16-dehydropregnenolone Acetate Research Articles

Novel d-Annulated Pentacyclic Steroids: Regioselective Synthesis and Biological Evaluation in Breast Cancer Cells.

The acid-catalyzed cyclization of benzylidenes based on 16-dehydropregnenolone acetate (16-DPA) was studied. It was found that these compounds readily undergo regioselective interrupted Nazarov cyclization with trapping chloride ion and an efficient method of the synthesis of d-annulated pentacyclic steroids based on this reaction was proposed. The structures of the synthesized pentacyclic steroids were determined by NMR and X-ray diffraction. It was found that the reaction affords a single diastereomer, but the latter can crystallize as two conformers depending on the structure. Antiproliferative activity of synthesized compounds was evaluated against two breast cancer cell lines: MCF-7 and MDA-MB-231. All tested compounds showed relatively high antiproliferative activity. The synthetic potential of the protocol developed was illustrated by the gram-scale experiment.

One pot synthesis of novel pregnane-sulphur prodrugs, spectroscopic investigation, conformational analysis, chemical reactivity, Fukui function and their mathematical model

Novel sulphur derivatives have been synthesized for the first time from 16-Dehydropregnenolone acetate (16-DPA) by adopting thia-Michael addition reaction yielding 2-[(3β-acetoxy) pregn–5-ene-20-one −16 –thio] propanoic acid, 2-[(3β-acetoxy) pregn–5-ene-20-one–16–thio] ethanoic acid, 3β-acetoxy 16α-(2-hydroxyethylthio)-pregn-5-ene-20-one and 3β-acetoxy-16β-(2-amino phenylthio)-pregn-5-ene-20-one. All the compounds were characterized with the help of 1H, 13C NMR, FT-IR spectroscopy and mass spectrometry. The molecular geometry and vibrational frequency of these compounds were calculated in ground state by density functional theory (DFT/B3LYP) using 6-31G (d, p) basis set. Conformational analysis of all the compounds was carried out to determine the most stable conformation. The electronic properties such as HOMO-LUMO energy were calculated by using time dependent density functional theory (TD-DFT). The topological parameters-electron density (ρBCP), Laplacian of electron density (∇2ρ(rBCP)), energy parameters-kinetic electron energy density (GBCP), potential electron density (VBCP) and the total electron energy density (HBCP) at the bond critical points (BCP) were analyzed by ‘Atoms in molecules’ AIM theory. Local reactivity descriptors like Fukui functions (fk+, fk−, fk0), local softness (sk+, Sk−, Sk0) and local electrophilicity indices (ωk+, ωk−, ωk0) analysis were performed to find out the reactive sites within the molecules. Molecular electrostatic potential of the synthesized compounds were also determined. Lastly a nonlinear mathematical model has been proposed and analyzed to study the effect of catalysts on these reactions. Local and global stability analysis of the mathematical model along with the persistence of the system was checked using theory of nonlinear ordinary differential equations.

Reactivity of Steroidal 1-Azadienes toward Carbonyl Compounds under Enamine Catalysis: Chiral Penta- and Hexacyclic Steroids.

The synthesis and reactivity of a steroidal N-sulfonyl-1-azadiene, derived from 16-dehydropregnenolone acetate, toward carbonyl compounds under enamine catalysis is disclosed. An unexpected annulation reaction was observed involving an initial stereoselective conjugate addition of the in situ generated enamine to the steroidal 1-azadiene. The developed diastereoselective synthetic methodology is a novel approach to a new class of chiral pentacyclic and hexacyclic steroids.

Continuous Flow Synthesis of 16-Dehydropregnenolone Acetate, a Key Synthon for Natural Steroids and Drugs

A telescoped multistep process to provide the continuous delivery of 16-dehydropregnenolone acetate (16-DPA) from diosgenin is described. The method was evaluated through batch screenings that helped to identify critical bottlenecks and flowability, and the best conditions were optimized in flow systems before the individual steps were telescoped together into a single integrated flow process. Further highlights of our approach include the use of efficient in-line extraction operations and reaction monitoring, the avoidance of time-consuming purifications between steps, and improvement of efficiency and safety standards.

Synthesis of condensed pregnano[17,16-d]triazolines under high pressure

Condensed pregnano[17,16-d]triazolines were produced in 1,3-dipolar cycloaddition of 16-dehydropregnenolone acetate with organic azides at 10 kbar. The structure of the synthesized compounds was determined by using two-dimensional NMR spectroscopy (1H—1H COSY, NOESY, HSQC, and HMBC).

Ionic hydrogenation-directed stereoselective construction of C-20(H) stereogenic center in steroid side chains: Scope and limitations

Stereoselective synthesis of steroidal C-20 tertiary alcohols with n-butyl, vinyl, furyl, thienyl, thiazolyl, aryl and pyridyl side chains via Grignard reaction or organolithium reagents have been realized starting from readily available 16-dehydropregnenolone acetate. The ionic hydrogenation of steroidal C-20 tertiary alcohols having furyl, methylfuryl, thienyl, phenyl and 4-methoxyphenyl side chains, resulted into the deoxygenated product with C-20 natural configuration in excellent yields. However, the alkyl, thiazolyl and pyridyl incorporated steroidal C-20 tertiary alcohols were failed under the same reaction condition. The scope of ionic hydrogenation is further highlighted through the stereoselective reduction of steroidal C-20,21-ene compounds with furyl, thienyl and 4-methoxyphenyl side chains gave the saturated compounds with C-20 natural configuration.

Bioconversion of 16-dehydropregnenolone Acetate to Exclusively 4-androstene-3,17-dione by Delftia acidovorans MTCC 3363.

Delftia acidovorans MTCC 3363 was found to convert 16-dehydropregnenolone acetate (16-DPA) exclusively to 4-androstene-3, 17-dione (AD). Addition of 9α-hydroxylase inhibitors was not required for preventing the accumulation of byproducts. The effect of pH, temperature, substrate concentration, surfactants and carrier solvents on this bioconversion has been studied. 16-DPA was maximally converted in buffered medium at pH 7.0, at temperature 30°C and 0.5 mg ml-1 substrate concentration. Detergent addition and temperature above 35°C had deleterious effect on bioconversion. Dioxan was found to be the best carrier solvent for biotransformation of 16-DPA to AD.

A study on the reaction of 16-dehydropregnenolone acetate with 2-aminobenzimidazole

The condensation of 16-dehydropregnenolone acetate with 2-aminobenzimidazole was studied. The polycyclic aromatic product was formed as a single regioisomer in a cascade reaction comprising addition, cyclization, autoxidation, and aromatization, in addition to the rearranged D-homo product. The reaction mechanism based on DFT calculations is proposed.

SeO2 mediated efficient synthesis of amides and α-ketoamides of secondary amines with wide substrate scope

SeO2 mediated oxidative amidation of acetophenones, phenylacetylenes, and phenylacetaldehydes to α-ketoamides and aldehydes to amides is reported. Amidation selectively proceeds with secondary amines. α-Ketoamide derivatives of natural products 16-dehydropregnenolone acetate (8), pregnenolone acetate (10), and progesterone (11) were synthesized.

Synthesis and biological activity of two pregnane derivatives with a triazole or imidazole ring at C-21

Pregnane derivatives are studied as agents for the treatment of different hormone-dependent diseases. The biological importance of these steroids is based on their potential use against cancer. In this study, we report the synthesis, characterization and biological activity of two pregnane derivatives with a triazole (3β-hydroxy-21-(1H-1,2,4-triazol-1-yl)pregna-5,16-dien-20-one; T–OH) or imidazole (3β-hydroxy-21-(1H-imidazol-1-yl)pregna-5,16-dien-20-one; I–OH) moieties at C-21. These derivatives were synthesized from 16-dehydropregnenolone acetate. The activity on cell proliferation of the compounds was measured on three human cancer cells lines: prostate cancer (PC-3), breast cancer (MCF7) and lung cancer (SK-LU-1). The cytotoxic and antiproliferative effects of T–OH and I–OH were assessed by using SBR and XTT methods, respectively. The gene expressions were evaluated by real time PCR. In addition, results were complemented by docking studies and transactivation assays using an expression vector to progesterone and androgen receptor.Results show that the two compounds inhibited the three cell lines proliferation in a dose-dependent manner. Compound I–OH downregulated the gene expression of the cyclins D1 and E1 in PC-3 and MFC7 cells; however, effect upon Ki-67, EAG1, BIM or survivin genes was not observed. Docking studies show poor interaction with the steroid receptors. Nevertheless, the transactivation assays show a weak antagonist effect of I–OH on progesterone receptor but not androgenic or antiandrogenic actions.In conclusion, the synthesized compounds inhibited cell proliferation as well as genes key to cell cycle of PC-3 and MCF7 cell lines. Therefore, these compounds could be considered a good starting point for the development of novel therapeutic alternatives to treat cancer.

Regio- and stereoselective synthesis of pregnane-fused isoxazolines by nitril-oxide/alkene 1,3-dipolar cycloaddition and an evaluation of their cell-growth inhibitory effect in vitro

Efficient syntheses of some pregnane-fused isoxazolines from 16-dehydropregnenolone acetate with different arylnitrile oxides were carried out by 1,3-dipolar cycloadditions. The intermolecular ring-closures occurred in a highly regio- and stereoselective manner permitting the formation of a single 16α,17α-condensed diastereomer in which the O terminus of the nitrile oxide dipole is attached to C-17 of the sterane core. The conversions were found to be affected significantly by the electronic character of the substituents on the aromatic moiety of the 1,3-dipoles. Deacetylation of the primary products resulted in the corresponding 3β-OH analogs. All of the synthesized compounds were subjected to in vitro pharmacological studies for the determination of their antiproliferative effects on four breast cancer cell lines (MCF7, T47D, MDA-MB-231 and MDA-MB-361).

Facile green synthesis of 16-dehydropregnenolone acetate (16-DPA) from diosgenin

ABSTRACTChromium- and MnO2-free green synthesis of industrially important steroidal drug intermediate 16-dehydropregnenolone acetate (16-DPA) starting from diosgenin is reported. The reaction sequence involves three steps: acetolysis followed by acetylation, oxidation, and hydrolysis. In the first step, Ac2O was used both as reagent and solvent in combination with a Lewis acid (AlCl3), which led to considerable reduction of high temperature and pressure requirements of earlier processes. The oxidation step was made catalytic with the use of KMnO4(5 mol%) in the presence of co-oxidant NaIO4, leading to less waste generation (of chromium, MnO2, etc.). Minimization of the temperature, pressure, time consumption, and use of nontoxic solvents makes the process very handy and simple.

Synthesis and activity of novel 16-dehydropregnenolone acetate derivatives as inhibitors of type 1 5α-reductase and on cancer cell line SK-LU-1

Testosterone (T) plays a crucial role in prostate growth. In androgen-dependent tissues T is reduced to dihydrotestosterone (DHT) because of the presence of the 5α-reductase enzyme. This androgen is more active than T, since it has a higher affinity for the androgen receptor (AR). When this mechanism is altered, androgen-dependent diseases, including prostate cancer, could result.The aim of this study was to synthesize several 16-dehydropregnenolone acetate derivatives containing a triazole ring at C-21 and a linear or alicyclic ester moiety at C-3 of the steroidal skeleton. These steroids were designed as potential inhibitors of the activity of both types (1 and 2) of 5α-reductase. The cytotoxic activity of these compounds was also evaluated on a panel of PC-3, MCF7, and SK-LU-1 human cancer cell lines.The results from this study showed that with the exception of steroids 20-oxo-21-(1H-1,2,4-triazole-1-yl)pregna-5,16-dien-3β-yl-propionate and 20-oxo-21-(1H-1,2,4-triazole-1-yl)pregna-5,16-dien-3β-yl-pentanoate, the compounds exhibit a lower inhibitory activity for both isoenzymes of 5α-reductase than finasteride. Furthermore the 3β-hydroxy-21-(1H-1,2,4-triazole-1-yl)pregna-5,16-dien-20-one and 20-oxo-21-(1H-1,2,4-triazole-1-yl)pregna-5,16-dien-3β-yl-acetate derivatives display 80% cytotoxic activity on the SK-LU-1 cell line.These results also indicated that the triazole derivatives, which have a hydroxyl or acetoxy group at C-3, could have an anticancer effect, whereas the derivatives with a alicyclic ester group at C-3 do not show biological activity.

Synthesis of chiral hexacyclic steroids via [8π + 2π] cycloaddition of diazafulvenium methides.

First examples of [8π + 2π] cycloaddition of 16-dehydropregnenolone (16-DPA) acetate with diazafulvenium methides leading to chiral 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused steroids are reported. These hexacyclic steroids were obtained exclusively or selectively with the approach of the 1,7-dipole by the less hindered α-face of 16-DPA. Quantum chemical calculations at the DFT level were carried out, using the cycloaddition of 1-methyl- and 1-benzyl-diazafulvenium methides with N-phenylmaleimide as model reactions, in order to rationalize the stereochemistry outcome. The results indicate that endo cycloadditions of the more stable dipole conformation, having the 1-substituent pointing outward, are significantly more favorable than the alternative exo cycloaddition.

Nano-Chromium Trioxide Preparation from Chromium-Containing Waste Liquid Accompanying 16-Dehydropregnenolone Acetate

In polysorbate 80 - alcohol system, Cr2O3 powder had been prepared by using chromium-containing waste liquid from 16-dehydropregnenolone acetate. A precipitation was obtained when water was separated from the wastewater. The nanosample was got after the precipitation was calcined at 250 °C and 600 °C. Cr2O3 powder structure was characterized by FT-IR, SEM and XRD. The results show that the powders are spherical hexagonal system Cr2O3 nanoparticles. The particles size prepared in polysorbate 80 and n-Amyl alcohol system are 50-95 nm. The average value is 78 nm.

Crystal Structure and Synthesis of <i>N</i>-cyclohexyl-3<i>β</i>-hydroxyandrost-5,16-diene-17-carboxamide dihydrate

The 5a-Reductase (5aR) [EC 1.3.99.5] has an important enzymatic role in amplifying the androgenic response at prostatic tissues. It catalyzes the NADPH-dependent reduction of testosterone into 5a-dihydrotestosterone (5a-DHT) which, in turn, is responsible for the development of prostatic pathologies, such as Benign Prostatic Hyperplasia (BPH) and Prostate Cancer (PC).1 According to World Health Organization, PC is most prevalent in a mature male,2 whereas BPH is the second leading cause of prostatic surgeries,3 making such conditions to be public health problems. Due to the biological role of 5aR in the development of BPH and CP, its inhibition is a strategic target for rational drug design. Continuing our research on 5aR inhibitors, in the present paper the synthesis and X-ray structure determination of a novel steroidal 17-N-cyclohexylcarboxamide are described. The title compound, N-cyclohexyl-3b-hydroxyandrost-5,16diene-17-carboxamide, was prepared from commercially available 16-dehydropregnenolone acetate. This compound was submitted to the bromoform reaction to yield carboxylic acid, whose alcohol in C3 was protected by acetylation to produce the ester. In order to form the 17-N-cyclohexylcarboxamide moiety it was necessary to originate in situ an acyl chloride derivative, which in turn reacted with cyclohexylamine. Finally, the alcohol in C3 (100 mg, 23 mmol dissolved in hot MeOH, 20 mL) was removed by basic hydrolysis (a 2% aqueous sodium hydroxide solution, 7 mL) to yield the N-cyclohexyl-3bhydroxyandrost-5,16-diene-17-carboxamide. The crude product was purified by silica-gel column chromatography (hexane:ethyl acetate, 7:3); yield, 80% of pure product. Crystals suitable for X-ray Structure Analysis Online

Crystal Structure and Synthesis of 3<i>β</i>-(<i>p</i>-Iodobenzoyloxy)-16<i>α</i>,17<i>α</i>-Epoxypregn-4-En-6,20-Dione

3β-(p-iodobenzoyloxy)-16α,17α-epoxypregn-4-en-6,20-dione (7), C28H31O5I, was synthesized from the commercially available 16-dehydropregnenolone acetate. X-ray diffraction analysis of (1) demonstrated that it consisted of four rings, three six-membered rings (A, B and C) and one five-membered ring (D). A, B, C and D rings occur in an envelope, deformed chair, deformed chair, and the half chair conformations, respectively. The absolute configurations of 7 for the chiral centers are 3S, 8S, 9S, 10R, 13S and 14S. The crystal of 3β-(p-iodobenzoyloxy)-16α,17α-epoxypregn-4-en-6,20-dione is in monoclinic crystal system with space group P21, lattice constants: a = 10.8567 (11), b = 7.5479 (7), c = 16.0391 (16) A, β = 109.473 (1)°, V = 1239.1 (2) A3, Dx = 1.518 g/cm3 and Z = 2. The molecules in the crystal are stabilized by C-H···O interactions and van der Waals forces.

Synthesis, structutre and biological activity of substituted [16α,17α]cyclopropapregn-4-ene-3,20-diones

Aryldiazomethanes generated by vacuum thermolysis of arenecarbaldehyde tosylhydrazone sodium salts react stereospecifically with 16-dehydropregnenolone acetate. Subsequent decomposition of the pyrazoline adducts yielded hitherto unknown substituted [16α,17α]-cyclopropaprogesterones bearing the aryl substituents at the position 3′. Interaction of such cyclopropaprogesterones with progesterone receptor from rat uterine cytosol was studied.

Comparison of anti amoebic activity of stereoisomeric diamino and monoamino pregnene alkaloids and their N-methylated analogs

The steroidal alkaloid 3β, 20α-diamino-pregn-5-ene (kurchamine) obtained from the stem bark of Holarrhena antidysenterica is reported to have appreciable amoebicidal activity. Its three stereoisomers namely 3α, 20β-diamino-pregn-5-ene, 3β, 20β-diamino-pregn-5-ene and 3α,20α-diamino-pregn-5-ene and their intermediate stereoisomeric monoamino pregnene alkaloids namely 3β-amino-pregn-5-ene-20-one, 3α-amino-pregn-5-ene-20-one, 20α -amino-pregn-5-ene-3β-ol, 20β-amino-pregn-5-ene-3β-ol were synthesized. The natural stereoisomer and synthesized diamino and monoamino stereoisomers were N-methylated and all the compounds were evaluated for amoebicidal activity comparison. The natural stereoisomer 3β,20α-diamino-pregn-5-ene (kurchamine) was found to be superior than other stereoisomers and N-methylation was found to have insignificant effect on amoebicidal activity of stereoisomers. Stereoisomers of kurchamine, the natural pregnene alkaloid of Holarrhena antidysenterica (stem bark) and their intermediate monoamino stereoisomers were synthesized from 16-dehydropregnenolone acetate (16-DPA). Kurchamine and synthesized stereoisomers along with their N-methylated analogs were evaluated for their antiamoebic activity.

Studies on the reaction of 16-dehydropregnenolone acetate (16-DPA) with m-chloroperbenzoic acid

Studies on the reaction of 16-dehydropregnenolone acetate (16-DPA) with m-chloroperbenzoic acid