Synthesis and biological activities of novel 1,2,4-triazole thiones and bis(1,2,4-triazole thiones) containing phenylpyrazole and piperazine moieties

Synthesis of modified Schiff base appended 1,2,4-triazole hybrids scaffolds: elucidating the in vitro and in silico α-amylase and α-glucosidase inhibitors potential

The current study involves the synthesis of Schiff bases based on 1,2,4-triazoles skeleton and assessing their α-amylase and α-glucosidase profile. Furthermore, the precise structures of the synthesized derivatives were elucidated using various spectroscopic methods such as 1H-NMR, 13C-NMR and HREI-MS. Using glimepiride as the reference standard, the in vitro α-glucosidase and α-amylase inhibitory activities of the synthesized compounds were evaluated in order to determine their potential anti-diabetic properties. All analogues showed varied range of inhibitory activity having IC50 values ranging from 17.09 ± 0.72 to 45.34 ± 0.03 μM (α-amylase) and 16.35 ± 0.42 to 42.31 ± 0.09 μM (α-glucosidase), respectively. Specifically, the compounds 1, 7 and 8 were found to be significantly active with IC50 values of 17.09 ± 0.72, 19.73 ± 0.42, and 23.01 ± 0.04 μM (against α-amylase) and 16.35 ± 0.42, 18.55 ± 0.26, and 20.07 ± 0.02 μM (against α-glucosidase) respectively. The obtained results were compared with the Glimepiride reference drug having IC50 values of 13.02 ± 0.11 μM (for α-glucosidase) and 15.04 ± 0.02 μM (for α-amylase), respectively. The structure-activity relationship (SAR) studies were conducted based on differences in substituent patterns at varying position of aryl rings A and B may cause to alter the inhibitory activities of both α-amylase and α-glucosidase enzymes. Additionally, the molecular docking study was carried out to explore the binding interactions possessed by most active analogues with the active sites of targeted α-amylase and α-glucosidase enzymes.

Recent Applications of the Multicomponent Synthesis for Bioactive Pyrazole Derivatives

Pyrazole and its derivatives are considered a privileged N-heterocycle with immense therapeutic potential. Over the last few decades, the pot, atom, and step economy (PASE) synthesis of pyrazole derivatives by multicomponent reactions (MCRs) has gained increasing popularity in pharmaceutical and medicinal chemistry. The present review summarizes the recent developments of multicomponent reactions for the synthesis of biologically active molecules containing the pyrazole moiety. Particularly, it covers the articles published from 2015 to date related to antibacterial, anticancer, antifungal, antioxidant, α-glucosidase and α-amylase inhibitory, anti-inflammatory, antimycobacterial, antimalarial, and miscellaneous activities of pyrazole derivatives obtained exclusively via an MCR. The reported analytical and activity data, plausible synthetic mechanisms, and molecular docking simulations are organized in concise tables, schemes, and figures to facilitate comparison and underscore the key points of this review. We hope that this review will be helpful in the quest for developing more biologically active molecules and marketed drugs containing the pyrazole moiety.

2-((4-Phenyl-5-(2-(p-tolylamino)ethyl)-4H-1,2,4-triazol-3-yl)thio)-N′-(1-phenylethylidene)acetohydrazide

A synthesis of 2-((4-phenyl-5-(2-(p-tolylamino)ethyl)-4H-1,2,4-triazol-3-yl)thio)-N’-(1-phenylethylidene)acetohydrazide from 2-[(3-{2-[(4-methylphenyl)amino]ethyl}-4-phenyl-4,5-dihydro-1H-1,2,4-triazol-5-yl)sulfanyl]acetohydrazide and acetophenone is reported. The title compound has been tested to possess 1.5-fold higher antioxidant ability than the control, butylated hydroxytoluene, as determined by a Ferric reducing antioxidant power assay.

Design and microwave-assisted synthesis of a novel Mannich base and conazole derivatives and their biological assessment

4-Amino-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (1) was converted to the corresponding Schiff base (2) by treatment with salicylaldehyde. 1,2,4-Triazoles were then converted to the corresponding Mannich bases containing fluroquinolone core using a one-pot three-component procedure. Moreover, the synthesis of six compounds, which can be considered as conazole analogues, was performed starting from 1,2,4-triazole-3-one compounds via three steps by either conventional or microwave-mediated conditions. All the newly synthesized compounds were screened for their antimicrobial activities. Most exhibited good to moderate antibacterial and/or antifungal activity. The structural assignments of the new compounds were based on elemental analysis and spectral (IR, 1H NMR, 13C NMR, and LC-MS) data.

1,2,4-Triazole: A Privileged Scaffold for the Development of Potent Antifungal Agents - A Brief Review

Over the past decades, a tremendous rise in invasive fungal infection diseases attributed to the yeast Candida albicans in immunocompromised individuals poses a seriously challenging issue. Another concern is the emergence of multi-drug resistant pathogens to the existing medicines due to their overuse and misuse. It was recently reported that 25-55% of the mortality rate is caused by invasive infection. Despite a large variety of drugs being available to treat invasive candidiasis, only two of them contain a 1,2,4-triazole core, namely Fluconazole and itraconazole, which are efficient in treating infection induced by fungal Candida species. Moreover, long-term therapy associated with azole medications has led to an increase in azole resistance as well as a high risk of toxicity. Despite numerous outstanding achievements in antifungal drug discovery, development of novel, safer and potent antifungal agents while overcoming the resistance problem associated with the current drugs is becoming the main focus of medicinal chemists. Therefore, this review outlines the breakthroughs in medicinal chemistry research regarding 1,2,4- triazole-based derivatives as potential antifungal agents in the past decade. In addition, the structureactivity relationship of these compounds is also discussed.

Hassan A, Makhlouf MM, Bräse S. Chemistry and Biological Activities of 1,2,4-Triazolethiones-Antiviral and Anti-Infective Drugs

Mercapto-substituted 1,2,4-triazoles are very interesting compounds as they play an important role in chemopreventive and chemotherapeutic effects on cancer. In recent decades, literature has been enriched with sulfur- and nitrogen-containing heterocycles which are used as a basic nucleus of different heterocyclic compounds with various biological applications in medicine and also occupy a huge part of natural products. Therefore, we shed, herein, more light on the synthesis of this interesting class and its application as a biologically active moiety. They might also be suitable as antiviral and anti-infective drugs.

Facile Synthesis and Antimicrobial Activities of Novel 1,4-Bis(3,5-dialkyl-4H-1,2,4-triazol-4-yl)benzene and 5-Aryltriaz-1-en-1-yl-1-phenyl-1H-pyrazole-4-carbonitrile Derivatives

A group of novel 1,4-bis(3,5-dialkyl-4H-1,2,4-triazol-4-yl)benzene and 5-aryltriaz-1-en-1-yl-1-phenyl-1H-pyrazole-4-carbonitrile derivatives have been successfully synthesized and characterized by spectroscopic analyses. The triazenes were obtained in moderate yield by a coupling reaction between 5-aminopyrazol-4-carbonitrile and aryl diazonium chlorides, and their structures were confirmed by detecting the CN functional group in both IR and 13C NMR spectra. Conversely, the novel 1,4-bis(3,5-dialkyl-4H-1,2,4-triazol-4-yl)benzene derivatives were obtained using a previously unreported and facile pathway starting with p-phenylenediamine with selected triethyl orthoalkylates and then hydrazine monohydrate, followed by refluxing in triethyl orthoalkylates. The structure of the methyl derivative was confirmed by X-ray analysis. The synthesized compounds were tested and evaluated as antimicrobial agents.

Multicomponent reactions in crop protection chemistry

An overview is given of the significance of multicomponent reactions in the synthesis of agrochemicals. The most important applications of multicomponent condensations, such as the Biginelli reaction, Bucherer-Bergs reaction, Hantzsch dihydropyridine synthesis, Kabachnik-Fields reaction, Mannich reaction, Passerini reaction, Petasis reaction, Strecker reaction, Ugi reaction and Willgerodt-Kindler reaction, to the synthesis of herbicidally, fungicidally and insecticidally active compounds are presented. Also the mode of action and biological activity of these multicomponent reaction products are reported.

Synthesis, molecular docking, dynamic simulations, kinetic mechanism, cytotoxicity evaluation of N-(substituted-phenyl)-4-{(4-[(E)-3-phenyl-2-propenyl]-1-piperazinyl} butanamides as tyrosinase and melanin inhibitors: In vitro, in vivo and in silico approaches

In the current research work, different N-(substituted-phenyl)-4-{(4-[(E)-3-phenyl-2-propenyl]-1-piperazinyl}butanamides have been synthesized according to the protocol described in scheme 1. The synthesis was initiated by reacting various substituted anilines (1a-e) with 4-chlorobutanoyl chloride (2) in aqueous basic medium to give various electrophiles, 4-chloro-N-(substituted-phenyl)butanamides (3a-e). These electrophiles were then coupled with 1-[(E)-3-phenyl-2-propenyl]piperazine (4) in polar aprotic medium to attain the targeted N-(substituted-phenyl)-4-{(4-[(E)-3-phenyl-2-propenyl]-1-piperazinyl}butanamides (5a-e). The structures of all derivatives were identified and characterized by proton-nuclear magnetic resonance (¹H NMR), carbon-nuclear magnetic resonance (¹³C NMR) and Infra-Red (IR) spectral data along with CHN analysis. The in vitro inhibitory potential of these butanamides was evaluated against Mushroom tyrosinase, whereby all compounds were found to be biologically active. Among them, 5b exhibited highest inhibitory potential with IC₅₀ value of 0.013 ± 0.001 µM. The same compound 5b was also assayed through in vivo approach, and it was explored that it significantly reduced the pigments in zebrafish. The in silico studies were also in agreement with aforesaid results. Moreover, these molecules were profiled for their cytotoxicity through hemolytic activity, and it was found that except 5e, all other compounds showed minimal toxicity. The compound 5a also exhibited comparable results. Hence, some of these compounds might be worthy candidates for the formulation and development of depigmentation drugs with minimum side effects.

SEM morphological analysis of irradiated polystyrene film doped by a Schiff base containing a 1,2,4-triazole ring system

A Schiff base containing the 1,2,4-triazole moiety was synthesized and added to polystyrene at low concentration for a homogenous blend. The polystyrene film was irradiated with ultraviolet light and the surface morphology was analyzed. Micrographs of the polystyrene/Schiff base blend after irradiation indicated the fabrication of a terrestrial crack-like material. This was ascribed to the presence of the Schiff base, relatively long irradiation time, and photostability induced by the base. After irradiation, the blank polystyrene film formed a cotton-like fibrous material.

Synthesis, Characterization, Free-radical Scavenging Capacity and Antioxidant Activity of Novel Series of Hydrazone, 1,3,4-oxadiazole and 1,2,4- triazole Derived from 3,5-dimethyl-1H-pyrazole

Background:

Pyrazole is an important class of heterocyclic compound, has been shown to exhibit diverse biological and pharmacological activities such as anti-inflammatory, anti-cancer, antioxidant, etc.

Methods:

In this study, a series of novel 3,5-dimethyl-1H-pyrazole derivatives containing hydrazine 4a-l have been synthesized via the reaction of the 2-(3,5-dimethyl-1H-pyrazol-1-yl)acetohydrazide. All synthesized compounds have been tested for their in vitro antioxidant activities via utilization of 1,1-biphenyl-2-picrylhydrazyl (DPPH) as a free radical scavenging reagent.

Results:

The data reported herein indicates that compound 4k showed potential radical scavenging capacity and compounds 4f and 4g exhibited best activity for the iron binding while comparing with positive controls.

Conclusion:

Good activity was noted for some compounds. In particular, compound 4k showed the highest antioxidant activity with IC50 values of 22.79 ± 3.64 and 1.35 ± 0.66 μg/mL in the DPPH and ABTS tests, respectively.

Synthesis, biological evaluation and SAR analysis of novel poly-heterocyclic compounds containing pyridylpyrazole group

BACKGROUND

In recent years, pyridylpyrazole derivatives, such as pyridylpyrazole-containing anthranilic diamide have attracted much attention by virtue of their useful insecticidal properties and unique action mode. Moreover, some pyridylpyrazole-containing compounds have also been found to possess significant fungicidal activities. With the aim of discovering new bioactive agrochemicals for crop protection, a series of poly-heterocyclic compounds containing pyridylpyrazole and aziridine, or β-lactam, or thiazolinone moieties were synthesized.

RESULTS

A series of pyridylpyrazole-containing poly-heterocyclic compounds were obtained, and confirmed through IR, ¹ H NMR, ¹³ C NMR, HRMS and elemental analysis. The crystalline structure of 4-(3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-3-chloro-1-mesitylazetidin-2-one (compound 13f) was determined to further illustrate a trans- configuration of the β-lactam motif. In addition, bioassays showed that most of these new compounds exhibited modest insecticidal activity towards Mythimna separate Walker at 200 µg mL^-1 . Some of the compounds displayed excellent fungicidal activity towards some plant fungi, including Cercospora arachidicola (13j: EC₅₀ = 14.5 µg mL^-1 ), Physalospora piricola (12d and 13d: EC₅₀ = 10.5 and 9.70 µg mL^-1 ), Alternaria solani Sorauer (13j: EC₅₀ = 7.29 µg mL^-1 ), Puccinia sorghi Schw. (13d: control efficacy 99.0 ± 2.1% at 200 µg mL^-1 ) and Erysiphe graminis (14d: control efficacy 95.0 ± 1.4% at 200 µg mL^-1 ).

CONCLUSION

Compounds 12b-12e, 13a, 13d, 13f, 13j, 13 k and 14d could be considered potential fungicidal lead compounds to do further structural optimization. The structure-activity relationship analysis in this study brings some new understanding to the biological activities of N-pyridylpyrazole-containing compounds, and provides important information for the research and development of novel agricultural fungicides with poly-heterocyclic structures. © 2017 Society of Chemical Industry.

Synthesis of readily available fluorophenylalanine derivatives and investigation of their biological activity

A series of thirty novel N-acetylated fluorophenylalanine-based aromatic amides and esters was synthesized using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide or phosphorus trichloride in pyridine. They were characterized by spectral methods and screened against various microbes (Mycobacterium tuberculosis, non-tuberculous mycobacteria, other bacteria, fungi), for their inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and cytotoxicity. All amino acids derivatives revealed a moderate inhibition of both cholinesterases with IC₅₀ values for AChE and BChE of 57.88-130.75µM and 8.25-289.0µM, respectively. Some derivatives were comparable or superior to rivastigmine, an established drug. Phenyl 2-acetamido-3-(4-fluorophenyl)propanoate was identified as the selective and most potent inhibitor of BChE. The esterification and amidation of parent acids led to an improved BChE inhibition. The esters are better inhibitors of BChE than the amides. The introduction of NO₂ and CH₃ groups into aniline ring and CF₃ moiety in phenol is translated into lower IC₅₀ values. Seven compounds showed selectivity index higher than 10 for at least one cholinesterase. Especially the esters exhibited a mild activity against Gram-positive bacteria, mycobacteria and several fungal strains with minimum inhibitory concentrations starting from 125µM. The highest susceptibility was recorded for Trichophyton mentagrophytes fungus.