Design, synthesis and biological evaluation of novel 2-aminobenzamides containing dithiocarbamate moiety as histone deacetylase inhibitors and potent antitumor agents

Dithiocarbamate as a Carbonyl Alternative in Pd-Catalyzed Carbonylative Homocoupling of Organoboronic Acids

We have developed a novel protocol for carbonylative homocoupling of arylboronic acids using dithiocarbamate esters as the carbonyl alternative. A series of arylboronic acids underwent smooth reaction with dithiocarbamate ester (Me2NCS2Me) in the presence of Pd(PPh3)2Cl2 catalyst, Cu(OAc)2·H2O additive, and Na2CO3 in DCE solvent, producing the biaryl ketones efficiently. The mechanism has been studied with the help of several control experiments that reveal the probability of thioamide intermediacy. Chemoselective homocoupling allows the postsynthetic modification of the product.

Photoinduced Decarboxylative Thioacylation of N-Hydroxyphthalimide Esters with Tetraalkylthiuram Disulfides

Dithiocarbamate is a key structural sequence in pharmaceuticals and agrochemicals, and its synthesis is crucial in organic chemistry. Although significant progress has been made in related synthesis research, developing a practical and universal synthesis method remains fascinating. Herein, we report a new visible-light-induced decarboxylation coupling reaction between N-hydroxyphthalimide esters and tetraalkylthiuram disulfides, which uses Ir(ppy)3 as a photocatalyst to promote the generation of corresponding decarboxylation thioacylation product-dithiocarbamates in high yields. This redox-neutral protocol uses inexpensive and readily available starting material under mild reaction conditions, exhibiting broad substrate scope and wide functional group compatibility. This method can be further used for post modification of complex natural products and bioactive drugs.

Synthetic Modifications of Andrographolide Targeting New Potential Anticancer Drug Candidates: A Comprehensive Overview

This review collects the synthetic modifications performed on andrographolide, a natural molecule derived from Andrographis paniculata, for oncology applications. Various pharmacomodulations were carried out, and the products were tested on different cancer cell lines. The impact of these modifications was analyzed with the aim of mapping the positions essential for activity to facilitate future research in this field. However, this study makes it clear that, in addition to structural modifications of the molecule, which can result in varying degrees of effectiveness in targeting interactions, the lipophilic capacity of the structures obtained through hemisynthesis is of significant importance.

Facile synthesis of tetrahydroquinoline containing dithiocarbamate derivatives via one-pot sequential multicomponent reaction

An efficient sequential multi-component method for the synthesis of tetrahydroquinoline containing dithiocarbamates has been developed. This reaction involved a boronic acid-catalysed reduction of quinolines to tertrahydroquinolines, followed by nucleophilic addition reaction with carbon disulphide to form dithiocarbamic acids and subsequent S-arylation via external base-free Chan-Evans-Lam coupling in a one-pot operation. The methodology is compatible with a wide variety of functional groups and also useful in the late-stage functionalization of pharmaceuticals. The dual role of the boronic acid as a catalyst (in the reduction of quinolines) and as a reagent (in the S-arylation) has been demonstrated for the first time herein.

Design, Synthesis, and Biological Evaluation of New Urushiol Derivatives as Potent Class I Histone Deacetylase Inhibitors

In the present study, a novel series of 11 urushiol-based hydroxamic acid histone deacetylase (HDAC) inhibitors was designed, synthesized, and biologically evaluated. Compounds 1-11 exhibited good to excellent inhibitory activities against HDAC1/2/3 (IC50 : 42.09-240.17 nM) and HDAC8 (IC50 : 16.11-41.15 nM) in vitro, with negligible activity against HDAC6 (>1409.59 nM). Considering HDAC8, docking experiments revealed some important features contributing to inhibitory activity. According to Western blot analysis, select compounds could notably enhance the acetylation of histone H3 and SMC3 but not-tubulin, indicating their privileged structure is appropriate for targeting class I HDACs. Furthermore, antiproliferation assays revealed that six compounds exerted greater in vitro antiproliferative activity against four human cancer cell lines (A2780, HT-29, MDA-MB-231, and HepG2, with IC50 values ranging from 2.31-5.13 μM) than suberoylanilide hydroxamic acid; administration of these compounds induced marked apoptosis in MDA-MB-231 cells, with cell cycle arrest in the G2/M phase. Collectively, specific synthesized compounds could be further optimized and biologically explored as antitumor agents.

Advances in epigenetic modifications and cervical cancer research

Cervical cancer (CC) is an important public health problem for women, and perspectives and information regarding its prevention and treatment are quickly evolving. Human papilloma virus (HPV) has been recognized as a major contributor to CC development; however, HPV infection is not the only cause of CC. Epigenetics refers to changes in gene expression levels caused by non-gene sequence changes. Growing evidence suggests that the disruption of gene expression patterns which were governed by epigenetic modifications can result in cancer, autoimmune diseases, and various other maladies. This article mainly reviews the current research status of epigenetic modifications in CC based on four aspects, respectively DNA methylation, histone modification, noncoding RNA regulation and chromatin regulation, and we also discuss their functions and molecular mechanisms in the occurrence and progression of CC. This review provides new ideas for early screening, risk assessment, molecular targeted therapy and prognostic prediction of CC.

Tacrine-Based Hybrids: Past, Present, and Future

Alzheimer's disease (AD) is a neurodegenerative disorder which is characterized by β-amyloid (Aβ) aggregation, τ-hyperphosphorylation, and loss of cholinergic neurons. The other important hallmarks of AD are oxidative stress, metal dyshomeostasis, inflammation, and cell cycle dysregulation. Multiple therapeutic targets may be proposed for the development of anti-AD drugs, and the "one drug-multiple targets" strategy is of current interest. Tacrine (THA) was the first clinically approved cholinesterase (ChE) inhibitor, which was withdrawn due to high hepatotoxicity. However, its high potency in ChE inhibition, low molecular weight, and simple structure make THA a promising scaffold for developing multi-target agents. In this review, we summarized THA-based hybrids published from 2006 to 2022, thus providing an overview of strategies that have been used in drug design and approaches that have resulted in significant cognitive improvements and reduced hepatotoxicity.

Targeting the epigenome in malignant melanoma: Facts, challenges and therapeutic promises

Malignant melanoma is the most lethal type of skin cancer with high rates of mortality. Although current treatment options provide a short-clinical benefit, acquired-drug resistance highlights the low 5-year survival rate among patients with advanced stage of the disease. In parallel, the involvement of an aberrant epigenetic landscape, (e.g., alterations in DNA methylation patterns, histone modifications marks and expression of non-coding RNAs), in addition to the genetic background, has been also associated with the onset and progression of melanoma. In this review article, we report on current therapeutic options in melanoma treatment with a focus on distinct epigenetic alterations and how their reversal, by specific drug compounds, can restore a normal phenotype. In particular, we concentrate on how single and/or combinatorial therapeutic approaches have utilized epigenetic drug compounds in being effective against malignant melanoma. Finally, the role of deregulated epigenetic mechanisms in promoting drug resistance to targeted therapies and immune checkpoint inhibitors is presented leading to the development of newly synthesized and/or improved drug compounds capable of targeting the epigenome of malignant melanoma.

Salvia miltiorrhiza in cancer: Potential role in regulating MicroRNAs and epigenetic enzymes

MicroRNAs are small non-coding RNAs that play important roles in gene regulation by influencing the translation and longevity of various target mRNAs and the expression of various target genes as well as by modifying histones and DNA methylation of promoter sites. Consequently, when dysregulated, microRNAs are involved in the development and progression of a variety of diseases, including cancer, by affecting cell growth, proliferation, differentiation, migration, and apoptosis. Preparations from the dried root and rhizome of Salvia miltiorrhiza Bge (Lamiaceae), also known as red sage or danshen, are widely used for treating cardiovascular diseases. Accumulating data suggest that certain bioactive constituents of this plant, particularly tanshinones, have broad antitumor effects by interfering with microRNAs and epigenetic enzymes. This paper reviews the evidence for the antineoplastic activities of S. miltiorrhiza constituents by causing or promoting cell cycle arrest, apoptosis, autophagy, epithelial-mesenchymal transition, angiogenesis, and epigenetic changes to provide an outlook on their future roles in the treatment of cancer, both alone and in combination with other modalities.

Design and Synthesis of New 2-Aminobenzamide Derivatives Containing Benzothiazole and Phenylamine Moiety and Their Cytotoxicity

Twelve new compounds including 2-aminobenzamide derivatives bearing benzothiazole and phenylamine moiety were designed and synthesized. The synthesized compounds were tested their cytotoxic activity against A549 and SW480 tumor cell lines. Compounds 3a and 3c exhibited cytotoxicity toward A549 cell line with IC50 values of 24.59 and 29.59 µM, respectively.

Classification models and SAR analysis on HDAC1 inhibitors using machine learning methods

Histone deacetylase (HDAC) 1, a member of the histone deacetylases family, plays a pivotal role in various tumors. In this study, we collected 7313 human HDAC1 inhibitors with bioactivities to form a dataset. Then, the dataset was divided into a training set and a test set using two splitting methods: (1) Kohonen's self-organizing map and (2) random splitting. The molecular structures were represented by MACCS fingerprints, RDKit fingerprints, topological torsions fingerprints and ECFP4 fingerprints. A total of 80 classification models were built by using five machine learning methods, including decision tree (DT), random forest, support vector machine, eXtreme Gradient Boosting and deep neural network. Model 15A_2 built by the XGBoost algorithm based on ECFP4 fingerprints showed the best performance, with an accuracy of 88.08% and an MCC value of 0.76 on the test set. Finally, we clustered the 7313 HDAC1 inhibitors into 31 subsets, and the substructural features in each subset were investigated. Moreover, using DT algorithm we analyzed the structure-activity relationship of HDAC1 inhibitors. It may conclude that some substructures have a significant effect on high activity, such as N-(2-amino-phenyl)-benzamide, benzimidazole, AR-42 analogues, hydroxamic acid with a middle chain alkyl and 4-aryl imidazole with a midchain of alkyl whose α carbon is chiral.

Sulfonamide-Derived Dithiocarbamate Gold(I) Complexes Induce the Apoptosis of Colon Cancer Cells by the Activation of Caspase 3 and Redox Imbalance

Two new families of dithiocarbamate gold(I) complexes derived from benzenesulfonamide with phosphine or carbene as ancillary ligands have been synthesized and characterized. In the screening of their in vitro activity on human colon carcinoma cells (Caco-2), we found that the more lipophilic complexes—those with the phosphine PPh₃—exhibited the highest anticancer activity whilst also displaying significant cancer cell selectivity. [Au(S₂CNHSO₂C₆H₅)(PPh₃)] (1) and [Au(S₂CNHSO₂-p-Me-C₆H₄)(IMePropargyl)] (8) produce cell death, probably by intrinsic apoptosis (mitochondrial membrane potential modification) and caspase 3 activation, causing cell cycle arrest in the G1 phase with p53 activation. Besides this, both complexes might act as multi-target anticancer drugs, as they inhibit the activity of the enzymes thioredoxin reductase (TrxR) and carbonic anhydrase (CA IX) with the alteration of the redox balance, and show a pro-oxidant effect.

Multicomponent Synthesis of S-Benzyl Dithiocarbamates from para-Quinone Methides and Their Biological Evaluation for the Treatment of Alzheimer's Disease

Multicomponent synthesis of biologically relevant S-benzyl dithiocarbamates from para-quinone methides, amines, and carbon disulfide are described under catalyst and additive-free conditions. The reactions proceeded at room temperature in a short span of time with excellent yields. One of the synthesized compounds, 3e showed considerable acetylcholinesterase (AChE) inhibitory (51.70 + 5.63% at 20 μm) and antioxidant (63.52 ± 1.15 at 20 μm) activities.

One-pot two-step dithiocarbamylation of styrenes: metal-free stereoselective synthesis of styrenyl dithiocarbamates

Styrenes have been functionalized to produce styrenyl dithiocarbamates by a one-pot two-step procedure without using any metal catalysts. Styrene was transformed into a bromo-derivative, which undergoes a domino nucleophilic substitution followed by elimination in the presence of a dithiocarbamate anion and triethylamine to produce trans-styrenyl dithiocarbamates exclusively. The reaction shows a wide substrate scope and good yields of products.

Design, synthesis and biological evaluation of novel o-aminobenzamide derivatives as potential anti-gastric cancer agents in vitro and in vivo

Although gastric cancer has become a major public health problem, oral agents applied in clinics for gastric cancer therapy are scarce. Therefore, to explore new oral chemical entities with high efficiency and low toxicity, 41 o-aminobenzamide derivatives based on the scaffolds of MS-275 and SAHA were designed, synthesized, and evaluated for their anti-gastric cancer abilities in vitro and in vivo. Structure-activity relationships were discussed, leading to the identification of compounds F8 (IC₅₀ = 0.28 μM against HGC-27 cell) and T9 (IC₅₀ = 1.84 μM against HGC-27 cell) with improved cytotoxicity, anti-gastric cancer proliferation potency, induction of cell apoptosis and cell cycle arrest ability, inhibition of cell migration and invasion. What is worth mentioning is that compound F8 was more efficient and less toxic than the positive drug capecitabine in vivo on the HGC-27-xenograft model. Meanwhile, compound F8 exhibited suitable pharmacokinetic properties and less acute toxicity (LD₅₀ > 1000 mg/kg). Besides, western blotting analysis, IHC analysis, differentially expressed proteins analysis and ABPP experiment indicated that compound F8 could modulate molecular pathways involved in apoptosis and cell cycle progression. Consequently, compound F8 is a strong candidate for the development of human gastric cancer therapy.

Tumor pyruvate kinase M2 modulators: a comprehensive account of activators and inhibitors as anticancer agents

Pyruvate kinase M2 (PKM2) catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate. It plays a central role in the metabolic reprogramming of cancer cells and is expressed in most human tumors. It is essential in indiscriminate proliferation, survival, and tackling apoptosis in cancer cells. This positions PKM2 as a hot target in cancer therapy. Despite its well-known structure and several reported modulators targeting PKM2 as activators or inhibitors, a comprehensive review focusing on such modulators is lacking. Herein we summarize modulators of PKM2, the assays used to detect their potential, the preferable tense (T) and relaxed (R) states in which the enzyme resides, lacunae in existing modulators, and several strategies that may lead to effective anticancer drug development targeting PKM2.

Design, synthesis, and evaluation of novel coumarin-dithiocarbamate derivatives (IDs) as anti-colorectal cancer agents

Colorectal cancer (CRC) is a common malignant tumour of human digestive tract. The high mortality rate of CRC is closely related to the limitations of existing treatments. Thus, there is an urgent need to search for new anti-CRC agents. In this work, twenty novel coumarin-dithiocarbamate derivatives (IDs) were designed, synthesized and evaluated in vitro. The results suggest that the most active compound ID-11 effectively inhibited the proliferation of CRC cell lines while shown little impact on normal colon epithelial cells. Mechanism studies revealed that ID-11 displayed bromodomain-containing protein 4 inhibitory activity, and induced G2/M phase arrest, apoptosis as well as decreased the expression levels of the key genes such as c-Myc and Bcl-2 in CRC cell lines. Moreover, the ADMET properties prediction results shown that ID-11 possess well metabolic characteristics without obvious toxicities. Our data demonstrated that compound ID-11 may be a promising anti-CRC agent and deserved for further development.

Targeting cancer epigenetic pathways with small-molecule compounds: Therapeutic efficacy and combination therapies

Epigenetics mainly refers to covalent modifications to DNA or histones without affecting genomes, which ultimately lead to phenotypic changes in cells or organisms. Given the abundance of regulatory targets in epigenetic pathways and their pivotal roles in tumorigenesis and drug resistance, the development of epigenetic drugs holds a great promise for the current cancer therapy. However, lack of potent, selective, and clinically tractable small-molecule compounds makes the strategy to target cancer epigenetic pathways still challenging. Therefore, this review focuses on epigenetic pathways, small molecule inhibitors targeting DNA methyltransferase (DNMT) and small molecule inhibitors targeting histone modification (the main regulatory targets are histone acetyltransferases (HAT), histone deacetylases (HDACs) and histone methyltransferases (HMTS)), as well as the combination strategies of the existing epigenetic therapeutic drugs and more new therapies to improve the efficacy, which will shed light on a new clue on discovery of more small-molecule drugs targeting cancer epigenetic pathways as promising strategies in the future.

In Vitro Enzymatic and Kinetic Studies, and In Silico Drug-Receptor Interactions, and Drug-Like Profiling of the 5-Styrylbenzamide Derivatives as Potential Cholinesterase and β-Secretase Inhibitors with Antioxidant Properties

The 5-(styryl)anthranilamides were transformed into the corresponding 5-styryl-2-(p-tolylsulfonamido)benzamide derivatives. These 5-styrylbenzamide derivatives were evaluated through enzymatic assays in vitro for their capability to inhibit acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-secretase (BACE-1) activities as well as for antioxidant potential. An in vitro cell-based antioxidant activity assay involving lipopolysaccharides (LPS)-induced reactive oxygen species (ROS) production revealed that compounds 2a and 3b have the capability of scavenging free radicals. The potential of the most active compound, 5-styrylbenzamide (2a), to bind copper (II) or zinc (II) ions has also been evaluated spectrophotometrically. Kinetic studies of the most active derivatives from each series against the AChE, BChE, and β-secretase activities have been performed. The experimental results are complemented with molecular docking studies into the active sites of these enzymes to predict the hypothetical protein–ligand binding modes. Their drug likeness properties have also been predicted.

Treatment with Non-specific HDAC Inhibitors Administered after Disease Onset does not Delay Evolution in a Mouse Model of Progressive Multiple Sclerosis

Drugs able to efficiently counteract progression of multiple sclerosis (MS) are still an unmet need. Several lines of evidence indicate that histone deacetylase inhibitors (HDACi) are clinically-available epigenetic drugs that might be repurposed for immunosuppression in MS therapy. Here, we studied the effects of HDACi on disease evolution in myelin oligodendrocyte glycoprotein (MOG)-immunized NOD mice, an experimental model of progressive experimental autoimmune encephalomyelitis (PEAE). To obtain data of potential clinical relevance, the HDACi panobinostat, givinostat and entinostat were administered orally adopting a daily treatment protocol after disease onset. We report that the 3 drugs efficiently reduced in vitro lymphocyte proliferation in a dose-dependent manner. Notably, however, none of the drugs delayed evolution of PEAE or reduced lethality in NOD mice. In striking contrast with this, however, the lymphocyte proliferation response to MOG as well as Th1 and Th17 spinal cord infiltrates were significantly lower in animals exposed to the HDACi compared to those receiving vehicle. When put into a clinical context, for the first time data cast doubt on the relevance of HDACi to treatment of progressive MS (PMS). Also, our findings further indicate that, akin to PMS, neuropathogensis of PEAE in NOD mice becomes independent from autoimmunity, thereby corroborating the relevance of this model to experimental PMS research.

An insight into medicinal attributes of dithiocarbamates: Bird's eye view

Dithiocarbamates are considered as an important motif owing to its extensive biological applications in medicinal chemistry. The synthesis of this framework can easily be achieved via a one-pot reaction of primary/secondary amines, CS₂, and alkyl halides under catalyst-free conditions or sometimes in the presence of a base. By virtue of its colossal pharmacological scope, it has been an evolving subject of interest for many researchers around the world. The present review aims to highlight various synthetic approaches for dithiocarbamates with the major emphasis on medicinal attributes of these architectures as leads in the drug discovery of small molecules such as HDAC inhibitor, lysine-specific demethylase 1 (LSD1) down-regulator, kinase inhibitor (focal adhesion kinase, pyruvate kinase, Bruton's tyrosine kinase), carbonic anhydrase inhibitor, DNA intercalators, and apoptosis-inducing agents. Moreover, recent medicinal advancements in the synthesis of dithiocarbamate derivatives as anticancer, antifungal, antibacterial, anti-Alzheimer, antitubercular, anti-glaucoma, anti-cholinergic, antihyperglycemic, anti-inflammatory activities have been elaborated with notable examples.

Exploring structural requirements of isoform selective histone deacetylase inhibitors: a comparative in silico study

Histone deacetylases (HDACs) are a widely popular class of epigenetic regulators, second only in importance to DNA methyltransferases. They are responsible for deacetylating the lysine residues of a wide range of proteins, both nuclear and cytoplasmic. Therefore, deregulated HDAC activity is implicated in disruption of important biological functions leading to cancerous, neuropathological, infectious and inflammatory diseased states. The current therapeutic strategies aimed at combating HDAC related pathologies consist of pan HDAC inhibitors that target multiple HDAC isoforms. Many side-effects of such therapeutics have been reported due to off-target effects. Hence, efforts need to be focused towards developing therapeutics targeting single isoforms. This work aims at recognizing structural features, both of receptors and inhibitors, that would help achieve selective inhibition of HDAC isoforms. Protein alignment studies have been carried out to define the receptor structure differences that can be exploited for this purpose. Binding modes of highly isoform selective inhibitors have been established through molecular docking studies to characterize the receptor-ligand interactions responsible for selective inhibition. This information is represented with the help of pharmacophore models.

The function of histone acetylation in cervical cancer development

Cervical cancer is the fourth most common female cancer in the world. It is well known that cervical cancer is closely related to high-risk human papillomavirus (HPV) infection. However, epigenetics has increasingly been recognized for its role in tumorigenesis. Epigenetics refers to changes in gene expression levels based on non-gene sequence changes, primarily through transcription or translation of genes regulation, thus affecting its function and characteristics. Typical post-translational modifications (PTMs) include acetylation, propionylation, butyrylation, malonylation and succinylation, among which the acetylation modification of lysine sites has been studied more clearly so far. The acetylation modification of lysine residues in proteins is involved in many aspects of cellular life activities, including carbon metabolism, transcriptional regulation, amino acid metabolism and so on. In this review, we summarize the latest discoveries on cervical cancer development arising from the aspect of acetylation, especially histone acetylation.

Medicinal chemistry of metal chelating fragments in metalloenzyme active sites: A perspective

Numerous metal-containing enzymes (metalloenzymes) have been considered as drug targets related to diseases such as cancers, diabetes, anemia, AIDS, malaria, bacterial infection, fibrosis, and neurodegenerative diseases. Inhibitors of the metalloenzymes have been developed independently, most of which are mimics of substrates of the corresponding enzymes. However, little attention has been paid to the interactions between inhibitors and active site metal ions. This review is focused on different metal binding fragments and their chelating properties in the metal-containing active binding pockets of metalloenzymes. We have enumerated over one hundred of inhibitors targeting various metalloenzymes and identified over ten kinds of fragments with different binding patterns. Furthermore, we have investigated the inhibitors that are undergoing clinical evaluation in order to help looking for more potential scaffolds bearing metal binding fragments. This review will provide deep insights for the rational design of novel inhibitors targeting the metal-containing binding sites of specific proteins.

Design, Synthesis and Cytotoxic Evaluation of Novel Lupane Triterpenoid and Ursolic Acid Derived 2-Aminobenzamides

Series of novel triterpenoid hybrids were designed and synthesized by introducing 2-aminobenzamide moiety at C28 position of triterpenoid derivatives. Thirteen new conjugates were thus successfully prepared and evaluated as cytotoxic agents, revealing an interesting anticancer activity in KB and HepG2 cancer cell lines.

Rational design and characterization of a DNA/HDAC dual-targeting inhibitor containing nitrogen mustard and 2-aminobenzamide moieties

Histone deacetylases (HDACs) play a key role not only in gene expression but also in DNA repair. Herein, we report the rational design and characterization of a compound named chlordinaline containing nitrogen mustard and 2-aminobenzamide moieties as a DNA/HDAC dual-targeting inhibitor. Chlordinaline exhibited moderate total HDAC inhibitory activity. The HDAC isoform selectivity assay indicated that chlordinaline mostly inhibits HDAC3. Chlordinaline exhibited both DNA and HDAC inhibitory activities and showed potent antiproliferative activity against all the six test cancer cell lines with IC50 values of as low as 3.1-14.2 μM, which is significantly more potent than reference drugs chlorambucil and tacedinaline. Chlordinaline could induce the apoptosis and G2/M phase cell cycle arrest of A375 cancer cells. This study demonstrates that combining nitrogen mustard and 2-aminobenzamide moieties into one molecule is an effective method to obtain DNA/HDAC dual-targeting inhibitors as potent antitumor agents. Chlordinaline as the first example of such DNA/HDAC dual-targeting inhibitors could be a promising candidate for cancer therapy and could also be a lead compound for further optimization.