesis of novel side chain isoxazoline derivatives.

Synthesis and biological evaluation of a series of A,B-ring modified 16,17-secoandrostane derivatives.

The starting compound for the synthesis of 16,17-secoandrostane derivatives with the 4-en-3-on, 1,4-dien-3-on, 4,6-dien-3-on, and 1,4,6-trien-3-on systems was 3beta-hydroxy-17-methyl-16,17-secoandrost-5-en-16-nitrile-17-one (1), the Oppenauer oxidation of which yielded the corresponding 4-en-3-one derivative 2. Dehydrogenation of compound 2 with the aid of 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) gave the three products: 17-methyl-16,17-secoandrosta-1,4-dien-3,17-dione-16-nitrile (3), 17-methyl-16,17-secoandrosta-4,6-dien-3,17-dione-16-nitrile (4), and 17-methyl-16,17-secoandrosta-1,4,6-trien-3,17-dione-16-nitrile (5). On the other hand, epoxidation of compound 2 resulted in a mixture of alpha and beta isomers of 4,5-epoxy-17-methyl-16,17-secoandrosta-3,17-dione-16-nitrile (6 and 7). Opening of the oxirane rings of the mixture of 6 and 7 by the action of formic acid yielded the 4-hydroxy-4-en derivative 8. Antiaromatase activity and in vitro cytotoxicity against three tumor cell lines (human breast adenocarcinoma ER+, MCF-7, human breast adenocarcinoma ER-, MDA-MB-231, and prostate cancer PC3) of selected compounds were evaluated. Compound 2 exhibited a relatively strong inhibition of aromatase and extremely potent cytotoxicity against PC3 cells. Compound 8 showed satisfactory cytotoxicity against MCF-7 cells.

1H,13C, 19F NMR, and ESI mass spectral characterization of two geminal difluorosteroids.

Two geminal difluorosteroids, 3,3-difluoro-5beta-cholan-24-oic acid (1) and 3,3-difluoro-5alpha-androstan-17-one (2), have been prepared from corresponding ketosteroids with diethylaminosulphurtrifluoride (DAST) treatment in moderate yields. The structures of 1 and 2 have been characterized by (1)H, (13)C, (19)F NMR, and ESI mass spectral techniques.

Syntheses of immunomodulating androstanes and stigmastanes: comparison of their TNF-alpha inhibitory activity.

In a previous work our group showed that some synthetic stigmastanes may play a role in immune-mediated inflammation. In this paper we report the syntheses of a series of new steroidal compounds derived from dehydroepiandrosterone and stigmasterol, and the evaluation of their in vitro inhibitory activity of the TNF-alpha production by macrophages. A preliminary qualitative structure-activity relationship was established.

Multicomponent access to androstano-arylpyrimidines under microwave conditions and evaluation of their anti-cancer activity in vitro.

Novel ring D- and A-fused pyrimidines in the androstane series were efficiently synthesized within 10-15min in polar protic solvents under microwave irradiation via two kinds of multicomponent heterocyclization reactions followed by spontaneous or promoted oxidation. The rates of the one-pot catalyst-free transformations of steroidal ß-ketoaldehydes, ammonium acetate and substituted benzaldehydes in EtOH were found to be affected slightly by the steric and electronic feature of the substituents on the aromatic ring of the arylaldehyde component and the different reactivities of rings D and A of the sterane core. At the same time, the acid-catalyzed Biginelli-type reaction of dihydrotestosterone acetate, urea and arylaldehydes, and subsequent Jones oxidation of the primarily formed dihydropyrimidinones led to the corresponding ring A-fused 1H-pyrimidin-2-ones in moderate yields independently of the substituents on the aromatic moiety. The synthesized compounds were tested in vitro on human cancer cell lines as well as on non-cancerous fibroblast cells by the MTT assay in order to investigate their biological effects. As a result of the pharmacological screen, a remarkable structure-function relationship has been observed as the acetylated Biginelli products exhibited higher toxicity compared to the deacetylated version of each compound. Furthermore, in case of three 2'-arylpyrimidine derivatives a strong prostate cancer cell specific activity has been identified.

Structure-activity relationships of new A,D-ring modified steroids as aromatase inhibitors: design, synthesis, and biological activity evaluation.

Inhibition of aromatase is an efficient approach for the prevention and treatment of breast cancer. New A,D-ring modified steroid analogues of formestane and testolactone were designed and synthesized and their biochemical activity was investigated in vitro in an attempt to find new aromatase inhibitors and to gain insight into their structure-activity relationships (SAR). All compounds tested were less active than formestane. However, the 3-deoxy steroidal olefin 3a and its epoxide derivative 4a proved to be strong competitive aromatase inhibitors (K(i) = 50 and 38 nM and IC50 = 225 and 145 nM, respectively). According to our findings, the C-3 carbonyl group is not essential for anti-aromatase activity, but 5alpha-stereochemistry and some planarity in the steroidal framework is required. Furthermore, modification of the steroidal cyclopentanone D-ring, by construction of a delta-lactone six-membered ring, decreases the inhibitory potency. From the results obtained, it may be concluded that the binding pocket of the active site of aromatase requires planarity in the region of the steroid A,B-rings and the D-ring structure is critical for the binding.

Syntheses of new androstane brassinosteroids with 17beta-ester groups--butyrates, heptafluorobutyrates, and laurates.

New androstane brassinosteroids with 17beta-ester groups - butyrates, heptafluorobutyrates, and laurates (4-18) - were prepared. Brassinolide activity was evaluated using both the bean second internode bioassay and the rice lamina inclination test. Brassinosteroid 16 was found to be the most active by the bean second internode bioassay. This activity in the bean second internode bioassay corresponded with the field yield, while the RLIT bioassay does not.