A Green Ultrasound Synthesis, Characterization and Antibacterial Evaluation of 1,4-Disubstituted 1,2,3-Triazoles Tethering Bioactive Benzothiazole Nucleus

Click chemistry beyond metal-catalyzed cycloaddition as a remarkable tool for green chemical synthesis of antifungal medications

Click chemistry is widely used for the efficient synthesis of 1,4-disubstituted-1,2,3-triazole, a well-known scaffold with widespread biological activity in the pharmaceutical sciences. In recent years, this magic ring has attracted the attention of scientists for its potential in designing and synthesizing new antifungal agents. Despite scientific and medical advances, fungal infections still account for more than 1.5 million deaths globally per year, especially in people with compromised immune function. This increasing trend is definitely related to a raise in the incidence of fungal infections and prevalence of antifungal drug resistance. In this condition, an urgent need for new alternative antifungals is undeniable. By focusing on the main aspects of reaction conditions in click chemistry, this review was conducted to classify antifungal 1,4-disubstituted-1,2,3-triazole hybrids based on their chemical structures and introduce the most effective triazole antifungal derivatives. It was notable that in all reactions studied, Cu(I) catalysts generated in situ by the reduction in Cu(II) salts or used copper(I) salts directly, as well as mixed solvents of t-BuOH/H2O and DMF/H2O had most application in the synthesis of triazole ring. The most effective antifungal activity was also observed in fluconazole analogs containing 1,2,3-triazole moiety and benzo-fused five/six-membered heterocyclic conjugates with a 1,2,3-triazole ring, even with better activity than fluconazole. The findings of structure-activity relationship and molecular docking of antifungal derivatives synthesized with copper-catalyzed azide-alkyne cycloaddition (CuAAC) could offer medicinal chemistry scientists valuable data on designing and synthesizing novel triazole antifungals with more potent biological activities in their future research.

Synthesis of Biologically Relevant 1,2,3- and 1,3,4-Triazoles: From Classical Pathway to Green Chemistry

Green Chemistry has become in the last two decades an increasing part of research interest. Nonconventional «green» sources for chemical reactions include micro-wave, mechanical mixing, visible light and ultrasound. 1,2,3-triazoles have important applications in pharmaceutical chemistry while their 1,2,4 counterparts are developed to a lesser extent. In the review presented here we will focus on synthesis of 1,2,3 and 1,2,4-triazole systems by means of classical and « green chemistry » conditions involving ultrasound chemistry and mechanochemistry. The focus will be on compounds/scaffolds that possess biological/pharmacophoric properties. Finally, we will also present the formal cycloreversion of 1,2,3-triazole compounds under mechanical forces and its potential use in biological systems.

Novel 1,2,3-Triazole Derivatives as Potential Inhibitors against Covid-19 Main Protease: Synthesis, Characterization, Molecular Docking and DFT Studies

The highly contagious nature of Covid-19 attracted us to this challenging area of research, mainly because the disease is spreading very fast and until now, no effective method of a safe treatment or a vaccine is developed. A library of novel 1,2,3-triazoles based 1,2,4-triazole, 1,3,4-oxadiazole and/or 1,3,4-thiadiazole scaffolds were designed and successfully synthesized. Different spectroscopic tools efficiently characterized all the newly synthesized hybrid molecules. An interesting finding is that some of the newly designed compounds revealed two isomeric forms. The ratio is affected by the size of the attached group as well as the type of the heteroatom forming the side ring attached to the central 1,2,3-triazole ring. The experimental spectroscopic data is in agreement with the DFT calculations at B3LYP 6-31G (d,p) with regard to the geometrical conformation of the prepared compounds. The DFT results revealed that the stability of one isomeric form over the other in the range of 0.057-0.161 Kcal mol-1. A docking study was performed using PyRx and AutoDockVina to investigate the activity of the prepared 1,2,3-triazoles as antiviral agents. Bond affinity scores of the 1,2,3-triazole derivatives were detected in the range of -6.0 to -8.8 kcal/mol showing binding to the active sites of the 6LU7 protease and hence could be anticipated to inhibit the activity of the enzyme. Verification of the docking results was performed using the Mpro alignment of coronaviruses substrate-binding pockets of COVID-19 against the ligands. As per these results, it can be proposed that the title hybrid molecules are acceptable candidates against COVID-19 for possible medicinal agents.

1,3-Dipolar Cycloaddition Reactions of Nitrile Oxides under "Non-Conventional" Conditions: Green Solvents, Irradiation, and Continuous Flow

The 1,3-dipolar cycloaddition reactions (DCs) of nitrile oxides (NOs) to alkenes and alkynes are useful methods for the synthesis of 2-isoxazolines and isoxazoles respectively, which are important classes of heterocyclic compounds in organic and medicinal chemistry. Most of these reactions are carried out in organic solvents and under thermal activation. Nevertheless the use of supercritical carbon dioxide (scCO₂ ) and ionic liquids (Ils) as alternative solvents and the application of microwave (MW) and ultrasound (US) as alternative activation procedures have evident advantages from the "Green Chemistry" point of view. The critical discussion on the applications of these "unconventional" activation methods and reaction conditions in the 1,3-DCs of NOs is the objective of the present Review.

Design and Synthesis of Novel Imidazole Derivatives Possessing Triazole Pharmacophore with Potent Anticancer Activity, and In Silico ADMET with GSK-3β Molecular Docking Investigations

A library of novel imidazole-1,2,3-triazole hybrids were designed and synthesized based on the hybrid pharmacophore approach. Therefore, copper(I)catalyzed click reaction of thiopropargylated-imidazole 2 with several organoazides yielded two sets of imidazole-1,2,3-triazole hybrids carrying different un/functionalized alkyl/aryl side chains 4a-k and 6a-e. After full spectroscopic characterization using different spectral techniques (IR, 1H, 13C NMR) and elemental analyses, the resulted adducts were screened for their anticancer activity against four cancer cell lines (Caco-2, HCT-116, HeLa, and MCF-7) by the MTT assay and showed significant activity. In-silico molecular docking study was also investigated on one of the prominent cancer target receptors, i.e., glycogen synthase kinase-3β (GSK-3β), revealing a good binding interaction with our potent compound, 4k and was in agreement with the in vitro cytotoxic results. In addition, the ADMET profile was assessed for these novel derivatives to get an insight on their pharmacokinetic/dynamic attributes. Finally, this research design and synthesis offered click chemistry products with interesting biological motifs mainly 1,2,3 triazoles linked to phenyl imidazole as promising candidates for further investigation as anticancer drugs.

Novel scaffold hopping of potent benzothiazole and isatin analogues linked to 1,2,3-triazole fragment that mimic quinazoline epidermal growth factor receptor inhibitors: Synthesis, antitumor and mechanistic analyses

A series of benzothiazole/isatin linked to 1,2,3-triazole moiety and terminal sulpha drugs 5a-e and 6a-e were synthesized and evaluated for cytotoxic activity against a panel of cancer cell lines. The novel compounds showed variable IC₅₀ range of activity and some of them were potent compared to reference drug. The promising compounds were subjected as postulated the mimicry proposal for quinazoline-based EGFR inhibitors for their inhibitory profile against EGFR TK enzyme. That data obtained revealed that most of these compounds were potent EGFR TK inhibitors at nanomolar concentrations. Among these, compounds 5a and 5b showed more potent activity on EGFR compared to erlotinib (IC₅₀ 103 and 104 versus 67.6 nM). Based upon the results, molecular docking analysis was performed on EGFR receptor and proved the strong contribution of fragments; benzothiazole, isatin, and triazole to the binding ATP pocket. When these selected compounds 5a and 5b were tested in an HepG2 model, they could effectively inhibited tumor growth, strongly induced cancer cell apoptosis, and suppressed cell cycle progression leading to DNA fragmentation. Well-DMET profile of the most active derivatives was presented and compared to the reference drugs. Taken together, we introduced novel triazole-sulpha drug hybrid for the first time as EGFR inhibitors and the results of our studies indicate that the newly discovered inhibitors have significant potential for anticancer treatment.

Heterocycle Compounds with Antimicrobial Activity

Background:

Bacterial infections are a growing problem worldwide causing morbidity and mortality mainly in developing countries. Moreover, the increased number of microorganisms, developing multiple resistances to known drugs, due to abuse of antibiotics, is another serious problem. This problem becomes more serious for immunocompromised patients and those who are often disposed to opportunistic fungal infections.

Objective:

The objective of this manuscript is to give an overview of new findings in the field of antimicrobial agents among five-membered heterocyclic compounds. These heterocyclic compounds especially five-membered attracted the interest of the scientific community not only for their occurrence in nature but also due to their wide range of biological activities.

Method:

To reach our goal, a literature survey that covers the last decade was performed.

Results:

As a result, recent data on the biological activity of thiazole, thiazolidinone, benzothiazole and thiadiazole derivatives are mentioned.

Conclusion:

It should be mentioned that despite the progress in the development of new antimicrobial agents, there is still room for new findings. Thus, research still continues.

Synthesis, SAR, Molecular Docking and Anti-Microbial Study of Substituted N-bromoamido-2-aminobenzothiazoles

BACKGROUND

Benzothiazoles are reported to have bioorganic and pharmaceutical chemistry applications.

INTRODUCTION

A series of substituted N-bromoamido-2-aminobenzothiazoles was synthesized from substituted anilines via 2-aminobenzothiazoles and it was further evaluated for its antimicrobial activity.

METHODS

All the newly synthesized compounds were characterized by FT-IR, NMR and mass spectra and purity profiles were studied by HPLC analysis. The antimicrobial testing (MIC determination) was newly performed with agar micro-broth dilution method for these analogs.

RESULTS

Among the synthesized compound 3b showed the highest activity with MIC value of 3.12 μg/mL against Bacillus, E. coli, S. aureus and Klebsiella and 6.25 μg/mL against C. albicans. The ADME properties as calculated by using Qikprop were found within acceptable range. Derivatives shows a good-moderate binding affinity towards target Cytochrome P450 14 alpha-sterol demethylase (CYP51) (PDB ID: 1EA1).

CONCLUSION

Our in-silico and in-vitro studies on a series of substituted aminobenzothiazoles may be helpful for further designing of more potent antimicrobials in future.

A Profile of the In Vitro Anti-Tumor Activity and In Silico ADME Predictions of Novel Benzothiazole Amide-Functionalized Imidazolium Ionic Liquids

A focused array of green imidazolium ionic liquids (ILs) encompassing benzothiazole ring and amide linkage were designed and synthesized using quaternization and metathesis protocols. The synthesized ILs have been fully characterized by usual spectroscopic methods and screened for their anticancer activities against human cancer cell lines originating from breast and colon cancers. Collectively, our biological data demonstrate that the newly synthesized series has variable anticancer activities in the examined cancer types. The synthesized ILs 8, 10 and 21-29 comprising the methyl and methyl sulfonyl benzothiazole ring emerged as the most potent compounds with promising antiproliferative activities relative to their benzothiazole ring counterparts. Furthermore, the mechanism underlying the observed anticancer activity was investigated. The most active compound 22 appears to exert its anticancer effect through apoptosis dependent pathway in breast cancer cells. Interestingly, compound 22 has also shown good in silico absorption (81.75%) along with high gastro-intestinal absorption as per ADME predictions.

Copper fluorapatite assisted synthesis of new 1,2,3-triazoles bearing a benzothiazolyl moiety and their antibacterial and anticancer activities

New 1,2,3-triazoles with a benzothiazolyl scaffold have been synthesized for the first time using copper fluorapatite as a catalyst and their antibacterial and anticancer activities are reported.

Design, Synthesis and Anticancer Screening of Novel Benzothiazole-Piperazine-1,2,3-Triazole Hybrids

A library of novel regioselective 1,4-di and 1,4,5-trisubstituted-1,2,3-triazole based benzothiazole-piperazine conjugates were designed and synthesized using the click synthesis approach in the presence and absence of the Cu(I) catalyst. Some of these 1,2,3-triazole hybrids possess in their structures different heterocyclic scaffold including 1,2,4-triazole, benzothiazole, isatin and/or benzimidazole. The newly designed 1,2,3-triazole hybrids were assessed for their antiproliferative inhibition potency against four selected human cancer cell lines (MCF7, T47D, HCT116 and Caco2). The majority of the synthesized compounds demonstrated moderate to potent activity against all the cancer cell lines examined. Further, we have established a structure activity relationship with respect to the in silico analysis of ADME (adsorption, distribution, metabolism and excretion) analysis and found good agreement with in vitro activity.

Design, synthesis, in silico and in vitro antimicrobial screenings of novel 1,2,4-triazoles carrying 1,2,3-triazole scaffold with lipophilic side chain tether

BACKGROUND

1,2,4-Triazoles and 1,2,3-triazoles have gained significant importance in medicinal chemistry.

RESULTS

This study describes a green, efficient and quick solvent free click synthesis of new 1,2,3-triazole-4,5-diesters carrying a lipophilic side chain via 1,3-dipolar cycloaddition of diethylacetylene dicarboxylate with different surfactant azides. Further structural modifications of the resulting 1,2,3-triazole diesters to their corresponding 1,2,4-triazole-3-thiones via multi-step synthesis has been also investigated. The structures of the newly designed triazoles have been elucidated based on their analytical and spectral data. These compounds were evaluated for their antimicrobial activities. Relative to the standard antimicrobial agents, derivatives of 1,2,3-triazole-bis-4-amino-1,2,4-triazole-3-thiones were the most potent antimicrobial agents with compound 7d demonstrating comparable antibacterial and antifungal activities against all tested microorganisms. Further, the selected compounds were studied for docking using the enzyme, Glucosamine-6-phosphate synthase.

CONCLUSIONS

The in silico study reveals that all the synthesized compounds had shown good binding energy toward the target protein ranging from - 10.49 to - 5.72 kJ mol-1 and have good affinity toward the active pocket, thus, they may be considered as good inhibitors of GlcN-6-P synthase.

Green ultrasound-assisted three-component click synthesis of novel 1H-1,2,3-triazole carrying benzothiazoles and fluorinated-1,2,4-triazole conjugates and their antimicrobial evaluation

The present study describes an efficient and ecofriendly, ultrasound, one-pot click cycloaddition approach for the construction of a novel series of 1,4-disubstituted-1,2,3-triazoles tethered with fluorinated 1,2,4-triazole-benzothiazole molecular conjugates. It involved three-component condensation of the appropriate bromoacetamide benzothiazole, sodium azide and 4-alkyl/aryl-5-(2-fluorophenyl)-3-(prop-2-ynylthio)-1,2,4-triazoles 4a-e through a Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction. This approach involves in situ generation of azidoacetamide benzothiazole, followed by condensation with terminal alkynes in the presence of CuSO4/Na-ascorbate in aqueous DMSO under both conventional and ultrasound conditions. Some of the designed 1,2,3-triazole conjugates 6a-o were recognized for their antimicrobial activity against some bacterial and fungal pathogenic strains.