Evaluation of A-ring fused pyridine d-modified androstane derivatives for antiproliferative and aldo-keto reductase 1C3 inhibitory activity

Development of new steroid-based hydrazide and (thio)semicarbazone compounds with anticancer properties

Most breast and prostate cancers are caused by abnormal production or action of steroidal hormones. Hormonal drugs based on steroid scaffolds represent a significant class of chemotherapeutics that are routinely used in chemotherapy. In this study, the synthesis of new 17a-homo lactone and 17α-(pyridine-2-ylmethyl) androstane derivatives with hydrazide and semicarbazone motifs is presented. All compounds were screened for their effect on cell viability against a panel of five cancer cell lines and one healthy cell line. Two compounds showed significant cytotoxicity against cancer cells, with low toxicity against healthy cells. The relative binding affinities of compounds for the ligand-binding domains of estrogen receptor α, estrogen receptor β, androgen receptor and glucocorticoid receptor were tested using a fluorescence screen in yeast. Potential for inhibition of aldo-keto reductase 1C3 and 1C4 activity was measured in vitro. Experimental results are analyzed in the context of molecular docking simulations. Our results could help guide design of steroid compounds with improved anticancer properties against androgen- and estrogen-dependent cancers.

2-Chloro-3-cyano-4-nitrobenzyl pyridinium bromide as a potent anti-lung cancer molecule prepared using a single-step solvent-free method

Mono-/dimeric-substituted pyridinium and pyrazolium bromides were prepared under conventional and solvent-free silica-supported domestic microwave conditions. The atom economy, environmental product mass intensity and product mass intensity for solvent-free reactions showed significant importance for the synthesis of target molecules. 4-Nitrobenzyl-substituted pyridinium bromide showed potent anticancer properties compared with mono-/dimeric-substituted pyridinium and pyrazolium bromides against a lung cancer cell line (A-549). Molecular simulation studies were carried out for mono-/dimeric-substituted pyridinium and pyrazolium bromide against protein human CDK1/cyclinB1/CKS2 using the AutoDock program.

Synthesis, in vitro and in silico anticancer evaluation of novel pyridin-2-yl estra-1,3,5(10)-triene derivatives

Aim: The aim of this study was the synthesis of steroid compounds with heterocyclic rings and good anticancer properties. Materials & methods: The synthesis, in silico and in vitro anticancer testing of novel pyridin-2-yl estra-1,3,5(10)-triene derivatives was performed. Results: All synthesized compounds have shown promising results for, antiproliferative activity, relative binding affinities for the ligand binding domains of estrogen receptors α, β and androgen receptor, aromatase binding potential, and inhibition of AKR1C3 enzyme. Conclusion: 3-Benzyloxy (17E)-pycolinilidene derivative 9 showed the best antitumor potential against MDA-MB-231 cell line, an activity that can be explained by its moderate inhibition of AKR1C3. Molecular docking simulation indicates that it binds to AKR1C3 in a very similar orientation and geometry as steroidal inhibitor EM1404.

Synthesis, biological activities, and future perspectives of steroidal monocyclic pyridines

Steroidal pyridines are a class of compounds that have been the subject of extensive research in recent years due to their potential biological activities. The introduction of a pyridine ring into the steroid skeleton can significantly alter the chemical and biological properties of the compound, making it more potent and/or selective for a particular target. Different synthetic methods have been developed for the preparation of steroidal pyridines. This review provides an overview of the synthesis, biological activities, and future perspectives of steroidal monocyclic dihydropyridines, tetrahydropyridines, and pyridines from 2005 to the present. The different synthetic methods that have been developed for the preparation of these steroids are discussed, as well as the proposed mechanisms and the biological activities that have been reported. Finally, the potential of steroidal monocyclic pyridines for the development of new drugs is discussed. This review is intended to provide a comprehensive overview of the field of steroidal monocyclic pyridines for researchers and scientists who are interested in this area of research. It is also hoped that this review will stimulate further research into the synthesis and biological activities of steroidal pyridines to develop new and improved drugs for the treatment of diseases.

Novel D-modified heterocyclic androstane derivatives as potential anticancer agents: Synthesis, characterization, in vitro and in silico studies

Cancer remains a major health concern worldwide. The most frequently diagnosed types of cancer are caused by abnormal production or action of steroid hormones. In the present study, the synthesis and structural characterization of new heterocyclic androstane derivatives with D-homo lactone, 17α-(pyridine-2''-ylmethyl) or 17(E)-(pyridine-2''-ylmethylidene) moiety are presented. All compounds were evaluated for their anti-proliferative activity against HeLa cervical cancer cell line and non-cancerous kidney MDCK cells, where A-homo lactam compound 9A showed the greatest selectivity. Based on in vitro binding assays, N-formyl lactam compound 18 appeared to be the strong and isoform-selective ligand for ERα, while compound 9A displayed binding affinity for the GR-LBD, but also inhibited aldo-keto reductase 1C4 enzyme. Out of four selected compounds, methylpyrazolo derivative 13 showed potential for aromatase binding, while in silico studies provided insight into experimentally confirmed protein-ligand interactions.

Synthesis of Nitrogen-Containing Heterocyclic Scaffolds through Sequential Reactions of Aminoalkynes with Carbonyls

Sequential reactions of aminoalkynes represent a powerful tool to easily assembly biologically important polyfunctionalized nitrogen heterocyclic scaffolds. Metal catalysis often plays a key role in terms of selectivity, efficiency, atom economy, and green chemistry of these sequential approaches. This review examines the existing literature on the applications of reactions of aminoalkynes with carbonyls, which are emerging for their synthetic potential. Aspects concerning the features of the starting reagents, the catalytic systems, alternative reaction conditions, pathways and possible intermediates are provided.

Discovery of highly potent proapoptotic antiestrogens in a series of androst-5,16-dienes D-modified with imidazole-annulated pendants

Heterocyclic derivatives of steroid hormones are potent anticancer agents, which are used in the chemotherapy of breast and prostate cancers. Here, we describe a novel series of androstenes, D-modified with imidazole-annulated pendants, with significant anticancer activity. Novel C17-linked imidazole-annulated heterocyclic derivatives of dehydropregnenolone acetate were synthesized by the cyclocondensation with amidines using 3β-acetoxy-21-bromopregna-5,16-dien-20-one as the substrate. The antiproliferative potency of all the synthesized compounds was evaluated against human prostate (22Rv1) and human breast (MCF7) cancer cell lines and cytochromes P450. The lead compound, imidazo[1,2-a]pyridine derivative 3h, was revealed to be a promising candidate for future anticancer drug design, particularly against ERα-positive breast cancer. Lead compound 3h was found to be selective against MCF7 cells with IC₅₀ of 0.1μM and to act as both a potent selective agent blocking estrogen receptor α, which is involved in the stimulation of breast cancer growth, and an effective apoptosis inducer. The potential ability of compound 3h to bind to ERα was studded using molecular docking and molecular dynamics simulation. The selectivity analysis showed that lead steroid 3h produces no effects on cytochromes P450 CYP17A1, CYP7A1, and CYP21A2.

Formation of nitrogen-containing six-membered heterocycles on steroidal ring system: A review

Steroidal heterocyclic compounds constitute interesting and promising scaffolds for drug discovery as they have displayed diverse chemical reactivity and several types of biological activities. This study is a concise report on the most recent advancements in the chemistry of the steroid skeleton, including reactions at the A, B, and D ring systems. The modern synthetic methods for the steroidal nitrogen-containing six-membered heterocyclic derivatives from 3-keto-, 6-keto-, 17-keto-, and 20-keto-steroids, as well as 2-Aldo-, 4-Aldo-, 6-Aldo-, and 16-Aldo-steroids, are discussed. However, some other methods for the synthesis of steroidal N-containing 6-membered heterocyclic derivatives are also included. These compounds have shown therapeutic potential as cytotoxic agents against various cell lines and have also shown antiproliferative, anti-inflammatory, and antioxidant activities. Therefore, they could be used as prospective candidates for the development of various medications. This paper not only describes synthetic details involved in creating N-containing 6-membered heterocyclic steroid derivatives, but also provides a brief overview of the medicinal applications of these compounds. This information will be highly useful for the medicinal chemists conducting research in this field.

X-ray structure of human aldo-keto reductase 1C3 in complex with a bile acid fused tetrazole inhibitor: experimental validation, molecular docking and structural analysis

Aldo-keto reductase 1C3 (AKR1C3) catalyzes the reduction of androstenedione to testosterone and reduces the effectiveness of chemotherapeutics. AKR1C3 is a target for treatment of breast and prostate cancer and AKR1C3 inhibition could be an effective adjuvant therapy in the context of leukemia and other cancers. In the present study, steroidal bile acid fused tetrazoles were screened for their ability to inhibit AKR1C3. Four C24 bile acids with C-ring fused tetrazoles were moderate to strong AKR1C3 inhibitors (37-88% inhibition), while B-ring fused tetrazoles had no effect on AKR1C3 activity. Based on a fluorescence assay in yeast cells, these four compounds displayed no affinity for estrogen receptor-α, or the androgen receptor, suggesting a lack of estrogenic or androgenic effects. A top inhibitor showed specificity for AKR1C3 over AKR1C2, and inhibited AKR1C3 with an IC₅₀ of ∼7 μM. The structure of AKR1C3·NADP⁺ in complex with this C-ring fused bile acid tetrazole was determined by X-ray crystallography at 1.4 Å resolution, revealing that the C24 carboxylate is anchored to the catalytic oxyanion site (H117, Y55); meanwhile the tetrazole interacts with a tryptophan (W227) important for steroid recognition. Molecular docking predicts that all four top AKR1C3 inhibitors bind with nearly identical geometry, suggesting that C-ring bile acid fused tetrazoles represent a new class of AKR1C3 inhibitors.

Development of highly potent and specific AKR1C3 inhibitors to restore the chemosensitivity of drug-resistant breast cancer

Aldo-keto reductase 1C3 (AKR1C3) is overexpressed in multiple hormone related cancers, such as breast and prostate cancer, and is correlated with tumor development and aggressiveness. As a phase I biotransformation enzyme, AKR1C3 catalyzes the metabolic processes that lead to resistance to anthracyclines, the "gold standard" for breast cancer treatment. Novel approaches to restore the chemotherapy sensitivity of breast cancer are urgently required. Herein, we developed a new class of AKR1C3 inhibitors that demonstrated potent inhibitory activity and exquisite selectivity for closely related isoforms. The best derivative 27 (S19-1035) exhibits an IC₅₀ value of 3.04 nM for AKR1C3 and >3289-fold selectivity over other isoforms. We determined the co-crystal structures of AKR1C3 with three of the inhibitors, providing a solid foundation for further structure-based drug optimization. Co-administration of these AKR1C3 inhibitors significantly reversed the doxorubicin (DOX) resistance in a resistant breast cancer cell line. Therefore, the novel AKR1C3 specific inhibitors developed in this work may serve as effective adjuvants to overcome DOX resistance in breast cancer treatment.

In silico ADMET analysis of the A-, B- and D-modified androstane derivatives with potential anticancer effects

The major challenge in the fight against cancer is to design new drugs that will be more selective for cancer cells, with fewer side effects. Synthetic steroids such as cyproterone, fulvestrant, exemestane and abiraterone are approved powerful drugs for the treatment of hormone-dependent diseases such as breast and prostate cancers. Therefore, androstane derivatives in 17-substituted, 17a-homo lactone and 16,17-seco series, with potent anticancer activity, were selected for pharmacokinetic and druglike predictions from the absorption, distribution, metabolism and excretion (ADME) models. In silico determination of physico-chemical and ADMET properties was performed using SwissADME and ProTox-II web tools. The possibility of gastrointestinal absorption and brain penetration was analyzed using the BOILED-Egg model, while the in silico evaluation of the similarities between selected steroid derivatives and FDA-approved drugs was carried out using the SwissSimilarity tool. Of all tested, two compounds that showed good in silico ADMET results, in addition to promising cytotoxicity and molecular docking results, could potentially be evaluated in in vivo tests.

Antitumor potential of novel 5α,6β-dibromo steroidal D-homo lactone

New steroidal D-homo androstane derivative, 5α,6β-dibromo-3β-hydroxy-17-oxa-17a-homoandrostan-16-one was synthesized and its structure was confirmed by NMR spectroscopy. In silico ADME properties of this compound were assessed using the SwissADME online prediction tool. Six human cancer cell lines (MDA-MB-231, MCF-7, PC3, HT-29, HeLa, and A549) and one human noncancerous cell line (MRC-5) were used for in vitro cytotoxicity testing. Novel steroidal dibromide was also tested for relative binding affinity for the ligand binding domain of estrogen receptor α and β or the androgen receptor using a published assay in yeast cells. Ligand binding domains of each steroid receptor were expressed in-frame with yellow fluorescent protein in yeast and the fluorescence intensity changes upon addition of test compound was measured. The new compound showed selective cytotoxic activity against HT-29 (colon adenocarcinoma) and A549 (lung adenocarcinoma) cell lines, as well as the potential to induce apoptosis in HT-29 cells, while results obtained from ligand binding assay in yeast suggested a lack of significant estrogenic or androgenic properties.

Hormone receptor binding, selectivity and cytotoxicity of steroid D-homo lactone loaded chitosan nanoparticles for the treatment of breast and prostate cancer cells

Chemically modified steroids have a long history as anti-neoplastic drugs. Incorporation of a lactone moiety in the steroid nucleus, as in previously obtained 3β-acetoxy-17-oxa-17a-homoandrost-5-en-16-one (A) and 3β-hidroxy-17-oxa-17a-homoandrost-5-en-16-one (B), often results in enhanced anticancer properties. In this work, chitosan-based (Ch) nanoparticles were created and loaded with potent anticancer steroidal compounds, A and B. Changes to hormone receptor binding and cytotoxicity were then measured. In agreement with our previous results for A and B, A- and B-loaded Ch displayed cytotoxic properties against cancer cell lines. Both A-Ch and B-Ch showed activity toward estrogen negative breast cancer (MDA-MB-231) and androgen negative prostate cancer cell lines (PC-3). Greater selectivity toward cancer cells versus healthy lung fibroblast (MRC-5) was observed for B-Ch particles. Cell viability and cytotoxicity measurements after a recovery period indicate more robust recovery of healthy cells versus malignant cells. Compounds A and B or their Ch-encapsulated forms were shown to have negligible affinity for the ligand binding domain of estrogen receptor β or the androgen receptor in a fluorescent yeast screen, suggesting a lack of estrogenicity and androgenicity. Steroid-loaded chitosan nanoparticles display strong cytotoxicity towards MDA-MB-231 and PC-3 with a lack of hormone activity, indicating their safety and efficacy.

Investigation of the potential of bile acid methyl esters as inhibitors of aldo-keto reductase 1C2: insight from molecular docking, virtual screening, experimental assays and molecular dynamics

Human aldo-keto reductase 1C isoforms catalyze reduction of endogenous and exogenous compounds, including therapeutic drugs, and are associated with chemotherapy resistance. AKR1C2 is involved in metastatic processes and is a target for the treatment of various cancers. Here we used molecular docking to explore a series of bile acid methyl esters as AKR1C2 inhibitors. Autodock 4.2 ranked 10 of 11 test compounds above decoys based on ursodeoxycholate, an AKR1C2 inhibitor, while 5 ranked above 94% of decoys in Autodock Vina. Seven inactives reported not to inhibit AKR1C2 ranked below the decoy threshold. Virtual screen of a natural product library in Autodock Vina using the same parameters, identified steroidal derivatives, bile acids, and other AKR1C ligands in the top 5%. In experiments, 6 out of 11 tested bile acid methyl esters inhibited >50% of AKR1C2 activity, while 2 compounds were AKR1C3 inhibitors. The top ranking compound showed dose-dependent inhibition of AKR1C2 (IC50 ~3.6 µM). Molecular dynamics was used to explore interactions between a bile acid methyl ester and the AKR1C2 active site. Our molecular docking results identify AKR1C2 as a target for bile acid methyl esters, which combined with virtual screening results provides new directions for the synthesis of AKR1C inhibitors.

Structural diversity of bioactive steroid compounds isolated from soft corals in the period 2015-2020

Marine soft corals are known as a good source of biologically active compounds, among which a large number of steroid compounds are identified. Structures and activities of these compounds have been used in drug discovery and development. From 2015 to 2020, 179 new steroid compounds were isolated from soft corals and structurally characterized. In this review, we report the structural classification and bioactivities of these compounds. The largest group of steroids from soft corals are hydroxysteroids, while the most common biological activity is anticancer. Besides, anticancer hydroxysteroids from soft corals exhibit anti-inflammatory and antibacterial activity. Unlike anticancer and antibacterial activity that can be observed in a number of steroid classes, antioxidant activity and antileishmanial effect were observed only in 19-oxygenated steroids, antiviral activity in pregnane-type steroids and spirosteroids, immunosuppressive activity in epoxy- and epidioxysteroids, and antibacterial activity in two steroid classes, hydroxysteroids and ketosteroids. This systematically analyzed link between the structure and activity of natural marine steroids is a good starting point for future drug design.

Pyridine moiety: An insight into recent advances in treatment of cancer

The incidence of cancer is increasing worldwide, affecting a vast majority of the human population. As new different anticancer agents are being developed now, the requirement is to deal somehow with them and evaluate their safety. Among them, pyridine based drugs are contributing a lot, as it is one of the imperative pharmacophores occurring synthetically as well as naturally in heterocyclic compounds, and having a wide range of therapeutic applications in the area of drug discovery, thereby offering many chances for further improvement in antitumor agents via acting onto numerous receptors of extreme prominence. Many pyridine derivatives have been reported to inhibit enzymes, receptors and many other targets for controlling and curing the global health issue of cancer. Nowadays, in combination with other moieties, researchers are focusing on the development of pyridine-based new derivatives for cancer treatment. Therefore, this review sheds light on the recent therapeutic expansions of pyridine together with its molecular docking, structure-activity-relationship, availability in the market, and a summary of recently patented and published research works that shall jointly help the scientists to produce effective drugs with the desired pharmacological activity.

Cu-Catalyzed Pyridine Synthesis via Oxidative Annulation of Cyclic Ketones with Propargylamine

A Cu-catalyzed, easily scalable one-pot synthesis of fused pyridines by the reaction of cyclic ketones with propargylamine is described. The protocol was optimized based on the results of more than 30 experiments. The highest product yields were achieved in i-PrOH as a solvent in the presence of 5.0 mol % CuCl₂ in air. In contrast to the well-known Au-catalyzed protocol, our procedure is "laboratory friendly", cost-effective, and suitable for preparing dozens of grams of fused pyridine-based building blocks and does not require a high-pressure autoclave technique. Decreasing the catalyst amount in the reaction to 1.25 mol % CuCl₂ provided a yield comparable to that achieved with 5 mol % catalyst, though a longer reaction time was required. A plausible reaction mechanism was proposed. The scope and limitation of the reaction were studied using 24 different cyclic ketones as starting materials. The fused pyridine yield decreased among cyclic ketones in the following order: six-membered ≫ eight-membered > five-membered ∼ seven-membered. The elaborated reaction conditions demonstrated tolerance to a number of protective functional groups in ketone such as ester, tert-butoxycarbonyl (Boc)-protected amine, and acetal moieties.

Synthesis and anticancer potential of novel 5,6-oxygenated and/or halogenated steroidal d-homo lactones

A series of 5,6-modified steroidal d-homo lactones, comprising of halogenated and/or oxygenated derivatives, was synthesized and evaluated for potential anticancer properties. Preparation of many of these compounds involved investigating alternative synthetic pathways. In silico ADME testing was performed for both novel and some previously synthesized compounds. Calculated physicochemical properties were in accordance with the Lipinski, Veber, Egan, Ghose and Muegge criteria, suggesting the potential of these molecules as orally active agents. Cytotoxicity of the synthesized steroid derivatives was tested on six tumor and one normal human cell line. None of the investigated derivatives was toxic to non-cancerous MRC-5 control cells. Most of the compounds showed significant cytotoxicity against the treated cancer cell lines. Most notably, the 3β,5α,6β-trihydroxy derivative exhibited strong cytotoxicity against multiple cell lines (MCF-7, MDA-MB-231 and HT-29), with the highest effect observed for lung adenocarcinoma (A549) cells, for which this steroid was more cytotoxic than all of the three commercial chemotherapeutic agents used as reference compounds. Molecular docking suggests the 3β,5α,6β-trihydroxy derivative could bind the EGFR tyrosine kinase domain with high affinity, providing a potential mechanism for its cytotoxicity via inhibition of EGFR signaling. The most active compounds were further studied for their potential to induce apoptosis by the double-staining fluorescence method; where the 5α,6β-dibromide, 5α,6β-dichloride and 3β,5α,6β-triol induced apoptotic changes in all three treated cell lines: MDA-MB-231, HT-29 and A549. To predict interactions with nuclear steroidal receptors, affinity for the ligand binding domains of ERα, ERβ and AR was measured using a yeast-based fluorescence assay. The 5β,6β-epoxide, dibromide and 5α-hydroxy-3,6-dioxo derivatives showed affinity for ERα, while the 5α-fluoro-6β-hydroxy and 3β-acetoxy-5α,6β-dihydroxy derivatives were identified as ERβ ligands. None of the tested compounds showed affinity for AR. Structure-activity relationships of selected compounds were also examined.

Novel alkylaminoethyl derivatives of androstane 3-oximes as anticancer candidates: synthesis and evaluation of cytotoxic effects

Steroid anticancer drugs are the focus of numerous scientific research efforts. Due to their high cytotoxic effects against tumor cells, some natural or synthetic steroid compounds seem to be promising for the treatment of different classes of cancer. In the present study, fourteen novel O-alkylated oxyimino androst-4-ene derivatives were synthesized from isomerically pure 3E-oximes, using different alkylaminoethyl chlorides. Their in vitro cytotoxic activity was evaluated against eight human cancer cell lines, as well as against normal fetal lung (MRC-5) and human foreskin (BJ) fibroblasts, to test the efficiency and selectivity of the compounds. Most derivatives displayed strong activity against malignant melanoma (G-361), lung adenocarcinoma (A549) and colon adenocarcinoma (HT-29) cell lines. Angiogenesis was assessed in vitro using migration scratch and tube formation assays on HUVEC cells, where partial inhibition of endothelial cell migration was observed for the 17α-(pyridin-2-yl)methyl 2-(morpholin-4-yl)ethyl derivative. Among the compounds that most impaired the growth of lung cancer A549 cells, the (17E)-(pyridin-2-yl)methylidene derivative bearing a 2-(pyrrolidin-1-yl)ethyl substituent induced significant apoptosis in these cells. In combination with low cytotoxicity toward normal MRC-5 cells, this molecule stands out as a good candidate for further anticancer studies. In addition, in vitro investigations against cytochrome P450 enzymes revealed that certain compounds can bind selectively in the active sites of human steroid hydroxylases CYP7, CYP17A1, CYP19A1 or CYP21A2, which could be important for the development of novel activity modulators of these enzymes and identification of possible side effects.

Novel steroid O-alkylated 3-oxyimino derivatives were synthesized and evaluated in vitro for their antitumor properties. The obtained data indicate the potential of these functionalities for the development of new candidates for tumor treatment.

Overview of AKR1C3: Inhibitor Achievements and Disease Insights

Human aldo-keto reductase family 1 member C3 (AKR1C3) is known as a hormone activity regulator and prostaglandin F (PGF) synthase that regulates the occupancy of hormone receptors and cell proliferation. Because of the overexpression in metabolic diseases and various hormone-dependent and -independent carcinomas, as well as the emergence of clinical drug resistance, an increasing number of studies have investigated AKR1C3 inhibitors. Here, we briefly review the physiological and pathological function of AKR1C3 and then summarize the recent development of selective AKR1C3 inhibitors. We propose our viewpoints on the current problems associated with AKR1C3 inhibitors with the aim of providing a reference for future drug discovery and potential therapeutic perspectives on novel, potent, selective AKR1C3 inhibitors.

l-Proline catalyzed one-pot synthesis of polysubstituted pyridine system incorporating benzothiazole moietyviasustainable sonochemical approach

The efficient, highly convenient synthesis of polysubstituted pyridine derivatives was established via the reaction of N-(benzothiazol-2-yl)-2-cyanoacetamides with an assortment of arylidene malononitriles and arylidene ethyl cyanoacetates in the presence of l-proline as an efficient organocatalyst for this type of ultrasonic-mediated Michael addition. The mechanistic pathway and factors affecting this reaction were also established. The main characteristics of this procedure are high yields, use of a cost-effective catalyst, and easy work-up and purification.

The l-proline catalyzed ultrasonic-mediated synthesis of polysubstituted pyridone derivatives through the reaction of N-(benzothiazol-2-yl)-2-cyanoacetamides with an assortment of arylidenes has demonstrated as an efficient protocol.