Synthesis, biological characterization and molecular modeling insights of spirochromanes as potent HDAC inhibitors

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.

Design, synthesis and structure-activity relationship studies of novel spirochromanone hydrochloride analogs as anticancer agents

Aim: Literature reports suggest spirochromanone derivatives exhibit anticancer activity. Methodology: The authors designed and synthesized 18 spirochromanone derivatives (Csp 1-18). The compounds were characterized and evaluated for anticancer activity against human breast cancer (MCF-7) and murine melanoma (B16F10) cell lines. Results: The anticancer activity ranged from 4.34 to 29.31 μm. The most potent compounds, Csp 12 and Csp 18, were less toxic against the human embryonic kidney (HEK-293) cell line and ∼ two/∼four fold selective toward MCF-7 than B16F10 in comparison to the reference, BG-45. Csp 12 caused 28.6% total apoptosis, leading to significant cytotoxicity, and arrested the G2 phase of the cell cycle in B16F10 cells. A molecular docking study of Csp 12 exhibited effective binding at the active site of the epidermal growth factor receptor kinase domain. Conclusion: This study highlights the importance of spirochromanones as anticancer agents.

Dissecting Histone Deacetylase 3 in Multiple Disease Conditions: Selective Inhibition as a Promising Therapeutic Strategy

The acetylation of histone and non-histone proteins has been implicated in several disease states. Modulation of such epigenetic modifications has therefore made histone deacetylases (HDACs) important drug targets. HDAC3, among various class I HDACs, has been signified as a potentially validated target in multiple diseases, namely, cancer, neurodegenerative diseases, diabetes, obesity, cardiovascular disorders, autoimmune diseases, inflammatory diseases, parasitic infections, and HIV. However, only a handful of HDAC3-selective inhibitors have been reported in spite of continuous efforts in design and development of HDAC3-selective inhibitors. In this Perspective, the roles of HDAC3 in various diseases as well as numerous potent and HDAC3-selective inhibitors have been discussed in detail. It will surely open up a new vista in the discovery of newer, more effective, and more selective HDAC3 inhibitors.

Recent advances of chromone-based reactants in the catalytic asymmetric domino annulation reaction

Chiral polycyclic chromanones are important heterocyclic frameworks that constitute the core structures of many natural products and bioactive molecules.

Zinc Dependent Histone Deacetylase Inhibitors in Cancer Therapeutics: Recent Update

BACKGROUND

Histone deacetylases (HDAC) are an important class of enzymes that play a pivotal role in epigenetic regulation of gene expression that modifies the terminal of core histones leading to remodelling of chromatin topology and thereby controlling gene expression. HDAC inhibitors (HDACi) counter this action and can result in hyperacetylation of histones, thereby inducing an array of cellular consequences such as activation of apoptotic pathways, generation of reactive oxygen species (ROS), cell cycle arrest and autophagy. Hence, there is a growing interest in the potential clinical use of HDAC inhibitors as a new class of targeted cancer therapeutics. Methodology and Result: Several research articles spanning between 2016 and 2017 were reviewed in this article and presently offer critical insights into the important strategies such as structure-based rational drug design, multi-parameter lead optimization methodologies, relevant SAR studies and biology of various class of HDAC inhibitors, such as hydroxamic acids, benzamides, cyclic peptides, aliphatic acids, summarising the clinical trials and results of various combination drug therapy till date.

CONCLUSION

This review will provide a platform to the synthetic chemists and biologists to cater the needs of both molecular targeted therapy and combination drug therapy to design and synthesize safe and selective HDAC inhibitors in cancer therapeutics.

Enantioselective Hetero-Diels-Alder Reaction and the Synthesis of Spiropyrrolidone Derivatives

An efficient enantioselective hetero-Diels-Alder reaction was developed under catalysis of a chiral copper complex. A variety of spiropyrrolidones, which bear a tetra-substituted carbon stereocenter, can be obtained in good yields with excellent enantioselectivities by virtue of this method. Furthermore, a substrate-dependent reaction pathway was proposed on the basis of the isolated intermediates.

4-Indolyl-N-hydroxyphenylacrylamides as potent HDAC class I and IIB inhibitors in vitro and in vivo

A series of 4,5-indolyl-N-hydroxyphenylacrylamides, as HDAC inhibitors, has been synthesized and evaluated in vitro and in vivo. 4-Indolyl compounds 13 and 17 functions as potent inhibitors of HDAC1 (IC₅₀ 1.28 nM and 1.34 nM) and HDAC 2 (IC₅₀ 0.90 and 0.53 nM). N-Hydroxy-3-{4-[2-(1H-indol-4-yl)-ethylsulfamoyl]-phenyl}-acrylamide (13) inhibited the human cancer cell growth of PC3, A549, MDA-MB-231 and AsPC-1 with a GI₅₀ of 0.14, 0.25, 0.32, and 0.24 μM, respectively. In in vivo evaluations bearing prostate PC3 xenografts nude mice model, compound 13 suppressed tumor growth with a tumor growth inhibition (TGI) of 62.2%. Immunohistochemistry of protein expressions, in PC-3 xenograft model indicated elevated acetyl-histone 3 and prominently inhibited HDAC2 protein expressions. Therefore, compound 13 could be a suitable lead for further investigation and the development of selective HDAC 2 inhibitors as potent anti-cancer compounds.

Design, synthesis and biological evaluation of quinoline derivatives as HDAC class I inhibitors

Inhibition of histone deacetylase (HDAC) has been regarded as a potential therapeutic approach for treatment of multiple diseases including cancer. Based on pharmacophore model of HDAC inhibitors, a series of quinoline-based N-hydroxycinnamamides and N-hydroxybenzamides were designed and synthesized as potent HDAC inhibitors. All target compounds were evaluated for their in vitro HDAC inhibitory activities and anti-proliferative activities and the best compound 4a surpass Vorinostat in both enzymatic inhibitory activity and cellular anti-proliferative activity. In terms of HDAC isoforms selectivity, compounds 4a exhibited preferable inhibition for class I HDACs, especially for HDAC8, the IC₅₀ value (442 nM) was much lower than that of Vorinostat (7468 nM). Subsequently, we performed class I & IIa HDACs whole cell enzyme assay to evaluate inhibitory activity in whole cell context. Compounds 4a and 4e displayed much better cellular activity for class I HDACs than that for class IIa HDACs, which indicated that 4a and 4e might be potent class I HDAC inhibitors. Meanwhile, flow cytometry analysis showed that compound 4a and 4e can promote cell apoptosis in vitro.

Design, synthesis and in vitro evaluation of amidoximes as histone deacetylase inhibitors for cancer therapy

Amindoximes are geometric isomers of N-hydroxyamidines which are bioisosteres of hydroxamates. Since amindoxime group is capable of chelating transition metal ions including zinc ion, amindoximes should possess histone deacetylases (HDACs) inhibitory activity. In this work, we designed and synthesized a series of amindoximes, examined their inhibitory activities against HDACs, and investigated their cytotoxicity to human cancer cells. Preliminary results demonstrated that amindoximes possessed submicromolar HDACs inhibitory activity, with noteworthy enhancement compared with hydroxamates. Furthermore, the amindoximes arrested HCT116 and A549 cells in G2/M phase and showed good efficacy in inducing cells death. We provided a proof-of-concept that amindoximes could be used as HDACs inhibitors and hold great promise as epigenetic drugs.

Histone deacetylase 3 (HDAC 3) as emerging drug target in NF-κB-mediated inflammation

Activation of inflammatory gene expression is regulated, among other factors, by post-translational modifications of histone proteins. The most investigated type of histone modifications is lysine acetylations. Histone deacetylases (HDACs) remove acetylations from lysines, thereby influencing (inflammatory) gene expression. Intriguingly, apart from histones, HDACs also target non-histone proteins. The nuclear factor κB (NF-κB) pathway is an important regulator in the expression of numerous inflammatory genes, and acetylation plays a crucial role in regulating its responses. Several studies have shed more light on the role of HDAC 1-3 in inflammation with a particular pro-inflammatory role for HDAC 3. Nevertheless, the HDAC-NF-κB interactions in inflammatory signalling have not been fully understood. An important challenge in targeting the regulatory role of HDACs in the NF-κB pathway is the development of highly potent small molecules that selectively target HDAC iso-enzymes. This review focuses on the role of HDAC 3 in (NF-κB-mediated) inflammation and NF-κB lysine acetylation. In addition, we address the application of frequently used small molecule HDAC inhibitors as an approach to attenuate inflammatory responses, and their potential as novel therapeutics. Finally, recent progress and future directions in medicinal chemistry efforts aimed at HDAC 3-selective inhibitors are discussed.

Design, synthesis and biological evaluation of bisthiazole-based trifluoromethyl ketone derivatives as potent HDAC inhibitors with improved cellular efficacy

Histone deacetylases (HDACs) are a class of epigenetic modulators with complex functions in histone post-translational modifications and are well known targets for antineoplastic drugs. We have previously developed a series of bisthiazole-based hydroxamic acids as novel potent HDAC inhibitors. In the present work, a new series of bisthiazole-based compounds with different zinc binding groups (ZBGs) have been designed and synthesized. Among them is compound 7, containing a trifluoromethyl ketone as the ZBG, which displays potent inhibitory activity towards human HDACs and improved antiproliferative activity in several cancer cell lines.