Synthesis, crystal structure and in silico studies of novel 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-ones

Alkoxy-functionalised dihydropyrimido[4,5-b]quinolinones enabling anti-proliferative and anti-invasive agents

In this communication, we explored the synthesis of novel alkoxy-functionalised dihydropyrimido[4,5-b]quinolinones using a microwave-assisted multicomponent reaction. All the synthesized molecules were screened for anti-proliferative and anti-invasive activity against glioblastoma cells. 5c shows the most potent anti-proliferative activity with a half maximal effective concentration of less than 3 μM against primary patient-derived glioblastoma cells. 5c effectively inhibited invasion and tumor growth of 3D primary glioma cultures in a basement membrane matrix. This suggests that the novel compounds could inhibit both the proliferation and invasive spread of glioma and they were selected for further study.

Experimental and density functional theory investigation of surface-modified biopolymer for improved adsorption of mixtures of per- and polyfluoroalkyl substances in water

Glutaraldehyde (GTH) cross-linked chitosan (CTN) biopolymer-based and polyethyleneimine (PEI) functionalized (GTHCTNPEI) aerogels were proven promising for removing mixtures of long- and short chain per- and polyfluoroalkyl substances (PFAS) in water. In this study, to further improve the performance of the aerogel for short-chain PFAS and undecafluoro-2-methyl-3-oxahexanoic acid (GenX) removal, GTHCTNPEI aerogel chunks with an average size of 13.4 mm were turned into flakes with an average size of 9.1 mm. The GTHCTNPEI flakes achieved >99 % removal of all target PFAS, including long- and short-chain PFAS and >97 % for GenX after 10 h. In addition, the flakes can be regenerated and reused for at least four cycles. When added to tap water spiked with PFAS at initial concentrations of 30, 70, or 100 ng/L, the flakes removed almost 100 % of all tested PFAS. Mechanistic investigations using density functional theory (DFT) revealed strong stabilizing hydrophobic and electrostatic interactions between the aerogels and PFAS, with GTHCTNPEI to PFAS binding energies ranging between -24.0 - -30.1 kcal/mol for PFOA; -41.3 - -48.5 kcal/mol for PFOS; and -40.5 - -47.3 kcal/mol for PFBS. These results demonstrate the great potential of the flakes for removing PFAS from drinking water, surface water, and groundwater.

A synthetic approach towards drug modification: 2-hydroxy-1-naphthaldehyde based imine-zwitterion preparation, single-crystal study, Hirshfeld surface analysis, and computational investigation

The current work is about the modification of primary amine functionalized drugs, pyrimethamine and 4-amino-N-(2,3-dihydrothiazol-2-yl)benzenesulfonamide, via condensation reaction with 2-hydroxy-1-naphthaldehyde to produce new organic zwitterionic compounds (E)-1-(((4-(N-(2,3-dihydrothiazol-2-yl)sulfamoyl)phenyl)iminio)methyl)naphthalen-2-olate (DSPIN) and (E)-1-(((4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl)iminio)methyl)naphthalen-2-olate (ACPIN) in methanol as a solvent. The crystal structures of both compounds were confirmed to be imine-based zwitterionic products via single-crystal X-ray diffraction (SC-XRD) analysis which indicated that the stabilization of both crystalline compounds is achieved via various noncovalent interactions. The supramolecular assembly in terms of noncovalent interactions was explored by the Hirshfeld surface analysis. Void analysis was carried out to predict the crystal mechanical response. Compound geometries calculated in the DFT (Density Functional Theory) study showed reasonably good agreement with the experimentally determined structural parameters. Frontier molecular orbital (FMO) analysis showed that the DSPIN HOMO/LUMO gap is by 0.15 eV smaller than the ACPIN HOMO/LUMO gap due to some destabilization of the DSPIN HOMO and some stabilization of its LUMO. The results of the charge analysis implied formation of intramolecular hydrogen bonds and suggested formation of intermolecular hydrogen bonding and dipole-dipole and dispersion interactions.

Multicomponent Strategy to Pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine Derivatives under Microwave Irradiation

A novel three-component reaction has been established that allows a flexible and practical approach to pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivatives from phenylglyoxal, β-ketoamide, and 5-aminopyrazole with acetic acid as the solvent. Various dihydropyrazolo[3,4-b]pyrrolo[3,4-d]pyridin-6(3H)-one were isolated in moderate to good yields with broad functional group tolerance.

Catalyst-Free, Room-Temperature Accessible Regioselective Synthesis of Spiroquinolines and Their Antioxidant Study

An efficient, regioselective, and environmentally benign approach was established using the multicomponent reaction-based synthesis of novel antioxidant spiroquinoline derivatives such as spiro[dioxolo[4,5-g]quinoline], spiro[dioxino[2,3-g]quinoline], and spiro[pyrazolo[4,3-f]quinoline] by reaction of aryl aldehyde, Meldrum's acid, and amine derivatives under an additive-free reaction in aqueous ethanol. Here, two asymmetric carbon centers, three new C-C bonds, and one C-N bond are developed in the final motif. This synthetic methodology offers excellent yields with an easy workup procedure, high diastereoselectivity [d.r. >50:1 (cis/trans)], admirable atom economy, and low E-factor values. Synthesized spiro compounds were investigated for their in vitro antioxidant activity by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. In the ABTS radical scavenging assay, compounds 4d, 4f, and 4l exhibit excellent potency, and in the DPPH radical scavenging assay, compounds 4a, 4d, 4f, and 4g, exhibit excellent potency.

Novel asymmetrical azines appending 1,3,4-thiadiazole sulfonamide: synthesis, molecular structure analyses, in silico ADME, and cytotoxic effect†

Toward finding potential and novel anticancer agents, we designed and prepared novel differently substituted unsymmetrical azine-modified thiadiazole sulfonamide derivatives using the “combi-targeting approach”. An efficient procedure for synthesizing the designed compounds starts with 5-acetyl-3-N-(4-sulfamoylphenyl)-2-imino-1,3,4-thiadi-azoline 4. The E/Z configuration for compound 5 was investigated based on spectral analysis combined with quantum mechanical calculation applying the DFT-B3LYP method and 6-31G(d) basis set. The computational results found that the E isomer was energetically more favorable than the Z isomer by 2.21 kcal mol⁻¹. Moreover, ¹H and ¹³C chemical shifts for the E and Z isomers in DMSO were predicted using the GIAO-B3LYP/6-31G(d) computations and IEF-PCM solvation model. The computed chemical shifts for both isomers are consistent with those observed experimentally, indicating that they exist in the solution phase. Moreover, the E/Z configuration for the synthesized azines 7a–c, 9, 11, 13, 15a and 15b was also studied theoretically using the DFT-B3LYP/6-31G(d) calculations. In silico prediction for the biological activities was reported regarding the HOMO–LUMO energy gaps and molecular reactivity descriptors besides the ADMT/drug-likeness properties. The cytotoxic effect of the synthesized compounds has been assayed via the determination of their IC₅₀.

Toward finding potential and novel anticancer agents, we designed and prepared novel differently substituted unsymmetrical azine-modified thiadiazole sulfonamide derivatives using the “combi-targeting approach”.

Synthesis of N-(4-chlorophenyl) substituted pyrano[2,3-c]pyrazoles enabling PKBβ/AKT2 inhibitory and in vitro anti-glioma activity

A series of N-(4-chlorophenyl) substituted pyrano[2,3-c]pyrazoles was synthesised and screened for their potential to inhibit kinases and exhibit anticancer activity against primary patient-derived glioblastoma 2D cells and 3D neurospheres. A collection of 10 compounds was evaluated against glioma cell lines, with compound 4j exhibiting promising glioma growth inhibitory properties. Compound 4j was screened against 139 purified kinases and exhibited low micromolar activity against kinase AKT2/PKBβ. AKT signalling is one of the main oncogenic pathways in glioma and is often targeted for novel therapeutics. Indeed, AKT2 levels correlated with glioma malignancy and poorer patient survival. Compound 4j inhibited the 3D neurosphere formation in primary patient-derived glioma stem cells and exhibited potent EC₅₀ against glioblastoma cell lines. Although exhibiting potency against glioma cells, 4j exhibited significantly less cytotoxicity against non-cancerous cells even at fourfold-fivefold the concentration. Herein we establish a novel biochemical kinase inhibitory function for N-(4-chlorophenyl) substituted pyrano[2,3-c]pyrazoles and further report their anti-glioma activity in vitro for the first time.KEY MESSAGEAnti-glioma pyrano[2,3-c]pyrazole 4j inhibited the 3D neurosphere formation in primary patient-derived glioma stem cells. 4j also displayed PKBβ/AKT2 inhibitory activity. 4j is nontoxic towards non-cancerous cells.

Synthesis and Anti-Leishmanial Properties of Quinolones Derived from Zanthosimuline

Quinoline derivatives and especially quinolones are considered as privileged structures in medicinal chemistry and are often associated with various biological properties. We recently isolated a series of original monoterpenyl quinolones from the bark of Codiaeum peltatum. As this extract was found to have a significant inhibitory activity against a Leishmania species, we decided to study the anti-leishmanial potential of this type of compound. Leishmaniasis is a serious health problem affecting more than 12 million people in the world. Available drugs cause harmful side effects and resistance for some of them. With the aim of finding anti-leishmanial compounds, we developed a synthetic strategy to access natural quinolones and analogues derived from zanthosimuline. We showed the versatility of this natural compound toward cyclization conditions, leading to various polycyclic quinolone-derived structures. The natural and synthetic compounds were evaluated against amastigote forms of Leishmania infantum. The results obtained confirmed the interest of this family of natural compounds but also revealed promising activities for some intermediates deriving from zanthosimuline. Following the same synthetic strategy, we then prepared 14 new analogues. In this work, we identified two promising molecules with good activities against intramacrophage L. infantum amastigotes without any cytotoxicity. We also showed that slight changes in amide functional groups affect drastically their anti-parasitic activity.

Microwave-assisted multicomponent synthesis of antiproliferative 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-ones†

In this study, we demonstrate a simple, highly efficient, rapid and convenient series of 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-ones 4a–v. Microwave irradiation facilitates the one-pot multicomponent reaction of different aromatic aldehydes, 6-amino-2,4-dimethoxypyrimidine and dimedone using glacial acetic acid. Metal-free multicomponent synthesis, shorter reaction time, higher product yield, easy product purification without column chromatography and outstanding green credential parameters are the key features of this protocol. We analysed 4a–v against six human tumour cell lines for antiproliferative activity. 4h, 4o, 4q and 4v show good antiproliferative activity with a good in silico ADMET profile. Furthermore, 4h, 4o, 4q and 4v also show drug-likeness properties by obeying drug-like filters.

Herein, we demonstrate a simple, rapid and green synthesis of 2,4-dimethoxy-THPQs under microwave irradiation and their antiproliferative activity, in silico ADMET and drug-likeness studies were carried out.