Development and interpretation of a QSAR model for in vitro breast cancer (MCF-7) cytotoxicity of 2-phenylacrylonitriles

The Arylhydrocarbon Receptor (AhR), a member of the Per-ARNT-SIM transcription factor family, has been as a potential new target to treat breast cancer sufferers. A series of 2-phenylacrylonitriles targeting AhR has been developed that have shown promising and selective activity against cancerous cell lines while sparing normal non-cancerous cells. A quantitative structure–activity relationship (QSAR) modeling approach was pursued in order to generate a predictive model for cytotoxicity to support ongoing synthetic activities and provide important structure-activity information for new structure design. Recent work conducted by us has identified a number of compounds that exhibited false positive cytotoxicity values in the standard MTT assay. This work describes a good quality model that not only predicts the activity of compounds in the MCF-7 breast cancer cell line, but was also able to identify structures that subsequently gave false positive values in the MTT assay by identifying compounds with aberrant biological behavior. This work not only allows the design of future breast cancer cytotoxic activity in vitro, but allows the avoidance of the synthesis of those compounds anticipated to result in anomalous cytotoxic behavior, greatly enhancing the design of such compounds.

A review of the recent progress on heterogeneous catalysts for Knoevenagel condensation

One of the most crucial attributes of synthetic organic chemistry is to design organic reactions under the facets of green chemistry for the sustainable production of chemicals. Thus, due to the intensified environmental and safety concern, the need for new technologies for conducting chemical transformation has grown. In this regard, there is enormous interest in the use of heterogeneous catalysts as they generally avoid the generation of waste, require fewer toxic reagents, as well as entail easier separation and recycling of the catalyst. α,β-Unsaturated acids have been widely used in various industrial applications and have been identified as one of the most promising chemicals obtained via the Knoevenagel condensation reaction. This review aims to discuss the most pertinent heterogeneous catalytic systems such as zeolites, mesoporous silica, ionic liquids, metal oxides, and graphitic carbon nitride-based catalysts in the Knoevenagel reaction. Ultimately, this review focuses not only on the catalyst but also provides an overall idea and guide for the preparation of new catalysts with outstanding properties by looking at the chemical and engineering aspects such as the reaction conditions and the mechanisms.

Modelling and Phenotypic Screening of NAP-6 and 10-Cl-BBQ, AhR Ligands Displaying Selective Breast Cancer Cytotoxicity in Vitro

To exploit the interaction of the aryl hydrocarbon receptor (AhR) pathway in developing breast-cancer-specific cytotoxic compounds, we examined the breast cancer selectivity and the docking pose of the AhR ligands (Z)-2-(2-aminophenyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (NAP-6; 5) and 10-chloro-7H-benzo[de]benzo[4,5]imidazo[2,1-a]isoquinolin-7-one (10-Cl-BBQ; 6). While the breast cancer selectivity of 5 in vitro is known, we discuss the SAR around this lead and, by using phenotypic cell-line screening and the MTT assay, show for the first time that 6 also presents with breast cancer selectivity, notably in the triple-negative (TN) receptor breast cancer cell line MDA-MB-468, the ER+ breast cancer cell lines T47D, ZR-75-1 and the HER2+ breast cancer cell line SKBR3 (GI₅₀ values of 0.098, 0.97, 0.13 and 0.21 μM, respectively). Indeed, 6 is 55 times more potent in MDA-MB-468 cells than normal MCF10A breast cells (GI₅₀ of 0.098 vs 5.4 μM) and more than 130 times more potent than in cell lines derived from pancreas, brain and prostate (GI₅₀ of 0.098 vs 10-13 μM). Molecular docking poses of 5 and 6 together with analogue synthesis and phenotypic screening show the importance of the naphthalene moiety, and an ortho-disposed substituent on the N-phenyl moiety for biological activity.

The aryl hydrocarbon receptor (AhR) as a breast cancer drug target

Breast cancer is the most common cancer in women, with more than 1.7 million diagnoses worldwide per annum. Metastatic breast cancer remains incurable, and the presence of triple-negative phenotypes makes targeted treatment impossible. The aryl hydrocarbon receptor (AhR), most commonly associated with the metabolism of xenobiotic ligands, has emerged as a promising biological target for the treatment of this deadly disease. Ligands for the AhR can be classed as exogenous or endogenous and may have agonistic or antagonistic activity. It has been well reported that agonistic ligands may have potent and selective growth inhibition activity in a number of oncogenic cell lines, and one (aminoflavone) has progressed to phase I clinical trials for breast cancer sufferers. In this study, we examine the current state of the literature in this area and elucidate the promising advances that are being made in hijacking the cytosolic-to-nuclear pathway of the AhR for the possible future treatment of breast cancer.

Dichlorophenylacrylonitriles as AhR Ligands That Display Selective Breast Cancer Cytotoxicity in vitro

Knoevenagel condensation of 3,4-dichloro- and 2,6-dichlorophenylacetonitriles gave a library of dichlorophenylacrylonitriles. Our leads (Z)-2-(3,4-dichlorophenyl)-3-(1H-pyrrol-2-yl)acrylonitrile (5) and (Z)-2-(3,4-dichlorophenyl)-3-(4-nitrophenyl)acrylonitrile (6) displayed 0.56±0.03 and 0.127±0.04 μm growth inhibition (GI₅₀ ) and 260-fold selectivity for the MCF-7 breast cancer cell line. A 2,6-dichlorophenyl moiety saw a 10-fold decrease in potency; additional nitrogen moieties (-NO₂ ) enhanced activity (Z)-2-(2,6-dichloro-3-nitrophenyl)-3-(2-nitrophenyl)acrylonitrile (26) and (Z)-2-(2,6-dichloro-3-nitrophenyl)-3-(3-nitrophenyl)acrylonitrile (27), with the corresponding -NH₂ analogues (Z)-2-(3-amino-2,6-dichlorophenyl)-3-(2-aminophenyl)acrylonitrile (29) and (Z)-2-(3-amino-2,6-dichlorophenyl)-3-(3-aminophenyl)acrylonitrile (30) being more potent. Despite this, both 29 (2.8±0.03 μm) and 30 (2.8±0.03 μm) were found to be 10-fold less cytotoxic than 6. A bromine moiety effected a 3-fold enhancement in solubility with (Z)-3-(5-bromo-1H-pyrrol-2-yl)-2-(3,4-dichlorophenyl)acrylonitrile 18 relative to 5 at 211 μg mL^-1 . Modeling-guided synthesis saw the introduction of 4-aminophenyl substituents (Z)-3-(4-aminophenyl)-2-(3,4-dichlorophenyl)acrylonitrile (35) and (Z)-N-(4-(2-cyano-2-(3,4-dichlorophenyl)vinyl)phenyl)acetamide (38), with respective GI₅₀ values of 0.030±0.014 and 0.034±0.01 μm. Other analogues such as 35 and 36 were found to have sub-micromolar potency against our panel of cancer cell lines (HT29, colon; U87 and SJ-G2, glioblastoma; A2780, ovarian; H460, lung; A431, skin; Du145, prostate; BE2-C, neuroblastoma; MIA, pancreas; and SMA, murine glioblastoma), except compound 38 against the U87 cell line. A more extensive evaluation of 38 ((Z)-N-(4-(2-cyano-2-(3,4-dichlorophenyl)vinyl)phenyl)acetamide) in a panel of drug-resistant breast carcinoma cell lines showed 10-206 nm potency against MDAMB468, T47D, ZR-75-1, SKBR3, and BT474. Molecular Operating Environment docking scores showed a good correlation between predicted binding efficiencies and observed MCF-7 cytotoxicity. This supports the use of this model in the development of breast-cancer-specific drugs.

Efficient method for Knoevenagel condensation in aqueous solution of amino acid ionic liquids (AAILs)

This work reports on the use of the amino acid ionic liquids (AAILs) which have been used as catalysts in Knoevenagel condensation of various aldehydes with malononitrile. For research we use tetrabutylammonium ionic liquids based on eight natural amino acids. The reaction was carried out in an aqueous medium. Using water as solvent provided efficient and simple method of isolation of pure product with high yield. Moreover, amino acid ionic liquid dissolved in water could be reused many times without any loss of its catalytic activity. The influence of the anion was studied. Moreover the effect of technological parameters such as: the temperature, the catalyst content, and the reaction time on yield of reaction were investigated.