Synthesis of quinoline derivatives for fluorescent imaging certain bacteria

Synthesis, DFT studies on a series of tunable quinoline derivatives

The synthesis, Density Functional Theory (DFT) calculations, and photo physical characteristics of a range of quinoline derivatives have been described in the present work. Initially, the innovative derivatives are synthesized through the cyclization of 2-amino-5-nitrobenzophenone with either acetyl acetone or ethyl acetoacetate, followed by reducing the nitro group to an amine. Subsequently, these compounds undergo an acid-amine cross-coupling reaction. The investigation shows the DFT and photo physical properties of these substances. It is noteworthy that compound 6z exhibits the most remarkable Stokes shift among the fluorophores investigated. Furthermore, the research also provides insights into the electrophilicity index, Electronegativity, chemical potential, chemical hardness and softness properties. These properties are determined by utilizing Density Functional Theory (DFT) calculations and evaluating electron potential efficiency and using computational methods Time-Dependent Density Functional Theory (TD-DFT) to predict absorption spectra in molecules at the B3LYP/6-31G'(d,p) level/basis.

Synthesis of tetrahydroquinazolines from 2-aminobenzonitriles and alkylidene malonates via 1,4-conjugate addition and an unprecedented rearrangement reaction

An efficient methodology for the synthesis of highly diverse tetrahydroquinazoline scaffolds from 2-aminobenzonitriles and alkylidene malonates via 1,4-conjugate addition followed by an unprecedented rearrangement has been demonstrated. The methodology is further applicable for the synthesis of quinazolines and tetracyclic compounds. Some of the synthesized compounds exhibit photophysical properties.

Fluorescent and Phosphorescent Nitrogen-Containing Heterocycles and Crown Ethers: Biological and Pharmaceutical Applications

Fluorescent molecules absorb photons of specific wavelengths and emit a longer wavelength photon within nanoseconds. Recently, fluorescent materials have been widely used in the life and material sciences. Fluorescently labelled heterocyclic compounds are useful in bioanalytical applications, including in vivo imaging, high throughput screening, diagnostics, and light-emitting diodes. These compounds have various therapeutic properties, including antifungal, antitumor, antimalarial, anti-inflammatory, and analgesic activities. Different neutral fluorescent markers containing nitrogen heterocycles (quinolones, azafluoranthenes, pyrazoloquinolines, etc.) have several electrochemical, biological, and nonlinear optic applications. Photodynamic therapy (PDT), which destroys tumors and keeps normal tissues safe, works in the presence of molecular oxygen with light and a photosensitizing drugs (dye) to obtain a therapeutic effect. These compounds can potentially be effective templates for producing devices used in biological research. Blending crown compounds with fluorescent residues to create sensors has been frequently investigated. Florescent heterocyclic compounds (crown ether) increase metal solubility in non-aqueous fluids, broadening the application window. Fluorescent supramolecular polymers have widespread use in fluorescent materials, fluorescence probing, data storage, bio-imaging, drug administration, reproduction, biocatalysis, and cancer treatment. The employment of fluorophores, including organic chromophores and crown ethers, which have high selectivity, sensitivity, and stability constants, opens up new avenues for research. Fluorescent organic compounds are gaining importance in the biological world daily because of their diverse functionality with remarkable structural features and positive properties in the fields of medicine, photochemistry, and spectroscopy.

UV Properties and Loading into Liposomes of Quinoline Derivatives

The scientific relevance of quinolines is strictly linked to the fine-tuning of their features by functionalizing the heterocyclic core. Consequently, the compounds of this class are very versatile and can be used as possible drugs for a lot of medical applications. In this work, the inclusion of eight synthetic quinoline derivatives in liposomes formulated with different lipids was investigated in terms of the encapsulation efficiency and to highlight the effect on the liposome size distribution and thermotropic behavior. Excellent encapsulation was accomplished with all the quinoline/phospholipid combinations. Differences in the interactions at the molecular level, dependent on the quinoline molecular scaffolds and lipid structure, were observed, which could significantly bias the interaction with the drug and its release in pharmaceutical applications. Experiments in combination with computational studies demonstrated that the UV absorption of quinolines with expanded conjugation could be affected by the environment polarity. This was probably due to a solvent-dependent ability of these quinolines to stack into aggregates, which could also occur upon inclusion into the lipid bilayer.

Sulfonamides and Sulphonyl Ester of Quinolines as Non-Acidic, Non- Steroidal, Anti-inflammatory Agents

Background:

Quinolines are an important class of heterocyclic compounds possessing a wide range of biological activities. Previously, we had identified Schiff bases of quinoline as potential anti-inflammatory agents, thus the current work is the continuation of our previous study.

Objective:

In the current study, 3-, 5-, and 8-sulfonamide and 8-sulfonate derivatives of quinoline (1-50) were synthesized and their anti-inflammatory potential was evaluated. These synthetic analogs were evaluated for their anti-inflammatory activity via ROS (Reactive oxygen species) inhibitory effect produced from phagocytes from human whole blood.

Methods:

The sulfonamide and sulfonate derivatives of quinoline were synthesized via treating 5-, 3-, 8-amino, and 8-hydroxy quinolines with different substituted sulfonyl chlorides in pyridine. The synthetic molecules were characterized using various spectroscopic techniques and screened for their anti-inflammatory potential.

Results:

Among the synthetic derivatives 1-50, six compounds showed good to moderate antiinflammatory activity. Compounds 47 (IC50 = 2.9 ± 0.5 μg/mL), 36 (IC50 = 3.2 ± 0.2 μg/mL), and 24 (IC50 = 6.7 ± 0.3 μg/mL) exhibited enhanced activity as compared to the standard ibuprofen (IC50 = 11.2 ± 1.9 μg/mL). Compounds 20 (IC50 = 25.5 ± 0.7 μg/mL), 50 (IC50 = 42.9 ± 5.6 μg/mL), and 8 (IC50 = 53.9 ± 3.1 μg/mL) were moderately active, however, rest of the compounds were found to be inactive.

Conclusion:

The sulfonamide and sulfonate derivatives of quinoline were found to have promising anti-inflammatory activity. Further studies on the modification of these molecules may lead to the discovery of new and potential anti-inflammatory agents.

Theoretical and Experimental Investigations of Large Stokes Shift Fluorophores Based on a Quinoline Scaffold

A series of novel styrylquinolines with the benzylidene imine moiety were synthesized and spectroscopically characterized for their applicability in cellular staining. The spectroscopic study revealed absorption in the ultraviolet-visible region (360-380 nm) and emission that covered the blue-green range of the light (above 500 nm). The fluorescence quantum yields were also determined, which amounted to 0.079 in the best-case scenario. The structural features that are behind these values are also discussed. An analysis of the spectroscopic properties and the theoretical calculations indicated the charge-transfer character of an emission, which was additionally evaluated using the Lippert-Mataga equation. Changes in geometry in the ground and excited states, which had a significant influence on the emission process, are also discussed. Additionally, the capability of the newly synthesized compounds for cellular staining was also investigated. These small molecules could effectively penetrate through the cellular membrane. Analyses of the images that were obtained with several of the tested styrylquinolines indicated their accumulation in organelles such as the mitochondria and the endoplasmic reticulum.

NHC-Catalyzed Chemoselective Reactions of Enals and Aminobenzaldehydes for Access to Chiral Dihydroquinolines

An N-heterocyclic carbene (NHC)-catalyzed reaction between α-bromoenals and 2-aminoaldehydes has been developed. Key steps include chemoselective reaction of the NHC catalyst with one of the aldehyde substrates (the bromoenal) to eventually generate an α,β-unsaturated acylazolium intermediate. Addition of the nitrogen atom of aminoaldehyde to the unsaturated azolium ester intermediate followed by intramolecular aldol reaction, β-lactone formation, and decarboxylation leads to chiral dihydroquinolines with high optical purity. The dihydroquinoline products, which are quickly prepared by using this method, can be readily transformed into a diverse set of functional molecules such as pyridines and chiral piperidines.

Progress in the Chemistry of Tetrahydroquinolines

Tetrahydroquinoline is one of the most important simple nitrogen heterocycles, being widespread in nature and present in a broad variety of pharmacologically active compounds. This Review summarizes the progress achieved in the chemistry of tetrahydroquinolines, with emphasis on their synthesis, during the period from mid-2010 to early 2018.

Modular Three-Component Synthesis of 4-Aminoquinolines via an Imidoylative Sonogashira/Cyclization Cascade

We developed a one-pot, two-stage synthetic route to substituted 4-aminoquinolines involving an imidoylative Sonogashira coupling followed by acid-mediated cyclization. This three-component reaction affords pharmaceutically valuable 4-aminoquinolines in a one-pot procedure from readily available starting materials. The reaction tolerates various substituents on the arene as well as the use of secondary and even primary isocyanides. Additionally, the wide tolerance for functionalized isocyanides allows for the one-pot synthesis of various substituted chloroquine analogues as well as other medicinally relevant products.

New iridium catalysts for the selective alkylation of amines by alcohols under mild conditions and for the synthesis of quinolines by acceptor-less dehydrogenative condensation

A novel family of iridium catalysts stabilised by P,N-ligands have been introduced. The ligands are based on imidazo[1,5-b]pyridazin-7-amines and can be synthesised with a broad variety of substitution patterns. The catalysts were synthesised quantitatively from the protonated ligands and a commercially available iridium precursor. The catalysts mediate the alkylation of amines by alcohols under mild conditions (70 °C). In addition, the synthesis of quinolines from secondary or primary alcohols and amino alcohols is reported. This sustainable synthesis proceeds through the liberation of two equivalents of water and two equivalents of dihydrogen. The investigations indicate that catalysts suitable for hydrogen autotransfer or borrowing hydrogen chemistry might also be suitable for acceptor-less dehydrogenative condensation reactions.