New library of pyrazole–imidazo[1,2‐α]pyridine molecular conjugates: Synthesis, antibacterial activity and molecular docking studies

Fluorinated azoles as effective weapons in fight against methicillin-resistance staphylococcus aureus (MRSA) and its SAR studies

The rapid spread of Methicillin-resistant Staphylococcus aureus (MRSA) and its difficult-to-treat skin and filmsy diseases are making MRSA a threat to human life. The most dangerous feature is the fast emergence of MRSA resistance to all recognized antibiotics, including vancomycin. The creation of novel, effective, and non-toxic drug candidates to combat MRSA isolates is urgently required. Fluorine containing small molecules have taken a centre stage in the field of drug development. Over the last 50 years, there have been a growing number of fluorinated compounds that have been approved since the clinical usage of fluorinated corticosteroids in the 1950 s and fluoroquinolones in the 1980 s. Due to its advantages in terms of potency and ADME (absorption, distribution, metabolism, and excretion), fluoro-pharmaceuticals have been regarded as a potent and useful tool in the rational drug design method. The flexible bioactive fluorinated azoles are ideal candidates for the development of new antibiotics. This review summarizes the decade developments of fluorinated azole derivatives with a wide antibacterial activity against diverged MRSA strains. In specific, we correlated the efficacy of structurally varied fluorinated azole analogues including thiazole, benzimidazole, oxadiazole and pyrazole against MRSA and discussed different angles of structure-activity relationship (SAR).

Synergistic antimicrobial activity, MD simulation studies and crystal structure of natural alcohol motif containing novel substituted cinnamates

A series of natural alcohols motif containing novel substituted cinnamates were developed and screened against five bacterial strains namely, Enterococcus faecal (E. faecalis), Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumonieae (K. pneumonieae). Among all cinnamates, YS17 was identified with 100% bacterial growth inhibition across the panel, except in E. faecalis with MIC values of 0.25 mg/mL against B. subtilis and P. aeruginosa whereas 0.125, 0.5 and 1 mg/mL against E. coli, K. pneumonieae and E. faecalis, respectively. The growth inhibitory property of YS17 was further validated by disk diffusion, synergistic study and in vitro toxicity assays. Interestingly, YS17 exhibits synergistic effect in combination with the standard drug Ampicillin (AMP). The single crystal structure analysis of YS4 and YS6 was also performed which reconfirmed their proposed structures. Molecular docking visualized significant non-covalent interactions between E. coli MetAP and YS17 and the structural and conformational changes were further analysed using MD simulation studies. Overall, the study provided a suitable core for further synthetic alterations for their optimization as an antibacterial agent. Communicated by Ramaswamy H. Sarma.

Inhibitors of glucosamine-6-phosphate synthase as potential antimicrobials or antidiabetics - synthesis and properties

Glucosamine-6-phosphate synthase (GlcN-6-P synthase) is known as a promising target for antimicrobial agents and antidiabetics. Several compounds of natural or synthetic origin have been identified as inhibitors of this enzyme. This set comprises highly selective l-glutamine, amino sugar phosphate or transition state intermediate cis-enolamine analogues. Relatively low antimicrobial activity of these inhibitors, poorly penetrating microbial cell membranes, has been improved using the pro-drug approach. On the other hand, a number of heterocyclic and polycyclic compounds demonstrating antimicrobial activity have been presented as putative inhibitors of the enzyme, based on the results of molecular docking to GlcN-6-P synthase matrix. The most active compounds of this group could be considered promising leads for development of novel antimicrobial drugs or antidiabetics, provided their selective toxicity is confirmed.

Synthetic Imidazopyridine-Based Derivatives as Potential Inhibitors against Multi-Drug Resistant Bacterial Infections: A Review

Fused pyridines are reported to display various pharmacological activities, such as antipyretic, analgesic, antiprotozoal, antibacterial, antitumor, antifungal, anti-inflammatory, and antiapoptotic. They are widely used in the field of medicinal chemistry. Imidazopyridines (IZPs) are crucial classes of fused heterocycles that are expansively reported on in the literature. Evidence suggests that IZPs, as fused scaffolds, possess more diverse profiles than individual imidazole and pyridine moieties. Bacterial infections and antibacterial resistance are ever-growing risks in the 21st century. Only one IZP, i.e., rifaximin, is available on the market as an antibiotic. In this review, the authors highlight strategies for preparing other IZPs. A particular focus is on the antibacterial profile and structure-activity relationship (SAR) of various synthesized IZP derivatives. This research provides a foundation for the tuning of available compounds to create novel, potent antibacterial agents with fewer side effects.

Medicinal Importance and Chemosensing Applications of Pyridine Derivatives: A Review

Pyridine derivatives are the most common and significant heterocyclic compounds, which play an important role in various fields ranging from medicinal to chemosensing applications. Pyridine derivatives possess different biological activities such as antifungal, antibacterial, antioxidant, antiglycation, analgesic, antiparkinsonian, anticonvulsant, anti-inflammatory, ulcerogenic, antiviral, and anticancer activity. Furthermore, these derivatives have a high affinity for various ions and neutral species and can be used as a highly effective chemosensor for the determination of different species. In this review article, generally used synthetic routes of pyridine, structural characterization, medicinal applications, and potential of pyridine derivatives in analytical chemistry as chemosensors have been discussed. We hope this study will support the new thoughts to design biological active compounds and highly selective and effective chemosensors for the detection of various species (anions, cations, and neutral species) in various samples (environmental, agricultural, and biological). [Figure: see text].

A Review of the Recent Development in the Synthesis and Biological Evaluations of Pyrazole Derivatives

Pyrazoles are five-membered heterocyclic compounds that contain nitrogen. They are an important class of compounds for drug development; thus, they have attracted much attention. In the meantime, pyrazole derivatives have been synthesized as target structures and have demonstrated numerous biological activities such as antituberculosis, antimicrobial, antifungal, and anti-inflammatory. This review summarizes the results of published research on pyrazole derivatives synthesis and biological activities. The published research works on pyrazole derivatives synthesis and biological activities between January 2018 and December 2021 were retrieved from the Scopus database and reviewed accordingly.

A Review of the Recent Developments of Molecular Hybrids Targeting Tubulin Polymerization

Microtubules are cylindrical protein polymers formed from αβ-tubulin heterodimers in the cytoplasm of eukaryotic cells. Microtubule disturbance may cause cell cycle arrest in the G2/M phase, and anomalous mitotic spindles will form. Microtubules are an important target for cancer drug action because of their critical role in mitosis. Several microtubule-targeting agents with vast therapeutic advantages have been developed, but they often lead to multidrug resistance and adverse side effects. Thus, single-target therapy has drawbacks in the effective control of tubulin polymerization. Molecular hybridization, based on the amalgamation of two or more pharmacophores of bioactive conjugates to engender a single molecular structure with enhanced pharmacokinetics and biological activity, compared to their parent molecules, has recently become a promising approach in drug development. The practical application of combined active scaffolds targeting tubulin polymerization inhibitors has been corroborated in the past few years. Meanwhile, different designs and syntheses of novel anti-tubulin hybrids have been broadly studied, illustrated, and detailed in the literature. This review describes various molecular hybrids with their reported structural–activity relationships (SARs) where it is possible in an effort to generate efficacious tubulin polymerization inhibitors. The aim is to create a platform on which new active scaffolds can be modeled for improved tubulin polymerization inhibitory potency and hence, the development of new therapeutic agents against cancer.

Antibacterial pyrazoles: tackling resistant bacteria

Bacterial resistance to antibiotics threatens our progress in healthcare, modern medicine, food production and ultimately life expectancy. Antibiotic resistance is a global concern, which spreads rapidly across borders and continents due to rapid travel of people, animals and goods. Derivatives of metabolically stable pyrazole nucleus are known for their wide range of pharmacological properties, including antibacterial activities. This review highlights recent reports of pyrazole derivatives targeting different bacterial strains focusing on the drug-resistant variants. Pyrazole derivatives target different metabolic pathways of both Gram-positive and Gram-negative bacteria.

Hydromagnesite sheets impregnated with cobalt-ferrite magnetic nanoparticles as heterogeneous catalytic system for the synthesis of imidazo[1,2-a]pyridine scaffolds

This paper manifests an A³-coupling strategy assisted by novel hydromagnesite sheets impregnated with cobalt ferrite (CoFe₂O₄-HMS) magnetic nanoparticles (MNPs) as an environmentally benign nanocomposite to synthesize imidazo[1,2-a]pyridine scaffolds under ultrasonication. The synthesis of these biologically active derivatives was achieved through A³-coupling employing 2-aminopyridines derivatives, pertinent aryl aldehydes, and phenylacetylene in the presence of polyethylene glycol 400 (PEG 400) as a green solvent under aerobic conditions. Based on its high product yield (up to 94%) in a short reaction time, with a modest catalyst loading, excellent catalyst, and solvent recyclability without substantial loss of operation (up to five synthetic cycles), as demonstrated by the high ecological compatibility and sustainability factors, this strategy follows the principles of green chemistry. The synthesized nanocomposite was characterized via several spectroanalytical techniques, including PXRD, FE-SEM, HR-TEM, EDAX, ICP-AES, FT-IR, Raman spectroscopy, CO₂-TPD, TGA-DTA-DTG analyses, magnetic studies, and nitrogen porosimetry. Furthermore, the structures of synthesized compounds were confirmed based on FT-IR, ¹H NMR, ¹³C NMR, mass spectroscopy, and elemental analysis data.

Sustainable synthesis of imidazo[1,2-a]pyridine scaffolds assisted by hydromagnesite sheets impregnated with cobalt–ferrite (CoFe₂O₄-HMS) magnetic nanoparticles (MNPs).

Pyrazole-based analogs as potential antibacterial agents against methicillin-resistance staphylococcus aureus (MRSA) and its SAR elucidation

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming lethal to humanity due to easy transmission and difficult-to-treat skin and flimsy diseases. The most threatening aspect is the rapid resistance development of MRSA to any approved antibiotics, including vancomycin. The development of new, efficient, and nontoxic drug candidate to fight against MRSA isolates is the need of the hour. The intriguing molecular structure and versatile bioactive pyrazole core attracting to development required novel antibiotics. This review presents the decade developments of pyrazole-containing derivatives with a broad antibacterial movement against diverged bacterial strains. In specific, we correlated the efficacy of structurally diversified pyrazole analogs against MRSA and discussed different angles of structure-activity relationship (SAR). The current survey highlights pyrazole hybrids' present scenario on MRSA studies, covering articles published from 2011 to 2020. This collective information may become an excellent platform to plan and develop new pyrazole-based small MRSA growth inhibitors with minimal side effects.

Synthesis, antimicrobial evaluation, and in silico studies of quinoline-1H-1,2,3-triazole molecular hybrids

Antimicrobial resistance has become a significant threat to global public health, thus precipitating an exigent need for new drugs with improved therapeutic efficacy. In this regard, molecular hybridization is deemed as a viable strategy to afford multi-target-based drug candidates. Herein, we report a library of quinoline-1H-1,2,3-triazole molecular hybrids synthesized via copper(I)-catalyzed azide-alkyne [3 + 2] dipolar cycloaddition reaction (CuAAC). Antimicrobial evaluation identified compound 16 as the most active hybrid in the library with a broad-spectrum antibacterial activity at an MIC₈₀ value of 75.39 μM against methicillin-resistant S. aureus, E. coli, A. baumannii, and multidrug-resistant K. pneumoniae. The compound also showed interesting antifungal profile against C. albicans and C. neoformans at an MIC₈₀ value of 37.69 and 2.36 μM, respectively, superior to fluconazole. In vitro toxicity profiling revealed non-hemolytic activity against human red blood cells (hRBC) but partial cytotoxicity to human embryonic kidney cells (HEK293). Additionally, in silico studies predicted excellent drug-like properties and the importance of triazole ring in stabilizing the complexation with target proteins. Overall, these results present compound 16 as a promising scaffold on which other molecules can be modeled to deliver new antimicrobial agents with improved potency.