Bis(4-hydroxy-2H-chromen-2-one): Synthesis and effects on leukemic cell lines proliferation and NF-κB regulation

Discovery of Di(het)arylmethane and Dibenzoxanthene Derivatives as Potential Anticancer Agents

A family of bifunctional dihetarylmethanes and dibenzoxanthenes is assembled via a reaction of acetals containing a 2-chloroacetamide moiety with phenols and related oxygen-containing heterocycles. These compounds demonstrated selective antitumor activity associated with the induction of cell apoptosis and inhibition of the process of glycolysis. In particular, bis(heteroaryl)methane containing two 4-hydroxy-6-methyl-2H-pyran-2-one moieties combine excellent in vitro antitumor efficacy with an IC50 of 1.7 µM in HuTu-80 human duodenal adenocarcinoma models with a high selectivity index of 73. Overall, this work highlights the therapeutic potential of dimeric compounds assembled from functionalized acetals and builds a starting point for the development of a new family of anticancer agents.

Drug Discovery Based on Oxygen and Nitrogen (Non-)Heterocyclic Compounds Developed @LAQV-REQUIMTE/Aveiro

Artur Silva's research group has a long history in the field of medicinal chemistry. The development of new synthetic methods for oxygen (mostly polyphenols, e.g., 2- and 3-styrylchromones, xanthones, flavones) and nitrogen (e.g., pyrazoles, triazoles, acridones, 4-quinolones) heterocyclic compounds in order to be assessed as antioxidant, anti-inflammatory, antidiabetic, and anticancer agents has been the main core work of our research interests. Additionally, the synthesis of steroid-type compounds as anti-Alzheimer drugs as well as of several chromophores as important dyes for cellular imaging broadened our research scope. In this review article, we intend to provide an enlightened appraisal of all the bioactive compounds and their biological properties that were synthesized and studied by our research group in the last two decades.

Chromones: Privileged scaffold in anticancer drug discovery

In the design and discovery of anticancer drugs, various natural heterocyclic scaffolds have attracted considerable interest as privileged structures. For rational drug design, some of the natural scaffolds such as chromones have exhibited wide acceptability due to their drug-like properties. Among the approved anticancer drugs, the scaffolds with high selectivity for a small group of closely related targets are of importance. In the development of selective anticancer agents, the natural, as well as synthetic, can generate highly selective compounds toward cancer targets. The present manuscript includes more particularly the development of cancer inhibitors incorporating the chromone scaffold, with a strong emphasis on their molecular interactions in the anticancer mechanism. It also includes the structure-activity relationship studies and related examples of lead optimization.

Novel Carbon-based Solid Acid from Green Pistachio Peel as an Efficient Catalyst for the Chemoselective Acylation, Acetalization and Thioacetalization of Aldehydes, Synthesis of Biscoumarins and Antimicrobial Evaluation

Background:

Much attention has been focused on heterogeneous catalysts. Reactions with these recoverable and reusable catalysts are clean, selective with high efficiency. Among the heterogeneous solid acid catalyst in organic synthesis, Carbon-Based Solid Acids (CBSAs), which are important solid acid with many practical and research applications have been extensively studied. In this work, green Pistachio peel, a biomass waste, was converted into a novel carbon-based solid acid catalyst (Pis-SO3H).

Objective:

The aim of this work is to synthesize highly sulfonated carbon as an efficient, recyclable, nontoxic solid acid catalyst by simultaneous sulfonation, dehydration and carbonization of green Pistachio peel as biomass and investigate the catalytic activity of Pis-SO3H in acetalization, thioacetalization, acylation of aldehydes and synthesis of 3,3'-Arylmethylene-bis(4-hydroxycoumarin) derivatives.

Method:

Pis-SO3H was synthesized by an integrated fast one-step hydrothermal carbonization and sulfonation process in the presence of sulfuric acid. The characterization of the physicochemical properties of Pis-SO3H was achieved by XRD, FT-IR, FE-SEM, and elemental analysis.

Results:

The result of acid-base titration showed that the total acidity of the catalyst was 7.75 mmol H+g−1. This new heterogeneous catalyst has been efficiently used for the chemoselective thioacetalization, acetalization and acylation of aldehyde and the synthesis of biscoumarins under solvent-free conditions. All the reactions work easily in high yields. The antimicrobial activity of some of the biscoumarins was evaluated in screening by disk diffusion assay for the zone of inhibition.

Conclusion:

The catalytic activity of the Pis-SO3H was investigated during acetalization, thioacetalization, acylation and synthesis of biscoumarins. The results of protection of carbonyl groups and synthesis of biscoumarins in the present work offer effective alternatives for environmentally friendly utilization of abundant biomass waste.

Preclinical Assessment of the Bioactivity of the Anticancer Coumarin OT48 by Spheroids, Colony Formation Assays, and Zebrafish Xenografts

In vitro and in vivo pre-clinical screening of novel therapeutic agents are an essential tool in cancer drug discovery. Although human cancer cell lines respond to therapeutic compounds in 2D (dimensional) monolayer cell cultures, 3D culture systems were developed to understand the efficacy of drugs in more physiologically relevant models. In recent years, a paradigm shift was observed in pre-clinical research to validate the potency of new molecules in 3D culture systems, more precisely mimicking the tumor microenvironment. These systems characterize the disease state in a more physiologically relevant manner and help to gain better mechanistic insight and understanding of the pharmacological potency of a given molecule. Moreover, with the current trend in improving in vivo cancer models, zebrafish has emerged as an important vertebrate model to assess in vivo tumor formation and study the effect of therapeutic agents. Here, we investigated the therapeutic efficacy of hydroxycoumarin OT48 alone or in combination with BH3 mimetics in lung cancer cell line A549 by using three different 3D culture systems including colony formation assays (CFA), spheroid formation assay (SFA) and in vivo zebrafish xenografts.

Chromone as a Privileged Scaffold in Drug Discovery: Recent Advances

The use of privileged structures in drug discovery has proven to be an effective strategy, allowing the generation of innovative hits/leads and successful optimization processes. Chromone is recognized as a privileged structure and a useful template for the design of novel compounds with potential pharmacological interest, particularly in the field of neurodegenerative, inflammatory, and infectious diseases as well as diabetes and cancer. This perspective provides the reader with an update of an earlier article entitled "Chromone: A Valid Scaffold in Medicinal Chemistry" ( Chem. Rev. 2014 , 114 , 4960 - 4992 ) and is mainly focused on chromones of biological interest, including those isolated from natural sources. Moreover, as drug repurposing is becoming an attractive drug discovery approach, recent repurposing studies of chromone-based drugs are also reported.

One-pot synthesis of functionalized benzo[c]coumarins and their precursors via the reaction of 2-(polyfluoroalkyl)chromones with 4-alkyl-3-cyanocoumarins

2-(Polyfluoroalkyl)chromones react with 4-alkyl-3-cyanocoumarins in dichloromethane in the presence of triethylamine to give a wide variety of functionalized benzo[c]coumarin derivatives in good yields.

4-Hydroxybenzoic acid derivatives as HDAC6-specific inhibitors modulating microtubular structure and HSP90α chaperone activity against prostate cancer

Histone deacetylase (HDAC)6 is a unique isoenzyme targeting specific substrates including α-tubulin and heat shock protein (HSP)90. HDAC6 is involved in protein trafficking and degradation, cell shape and migration. Deregulation of HDAC6 activity is associated with a variety of diseases including cancer leading to a growing interest for developing HDAC6 inhibitors. Here, we identified two new structurally related 4-hydroxybenzoic acids as selective HDAC6 inhibitors reducing proliferation, colony and spheroid formation as well as viability of prostate cancer cells. Both compounds strongly enhanced α-tubulin acetylation leading to remodeling of microtubular organization. Furthermore, 4-hydroxybenzoic acids decreased HSP90α regulation of the human androgen receptor in prostate cancer cells by increasing HSP90α acetylation levels. Collectively, our data support the potential of 4-hydroxybenzoic acid derivatives as HDAC6-specific inhibitors with anti-cancer properties.