Synthesis, molecular modeling and anti-inflammatory screening of novel fluorinated quinoline incorporated benzimidazole derivatives using the Pfitzinger reaction

Quinoline Hydrazide/Hydrazone Derivatives: Recent Insights on Antibacterial Activity and Mechanism of Action

Antibiotics are becoming gradually ineffective due to drug resistance, leading to greater difficulty in the treatment of infectious diseases. Therefore, the development of new chemical entities with different mechanisms of action is essential in the fight against resistant microorganisms. Various studies have shown that quinoline hydrazide/hydrazone derivatives possess several biological activities, such as antimalarial, antitubercular, anticancer, anti-inflammatory, and antimicrobial. Among these activities, the antibacterial activity of quinoline hydrazide/hydrazone derivatives is noteworthy. The synthetic flexibility of the quinoline ring has led to the development of a wide range of structurally diverse quinoline hydrazide/hydrazone derivatives, which can act at various bacterial targets such as DNA gyrase, glucosamine-6-phosphate synthase, enoyl ACP reductase, and 3-ketoacyl ACP reductase. This review emphasizes the antibacterial potential of various reported quinoline hydrazide/hydrazone derivatives based on substitution in the quinoline ring. The antibacterial activity of various metal-quinoline hydrazide/hydrazone complexes is also discussed. The aim of this review is to assemble and scrutinize the latest reports in this promising area of drug development.

In vitro and in silico studies of fluorinated 2,3-disubstituted thiazolidinone-pyrazoles as potential α-amylase inhibitors and antioxidant agents

As part of our effort to identify potent α-amylase inhibitors, in the present study, a novel series of fluorinated thiazolidinone-pyrazole hybrid molecules were prepared by the condensation of 3-(aryl/benzyloxyaryl)-pyrazole-4-carbaldehydes with fluorinated 2,3-disubstituted thiazolidin-4-ones. The structures of the newly synthesized compounds were confirmed by infrared, ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and liquid chromatography-mass spectrometry data. All the compounds were screened for their α-amylase inhibitory and free radical scavenging activities by DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS methods. Among the tested compounds, compound 8g emerged as a promising α-amylase inhibitor with IC₅₀  = 0.76 ± 1.23 µM, and it was found to be more potent than the standard drug acarbose (IC₅₀  = 0.86 ± 0.81 μM). Compounds 8b and 8g showed strong free radical scavenging activity compared to the standard butylated hydroxyl anisole. The kinetic study of compound 8g revealed the reversible, classical competitive inhibition mode on the α-amylase enzyme. Molecular docking and dynamic simulations studies were performed for the most potent compound 8g, which displayed remarkable hydrogen bonding with the α-amylase protein (PDB ID: 1DHK).

Discovery of Novel Pyridazine-Based Cyclooxygenase-2 Inhibitors with a Promising Gastric Safety Profile

Cyclooxygenase-2 (COX-2) is implicated in the development of chronic inflammatory diseases. Recently, pyridazine derivatives have emerged as a novel prototype to develop COX-2 inhibitors. Accordingly, some pyridazine-based COX-2 inhibitors are reported herein. The reaction of aldehyde 3 and different hydrazines yielded the corresponding hydrazones. The hydrazones were further derivatized to the title compounds, which were assessed for COX-1 and COX-2 inhibitory action, gastric ulcerogenic effects, and lipid peroxidation properties. Molecular docking studies and determination of the physicochemical parameters were also carried out. The allocated structures of the reported compounds were coherent with their spectroscopic data. The compounds 9a (IC₅₀ = 15.50 nM, 114.77%), 9b (IC₅₀ = 17.50 nM, 101.65%), 12 (IC₅₀ = 17.10 nM, 104.03%), 16b (IC₅₀ = 16.90 nM, 105.26%), and 17 (IC₅₀ = 17.70 nM, 100.5%) displayed better COX-2 inhibition than celecoxib (IC₅₀ = 17.79 nM, 100%). These outcomes were harmonious with the molecular docking studies of 9a, 9b, 12, 16b, and 17. These compounds also displayed comparable onset and the duration of action concerning celecoxib and indomethacin in the in vivo studies. No ulcerogenic effects were observed for 9a and 12, whereas 9b, 16b, and 17 showed an insignificant ulcerogenic effect compared to celecoxib. The compounds 9a, 9b, 12, 16b, and 17 displayed a better lipid peroxidation profile than celecoxib and indomethacin. The compounds 9a (%ABS = 84.09), 9b (%ABS = 84.09), 12 (%ABS = 66.87), 16b (%ABS = 75.02), and 17 (%ABS = 81.42) also displayed appreciable calculated absorption compared to celecoxib (%ABS = 82.09). The compounds 9a, 9b, 11, 16b, and 17 have been recognized and postulated as non-ulcerogenic COX-2 inhibitors with promising physicochemical parameters and gastric safety profile. These compounds may be useful candidates to combat diseases caused by higher levels of COX-2.

Pharmacological significance of heterocyclic 1H-benzimidazole scaffolds: a review

Heterocyclic compounds are inevitable in a numerous part of life sciences. These molecules perform various noteworthy functions in nature, medication and innovation. Nitrogen-containing heterocycles exceptionally azoles family are the matter of interest in synthesis attributable to the way that they happen pervasively in pharmacologically dynamic natural products, multipurpose arranged useful materials also profoundly powerful pharmaceuticals and agrochemicals. Benzimidazole moiety is the key building block for several heterocyclic scaffolds that play central role in the biologically functioning of essential molecules. They are considered as promising class of bioactive scaffolds encompassing diverse varieties of activities like antiprotozoal, antihelminthic, antimalarial, antiviral, anti-inflammatory, antimicrobial, anti-mycobacterial and antiparasitic. Therefore in the present review we tried to compile the various pharmacological activities of different derivatives of heterocyclic benzimidazole moiety.

Antimicrobial potential of 1H-benzo[d]imidazole scaffold: a review

Background

Benzimidazole is a heterocyclic moiety whose derivatives are present in many of the bioactive compounds and posses diverse biological and clinical applications. Benzimidazole agents are the vital pharmacophore and privileged sub-structures in chemistry of medicine. They have received much interest in drug discovery because benzimidazoles exhibited enormous significance. So attempts have been made to create repository of molecules and evaluate them for prospective inherent activity. They are extremely effective both with respect to their inhibitory activity and favorable selectivity ratio.

Conclusion

Benzimidazole is most promising category of bioactive heterocyclic compound that exhibit a wide variety of biological activities in medicinal field. The present review only focus on antimicrobial activity of reported benzimidazole derivatives may serve as valuable source of information for researchers who wish to synthesize new molecules of benzimidazole nucleus which have immense potential to be investigated for newer therapeutic possibilities.

Design, synthesis and therapeutic potential of 3-(2-(1H-benzo[d]imidazol-2-ylthio)acetamido)-N-(substituted phenyl)benzamide analogues

Background

The emergence of bacterial resistance is a major public health problem. It is essential to develop and synthesize new therapeutic agents with better activity. The mode of actions of certain newly developed antimicrobial agents, however, exhibited very limited effect in treating life threatening systemic infections. Therefore, the advancement of multi-potent and efficient antimicrobial agents is crucial to overcome the increased multi-drug resistance of bacteria and fungi. Cancer, which remains as one of the primary causes of deaths and is commonly treated by chemotherapeutic agents, is also in need of novel and efficacious agents to treat resistant cases. As such, a sequence of novel substituted benzamides was designed, synthesized and evaluated for their antimicrobial and anticancer activities.

Methodology

All synthesized compounds were characterized by IR, NMR, Mass and elemental analysis followed by in vitro antimicrobial studies against Gram-positive (Staphylococcus aureus), Gram-negative (Salmonella typhi and Klebsiella pneumoniae) bacterial and fungal (Candida albicans and Aspergillus niger) strains by the tube dilution method. The in vitro anticancer evaluation was carried out against the human colorectal carcinoma cell line (HCT116), using the Sulforhodamine B assay.

Results, discussion and conclusion

Compound W6 (MIC_{sa, st, kp} = 5.19 µM) emerged as a significant antibacterial agent against all tested bacterial strains i.e. Gram-positive (S. aureus), Gram-negative (S. typhi, K. pneumoniae) while compound W1 (MIC_{ca, an} = 5.08 µM) was most potent against fungal strains (A. niger and C. albicans) and comparable to fluconazole (MIC = 8.16 µM). The anticancer screening demonstrated that compound W17 (IC₅₀ = 4.12 µM) was most potent amongst the synthesized  compounds and also more potent than the standard drug 5-FU (IC₅₀ = 7.69 µM).

Synthesis, molecular modeling and biological screening of some pyrazole derivatives as antileishmanial agents

Aim: Novel open chain and cyclized derivatives containing pyrazole scaffold were designed, synthesized and evaluated as antileishmanial compounds. Methodology & results: In silico reverse docking experiment suggested Leishmania major pteridine reductase (Lm-PTR1) as a putative target for the synthesized compounds. In vitro antileishmanial screening against L. major promastigotes and amastigotes using miltefosine and amphotericin B as references showed that the majority of the compounds displayed activity higher than miltefosine. Compounds 3i and 5 showed the highest antileishmanial activity with IC50 values of 1.45 ± 0.08 μM and 2.30 ± 0.09 μM, respectively, for the amastigote form. In silico drug-likeness and toxicity predictions showed acceptable profiles for most of the compounds, which were validated by experimental toxicity studies. Conclusion: This study offers promising entities for antileishmanial activity.

An efficient, one-pot three-component synthesis of 4H-thiazolo[3,2-a][1,3,5]triazin-6-one derivatives

A simple and efficient protocol was established to synthesize thiazolo[3,2-a][1,3,5]triazin-6-ones via three-component one-pot condensation reaction of readily available thioglycolic acid or ethyl thioglycolate, aldehydes or ketones and dicyandiamide in the presence of ammonium acetate. All of the newly synthesized compounds were characterized by spectroscopic analyses.

One-Pot Synthesis, Spectroscopic and Physicochemical Studies of Quinoline Based Blue Emitting Donor-Acceptor Chromophores with Their Biological Application

Blue emitting cyano substituted isoquinoline dyes were synthesized by one-pot multicomponent reactions (MCRs) of aldehydes, malononitrile, 6-methoxy-1,2,3,4-tetrahydro-naphthalin-1-one and ammonium acetate. Results obtained from spectroscopic (FT-IR, (1)H-NMR, (13)C-NMR, EI-MS) and elemental analysis of synthesized compounds was in good agreement with their chemical structures. UV-vis and fluorescence spectroscopy measurements proved that all compounds are good absorbent and fluorescent. Fluorescence polarity study demonstrated that these compounds were sensitive to the polarity of the microenvironment provided by different solvents. In addition, spectroscopic and physicochemical parameters, including electronic absorption, excitation coefficient, stokes shift, oscillator strength, transition dipole moment and fluorescence quantum yield were investigated in order to explore the analytical potential of synthesized compounds. The anti-bacterial activity of these compounds were first studied in vitro by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria then the minimum inhibitory concentration (MIC) was determined with the reference of standard drug chloramphenicol. The results displayed that compound 3 was better inhibitors of both types of the bacteria (Gram-positive and Gram-negative) than chloramphenicol. Graphical Abstract ᅟ.

Synthesis, molecular docking and anti-inflammatory screening of novel quinoline incorporated pyrazole derivatives using the Pfitzinger reaction II

In continuation of our study of novel quinolines with anti-inflammatory activity using the Pfitzinger reaction, several new quinoline derivatives were synthesized and tested for their anti-inflammatory and ulcerogenic effect. A docking study on the COX-2 binding pocket was carried out for the target compounds to rationalize the possible selectivity of them against COX-2 enzyme. The most active compounds (5a, 8a and 11a) were found to be superior to celecoxib. Compound 11a demonstrated the highest anti-inflammatory activity as well as the best binding profiles into the COX-2 binding site. Moreover, compounds 9c, 9e, 10a and 11a were devoid of ulcerogenic activity.