Antioxidant and antibacterial studies of arylazopyrazoles and arylhydrazonopyrazolones containing coumarin moiety

Direct Growth Control of Antibiotic-Resistant Bacteria Using Visible-Light-Responsive Novel Photoswitchable Antibiotics

In addition to the discovery of new (modified) potent antibiotics to combat antibiotic resistance, there is a critical need to develop novel strategies that would restrict their off-target effects and unnecessary exposure to bacteria in our body and environment. We report a set of new photoswitchable arylazopyrazole-modified norfloxacin antibiotics that present a high degree of bidirectional photoisomerization, impressive fatigue resistance and reasonably high cis half-lives. The irradiated isomers of most compounds were found to exhibit nearly equal or higher antibacterial activity than norfloxacin against Gram-positive bacteria. Notably, against norfloxacin-resistant S. aureus bacteria, the visible-light-responsive p-SMe-substituted derivative showed remarkably high antimicrobial potency (MIC of 0.25 μg/mL) in the irradiated state, while the potency was reduced by 24-fold in case of its non-irradiated state. The activity was estimated to be retained for more than 7 hours. This is the first report to demonstrate direct photochemical control of the growth of antibiotic-resistant bacteria and to show the highest activity difference between irradiated and non-irradiated states of a photoswitchable antibiotic. Additionally, both isomers were found to be non-harmful to human cells. Molecular modellings were performed to identify the underlying reason behind the high-affinity binding of the irradiated isomer to topoisomerase IV enzyme.

Photoswitchable Antibiotic Hybrids: Spacer Length-Dependent Photochemical Control of Antibacterial Activity

Photopharmacology holds huge potential for the permanent (long-term) eradication of antibiotic resistance by the application of photoswitchable antibiotics. To construct such antibiotics, various methods have been employed to modify known antibiotics with photoswitches, such that the irradiated state shows activity comparable to or higher than that of the parent antibiotic and that a large activity difference between irradiated and nonirradiated states is achieved. However, most of those methods are ineffective when dealing with more than one drug with dissimilar structures. Here, we have demonstrated a new approach, in which two pharmacophores, one being a photoswitch, are covalently linked via a spacer of variable lengths, leading to a set of azopyrazole-norfloxacin antibiotic hybrids. All compounds showed a high degree of bidirectional photoisomerization, long thermal cis half-lives, and excellent photoresistance. Notably, the hybrid with an optimal four-carbon spacer length enabled the irradiated state to become 12-fold more potent than its nonirradiated state without losing much antimicrobial activity of norfloxacin. Only Gram-positive bacteria were found to be sensitive to this hybrid, and the full antibacterial potency of its irradiated state was found to be retained for nearly 24 h.

Powerful Potential of Polyfluoroalkyl-Containing 4-Arylhydrazinylidenepyrazol-3-ones for Pharmaceuticals

4-Arylhydrazinylidene-5-(polyfluoroalkyl)pyrazol-3-ones (4-AHPs) were found to be obtained by the regiospecific cyclization of 2-arylhydrazinylidene-3-(polyfluoroalkyl)-3-oxoesters with hydrazines, by the azo coupling of 4-nonsubstituted pyrazol-5-oles with aryldiazonium chlorides or by the firstly discovered acid-promoted self-condensation of 2-arylhydrazinylidene-3-oxoesters. All the 4-AHPs had an acceptable ADME profile. Varying the substituents in 4-AHPs promoted the switching or combining of their biological activity. The polyfluoroalkyl residue in 4-AHPs led to the appearance of an anticarboxylesterase action in the micromolar range. An NH-fragment and/or methyl group instead of the polyfluoroalkyl one in the 4-AHPs promoted antioxidant properties in the ABTS, FRAP and ORAC tests, as well as anti-cancer activity against HeLa that was at the Doxorubicin level coupled with lower cytotoxicity against normal human fibroblasts. Some Ph-N-substituted 4-AHPs could inhibit the growth of N. gonorrhoeae bacteria at MIC 0.9 μg/mL. The possibility of using 4-AHPs for cell visualization was shown. Most of the 4-AHPs exhibited a pronounced analgesic effect in a hot plate test in vivo at and above the diclofenac and metamizole levels except for the ones with two chlorine atoms in the aryl group. The methylsulfonyl residue was proved to raise the anti-inflammatory effect also. A mechanism of the antinociceptive action of the 4-AHPs through blocking the TRPV1 receptor was proposed and confirmed using in vitro experiment and molecular docking.

Synthesis and antimicrobial activity of aryldiazenyl/arylhydrazono pyrazoles

We report the design, synthesis, and in vitro antimicrobial evaluation of functionalized pyrazoles containing a hydrazono/diazenyl moiety. Among these newly synthesized derivatives, 4-[2-(4-chlorophenyl)hydrazono]-5-methyl-2-[2-(naphthalen-2-yloxy)acetyl]-2,4-dihydro-3 H-pyrazol-3-one is a promising antimicrobial agent against Staphylococcus aureus (minimum inhibitory concentration 0.19 μg mL−1). Structure–activity relationship studies reveal that the electronic environment on the distal phenyl ring has a considerable effect on the antimicrobial potential of the hybrid analogues. Molecular docking studies into the active site of S. aureus dihydrofolate reductase also prove the usefulness of hybridizing a pyrazole moiety with azo and hydrazo groups in the design of new antimicrobial agents.

Novel heterocyclic hybrids of pyrazole targeting dihydrofolate reductase: design, biological evaluation and in silico studies

A novel series of pyrazole analogues including hydrazones, pyrazolo[4,3-c]-pyridazines, pyrazolo[3,4-e][1,2,4]triazine and pyrazolo[3,4-d][1,2,3]triazoles was designed, synthesised and screened for their in vitro antimicrobial and DHFR inhibition activity. Compounds bearing benzenesulphonamide moiety incorporated with 3-methyl-5-oxo-1H-pyrazol-4(5H)-ylidene) hydrazine 3a or 6-amino-7-cyano-3-methyl-5H-pyrazolo[4,3-c]pyridazine 6a revealed excellent and broad spectrum antimicrobial activity comparable to ciprofloxacin and amphotericin B as positive antibiotic and antifungal controls, respectively. Furthermore, these derivatives proved to be the most active DHFR inhibitors with IC₅₀ values 0.11 ± 1.05 and 0.09 ± 0.91 µM, in comparison with methotrexate (IC₅₀ = 0.14 ± 1.25 µM). The in silico studies were done to calculate the drug-likeness and toxicity risk parameters of the newly synthesised derivatives. Additionally, the high potency of the pyrazole derivatives bearing sulphonamide against DHFR was confirmed with molecular docking and might be used as an optimum lead for further modification.

Synthesis, anticancer and antimicrobial evaluation of new benzofuran based derivatives: PI3K inhibition, quorum sensing and molecular modeling study

A new series of benzofuran derivatives has been designed and synthesized. The structures of the synthesized compounds have been confirmed by the use of ¹H NMR, ¹³C NMR, 2D ¹H-¹H NOESY NMR, and IR. Anticancer activity is evaluated against Hepatocellular carcinoma (HePG2), mammary gland breast cancer (MCF-7), Epitheliod carcinoma cervix cancer (Hela) and human prostate cancer (PC3). Compounds 8, 9, and 11 showed the highest activity towards the four cell lines with an IC₅₀ range of 8.49-16.72 µM, 6.55-13.14 µM and 4-8.99 µM respectively in comparison to DOX (4.17-8.87 µM). Phosphatidylinositol-3-kinases (PI3K) inhibition was evaluated against the most active anticancer compounds 8, 9 and 11. Compounds 8, 9 and 11 showed good inhibitory activity against PI3Kα with IC₅₀ values 4.1, 7.8, and 20.5 µM, respectively in comparison to 6.18 µM for the reference compound LY294002. In addition, activity of compounds 8 and 9 on cell cycle arrest and induction of apoptosis in different phases of MCF-7 cells were assessed and detected pre-G1 apoptosis and cell growth arrest at G2/M. Also, both extrinsic and intrinsic apoptosis in MCF-7 cells induced by compounds 8 and 9. Molecular docking, binding affinity surface mapping, and contact preference of the synthesized compounds 8, 9 and 11 against PI3K were estimated and studied computationally using molecular operating environment software (MOE) and showed good interaction with essential residues for inhibition Val851. In addition, antimicrobial activity was evaluated against gram positive isolates as Staphylococcus aureus and Bacillus cereus, gram negative isolate as Escherichia coli, Pseudomonas aeruginosa and antifungal potential against Candida albicans. Compound 17 showed outstanding anti Gram-positive activity with MIC values 8 and 256 µg/mL in Staphylococcus aureus and Bacillus cereus respectively. Also, compounds 15, 17, 18 and 21 showed good anti Gram-negative activity with MIC value 512 µg/mL for all compounds. In addition, the state-of-art quorum sensing (QS) inhibiting effects were detected using Chromobacterium violaceum and compounds 7, 9, 10, 11, and 12 showed good QS inhibition (3, 3, 5, 2, and 7 mm).

Recent Advances in the Synthesis of Pyrazole Derivatives

Pyrazole and its derivatives have gained wide attention in pharmaceutical, agrochemical and biological fields as well as in industry. They exhibit various biological activities such as anti-pyretic, anti-microbial, anti- inflammatory, anti-tumor, anti-viral, anti-histaminic, anti-convulsant, fungicidal, insecticidal, etc. In this review, we summarise the recent advances in the synthesis of pyrazole derivatives using various methodologies and covers literature from 2017-2020.

Investigation of antioxidant and anti-nociceptive potential of isoxazolone, pyrazolone derivatives, and their molecular docking studies

A series of new isoxazolone (3a-d) and pyrazolone (4a-d) derivatives were synthesized and assessed for their antioxidant and analgesic activity. Among synthesized compounds, 3b and 4b having nitro (NO₂ ) group show high analgesic activity at a dose of 6 mg/kg. Analgesic activity was further proceeded to explore the contribution of opioidergic mechanisms in the mediation of analgesic effects. Animals were administered with naloxone, a nonselective opioid inverse agonist, at the dose of 0.5 mg/kg. The results obtained suggested that the analgesic effects of the synthesized compounds were not reversed by naloxone, specifying that the compounds 3b and 4b do not follow the opioidergic pathway in order to relieve pain in animal models. Further, the binding interactions of compounds 3b and 4b were analyzed by docking them against nonopioid receptors COX-1 (3N8X) and COX-2 (3LN1). The results demonstrate the analgesic potential of isoxazolone and pyrazolone derivatives, especially compounds 3b and 4b can be considered promising lead molecules for further investigation and development into potent analgesic drugs. In addition, the antioxidant potential of compounds was also found to be related to better analgesic activity, thus providing an insight into the role of oxidative stress in the mediation of analgesia.

Synthesis, Characterization and Antioxidant Properties of a New Lipophilic Derivative of Edaravone

As part of a program aimed to obtain antioxidants able to interact with cell membrane, edaravone (EdV, 3-methyl-1-phenyl-2-pyrazolin-5-one), a well-known free radical scavenger, has been modified by alkylation at its allylic position (4) with a C-18 hydrocarbon chain, and the increased lipophilicity has been determined towards the interaction with liposomes. The obtained derivative has been studied by means of density functional theory (DFT) methods in order to characterize its lowest energy conformers and predict its antioxidant properties with respect to the parent compound EdV. The in vitro antioxidant activity of C18-edaravone was studied by means of the α,α-diphenyl-β-picrylhydrazyl (DPPH) assay and in lipid peroxidation experiments performed on artificial lipid membranes using water-soluble as well as lipid-soluble radical initiators. Moreover, since oxidative stress is involved in numerous retinal degenerative diseases, the ability of C18-edaravone to contrast 2,2-azobis (2-amidinopropane hydrochloride) (AAPH)-induced cell death was assessed in adult retinal pigmented epithelium (ARPE-19) cells. Overall, the results demonstrated that the newly synthesized molecule has a high affinity for lipid membrane, increasing the efficacy of the unmodified edaravone under stress conditions.

Antibacterial and antioxidant activities for natural and synthetic dual-active compounds

Antimicrobial resistance is widely recognized as a grave threat to global health in the 21st century, since the past decades have seen a dramatic increase in human-pathogenic bacteria that are resistant to one or multiple antibiotics. New antimicrobial agents are urgently required, particularly in the treatment of chronic infections such as cystic fibrosis, often associated with persistent colonization by drug-resistant pathogens and epithelial damage by pulmonary oxidative stress. In such events, it would be favourable to find agents that could have antioxidant and antibacterial activities combined in one molecule. The discovery of compounds that can show a dual-target activity considerably increased in the last years, reflecting the growing confidence that this new approach could lead to better therapeutic solutions for complex multigenic diseases. The aim of this review is to report those natural and synthetic compounds displaying significant antioxidant and antibacterial activities. In recent years there has been a growing attention on plant-derived antimicrobials as an alternative to antibiotics, for their efficacy and low tendency in developing bacterial resistance. Moreover, it was found that some natural products could enhance the activity of common antibiotics displaying a synergistic effect. We then report some selected synthetic compounds with an in-built capacity to act on two targets or with the combination in a single structure of two pharmacophores with antioxidant and antibacterial activities. Recent literature instances were screened and the most promising examples of dual-active antibacterial-antioxidant molecules were highlighted.

Current progress on antioxidants incorporating the pyrazole core

The search of new antioxidants, as drugs candidates, is an active field of medicinal chemistry. The synthesis of compounds with antioxidant potential has increased in recent years and a high number of structurally diverse compounds have been published. This review aims to show the current state-of-the-art on the development of antioxidant compounds incorporating the pyrazole pharmacophore. It is a well-timed review driven by the increasing number of papers, on this issue, that have been published since the beginning of the 21st century (from 2000 to 2017). The aim is to look deeper into the structures already published in the literature containing the pyrazole core as the unique pharmacophore or combined with other pharmacophores and see the relationship between the presence of this five-membered nitrogen heterocycle and the behaviour of the compounds as potential antioxidant agents. An attempt was made to whenever possible establish structure-activity relationships that could help the design of new and more potent antioxidant agents containing this important pharmacophore.

Efficient Synthesis of Five Types of Heterocyclic Compounds via Intramolecular Elimination Using Ultrasound-Static Heating Technique

An experimental technique, ultrasound-static heating, has been developed for the efficient synthesis of heterocyclic compounds. The technique involves ultrasonic irradiation and static heating processes. First, the ultrasonic irradiation process is performed to form an intermediate of the heterocyclic compound under mild conditions and the subsequent static heating process (heating the intermediate under solvent-free conditions without stirring) produces the target heterocyclic compounds via intramolecular elimination.

Design, synthesis, DFT, docking studies and ADME prediction of some new coumarinyl linked pyrazolylthiazoles: Potential standalone or adjuvant antimicrobial agents

The control of antimicrobial resistance (AMR) seems to have come to a dead end. The major consequences of the use and abuse of antibacterial drugs are the development of resistant strains due to genetic mutability of both pathogenic and nonpathogenic microorganisms. We, herein, report the synthesis, characterization and biological activities of coumarin-thiazole-pyrazole (CTP) molecular hybrids with an effort to explore and overcome the increasing antimicrobial resistance. The compounds were characterized by analyzing their IR, Mass, 1H and13C NMR spectral data and elemental analysis. The in vitro antimicrobial activity of the synthesized compounds was investigated against various pathogenic strains; the results obtained were further explained with the help of DFT and molecular orbital calculations. Compound 1b and 1f displayed good antimicrobial activity and synergistic effects when used with kanamycin and amphotericin B. Furthermore, in vitro cytotoxicity of compounds 1b and 1f were studied against HeLa cells (cervical cancer cell) and Hek-293 cells. The results of molecular docking study were used to better rationalize the action and prediction of the binding modes of these compounds.

Efficient pseudo five-component synthesis of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives promoted by a novel ionic liquid catalyst

In this research, initial production and characterization of a novel Brønsted-acidic ionic liquid, namely, N,N,N′,N′-tetramethylethylenediaminium-N,N′-disulfonic acid hydrogen sulfate ([TMEDSA][HSO4]2), has been described (characterization was achieved using Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR), 13C NMR, and mass and thermal gravimetric spectra). Thereafter, utilization of [TMEDSA][HSO4]2 as a highly effectual catalyst for the synthesis of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives through the one-pot pseudo five-component reaction of phenylhydrazine (2 eq.) with ethyl acetoacetate (2 eq.) and arylaldehydes (1 eq.) in relatively mild conditions, has been reported.

Synthesis, characterization and in vitro antimicrobial activity of novel fused pyrazolo[3,4-c]pyridazine, pyrazolo[3,4-d]pyrimidine, thieno[3,2-c]pyrazole and pyrazolo[3',4':4,5]thieno[2,3-d]pyrimidine derivatives

Background

Some novel substituted pyrazolone, pyrazolo[3,4-c]pyridazine, pyrazolo[3,4-d]pyrimidine, pyrazolo[3,4-d]thiazolo[3,2-a]pyrimidinone, thieno[3,2-c]pyrazole and pyrazolo[3′,4′:4,5]thieno[2,3-d]pyrimidine derivatives have been reported to possess various pharmacological activities like antimicrobial, antitumor and anti-inflammatory.

Results

A novel series of azoles and azines were designed and prepared via reaction of 1,3-diphenyl-1H-pyrazol-5(4H)-one with some electrophilic and nucleophilic reagents. The structures of target compounds were confirmed by elemental analyses and spectral data.

Conclusions

The antimicrobial activity of the target synthesized compounds were tested against various microorganisms such as Escherichia coli; Bacillus megaterium; Bacillus subtilis (Bacterial species), Fusarium proliferatum; Trichoderma harzianum; Aspergillus niger (fungal species) by the disc diffusion method. In general, the novel synthesized compounds showed a good antimicrobial activity against the previously mentioned microorganisms.