A series of indol-3-yl morpholino derivatives containing a hydrazone moiety were designed and synthesized using indole-3-carboxylic acid as the starting material. The antiviral activities of the synthesized compounds were systematically evaluated. Compound D35, optimized using the comparative molecular field analysis (CoMFA) model, exhibited the most potent inhibitory activity against Tobacco mosaic virus (TMV) in vivo with a 50% effective concentration (EC50) value of 69.9 mg/L and exceeded that of Ningnanmycin (142.4 mg/L). Molecular docking and molecular dynamics simulations revealed that compound D35 could form stable interactions with the TMV coat protein (CP), exhibiting a lower binding energy of -9.37 kcal/mol compared to that of Ningnanmycin (-8.55 kcal/mol). Microscale thermophoresis (MST) experiments further confirmed the stronger binding affinity of compound D35 for the TMV CP than Ningnanmycin. Additionally, transmission electron microscopy (TEM) demonstrated that compound D35 effectively disrupts the TMV particles and inhibits their spread. These collective findings strongly suggest that compound D35 has the potential to serve as a lead compound for the development of novel antiviral agents.

Histone deacetylases (HDAC) represent promising epigenetic targets for several diseases including different cancer types. The HDAC inhibitors approved to date are pan-HDAC inhibitors and most show a poor selectivity profile, side effects, and in particular hydroxamic-acid-based inhibitors lack good pharmacokinetic profiles. Therefore, the development of isoform-selective non-hydroxamic acid HDAC inhibitors is a highly regarded field in medicinal chemistry. In this study, we analyzed different ligand-based and structure-based drug design techniques to predict the binding mode and inhibitory activity of recently developed alkylhydrazide HDAC inhibitors. Alkylhydrazides have recently attracted more attention as they have shown promising effects in various cancer cell lines. In this work, pharmacophore models and atom-based quantitative structure-activity relationship (QSAR) models were generated and evaluated. The binding mode of the studied compounds was determined using molecular docking as well as molecular dynamics simulations and compared with known crystal structures. Calculated free energies of binding were also considered to generate QSAR models. The created models show a good explanation of in vitro data and were used to develop novel HDAC3 inhibitors.

Class I histone deacetylases (HDACs) are key regulators of cell proliferation and they are frequently dysregulated in cancer cells. We report here the synthesis of a novel series of class-I selective HDAC inhibitors (HDACi) containing a 2-aminobenzamide moiety as a zinc-binding group connected with a central (piperazin-1-yl)pyrazine or (piperazin-1-yl)pyrimidine moiety. Some of the compounds were additionally substituted with an aromatic capping group. Compounds were tested in vitro against human HDAC1, 2, 3, and 8 enzymes and compared to reference class I HDACi (Entinostat (MS-275), Mocetinostat, CI994 and RGFP-966). The most promising compounds were found to be highly selective against HDAC1, 2 and 3 over the remaining HDAC subtypes from other classes. Molecular docking studies and MD simulations were performed to rationalize the in vitro data and to deduce a complete structure activity relationship (SAR) analysis of this novel series of class-I HDACi. The most potent compounds, including 19f, which blocks HDAC1, HDAC2, and HDAC3, as well as the selective HDAC1/HDAC2 inhibitors 21a and 29b, were selected for further cellular testing against human acute myeloid leukemia (AML) and erythroleukemic cancer (HEL) cells, taking into consideration their low toxicity against human embryonic HEK293 cells. We found that 19f is superior to the clinically tested class-I HDACi Entinostat (MS-275). Thus, 19f is a new and specific HDACi with the potential to eliminate blood cancer cells of various origins.

Histone deacetylases (HDACs) are epigenetic regulators and additionally control the activity of non-histone substrates. We recently demonstrated that inhibition of HDAC8 overexpressed in various of cancers reduces hepatocellular carcinoma tumorigenicity in a T cell-dependent manner. Here, we present alkylated hydrazide-based class I HDAC inhibitors in which the n-hexyl side chain attached to the hydrazide moiety shows HDAC8 selectivity in vitro. Analysis of the mode of inhibition of the most promising compound 7d against HDAC8 revealed a substrate-competitive binding mode. 7d marked induced acetylation of the HDAC8 substrates H3K27 and SMC3 but not tubulin in CD4+ T lymphocytes, and significantly upregulated gene expressions for memory and effector functions. Furthermore, intraperitoneal injection of 7d (10 mg/kg) in C57BL/6 mice increased interleukin-2 expression in CD4+ T cells and CD8+ T cell proportion with no apparent toxicity. This study expands a novel chemotype of HDAC8 inhibitors with T cell modulatory properties for future therapeutic applications.

Histone deacetylases (HDACs) are modulators of epigenetic gene regulation and additionally control the activity of non-histone protein substrates by removing acyl or acetyl groups from modified lysine residues. We recently demonstrated that pharmacological inhibition of the HDAC8 enzyme belonging to class I of HDACs and overexpressed in a variety of human cancers controls histone H3 lysine 27 (H3K27)-acetylation and reduces hepatocellular carcinoma tumorigenicity in a T cell-dependent manner. Here, we present a new chemotype of alkylated hydrazide-based class I HDAC inhibitors in which the n-hexyl side chain attached to the hydrazide moiety show HDAC8 selectivity in vitro. An enzymatic assay provided important structure-activity relationships for this new series of alkyl hydrazides. Analysis of the mode of inhibition of the alkyl hydrazides against HDAC8 revealed a substrate-competitive binding mode. The most promising compound 7d marked induced acetylation of the HDAC8 substrates H3K27 and SMC3 at 10 μM but not tubulin in CD4+ T lymphocytes, and significantly upregulated gene expressions for memory and effector functions. Furthermore, intraperitoneal injection administration of 7d (10 mg/kg) in C57BL/6 mice increased interleukin-2 expression in CD4+ T cells and CD8+ T cell proportion with no apparent toxicity. This study expands a novel chemotype of highly potent class I HDAC inhibitors with T cell modulatory properties for future therapeutic applications.

An atom-economical synthesis of chiral polyfunctionalized spiropyrazolone derivatives based on the development of a new organocatalytic enantioselective one-pot sequential Michael/Michael/Aldol reaction of 1,3-dicarbonyl compounds with unsaturated pyrazolones and alpha,beta-unsaturated aldehydes has been developed. The notable features of this one-pot sequential process include the generation of up to six consecutive stereogenic carbon centers including one quaternary stereocenter and five tertiary stereocenters with high enantioselectivities (up to 95% ee) and excellent diastereoselectivities (>99:1 d.r.). (C) 2014 Elsevier Ltd. All rights reserved.