Discovery of anthranilamides as a novel class of inhibitors of neurotropic alphavirus replication

Antiviral Activity of Anthranilamide Peptidomimetics against Herpes Simplex Virus 1 and a Coronavirus

The development of potent antiviral agents is of utmost importance to combat the global burden of viral infections. Traditional antiviral drug development involves targeting specific viral proteins, which may lead to the emergence of resistant strains. To explore alternative strategies, we investigated the antiviral potential of antimicrobial peptidomimetic compounds. In this study, we evaluated the antiviral potential of 17 short anthranilamide-based peptidomimetic compounds against two viruses: Murine hepatitis virus 1 (MHV-1) which is a surrogate of human coronaviruses and herpes simplex virus 1 (HSV-1). The half-maximal inhibitory concentration (IC50) values of these compounds were determined in vitro to assess their potency as antiviral agents. Compounds 11 and 14 displayed the most potent inhibitory effects with IC50 values of 2.38 μM, and 6.3 μM against MHV-1 while compounds 9 and 14 showed IC50 values of 14.8 μM and 13 μM against HSV-1. Multiple antiviral assessments and microscopic images obtained through transmission electron microscopy (TEM) collectively demonstrated that these compounds exert a direct influence on the viral envelope. Based on this outcome, it can be concluded that peptidomimetic compounds could offer a new approach for the development of potent antiviral agents.

Synthesis, Biological Evaluation and in Silico Study of N-(2- and 3-Pyridinyl)benzamide Derivatives as Quorum Sensing Inhibitors against Pseudomonas aeruginosa

The effectiveness of treating bacterial infections is seriously threatened by the emergence of bacterial resistance to chemical treatment. Growth of microbes in biofilm is one of the main causes of resistance to antimicrobial drugs. Quorum sensing (QS) inhibition, which targets the QS signalling system by obstructing cell-cell communication, was developed as an alternative treatment by creating innovative anti-biofilm drugs. Therefore, the goal of this study is to develop novel antimicrobial drugs that are effective against Pseudomonas aeruginosa by inhibiting QS and acting as anti-biofilm agents. In this study, N-(2- and 3-pyridinyl)benzamide derivatives were selected to design and syntheses. Antibiofilm activity was revealed by all the synthesized compounds and the biofilm was visibly impaired, and the OD_595nm readings of solubilized biofilm cells presented a momentous difference between the treated and untreated biofilms. The best anti-QS zone was observed for compound 5d and found to be 4.96 mm. Through in silico research, the physicochemical characteristics and binding manner of these produced compounds were examined. For the purpose of understanding the stability of the protein and ligand complex, molecular dynamic simulation was also carried out. The overall findings showed that N-(2- and 3-pyridinyl)benzamide derivatives could be the key to creating effective newer anti-quorum sensing drugs that are effective against different bacteria.

N-Arylation of 3-Formylquinolin-2(1H)-ones Using Copper(II)-Catalyzed Chan-Lam Coupling

3-formyl-2-quinolones have attracted the scientific community's attention because they are used as versatile building blocks in the synthesis of more complex compounds showing different and attractive biological activities. Using copper-catalyzed Chan-Lam coupling, we synthesized 32 new N-aryl-3-formyl-2-quinolone derivatives at 80 °C, in air and using inexpensive phenylboronic acids as arylating agents. 3-formyl-2-quinolones and substituted 3-formyl-2-quinolones can act as substrates, and among the products, the p-methyl derivative 9a was used as a substrate to obtain different derivatives such as alcohol, amine, nitrile, and chalcone.

Synthesis and biological activity of conformationally restricted indole-based inhibitors of neurotropic alphavirus replication: Generation of a three-dimensional pharmacophore

We have previously reported the development of indole-based CNS-active antivirals for the treatment of neurotropic alphavirus infection, but further optimization is impeded by a lack of knowledge of the molecular target and binding site. Herein we describe the design, synthesis and evaluation of a series of conformationally restricted analogues with the dual objectives of improving potency/selectivity and identifying the most bioactive conformation. Although this campaign was only modestly successful at improving potency, the sharply defined SAR of the rigid analogs enabled the definition of a three-dimensional pharmacophore, which we believe will be of value in further analog design and virtual screening for alternative antiviral leads.

In Vitro Enzymatic and Kinetic Studies, and In Silico Drug-Receptor Interactions, and Drug-Like Profiling of the 5-Styrylbenzamide Derivatives as Potential Cholinesterase and β-Secretase Inhibitors with Antioxidant Properties

The 5-(styryl)anthranilamides were transformed into the corresponding 5-styryl-2-(p-tolylsulfonamido)benzamide derivatives. These 5-styrylbenzamide derivatives were evaluated through enzymatic assays in vitro for their capability to inhibit acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-secretase (BACE-1) activities as well as for antioxidant potential. An in vitro cell-based antioxidant activity assay involving lipopolysaccharides (LPS)-induced reactive oxygen species (ROS) production revealed that compounds 2a and 3b have the capability of scavenging free radicals. The potential of the most active compound, 5-styrylbenzamide (2a), to bind copper (II) or zinc (II) ions has also been evaluated spectrophotometrically. Kinetic studies of the most active derivatives from each series against the AChE, BChE, and β-secretase activities have been performed. The experimental results are complemented with molecular docking studies into the active sites of these enzymes to predict the hypothetical protein–ligand binding modes. Their drug likeness properties have also been predicted.

Competing HB acceptors: an extensive NMR investigations corroborated by single crystal XRD and DFT calculations

A series of N-benzoylanthranilamide derivatives have been synthesized with the substitution of competitive HB acceptors and investigated by NMR spectroscopy and single crystal XRD. The interesting rivalry for HB acceptance between [double bond splayed left]C[double bond, length as m-dash]O and X (F or OMe) is observed in the investigated molecules which leads to an unusual increase in the electron density at the site of one of the NH protons, reflecting in the high field resonance in the 1H NMR spectrum. The NMR experimental findings and single crystal XRD are further reinforced by the DFT studies.

A compendium of small molecule direct-acting and host-targeting inhibitors as therapies against alphaviruses

Alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally widespread, infecting a large variety of terrestrial animals, birds, insects and even fish. Moreover, they are capable of surviving and circulating in both sylvatic and urban environments, causing considerable human morbidity and mortality. The re-emergence of Chikungunya virus (CHIKV) in almost every part of the world has caused alarm to many health agencies throughout the world. The mosquito vector for this virus, Aedes, is globally distributed in tropical and temperate regions and capable of thriving in both rural and urban landscapes, giving the opportunity for CHIKV to continue expanding into new geographical regions. Despite the importance of alphaviruses as human pathogens, there is currently no targeted antiviral treatment available for alphavirus infection. This mini-review discusses some of the major features in the replication cycle of alphaviruses, highlighting the key viral targets and host components that participate in alphavirus replication and the molecular functions that were used in drug design. Together with describing the importance of these targets, we review the various direct-acting and host-targeting inhibitors, specifically small molecules that have been discovered and developed as potential therapeutics as well as their reported in vitro and in vivo efficacies.

Direct N-alkylation of unprotected amino acids with alcohols

N-alkyl amino acids find widespread application as highly valuable, renewable building blocks. However, traditional synthesis methodologies to obtain these suffer from serious limitations, providing a major challenge to develop sustainable alternatives. We report the first powerful catalytic strategy for the direct N-alkylation of unprotected α-amino acids with alcohols. This method is highly selective, produces water as the only side product leading to a simple purification procedure, and a variety of α-amino acids are mono- or di-N-alkylated, in most cases with excellent retention of optical purity. The hydrophobicity of the products is tunable, and even simple peptides are selectively alkylated. An iron-catalyzed route to mono-N-alkyl amino acids using renewable fatty alcohols is also described that represents an ideal green transformation for obtaining fully bio-based surfactants.

General, Mild, and Metal-Free Synthesis of Phenyl Selenoesters from Anhydrides and Their Use in Peptide Synthesis

A mild, practical, and simple procedure for phenyl selenoesters synthesis from several anhydrides and diphenyl diselenide was developed. This transition-metal-free method provides a straightforward entry to storable Fmoc-amino acid selenoesters which are effective chemoselective acylating reagents. An application to oligopeptide synthesis was illustrated.