Steroid Dimers Research Articles

Mono- and bis(steroids) containing a cyclooctane core: Synthesis, antiproliferative activity, and action on cell cytoskeleton microtubules.

Steroid dimers of natural and synthetic origin possess an unusual and complex molecular architecture that may lead to the realization of peculiar effects in biological systems, in particular in different cancer cell lines. In the present work, diastereoselective ring-opening of mono- and polyoxiranes, containing a cyclooctane core, by azide-anion was performed to yield a series of azidoalcohols with different types of symmetry. The products were involved in copper-catalyzed azyde-alkyne cycloaddition (CuAAC) reaction with ethinylestradiol and ethinyltestosterone, and the resulting steroids and steroid dimers with triazole linkers were screened for their antiproliferative activity via (3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide) assay. All the compounds revealed cytotoxicity toward several cancer cell lines. The effect of the most potent compound, containing two estradiol moieties, on the microtubules (MT) dynamics was investigated by immunofluorescent microscopy. The disruption of the majority of interphase cell cytoplasmic MT and mitotic event disturbances in the presence of the studied compound were observed. The latter effect caused the appearance of numerous multinucleated cells.

Facile Synthesis of Hydroquinone Linked 3,3’‐Steroid Dimers via a Modified Mitsunobu Protocol

AbstractA successful approach for the construction of steroid dimers with a hydroquinone linker under PBu3/TMAD/Et3N/toluene conditions is described. This study provided a new one‐step methodology for the design and synthesis of bis‐steroidal 1,4‐phenylene diethers using mild and effective reagents.

Synthesis of Pseudo-Glycoside hybrid steroid dimers NMR and X-ray characterization

The synthesis of pseudo-glycoside hybrid dimers in which 4-oxa-5α-cholestane and cholest-5-ene units are bridged through an α- or β-glycosidic bond is described. The structures of both steroid pseudo-glycosides were elucidated by combined 1D and 2D NMR techniques. Single crystal X-ray Diffraction studies corroborated the proposed structures.

Synthesis and characterization of a highly fluorescent benzofuran dimer derived from estradiol

AbstractPd‐catalyzed cyclization of a fluorescent dimer in which two cores of the potent estrogenic estradiol are bridged by the 1,4‐diethynil benzene moiety led to a steroid dimer bearing the 1,4‐di(benzofuran‐2‐yl)benzene. The obtained compound showed an intense blue fluorescence characterized by a broad emission band between 350 and 550 nm, with four maxima at 384, 403, 435, and 456 nm. The benzofuran dimer showed an 18‐fold increased quantum yield compared with that of its synthetic precursor.

Differentiation of steroid isomers by steroid analogues adducted trapped ion mobility spectrometry-mass spectrometry.

Steroids are one of the important indicators of health and disease. However, due to the high similarity of steroid structures, there are several potential obstacles in the differentiation of steroids, especially for their isomers. Herein, we described a trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) approach based on the steroid analogue adduction for isomer-specific identification of steroids. The application of dexamethasone (DEX) to form heterodimers with steroids enhanced the separation of their isomers in TIMS. Two isomer pairs including 17-hydroxyprogesterone/11-deoxycorticosterone and androsterone/epiandrosterone were successfully separated as the heterodimers with DEX by TIMS. The stability of DEX-adducted heterodimers is comparable with steroid dimers. Owing to the high separation efficiency and stability, the relative quantification of steroid isomers was demonstrated with the proposed method.

Montmorillonite Catalyzed Synthesis of Novel Steroid Dimers.

The reactions of sterols (androst-5-en-3β-ol-17-one, diosgenin, and cholesterol) and their tosylates with hydroquinone aimed at the synthesis of O,O-1,4-phenylene-linked steroid dimers were studied. The reaction course strongly depended on the conditions used. The study has shown that the major reaction products are the elimination products and unusual steroid dimers resulting from the nucleophilic attack of the hydroquinone C2 carbon atom on the steroid C3 position, followed by an intramolecular addition to the C5-C6 double bond. A different reaction course was observed when montmorillonite K10 was used as a catalyst. The reaction of androst-5-en-3β-ol-17-one under the promotion of this catalyst afforded the O,O-1,4-phenylene-linked steroid dimer in addition to the disteroidal ether. The formation of the latter compound was suppressed by using 3-tosylate as a substrate instead of the free sterol. The reactions of androst-5-en-3β-ol-17-one tosylate and cholesteryl tosylate with hydroquinone catalyzed by montmorillonite K10 carried out under optimized conditions afforded the desired dimers in 31% and 67% yield, respectively.

Synthesis, NMR characterization and cytotoxic activity of hybrid spirostanic sapogenins-estradiol dimers

Four hybrid steroid dimers were obtained by BF3·Et2O-catalyzed aldol condensation of acetylated steroid sapogenins with 2-formyl-estradiol diacetate. The structures of the obtained dimers were unambiguously established by NMR. The hybrid dimers 9a (IC50 18.37 μM) and 9c (IC50 9.4 μM) with the 5α configuration at the A/B rings junction showed the higher cytotoxicity against HeLa, with selectivity index of 4.36 and 11.8 respectively. The presence of a carbonyl function at position C-12 produced the highest cytotoxic effect, which is in line with our previous reports.

A Crystalline Dimeric Steroidal Diboronate with Electronically Impeded Rotation

The dimeric steroid SMR-3, featuring a 1,4-phenyldiboronic ester flanked by two pregnan-triol frameworks, was synthesized to explore the intramolecular dynamics of its central component. The structural data from single-crystal X-ray diffraction studies and the Hirshfeld analyses indicate small steric effects around the aromatic ring that should favor the intended motion. However, solid-state NMR data obtained through VT 13C{1H} CPMAS and 2H spin-echo experiments, using the deuterated analogue SMR-3D4, revealed that this component is rigid even at temperatures where other reported steroidal molecular rotors experience fast rotation (85 °C). A combination of classical molecular dynamics, molecular mechanics, and correlated ab initio calculations allowed us to distinguish the steric and electronic factors that restrict the potential motion in this compound. The experimental and computational data reveal that electronic components dominate the behavior and are responsible for the high rotational barrier in the SMR-3 crystal.

Synthesis and characterization of a fluorescent steroid dimer linked through C-19 by a 1,4-Bis(phenylethynyl)phenylene fragment

The synthesis and characterization of a dimer in which two nuclei of 3β-acetoxy-19-hydroxyandrost-5-en-17-one are linked by the fluorescent 1,4-bis(phenylethynyl)phenylene bridge attached to the oxygenated functions at positions C-19 of each steroid fragment is described. The compound was obtained in five steps and 23 % overall yield and showed a strong blue emission with a quantum yield of 0.66.

Synthesis and Characterization of Hybrid Dimeric Steroid Spiroketals

AbstractThe synthesis of six dimeric spiroketals bearing an estradiol half fused to the 5α- or 5β-epimers of androstane, cholestane, and spirostane nuclei is described. The synthetic procedure comprises the Sonogashira­ coupling of different steroid alkynes with 2-iodoestradiol 17-monoacetate, followed by Pd-catalyzed spiroketalization. The structural characterization of the obtained hybrid dimers was performed using a combination of 1D and 2D NMR techniques, and was assisted by DFT calculations. Single crystal X-ray diffraction of one of the obtained compounds confirmed the proposed structures.

Reductive desymmetrization of steroid dimers

NaBH3CN reduction of symmetric dimers in which two steroid units are linked by a 1,4-dimethylidenebenzene moiety followed two different courses: (a) hydrogenation of the benzylic double bond and (b) reductive F ring opening of the side chain. While courses a and b led to symmetrical dimers, the combination of both pathways produced an unsymmetrical dimer that bears different side chains in each half. The exhaustive NMR characterization of all obtained compounds is presented.

A review on steroid dimers: 2011–2019

The first review article on steroid dimers by Li and Dias in 1997, followed by the second review and a book on steroid dimers by Nahar and Sarker in 2007 and 2012, respectively, covered steroid dimers reported until the end of 2010. Since then, there have been considerable amounts of research carried out on steroid dimers, prompting the need for another comprehensive review on this topic. Therefore, this present review appraises the literature published during the period 2011–2019 on various aspects of steroid dimers, including isolation from natural sources, synthesis and applications. A structured and systematic literature search was performed, using the key words: steroid dimer, steroidal dimer, dimeric steroid, bis-steroid, bis-steroidal conjugates, molecular umbrella, cephalostatins, ritterazines and crellastatins. Several databases like Web of Knowledge, Science Direct, PubMed and Google Scholar were consulted. During the period covered in this review, well over 200 new synthetic steroidal dimers, ring A-ring A connection being the major group, have been reported, only one natural steroid dimer has been isolated, and potential applications of steroid dimers in the treatment of cancers and tumors, and microbial infections have been indicated.

Synthesis and Solid-State Dynamics of a Crystalline Steroid Molecular Rotor without the Alkyne Axle: Steroid Dimers Based on a 1,4-Di(1,3-dioxan-2-yl)benzene Moiety.

Two diastereomeric crystalline steroid dimers were obtained by acid-catalyzed double acetalization of (20S)-5α-pregnan-3β,16β,20-triol 3-monoacetate with terephtalaldehyde. These compounds were characterized by NMR in solution, MS, single-crystal X-ray diffraction, and variable-temperature solid-state NMR by 13C cross-polarization magic angle spinning (CPMAS). While the phenylene rotator in the SR diastereomer remains static even at 373 K, the RR isomer shows a slow rotational process of the phenylene ring at temperatures above room temperature and thus may be considered the first crystalline steroid molecular rotor without the alkyne axle.

STEROID CONJUGATES AS POTENTIAL ANTI-CANCER AGENTS

The review is dedicated to results of investigations of steroid conjugates published predominantly over the past decade. It consists of three parts in which the data concerning biological activity of steroid conjugates with known drugs, steroid dimers, and steroid conjugates with some natural compounds, their fragments and related derivatives and analogs, are discussed. The structures of 231 steroid conjugates and their anti-cancer properties are presented.

Mesoscale Assembly of Bisteroidal Esters from Terephthalic Acid.

A new series of bisteroidal esters was synthesized using a spacer group, sterols and sapogenins as substrates. Steroidal dimers were prepared in high yields employing diesters of terephthalic acid as linkages at the 3β, 3′β steroidal positions. In all attempts to crystallize bisteroids, it was observed that the compounds tended to self-organize in solution, which was detected when employing various solvent systems. The non-covalent interactions (van der Waals) of the steroidal moieties of this series of symmetrical bisteroids, the polarity of the solvents systems, and the different solubilities of the bisteroid aggregates, indeed induce the molecules to self-assemble into supramolecular structures with well-defined organization. Our results show that the self-assembled structures for the bisteroidal derivatives depend on the solvent system used: with hexane/EtOAc, membrane-shaped structures were obtained, while pure EtOAc afforded strand-shaped arrangements. In the CHCl3/CH3OH system, thin strands were formed, since van der Waals interactions are lowered in this system, as a consequence of the increased solubility of the bisteroids in CHCl3. Based on the characterization by SEM and XRD, we show evidence that the phenomenon of self-assembly of bisteroids occurs presenting different morphologies depending on the solvent used. The new steroidal dimer derivatives were characterized by NMR, TGA, DSC, SEM, and XRD. Finally, the molecular structure of one bisteroid was confirmed by single-crystal X-ray analysis.

Design, Synthesis, and Biological Evaluation of Two Series of Novel A-Ring Fused Steroidal Pyrazines as Potential Anticancer Agents.

Background: Increasingly, different heterocyclic systems have been introduced into the steroid nucleus to significantly enhance the antitumor activities of steroid molecules. However, in this study, few literature precedents describing the pyrazine heterocyclic-condensed modification to an A-ring of steroid monomers were found, although the pyrazine group is thought to be essential for the potent anticancer activity of clinically relevant drugs and natural steroid dimers. Methods and Results: Two series of novel A-ring fused steroidal pyrazines were designed and efficiently synthesized from commercially available progesterone via key α-ketoenol intermediates. Through a cell counting kit-8 cytotoxic assay of 36 derivatives for three tumor cells, 14 compounds displayed significant antiproliferative activity compared to 5-fluorouracil, especially for human prostatic tumor cells (PC-3) in vitro. Further mechanistic studies indicated that the most active compound, 12n (IC50, 0.93 μM; SI, 28.71), could induce the cell apoptosis of PC-3 cells in a dose-dependent manner and cause cell cycle arrest in the G2/M phase. The molecular docking study suggested that compound 12n fitted the active sites of cytochrome P450 17A1 (6CIZ) well. Conclusions: 12n might serve as a promising lead compound for the development of novel anticancer drugs. This facile ring-closing strategy may provide a novel and promising avenue for the cycloaddition reaction of the steroidal skeleton through α-ketoenol intermediates.

Synthesis, complete NMR assignment and structural study of a steroidal dimer of 17α-ethynyl-5α,10α-estran-17β-ol with diethynylbenzene spacer

A phenylene-bridged steroidal dimer derived from 17α-ethynyl-5α,10α-estran-17β-ol with molecular rotor-like architecture was synthesized to investigate the supramolecular interactions directing the crystallization of these systems. Structures with varying importance in complementarity between H-bonding and hydrophobic interactions can be observed directing the packing of the obtained crystals, depending on the synthetic stage, though conserving the same space group for both systems. Such behavior clearly shows the versatility achievable using steroids as crystal packing directors. Alongside this structural study, the complete NMR assignment is presented for the dimer, and precursors, in which the steroids present an unconventional and noteworthy A-B ring fusion.

Synthesis of Dimeric Steroid Trioxabispiroacetals Scaffolds by Gold(I)‐Catalyzed Hydroalkoxylation–Hydration of Diynediols

Five novel dimers in which the steroid cores are bridged by a 6,5,6‐trioxabispiroacetal moiety were synthesized by gold(I)‐catalyzed hydroalkoxylation–hydration of steroid diynediols. The double spiroacetalization proceeded with excellent yield and produced almost exclusively the C2 symmetrical trans diastereomer. A small amount of the cis unsymmetrical diastereomer was isolated only in one case. Density Functional Theory calculations were used to further analyze and justify the population of the diastereomers. Characterization of the obtained dimers was based on combined 1D and 2D NMR techniques. X‐ray diffraction of one of the obtained dimers corroborated the anticipated V‐shaped structure and provided additional structural insights on the crystal network. Unexpectedly, the crystalline array showed interconnected voids, resulting in channels that make this new class of steroid dimers suitable candidates for the development of applications on solid state supramolecular chemistry.

Synthesis of Symmetrical and Hybrid Dimeric Steroids by Double Suzuki–Miyaura Cross Coupling of 4-Bromo-3-oxo Steroids and Benzene-1,4-diboronic Acid

Two symmetrical dimers and one hybrid dimer in which the steroid cores are connected by a 1,4-phenylene moiety were obtained by double Suzuki–Miyaura cross coupling of benzene-1,4-diboronic acid with 4-bromo-4-en-3-oxosteroids derived from cholesterol and diosgenin. Detailed NMR characterization of the obtained dimers is described.

Steroidal dimer by001 inhibits proliferation and migration of esophageal cancer cells via multiple mechanisms.

To investigate the potential inhibitory effects of structurally novel steroidal dimer by001 in esophageal cancer in vitro. The cytotoxicity of by001 on esophageal, gastric, neuroblastoma and prostate cancer cells was examined MTT assay and colony formation assay. By001 induced apoptosis and production of intracellular reactive oxygen species on esophageal cancer cells Ec109, TE-1 and human normal gastric epithelial cells GES-1 was detected by flow cytometry. The effect of by001 on mitochondrial membrane potential was detected by fluorescence microscope through JC-1 staining. The level of intracellular reactive oxygen species was measured by fluorescence microscope and flow cytometry via DCFH-DA staining. The effect of by001 on members of Bcl-2 family, Fas, LC3, PARP and caspases was determined by Western blot. The effect of by001 on migration was measured by transwell assay. By001 effectively inhibited proliferation of esophageal, gastric, neuroblastoma and prostate cancer cells in a time- and concentration-dependent manner in vitro. By001 reduced the number and the size of colonies at low micromolar concentrations, elevated cellular ROS levels and caused mitochondrial dysfunction in esophageal cancer cells. Molecular mechanistic studies showed that by001 triggered apoptosis through regulating members of Bcl-2 family and Fas. These findings suggested that by001 may inhibited proliferation of esophageal cancer cells through mitochondria and death receptor-mediated apoptotic pathways, autophagy induction, as well as suppressed migration of esophageal cancer cells.