A Comprehensive Review of the Diverse Spectrum Activity of 1,2,3-Triazole-linked Isatin Hybrids

Heterocyclic compounds containing 1,2,3-triazole and isatin as core structures have emerged as promising drug candidates due to their diverse biological activities such as anti-cancer, antifungal, antimicrobial, antitumor, anti-epileptic, antiviral, and more. The presence of 1,2,3-triazoles and isatin heterocycles in these hybrids, both individually known for their medicinal significance, has increasingly piqued the interest of drug discovery researchers, as they seek to delve deeper into their extensive pharmacological potential for enhancing therapeutic efficacy. Moreover, these hybrid compounds are synthetically accessible using readily available materials. Therefore, there is a pressing need to provide a comprehensive overview of the existing knowledge in this field, offering valuable insights to readers and paving the way for the discovery of novel 1,2,3-triazole-linked isatin hybrids with therapeutic potential.

Design, synthesis, and molecular modeling studies of novel 2-quinolone-1,2,3-triazole-α-aminophosphonates hybrids as dual antiviral and antibacterial agents

With the aim to identify new antiviral agents with antibacterial properties, a series of 2-quinolone-1,2,3-triazole derivatives bearing α-aminophosphonates was synthesized and characterized by 1H NMR, 13C NMR, 31P NMR, single crystal XRD and HRMS analyses. These compounds were examined against five RNA viruses (YFV, ZIKV, CHIKV, EV71 and HRV) from three distinct families (Picornaviridae, Togaviridae and Flaviviridae) and four bacterial strains (S. aureus, E. feacalis, E. coli and P. aeruginosa). The α-aminophosphonates 4f, 4i, 4j, 4k, 4p and 4q recorded low IC50 values of 6.8-10.91 μM, along with elevated selectivity indices ranging from 2 to more than 3, particularly against YFV, CHIKV and HRV-B14. Besides, the synthesized compounds were generally more sensitive toward Gram-positive bacteria, with the majority of them displaying significant potency against E. feacalis. Specifically, an excellent anti-enterococcus activity was obtained by compound 4q with MIC and MBC values of 0.03 μmol/mL, which were 8.7 and 10 times greater than those of the reference drugs ampicillin and rifampicin, respectively. Also, compounds 4f, 4p and 4q showed potent anti-staphylococcal activity with MIC values varying between 0.11 and 0.13 μmol/mL, compared to 0.27 μmol/mL for ampicillin. The results from DFT and molecular docking simulations were in agreement with the biological assays, proving the binding capability of hybrids 4f, 4i, 4j, 4k, 4p and 4q with viral and bacterial target enzymes through hydrogen bonds and other non-covalent interactions. The in silico ADME/Tox prediction revealed that these molecules possess moderate to good drug-likeness and pharmacokinetic properties, with a minimal chance of causing liver toxicity or carcinogenic effects.

Design, synthesis and biological evaluation of 1,2,3-triazole benzothiazole derivatives as tubulin polymerization inhibitors with potent anti-esophageal cancer activities

In this work, we utilized the molecular hybridization strategy to design and synthesize novel 1,2,3-triazole benzothiazole derivatives K1-26. The antiproliferative activities against MGC-803, Kyse30 and HCT-116 cells were explored, and their structure-activity relationship were preliminarily conducted and summarized. Among them, compound K18, exhibited the strongest proliferation inhibitory activity, with esophageal cancer cells Kyse30 and EC-109 being the most sensitive to its effects (IC50 values were 0.042 and 0.038 μM, respectively). Compound K18 effectively inhibited tubulin polymerization (IC50 = 0.446 μM), thereby hindering tubulin polymerize into filamentous microtubules in Kyse30 and EC-109 cells. Additionally, compound K18 induced the degradation of oncogenic protein YAP via the UPS pathway. Based on these dual molecular-level effects, compound K18 could induce G2/M phase arrest and cell apoptosis in Kyse30 and EC-109 cells, as well as regulate the expression levels of cell cycle and apoptosis-related proteins. In summary, our findings highlight a novel 1,2,3-triazole benzothiazole derivative K18, which possesses significant potential for treating esophageal cancers.

Click chemistry-aided drug discovery: A retrospective and prospective outlook

Click chemistry has emerged as a valuable tool for rapid compound synthesis, presenting notable advantages and convenience in the exploration of potential drug candidates. In particular, in situ click chemistry capitalizes on enzymes as reaction templates, leveraging their favorable conformation to selectively link individual building blocks and generate novel hits. This review comprehensively outlines and introduces the extensive use of click chemistry in compound library construction, and hit and lead discovery, supported by specific research examples. Additionally, it discusses the limitations and precautions associated with the application of click chemistry in drug discovery. Our intention for this review is to contribute to the development of a modular synthetic approach for the rapid identification of drug candidates.

Design, synthesis, and anti-respiratory syncytial virus potential of novel 3-(1,2,3-triazol-1-yl)furoxazine-fused benzimidazole derivatives

Respiratory syncytial virus (RSV) is a major cause of serious lower respiratory tract infections in infants, children, and older persons. Currently, the only approved anti-viral chemotherapeutic drug for RSV treatment is ribavirin aerosol; however, its significant toxicity has led to restricted clinical use. In a previous study, we developed various benzimidazole derivatives against RSV. In this study, we synthesised 3-azide substituted furoxazine-fused benzimidazole derivatives by sulfonylation and azide substitution of the 3-hydroxyl group of the furoxazine-fused benzimidazole derivatives. Subsequently, a series of 3-(1,2,3-triazol-1-yl)-substituted furoxazine-fused benzimidazole derivatives were synthesised using the classical click reaction. Biological evaluations of the target compounds indicated that compound 4a-2 had higher activity against RSV (EC50 = 12.17 μM) and lower cytotoxicity (CC50 = 390.64 μM). Compound 4a-2 exerted anti-viral effects against the RSV Long strain by inhibiting apoptosis and the elevation of reactive oxygen species (ROS) and inflammatory factors caused by viral infection in vitro. Additionally, the clinical symptoms of the virus-infected mice were markedly relieved, and the viral load in the lung tissues was dramatically decreased. The biosafety profile of compound 4a-2 was also favourable, showing no detectable adverse effects on any of the major organs in vivo. These findings underscore the potential of compound 4a-2 as a valuable therapeutic option for combating RSV infections while also laying the foundation for further research and development in the field.

Design, synthesis and anticancer activity of 5-((2-(4-bromo/chloro benzoyl) benzofuran-5-yl) methyl)-2-((1-(substituted)-1H-1,2,3-triazol-4-yl)methoxy)benzaldehyde analogues

Novel 5-((2-(4-bromo/chloro benzoyl) benzofuran-5-yl) methyl)-2-((1-(substituted)-1H-1,2,3-triazol-4-yl)methoxy)benzaldehyde analogues about twenty-one were synthesized all through standard chemical procedures. The structure of the compounds were confirmed by 1H NMR, 13C NMR and Mass spectral analysis after purification. All the compounds were screened for In Vitro lung and cervical cancer activity against A-549 and HeLa cell lines, respectively, by MTT assay protocol using various nanomolar (nM) concentrations. IC50 value were calculated from cell viability data. 2-(trifluoromethyl)benzyl substituted derivative presented outstanding activity against both the cell lines compared to standard drug doxorubicin. The methoxy, chloro, fluoro and formyl substituted analogues showed a moderate activity and whereas methyl substituted analogues activity was poor. The morphological deformation of both cell lines by best IC50 value analogues proved as potent inhibitors of cancer cells growth. Molecular docking studies were performed against extracellular signal-regulated kinase 2 and fibroblast growth factor receptor 2 these results are incredibly in agreement with the investigational data.

Recent advances in triazoles as tyrosinase inhibitors

The tyrosinase enzyme, which is widely found in microorganisms, animals and plants, has a significant position in melanogenesis, plays an important role in undesirable browning of fruits and vegetables, antibiotic resistance, skin pigment formation, sclerotization of cuticle, neurodegeneration, etc. Therefore, with the wide potential application fields of tyrosinase in food, agriculture, cosmetics and pharmaceutical industries, which has become the target enzyme for the development of therapeutic agents such as antibrowning, anticancer, antibacterial, skin whitening, insecticides, etc., a large number of synthetic tyrosinase inhibitors have been widely reported in recent years. The triazole ring, which has a broad spectrum of biological action, is of increasing interest in the synthesis of new tyrosinase inhibitors. In this review, tyrosinase inhibition effects, structure-activity relationships, enzyme inhibition kinetics and mechanisms of action of 1,2,3- or 1,2,4-triazole derivatives were investigated. The data gathered is anticipated to supply rational guidance and an influential strategy for the development of novel, potent and safe tyrosinase inhibitors for better practical application in the future.

A Rhodamine-coumarin Triazole Conjugate as a Fluorescent Chemodosimeter for Cu(II) Detection and its Application in Live Cell Bioimaging

A rhodamine-triazole fluorescent probe bearing a coumarin moiety RTC was synthesized using the Cu(I)-catalyzed click reaction. The rhodamine-triazole conjugate was highly selective to Cu2+ among other metal ions, including Ca2+, Co2+, Cu2+, Cd2+, Mg2+, Fe2+, Fe3+, Hg2+, Zn2+, Ni2+, Pd2+ and Pb2+ in physiological conditions. Upon the addition of Cu2+, the colorless RTC solution turned pink and exhibited a significant fluorescence emission centered at 578 nm. The binding of Cu2+ induced a hydrolysis reaction, leading to a release of the coumarin unit from the rhodamine probe, as confirmed by mass spectrometric data. From the fluorescence titration, the detection limit of RTC for Cu2+ was determined to be 21 nM (1.3 ppb). The sensor was responsive to Cu2+ in a wide pH range and successfully applied to monitor Cu2+ in HEK293T cells by confocal fluorescence imaging.

Recent developments in the synthesis of hybrid antimalarial drug discovery

In this 21st century, Malaria remains a global burden and causes massive economic trouble to disease-endemic nations. The control and eradication of malaria is a major challenge that requires an urgent need to develop novel antimalarial drugs. To overcome the aforementioned situation, several researchers have given significant effort to develop hybrid antimalarial agents in the search for new antimalarial drugs. Hence, we have summarized those developments of hybrid antimalarial agents from 2017 to till date. This review illustrates the current progress in the recent synthesis of hybrid antimalarial agents along with focusing on their antimalarial evaluation to find the most potent hybrids. This present mini-review will also be useful for the scientific community for the development of new antimalarial drugs to eradicate malaria.

Diversity-oriented synthesis of 1H-1,2,3-triazole tethered pyrazolo[5,1-b]quinazoline hybrids as antimicrobial agents

A straightforward and high yielding synthetic approach is employed to synthesize the novel 1H-1,2,3-triazole tethered pyrazolo[5,1-b]quinazoline hybrids 7(a-t) as new antimicrobial agents with two pharmacophore in the effective two step synthesis. The first step is the four component one-pot synthesis of highly functionalized pyrazolo[5,1-b]quinazolines 5(a-j) catalysed by TBAB, with the advantages of an environmentally benign reaction, high yielding, quick reaction time, and operational simplicity. In the subsequent stage, CuSO4/NaAsc system was employed to synthesize the 1H-1,2,3-triazole tethered pyrazolo[1,5-b]quinazoline hybrids as 1H-1,2,3-triazoles are the structures of great diversity and importance in diverse therapeutics containing numerous biological activities. The antimicrobial activity of all the synthesized hybrid compounds have been preliminary tested using the broth dilution technique against two gram-positive and two gram-negative bacterial strains as well as two fungal strains. In comparison to standard drugs, the majority of compounds exhibited good to moderate activity. Among the all the compounds, 7a (MIC 18.54 μM) against Pseudomonas aeruginosa, 7j (MIC 89.76 μM) against Bacillus subtilis as well as Rhizopus oryzae and 7t (MIC 84.88 μM) against Aspergillus parasiticus have remarkable antimicrobial potency as compared to standard drug.

In vitro trypanocidal activities and structure-activity relationships of ciprofloxacin analogs

Tropical diseases, such as African trypanosomiasis, by their nature and prevalence lack the necessary urgency regarding drug development, despite the increasing need for novel, structurally diverse antitrypanosomal drugs, using different mechanisms of action that would improve drug efficacy and safety. Traditionally antibacterial agents, the fluoroquinolones, reportedly possess in vitro trypanocidal activities against Trypanosoma brucei organisms. During our research, the fluroquinolone, ciprofloxacin (1), and its analogs (2-24) were tested against bloodstream forms of T. brucei brucei, T. b. gambiense, T. b. rhodesiense, T. evansi, T. equiperdum, and T. congolense and Madin-Darby bovine kidney cells (cytotoxicity). Ciprofloxacin [CPX (1)] demonstrated selective trypanocidal activity against T. congolense (IC₅₀ 7.79 µM; SI 39.6), whereas the CPX derivatives (2-10) showed weak selective activity (25 < IC₅₀ < 65 µM; 2 < SI < 4). Selectivity and activity of the CPX and 1,2,3-triazole (TZ) hybrids (11-24) were governed by their chemical functionality at C-3 (carboxylic acid, or 4-methylpiperazinyl amide) and their electronic effect (electron-donating or electron-withdrawing para-benzyl substituent), respectively. Trypanocidal hits in the micromolar range were identified against bloodstream forms of T. congolense [CPX (1); CPX amide derivatives 18: IC₅₀ 8.95 µM; SI 16.84; 22: IC₅₀ 5.42 µM; SI 25.2] and against T. brucei rhodesiense (CPX acid derivative 13: IC₅₀ 4.51 µM; SI 10.2), demonstrating more selectivity toward trypanosomes than mammalian cells. Hence, the trypanocidal hit compound 22 may be optimized by retaining the 4-methylpiperazine amide functional group (C-3) and the TZ moiety at position N-15 and introducing other electron-withdrawing ortho-, meta-, and/or para-substituents on the aryl ring in an effort to improve the pharmacokinetic properties and increase the trypanocidal activity. Structure-activity relationships of ciprofloxacin-1,2,3-triazole hybrids were governed by the chemical functionality at C-3 and electronic effect.

Indole-carbohydrazide linked phenoxy-1,2,3-triazole-N-phenylacetamide derivatives as potent α-glucosidase inhibitors: design, synthesis, in vitro α-glucosidase inhibition, and computational studies

BACKGROUND

A new series of indole-carbohydrazide-phenoxy-1,2,3-triazole-N-phenylacetamide hybrids 11a-o was designed based on molecular hybridization of the active pharmacophores of the potent α-glucosidase inhibitors. These compounds were synthesized and evaluated against α-glucosidase.

METHODS

The 15 various derivatives of indole-carbohydrazide-phenoxy-1,2,3-triazole-N-phenylacetamide scaffold were synthesized, purified, and fully characterized. These derivatives were evaluated against yeast α-glucosidase in vitro and in silico. ADMET properties of the most potent compounds were also predicted.

RESULTS

All new derivatives 11a-o (IC₅₀ values = 6.31 ± 0.03-49.89 ± 0.09 µM) are excellent α-glucosidase inhibitors in comparison to acarbose (IC₅₀ value = 750.0 ± 10.0 µM) that was used as a positive control. Representatively, (E)-2-(4-((4-((2-(1H-indole-2-carbonyl)hydrazono)methyl) phenoxy)methyl)-1H-1,2,3-triazol-1-yl)-N-(4-methoxyphenyl)acetamide 11d with IC₅₀ = 6.31 µM against MCF-7 cells, was 118.8-times more potent than acarbose. This compound is an uncompetitive inhibitor against α-glucosidase and showed the lowest binding energy at the active site of this enzyme in comparison to other potent compounds. Furthermore, computational calculations predicted that compound 11d can be an orally active compound.

CONCLUSION

According to obtained data, compound 11d can be a valuable lead compound for further structural development and assessments to obtain effective and potent new α-glucosidase inhibitors.

Design, synthesis, anticancer evaluation and molecular docking studies of 1,2,3-triazole incorporated 1,3,4-oxadiazole-Triazine derivatives

A new library of 1,2,3-triazole-incorporated 1,3,4-oxadiazole-triazine derivatives (9a-j) was designed, synthesized, and tested in vitro for anticancer activity against PC3 and DU-145 (prostate cancer), A549 (lung cancer), and MCF-7 (breast cancer) cancer cell lines using the MTT assay with etoposide as the control drug. The compounds exhibited remarkable anticancer activity, with IC50 values ranging from 0.16 ± 0.083 μM to 11.8 ± 7.46 μM, whereas the positive control ranged from 1.97 0.45 μM to 3.08 0.135 μM. Compound 9 d with a 4-pyridyl moiety shown exceptional anticancer activity against PC3, A549, MCF-7, and DU-145 cell lines, with IC50 values of 0.17 ± 0.063 μM, 0.19 ± 0.075 μM, 0.51 ± 0.083 μM, and 0.16 ± 0.083 μM, respectively.

Biological activity of 1,2,3-triazole-2-amino-1,4-naphthoquinone derivatives and their evaluation as therapeutic strategy for malaria control

Malaria can be caused by several Plasmodium species and the development of an effective vaccine is challenging. Currently, the most effective tool to control the disease is the administration of specific chemotherapy; however, resistance to the frontline antimalarials is one of the major problems in malaria control and thus the development of new drugs becomes urgent. The study presented here sought to evaluate the antimalarial activities of compounds derived from 2-amino-1,4-naphthoquinones containing 1,2,3-triazole using in vivo and in vitro models. 1H-1,2,3-Triazole 2-amino-1,4-naphthoquinone derivatives were synthesized and evaluated for antimalarial activity in vitro, using P. falciparum W2 chloroquine (CQ) resistant strain and in vivo using the murine-P. berghei ANKA strain. Acute toxicity was determined as established by the OECD (2001). Cytotoxicity was evaluated against HepG2 and Vero mammalian cell lines. Transmission electron microscopy of the Plasmodium falciparum trophozoite (early and late stages) was used to evaluate the action of compounds derived at ultra-structural level. The compounds displayed low cytotoxicity CC₅₀ > 100 μM, neither did they cause hemolysis at the tested doses and nor the signs of toxicity in the in vivo acute toxicity test. Among the five compounds tested, one showed IC₅₀ values in submicromolar range of 0.8 μM. Compounds 7, 8 and 11 showed IC₅₀ values < 5 μM, and selectivity index (SI) ranging from 6.8 to 343 for HepG2, and from 13.7 to 494.8 for Vero cells. Compounds 8 and 11 were partially active against P. berghei induced parasitemia in vivo. Analysis of the ultrastructural changes associated with the treatment of these two compounds, showed trophozoites with completely degraded cytoplasm, loss of membrane integrity, organelles in the decomposition stage and possible food vacuole deterioration. Our results indicated that compounds 8 and 11 may be considered hit molecules for antimalarial drug discovery platform and deserve further optimization studies.

Phthalazone tethered 1,2,3-triazole conjugates: In silico molecular docking studies, synthesis, in vitro antiproliferative, and kinase inhibitory activities

New phthalazone tethered 1,2,3-triazole derivatives 12-21 were synthesized utilizing the Cu(I)-catalyzed click reactions of alkyne-functionalized phthalazone 1 with functionalized azides 2-11. The new phthalazone-1,2,3-triazoles structures 12-21 were confirmed by different spectroscopic tools, like IR; 1H, 13C, 2D HMBC and 2D ROESY NMR; EI MS, and elemental analysis. The antiproliferative efficacy of the molecular hybrids 12-21 against four cancer cell lines was evaluated, including colorectal cancer, hepatoblastoma, prostate cancer, breast adenocarcinoma, and the normal cell line WI38. The antiproliferative assessment of derivatives 12-21 showed potent activity of compounds 16, 18, and 21 compared to the anticancer drug doxorubicin. Compound 16 showed selectivity (SI) towardthe tested cell lines ranging from 3.35 to 8.84 when compared to Dox., that showed SI ranged from 0.75 to 1.61. Derivatives 16, 18 and 21 were assessed towards VEGFR-2 inhibitory activity and result in that derivative 16 showed the potent activity (IC50 = 0.123 µM) in comparison with sorafenib (IC50 = 0.116 µM). Compound 16 caused an interference with the cell cycle distribution of MCF7 and increased the percentage of cells in S phase by 1.37-fold. In silico molecular docking of the effective derivatives 16, 18, and 21 against vascular endothelial growth factor receptor-2 (VEGFR-2) confirmed the formation of stable protein-ligand interactions within the pocket.

Synthesis, antimicrobial, antibiofilm and computational studies of isatin-semicarbazone tethered 1,2,3-triazoles

In present era, heterocyclic compounds containing two or three nitrogen atoms play a vital role in drug discovery. In this context, a new class of isatin-semicarbazone tethered 1,2,3-triazole hybrids was synthesized via Cu(I)-mediated azide alkyne cycloaddition reaction. Structural characteristics of the newly derived compounds were identified by various spectral techniques like FTIR, ¹H NMR, ¹³C NMR, HRMS and single crystal X-ray crystallography. Synthesized derivatives were also screened for in vitro antimicrobial and antibiofilm activity against different microbial species. Triazole hybrid 7e showed significant efficacy towards E. coli having MIC of 0.0063 µmol/mL, whereas 6a, 6b, 7a, 7c, 7e, and 7f showed highest percentage of biofilm inhibition against P. aeruginosa. Bioassay results suggested that these triazole hybrids could act as biomaterial for antimicrobial and antibiofilm applications and may constitute a new promising class of antimicrobial and antibiofilm agents. These results were further supported by in silico docking, DFT calculations and ADME studies.

Design, synthesis, spectroscopic characterization, single crystal X-ray analysis, in vitro α-amylase inhibition assay, DPPH free radical evaluation and computational studies of naphtho[2,3-d]imidazole-4,9-dione appended 1,2,3-triazoles

In our quest to design and develop N/O-containing inhibitors of α-amylase, we have tried to synergize the inhibitory action of 1,4-naphthoquinone, imidazole and 1,2,3-triazole motifs by incorporating these structures into a single matrix. For this, a series of novel naphtho[2,3-d]imidazole-4,9-dione appended 1,2,3-triazoles is synthesized by a sequential approach involving [3 + 2] cycloaddition of 2-aryl-1-(prop-2-yn-1-yl)-1H-naphtho[2,3-d]imidazole-4,9-diones with substituted azides. The chemical structures of all the compounds are established with the help of 1D-NMR, 2D-NMR, IR, mass and X-ray studies. The developed molecular hybrids are screened for their inhibitory action on the α-amylase enzyme using the reference drug, acarbose. Different substituents present on the attached aryl part of the target compounds show amazing variations in inhibitory action against the α-amylase enzyme. Based on the type of substituents and their respective positions, it is observed that compounds containing -OCH₃ and -NO₂ groups show more inhibition potential than others. All the tested derivatives display α-amylase inhibitory activity with IC₅₀ values in the range of 17.83 ± 0.14 to 26.00 ± 0.17 μg/mL. Compound 2-(2,3,4-trimethoxyphenyl)-1-{[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl]methyl}-1H-naphtho[2,3-d]imidazole-4,9-dione (10y) show maximum inhibition of amylase activity with IC₅₀ value 17.83 ± 0.14 μg/mL as compared to reference drug acarbose (18.81 ± 0.05 μg/mL). A molecular docking study of the most active derivative (10y) is performed with A. oryzae α-amylase (PDB ID: 7TAA) and it unveils favourable binding interactions within the active site of the receptor molecule. The dynamic studies reveal that the receptor-ligand complex is stable as the RMSD of less than 2 is observed in 100 ns molecular dynamic simulation. Also, the designed derivatives are assayed for their DPPH free radical scavenging ability and all of them exhibit comparable radical scavenging activity with the standard, BHT. Further, to assess their drug-likeness properties, ADME properties are also evaluated and all of them demonstrate worthy in silico ADME results.

Synthesis and biological activity profile of novel triazole/quinoline hybrids

Based on the significant and diverse pharmacophore features of triazole ring and considering the potent antimicrobial properties of quinoline scaffold, a novel series of 1,2,3-triazole-based polyaromatic compounds containing chloroquinoline moiety were synthesized through a well-established synthetic methodology, named click chemistry. The structure of the synthetic compounds was characterized by various spectroscopic methods. The final products of triazole/quinoline hybrids and ((prop-2-yn-1-yloxy)methyl)benzene intermediates were screened for their antibacterial (Staphylococcus aureus, Escherichia coli, Shigella flexneri, and Salmonella enterica), antifungal (Candida albicans, Saccharomyces cerevisiae, and Aspergillus fumigatus), and cytotoxic activities. The best antifungal compounds exhibited minimum inhibitory concentration (MIC), in the range of 0.35-0.63 µM, against S. cerevisiae without any cytotoxic effect. These compounds can be selected as the potential candidates for treating invasive fungal infections caused by S. cerevisiae, after further investigation. Preliminary in silico ADME studies also predicted the favorable pharmacokinetic attributes of most compounds.

Synthesis and biological testing of 3,5-bis(arylidene)-4-piperidone conjugates with 2,5-dihydro-5H-1,2-oxaphospholenes

Using the methodology of "click" chemistry, a series of conjugates of 3,5-bis(benzylidene)-1-(prop-2-yn)piperidin-4-ones with 4-alkyl-3-azidomethyl-2-ethoxy-2,5-dihydro-5H-1,2 oxaphosphol 2-oxides was synthesized. All newly obtained compounds 8-18 were characterized by ¹H, ¹³C, ³¹P, ¹⁹F NMR and IR spectroscopy. The potential antitumor activity of the synthesized conjugates8-18was studied in terms of their ability to influence the viability of variouscancercell lines, including A549, SH-SY5Y, Hep-2, and HeLa. Compound 15, which contains two fluorine atoms in the benzene ring, was shown to be the most promising. The mechanism of the cytotoxic action of this conjugate is supposed to be associated with the ability to inhibit the glycolytic profile of transformed cells.

Flavone-1,2,3-triazole derivatives as potential α-glucosidase inhibitors: Synthesis, enzyme inhibition, kinetic analysis and molecular docking study

α-Glucosidase inhibitors are considered prime therapeutics in the management of type-2 diabetes and are preferred due to their localized action ushered by limited side effects. In this regard, nineteen new flavone-1,2,3-triazole derivatives have been designed and synthesized via utilizing an efficient click reaction protocol, and screened for the inhibition of the α-glucosidase enzyme. The reaction conditions were mild, good yielding and required easy work up. All the synthesized flavone-triazole derivatives were found more active against the yeast α-glucosidase with IC₅₀ values ranging from 24.37 ± 0.55-168.44 ± 0.77 μ M as compared to standard inhibitor acarbose (IC₅₀ = 844.81 ± 0.53 μM). The derivatives with 2,5‑dichloro 9k (IC₅₀ = 24.37 ± 0.55 μM) and 4‑chloro 9d (IC₅₀ = 24.77 ± 0.30 μM) substituent bearing an amide linkage were the most active. In the kinetic study of most active derivatives 9k and 9d, they were found to be mixed and uncompetitive inhibitors, respectively. In molecular docking studies, blind docking of the most active compounds was accomplished to find the interactions between the compounds and α-glucosidase that further confirms the mixed or uncompetitive nature of the inhibitors.

Synthesis and biological evaluation of antibacterial activity of novel clarithromycin derivatives incorporating 1,2,3-triazole moieties at the 4''- and 11-OH positions

Bacterial infection is still one of the diseases that threaten human health, and bacterial drug resistance is widespread worldwide. As a result, their eradication now largely relies on antibacterial drug discovery. Here, we reveal a novel approach to the development of 14-membered macrolide antibiotics by describing the design, synthesis, and evaluation of novel clarithromycin derivatives incorporating 1,2,3-triazole moieties at the 4''- and 11-OH positions. Using chemical synthesis, 35 clarithromycin derivatives were prepared, and their antibacterial properties were profiled. We found that compounds 8e-8h, 8l-8o, 8v, and 19d were as potent as azithromycin against Enterococcus faecalis ATCC29212. Furthermore, compounds 8c, 8d, 8n, and 8o showed slightly improved antibacterial activity (2-fold) against Acinetobacter baumannii ATCC19606 when compared with azithromycin and clarithromycin. In addition, compounds 8e, 8f, 8h, 8l, and 8v exhibited excellent antibacterial activity against Staphylococcus aureus ATCC43300, Staphylococcus aureus PR, and Streptococcus pneumoniae ER-2. These compounds were generally 64- to 128-fold more active than azithromycin, and 32- to 128-fold more active than clarithromycin. The results of molecular docking indicated that compound 8f may bind to the nucleotide residue A752 through hydrogen-bonding, hydrophobic, electrostatic, or π-π stacking interactions. The predicted ClogP data suggested that higher values of ClogP (>6.65) enhanced the antibacterial activity of compounds such as 8e, 8f, 8h, 8l, and 8v. The determination of the minimum bactericidal concentration showed that most of the tested compounds were bacteriostatic agents. From this study of bactericidal kinetics, we can conclude that compound 8f had a concentration- and time-dependent effect on the proliferation of Staphylococcus aureus ATCC43300. Finally, the results of the cytotoxicity assay showed that compound 8f exhibited no toxicity at the effective antibacterial concentration.

Benchmarking the ability of novel compounds to inhibit SARS-CoV-2 main protease using steered molecular dynamics simulations

BACKGROUND

The SARS-CoV-2 main protease (M^pro) is an attractive target in the COVID-19 drug development process. It catalyzes the polyprotein's translation from viral RNA and specifies a particular cleavage site. Due to the absence of identical cleavage specificity in human cell proteases, targeting M^pro with chemical compounds can obstruct the replication of the virus.

METHODS

To explore the potential binding mechanisms of 1,2,3-triazole scaffolds in comparison to co-crystallized inhibitors 11a and 11b towards M^pro, we herein utilized molecular dynamics and enhanced sampling simulation studies.

RESULTS AND CONCLUSION

All the 1,2,3-triazole scaffolds interacted with catalytic residues (Cys145 and His41) and binding pocket residues of M^pro involving Met165, Glu166, Ser144, Gln189, His163, and Met49. Furthermore, the adequate binding free energy and potential mean force of the topmost compound 3h was comparable to the experimental inhibitors 11a and 11b of M^pro. Overall, the current analysis could be beneficial in developing the SARS-CoV-2 M^pro potential inhibitors.

Merging antimicrobial and visible emission properties within 1,3,4-trisubstituted-1,2,3-triazolium salts

Bioactive molecules displaying visible wavelength emission can be useful for bioimaging, chemosensing and photodynamic therapy applications. Reported herein are 1,3,4-trisubsituted-1,2,3-triazolium salts displaying both antimicrobial and visible emission properties. Using a click chemistry approach, 2-fluorenyl, 1-naphthyl, 2-naphthyl, 2-anthracenyl and 1-pyrenyl units were incorporated at the N1 position, imparting visible emission properties to their triazolium bromide salts with Stokes shifts greater than 100 nm relative to the emission of their triazole precursors. The increasing size of such hydrophobic aryl units impacts minimum inhibitory concentration (MIC) values against Gram-positive bacteria, Gram-negative bacteria and yeast, and can be counterbalanced by hydrophobic substituent variation at other positions of the molecule in order to preserve bioactivity. Among the series of compounds studied are analogs displaying blue, green and yellow colored emission and MIC values as low as 0.4 μM (Gram-positive bacteria), 8 μM (Gram-negative bacteria) and 2 μM (yeast). XRD analysis validates the regioselective benzylation at the N3 position of the 1,2,3-triazole ring and the ability of such compounds to associate through dimeric intermolecular π-stacking interactions.

Recent advances in synthesis and anticancer potential of triazole containing scaffolds

Cancer is the most lethal disease that may be found anywhere on the globe. Approximately 10% of individuals die as a result of cancer of various types, with 19.3 million new cancer cases and 10 million deaths expected in 2020. More than 100 medications are commercially available for the treatment of cancer, but only a few candidates have high specificity, resulting in several side effects. The scientific community has spent the past decades focusing on drug discovery. Natural resources are used to isolate pharmaceutically active candidates, which are then synthesized in laboratories. More than 60% of all prescribed drugs are made from natural ingredients. Unique five-membered heteroaromatic center motifs with sulfur, oxygen and nitrogen atoms are found in heterocyclic compounds such as indazole, thiazole, triazole, triazole, and oxazole, and are used as a core scaffold in many medicinally important therapies. Triazole possesses a wide range of pharmacological activities including anticancer, antibacterial, antifungal, antibiotic antiviral, analgesic, anti-inflammatory, anti-HIV, antidiabetic, and antiprotozoal activities. Novel Triazole motifs with a variety of biological characteristics have been successfully synthesized using versatile synthetic methods. We intend here to facilitate the rational design and development of innovative triazole-based anti-cancer medicines with increased selectivity for various cancer cell lines by providing insight into various ligand-receptor interactions.

Novel 3'-[4-fluoroaryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidine analogues: Design, synthesis, characterization and their potential as anticancer agents

Novel 3'-[4-fluoroaryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidine analogues (7a-l) were developed by the Cu alkyne-azide cycloaddition (CuAAC) reaction. The obtained lead compounds were confirmed by using ¹H NMR, ¹³C NMR, 2 D NMR, HRMS and their anticancer activities were screened against Huh-7 liver cancer cells and U87MG human glioblastoma cells. Among the synthesized fluorinated 1,2,3-triazolyl nucleosides, three compounds (7i, 7a-b) demonstrated promising anti-proliferative against Huh-7 and U87MG cell lines. Significantly, compound 7i has displayed remarkable promising anticancer activity with IC₅₀ value in the micromole range (22.41-24.92 µM) and (18.12-21.36 µM) against Huh-7 cancer cells and U87MG glioblastoma cells, respectively.

Novel 3-chloro-6-nitro-1H-indazole derivatives as promising antileishmanial candidates: synthesis, biological activity, and molecular modelling studies

An efficient pathway was disclosed for the synthesis of 3-chloro-6-nitro-1H-indazole derivatives by 1,3-dipolar cycloaddition on dipolarophile compounds 2 and 3. Faced the problem of separation of two regioisomers, a click chemistry method has allowed us to obtain regioisomers of triazole-1,4 with good yields from 82 to 90% were employed. Also, the antileishmanial biological potency of the compounds was achieved using an MTT assay that reported compound 13 as a promising growth inhibitor of Leishmania major. Molecular docking demonstrated highly stable binding with the Leishmania trypanothione reductase enzyme and produced a network of hydrophobic and hydrophilic interactions. Molecular dynamics simulations were performed for TryR-13 complex to understand its structural and intermolecular affinity stability in a biological environment. The studied complex remained in good equilibrium with a structure deviation of ∼1-3 Å. MM/GBSA binding free energies illustrated the high stability of TryR-13 complex. The studied compounds are promising leads for structural optimisation to enhance the antileishmanial activity.

New Pyrazine Conjugates: Synthesis, Computational Studies, and Antiviral Properties against SARS-CoV-2

Currently, limited therapeutic options are available for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We have developed a set of pyrazine-based small molecules. A series of pyrazine conjugates was synthesized by microwave-assisted click chemistry and benzotriazole chemistry. All the synthesized conjugates were screened against the SAR-CoV-2 virus and their cytotoxicity was determined. Computational studies were carried out to validate the biological data. Some of the pyrazine-triazole conjugates (5 d-g) and (S)-N-(1-(benzo[d]thiazol-2-yl)-2-phenylethyl)pyrazine-2-carboxamide 12 i show significant potency against SARS-CoV-2 among the synthesized conjugates. The selectivity index (SI) of potent conjugates indicates significant efficacy compared to the reference drug (Favipiravir).

Thiazolidinone-linked1,2,3-triazoles with monoterpenic skeleton as new potential anticancer agents: Design, synthesis and molecular docking studies

A novel series of 1,2,3-triazole-thiazolidinone-carvone hybrid compounds has been designed and synthesized using the copper-catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition (CuAAC) process based on (R)-Carvone-O-propargylated 5-hydroxybenzylidene-thiazolidin-4-one derivative as starting material. All compounds were characterized and identified based on their NMR and HRMS spectroscopic data. HMBC correlations confirm that under the CuAAC reaction conditions, only the 1,4-disubstituted triazole regioisomers were formed. The targeted 1,2,3-triazole-thiazolidinone-carvone hybrids and their precursors were evaluated for their cytotoxic activity against four human cancer cell lines, including fibrosarcoma (HT-1080), lung carcinoma (A-549), and breast carcinoma (MCF-7 and MDA-MB-231). The obtained data showed that most of these compounds have moderate anti-proliferative activity with IC₅₀ values between 15.04 ± 0.71 and 42.22 ± 1.20 µM. The mechanism of action of the most active compounds 14e and 14f suggested that they induce apoptosis through caspase-3/7 activation, and the compound 14e elicited S-phase arrest, while compound 14f evoked G2/M phase blockade. The molecular docking confirmed that compounds 14e and 14f were nicely bonded with caspace-3 leading up to stable protein-ligand complexes.

Chitotriazolan (poly(β(1-4)-2-(1H-1,2,3-triazol-1-yl)-2-deoxy-d-glucose)) derivatives: Synthesis, characterization, and evaluation of antibacterial activity

Here we describe the first synthesis of a new type of polysaccharides derived from chitosan. In these structures, the 2-amino group on the pyranose ring was quantitively replaced by an aromatic 1,2,3-triazole moiety. The 2-amino group of chitosan and di-TBDMS chitosan was converted into an azide by diazo transfer reaction. The chitosan azide and TBDMS-chitosan azide were poorly soluble but could be fully converted to triazoles by "copper-catalysed Huisgen cycloaddition" in DMF or DMSO. The reaction could be done with different alkynes but derivatives lacking cationic or anionic groups were poorly soluble or insoluble in tested aqueous and organic solvents. Derivatives with N,N-dimethylaminomethyl, N,N,N-trimethylammoniummethyl, sulfonmethyl, and phosphomethyl groups linked to the 4-position of the triazole moiety were soluble in water at neutral or basic conditions and could be analyzed by ¹H, ¹³C APT, COSY, and HSQC NMR. The quaternized cationic chitotriazolan's had high activity against S. aureus and E. coli, whereas the anionic chitotriazolan's lacked activity.

Synthesis of alkynylated 1,2,4-oxadiazole/1,2,3-1H-triazole glycoconjugates: Discovering new compounds for use in chemotherapy against lung carcinoma and Mycobacterium tuberculosis

A total of forty-three compounds were synthesized, including thirty-two new ones. Among those compounds, seventeen were selected and tested on human tumor cell lines: PC-3 (prostate adenocarcinoma), HCT-116 (colorectal tumor), NCIH-460 (lung carcinoma), SKMEL-103 (melanoma) and AGP-01 (gastric tumor). Alkynylated 1,2,4-oxadiazoles 2m, 3g and 3k exhibited antiproliferative activities against NCIH-460 in culture. Alkynylated N-cyclohexyl-1,2,4-oxadiazoles 3a-m and bis-heterocycle glucoglycero-1,2,3-triazole-N-cyclohexyl-1,2,4-oxadiazole derivatives 5a-k and 6-11 were evaluated for their in vitro efficacy towards Mycobacterium tuberculosis (Mtb) H₃₇Ra and H₃₇Rv strains. In general, glycerosugars conjugated to 1,2,4-oxadiazole via a 1,2,3-triazole linkage (5a, 5e, 5j, 5k, and 7) showed in vitro inhibitory activity against Mtb (H₃₇Rv). The largest molecules bis-triazoles 10 and 11, proved inactive against TB. Probably, the absence of the N-cyclohexyl group in compound 8 and 1,2,4-oxadiazole nucleus in compound 9 were responsible for its low activity. Glucoglycero-triazole-oxadiazole derivatives 5e (10 μM) and 7 (23.9 μM) were the most promising antitubercular compounds, showing a better selective index than when tested against RAW 264.7 and HepG2 cells. Vero cell were used to investigate cytotoxicity of compounds 5a, 5h, 5j, 5k, and these compounds showed good cell viability. Further, in silico studies were performed for most active compounds (5e and 7) with potential drug targets, DprE1 and InhA of Mtb to understand possible interactions aided with molecular dynamic simulation (100ns).

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.

Synthesis, in vitro evaluation, and molecular docking studies of novel hydrazineylideneindolinone linked to phenoxymethyl-1,2,3-triazole derivatives as potential α-glucosidase inhibitors

In this work, a novel series of hydrazineylideneindolinone linked to phenoxymethyl-1,2,3-triazole derivatives were designed, synthesized, and evaluated for their anti-α-glucosidase activity due to an urgent need to develop effective anti-diabetic agents. Among tested 15 compounds, 8 derivatives (9a, 9b, 9c, 9d, 9e, 9f, 9h, and 9o) demonstrated superior potency compared to that of positive control, acarbose. Particularly, compound 9d possessed the best anti-α-glucosidase activity with around a 46-fold improvement in the inhibitory activity. Additionally, 9d showed a competitive type of inhibition in the kinetic study and the molecular docking study demonstrated that it well occupied the binding pocket of the catalytic center through desired interactions with residues, correlating to the experimental results.

Synthesis, in silico ADME, molecular docking and in vitro cytotoxicity evaluation of stilbene linked 1,2,3-triazoles

Series of (E)-1-benzyl-4-((4-styrylphenoxy)methyl)-1H-1,2,3-triazoles 7a-x were obtained by Wittig reaction between 4-((1-benzyl-1H-1,2,3-triazol-4-yl)methoxy)benzaldehydes 5a-d and benzyl triphenylphosphonium halides 6a-f in benzene. The structures of the synthesized compounds were confirmed by FTIR, NMR (1H and 13C NMR) spectroscopy, and mass spectrometry. All synthesized compounds were screened for their cytotoxic activity against human cancer cell lines including pancreatic carcinoma, colorectal carcinoma, lung carcinoma, and leukemias such as acute lymphoblastic, chronic myeloid, and non-Hodgkinson lymphoma cell lines. In vitro cytotoxicity data showed that compounds 7c, 7e, 7h, 7j, 7k, 7r, and 7w were moderately cytotoxic (11.6-19.3 μM) against the selected cancer cell lines. These cytotoxicity findings were supported using molecular docking studies of the compounds against 1TUB receptor. The drug-likeness properties of the compounds evaluated by in silico ADME analyses. Resveratrol linked 1,2,3-triazoles were more sensitive towards human carcinoma cell lines but least sensitive towards leukemia and lymphoma cell lines.

Triazolization of Enolizable Ketones with Primary Amines: A General Strategy toward Multifunctional 1,2,3-Triazoles

The development of metal-free syntheses toward 1,2,3-triazoles has been a burgeoning research area throughout the past decade. Despite the numerous advances, the scarceness of methods for the preparation of 1,5-disubstituted 1,2,3-triazoles from readily available substrates remained a challenge that was addressed by our group in 2016. A metal-free three-component reaction, which we have dubbed the triazolization reaction, was established for the rapid synthesis of 1,5-disubstituted, fully functionalized and NH-1,2,3-triazoles. This novel approach stands out because it utilizes widely available starting materials, namely primary amines and enolizable ketones. Furthermore, the broad substrate scope is a major advantage, and was further expanded by the number of modified protocols that have been reported. Triazolization products have successfully found utility as intermediates in various synthetic transformations, and were the subject of a few interesting biological activity studies.

Design, synthesis, and in vitro and in vivo anti-angiogenesis study of a novel vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitor based on 1,2,3-triazole scaffold

In the past five years, our team had been committed to click chemistry research, exploring the biological activity of 1,2,3-triazole by synthesizing different target inhibitors. In this study, a series of novel indole-2-one derivatives based on 1,2,3-triazole scaffolds were synthesized for the first time, and their inhibitory activity on vascular endothelial growth factor receptor-2 (VEGFR-2) was tested. Most of the compounds had shown promising activity in the VEGFR-2 kinase assay and had low toxicity to human umbilical vein endothelial cells (HUVECs). The compound 13d (IC₅₀ = 26.38 nM) had better kinase activity inhibition ability than sunitinib (IC₅₀ = 83.20 nM) and was less toxic to HUVECs. Moreover, it had an excellent inhibitory effect on HT-29 and MKN-45 cells. On the one hand, by tube formation assay, transwell, and Western blot analysis, compound 13d could inhibit VEGFR-2 protein phosphorylate on HUVECs, thereby inhibiting HUVECs migration and tube formation. In vivo study, the zebrafish model with VEGFR-2 labeling also verified that compound 13d had more anti-angiogenesis ability than sunitinib. On the other hand, molecular docking and molecular dynamics (MD) simulation results showed that compound 13d could stably bind to the active site of VEGFR-2. Based on the above findings, compound 13d could be considered an effective anti-angiogenesis drug and has more development value than sunitinib.

Design, synthesis and biological evaluation of novel pleuromutilin derivatives containing piperazine and 1,2,3-triazole linker

A series of novel pleuromutilin derivatives containing piperazine ring, 1, 2, 3-triazoles and secondary amines on the side chain of C14 were synthesized under mild conditions via click reaction. The in vitro antibacterial activities of the synthesized derivatives against four strains of Staphylococcus aureus (MRSA ATCC 43300, ATCC 29213 ,144 and AD3) and one strain of Escherichia coli (ATCC 25922) were evaluated by the broth dilution method. Among these derivatives, 22-[2-(4-((4-nitrophenyl piperazine)methyl)-1,2,3-triazol-1-yl)-1-(piperazine-1-yl) ethyl-1-one] deoxy pleuromutilin (compound 59) showed the most prominent in vitro antibacterial effect against MRSA (MIC = 1 μg/mL). Furthermore, compound 59 displayed more rapid bactericidal kinetic than tiamulin time-kill studies and possessed a longer PAE than tiamulin against MRSA in vitro. In addition, in vivo antibacterial activities of compound 59 against MRSA were further evaluated employing thigh infection model. And compound 59 (-8.89 log10 CFU/mL) displayed superior activities than tiamulin. Compound 59 was further evaluated in CYP450 inhibition assay and the results showed that it exhibited low to moderate inhibitory effects on CYP1A2, CYP2E1, CYP2D6 and CYP3A4 enzymes. The PK properties of compound 59 were then measured. The half-life (t1/2), clearance rate (Cl) and the area under the plasma concentration time curve (AUC0→∞) of compound 59 were 0.74 h, 0.29 L/h/kg and 46.28 μg·h/mL, respectively.

Design, synthesis and antitumor activity of icotinib derivatives

EGFR-TK pathway is of high importance for the treatment of non-small-cell lung cancers (NSCLC), and it will be challenging to develop anti-tumor drugs that could inhibit both EGFR wild-type and mutant tumor cells. Here, a series of icotinib derivatives containing 1,2,3-triazole moiety were designed and synthesized through copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. Preliminary CCK-8 assay showed that the prepared icotinib-1,2,3-triazole compounds such as a7 or a12 demonstrated potent in vitro antitumor activity against the NSCLC cells expressing both wild type EGFR and mutational EGFR. Further, the mechanism of action for compounds a7 and a12 induced NSCLC cells death was also detailed, and the results suggested a possible induced NSCLC cells death via inducing mitochondrial apoptosis and arresting cell cycle. Remarkably, the inhibition of EGFR by these icotinib derivatives was also studied. The results showed that compound a12 was a potent inhibitor for EGFR with IC₅₀ value of 1.49 μM. Combining these results, an EGFR inhibitor a12 represents a promising new anti-NSCLC candidate that could induce apoptosis and arrest cell cycle.

Discovery of fast-acting dual-stage antimalarial agents by profiling pyridylvinylquinoline chemical space via copper catalyzed azide-alkyne cycloadditions

To identity fast-acting, multistage antimalarial agents, a series of pyridylvinylquinoline-triazole analogues have been synthesized via CuAAC. Most of the compounds display significant inhibitory effect on the drug-resistant malarial Dd2 strain at low submicromolar concentrations. Among the tested analogues, compound 60 is the most potent molecule with an EC₅₀ value of 0.04 ± 0.01 μM. Our current study indicates that compound 60 is a fast-acting antimalarial compound and it demonstrates stage specific action at the trophozoite phase in the P. falciparum asexual life cycle. In addition, compound 60 is active against both early and late stage P. falciparum gametocytes. From a mechanistic perspective, compound 60 shows good activity as an inhibitor of β-hematin formation. Collectively, our findings suggest that fast-acting agent 60 targets dual life stages of the malarial parasites and warrant further investigation of pyridylvinylquinoline hybrids as new antimalarials.

Synthesis of 1,2,3-triazolyl nucleoside analogues and their antiviral activity

Abstract

Based on the fact that a search for influenza antivirals among nucleoside analogues has drawn very little attention of chemists, the present study reports the synthesis of a series of 1,2,3-triazolyl nucleoside analogues in which a pyrimidine fragment is attached to the ribofuranosyl-1,2,3-triazol-4-yl moiety by a polymethylene linker of variable length. Target compounds were prepared by the Cu alkyne-azide cycloaddition (CuAAC) reaction. Derivatives of uracil, 6-methyluracil, 3,6-dimethyluracil, thymine and quinazolin-2,4-dione with ω-alkyne substituent at the N1 (or N5) atom and azido 2,3,5-tri-O-acetyl-D-β-ribofuranoside were used as components of the CuAAC reaction. All compounds synthesized were evaluated for antiviral activity against influenza virus A/PR/8/34/(H1N1) and coxsackievirus B3. The best values of IC₅₀ (inhibiting concentration) and SI (selectivity index) were demonstrated by the lead compound 4i in which the 1,2,3-triazolylribofuranosyl fragment is attached to the N1 atom of the quinazoline-2,4-dione moiety via a butylene linker (IC₅₀ = 30 μM, SI = 24) and compound 8n in which the 1,2,3-triazolylribofuranosyl fragment is attached directly to the N5 atom of the 6-methyluracil moiety (IC₅₀ = 15 μM, SI = 5). According to theoretical calculations, the antiviral activity of the 1,2,3-triazolyl nucleoside analogues 4i and 8n against H1N1 (A/PR/8/34) influenza virus can be explained by their influence on the functioning of the polymerase acidic protein (PA) of RNA-dependent RNA polymerase (RdRP).

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s11030-020-10141-y) contains supplementary material, which is available to authorized users.

2H-1,2,3-Triazole-chalcones as novel cytotoxic agents against prostate cancer

Prostate cancer is an important cause of death in the male population and for which there is no satisfactory chemotherapy. Herein a new series of chalcone hybrids containing 2H-1,2,3-triazole core as the ring B has been synthesized and evaluated in vitro against PC-3 prostate cancer cell line. Compounds 4a, 4c and 4e significantly reduced cell viability and showed IC₅₀ of 28.55, 15.64 and 25.56 µM, respectively. The structure-activity relationship supported by computational chemistry points that the polarity of the molecular surface area should have some relevance to the efficiency of the compounds, in particular the ratio of the partial positive charge sites and the total molecular surface area exposed to the cell environment.

The design, synthesis and anti-tumor mechanism study of new androgen receptor degrader

Targeted protein degradation using small molecules is a novel strategy for drug development. In order to solve the problem of drug resistance in the treatment of prostate cancer, proteolysis-targeting chimeras (PROTAC) was introduced into the design of anti-prostate cancer derivatives. In this work, we synthesized two series of selective androgen receptor degraders (SARDs) containing the hydrophobic degrons with different linker, and then investigated the structure-activity relationships of these hybrid compounds. Most of the synthesized compounds exhibited moderate to good activity against all the cancer cell lines selected. Among them, compound A9 displayed potent inhibitory activity against LNCaP prostate cancer cell line with IC₅₀ values of 1.75 μM, as well as excellent AR degradation activity. Primary mechanism studies elucidated compound A9 arrested cell cycle at G0/G1 phase and induced a mild apoptotic response in LNCaP cells. Further study indicated that the degradation of AR was mediated through proteasome-mediated process. For all these reasons, compound A9 held promising potential as anti-proliferative agent for the development of highly efficient SARDs for drug-resistance prostate cancer therapies.

Design, synthesis and structure-activity relationships of 4-phenyl-1H-1,2,3-triazole phenylalanine derivatives as novel HIV-1 capsid inhibitors with promising antiviral activities

HIV-1 CA is involved in different stages of the viral replication cycle, performing essential roles in both early (uncoating, reverse transcription, nuclear import, integration) and late events (assembly). Recent efforts have demonstrated HIV-1 CA protein as a prospective therapeutic target for the development of new antivirals. The most extensively studied CA inhibitor, PF-3450074 (PF-74, discovered by Pfizer), that targets an inter-protomer pocket within the CA hexamer. Herein we reported the design, synthesis, and biological evaluation of a series of 4-phenyl-1H-1,2,3-triazole phenylalanine derivatives as HIV-1 CA inhibitors based on PF-74 scaffold. Most of the analogues demonstrated potent antiviral activities, among them, the anti-HIV-1 activity of 6a-9 (EC50 = 3.13 μM) is particularly prominent. The SPR binding assay of selected compounds (6a-9, 6a-10, 5b) suggested direct and effective interaction with recombinant CA proteins. The mechanism of action studies also demonstrated that 6a-9 displays the effects in both the early and late stages of HIV-1 replication. To explore the potential binding mode of the here presented analogues, 6a-9 was analyzed by MD simulation to predict its binding to the active site of HIV-1 CA monomer. In conclusion, this novel series of antivirals can serve as a starting point for the development of a new generation of HIV-1 treatment regimen and highlights the potentiality of CA as a therapeutic target.

Rationally designed phenanthrene derivatized triazole as a dual chemosensor for fluoride and copper recognition

A 1,2,3-triazole chemosensor containing phenanthrene and phenol moieties (PhTP) was efficiently synthesized via copper (I)-catalyzed azide-alkyne cycloaddition, "click chemistry". PhTP is a dual analyte sensor for fluoride and copper (II) ions in homogeneous medium. Deprotonation of the phenolic OH proton by the fluoride ion is responsible for a change in fluorescence color from blue (PhTP) to yellowish-orange (PhTP-fluoride adduct), while a charge transfer between the triazole nitrogen of the chemosensor and Cu²⁺ revealed a turn-off fluorescence output. The detection capability of PhTP was analyzed with a series of anions (F^-, Cl^-, Br^-, I^-, H₂PO₄^-, ClO₄^-, OAc^-, BF₄^-) and cations (Fe³⁺, Fe²⁺, Cu²⁺, Ag⁺, Cr³⁺, Al³⁺, Co²⁺, Ni²⁺, Cd²⁺, Zn²⁺). With anions, competitive fluorescence responses under UV lamp were observed for acetate and dihydrogen phosphate anions, but maximum response from fluoride ion was substantiated from steady state absorption and fluorescence experiments. With cations, PhTP displayed a selective and sensitive recognition towards Cu²⁺ ion through spectral modulation in absorption spectroscopy and a turn-off fluorescence response. Nuclear magnetic resonance (NMR) spectroscopic titration studies supported the results obtained through photophysical studies and provided evidence for the ion-binding sites on the probe.

1,2,3-Triazole-Chalcone hybrids: Synthesis, in vitro cytotoxic activity and mechanistic investigation of apoptosis induction in multiple myeloma RPMI-8226

A new series of 1,2,3-triazole-chalcone hybrids has been synthesized and screened in vitro against a panel of 60 human cancer cell lines according to NCI (USA) protocol. Compound 4d having 3, 4-dimethoxyphenyl chalcone moiety, the most potent derivative, inhibited the growth of RPMI-8226 and SR leukemia cell lines by 99.73% and 94.95% at 10 μM, respectively. Also, it inhibited the growth of M14 melanoma, K-562 leukemia, and MCF7 breast cancer cell lines by more than 80% at the same test concentration. 4d showed IC₅₀ values less than 1 μM on six types of tumor cells and high selectivity index reached to 104 fold on MCF7. Compound 4d showed superior activity than methotrexate and gefitinib against the most sensitive leukemia cell lines in addition to higher or comparable activity against the rest sensitive cell lines. Flow cytometry analysis in RPMI-8226 cells revealed that compound 4d caused cell cycle arrest at G2/M phase and induced apoptosis in a dose dependant manner. Mechanistic evaluation referred this apoptosis induction to triggering mitochondrial apoptotic pathway through inducing ROS accumulation, increasing Bax/Bcl-2 ratio and activation of caspases 3, 7 and 9.

Design and synthesis of benzodiazepine-1,2,3-triazole hybrid derivatives as selective butyrylcholinesterase inhibitors

A new series of compounds based on benzodiazepine-1,2,3-triazole were synthesized and evaluated as cholinesterase inhibitors by Ellman's method. The compounds proved to be selective inhibitors of butyrylcholinesterase (BuChE) over acetylcholinesterase. The most potent compound was 3,3-dimethyl-11-(3-((1-(4-nitrobenzyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-one, identified as a submicromolar inhibitor of BuChE with IC₅₀ value of 0.2 µM. In addition, the amyloid-β self-aggregation evaluation studies for selected compounds showed potent inhibitory effects compared to donepezil. The docking and cell viability studies supported the potential of compound 9b-6 as significant BuChE inhibitor.

Ru(II) coordination compounds of N-N bidentate chelators with 1,2,3 triazole and isoquinoline subunits: Synthesis, spectroscopy and antimicrobial properties

Bidentate chelators 1-(1-benzyl-1,2,3-triazol-4-yl)isoquinoline and 3-(1-benzyl-1,2,3-triazol-4-yl)isoquinoline were prepared from benzyl bromide and trimethylsilylethynylisoquinoline precursors using a tandem deprotection/substitution/CuAAC synthetic approach. Each chelator is capable of forming a stable 3:1 Ru(II) coordination compound, which forms as a geometric isomer mixture. These Ru(II) complexes possess unique MLCT absorbance signatures at 450/472 nm (1-isomer) and 367 nm (3-isomer) relative to their constituent chelating units. Minimum inhibitory concentration values as low as 0.4 μM are observed for Ru(II) complexes against representative Gram-positive bacteria Bacillus subtilis and Staphylococcus epidermidis. Comparing the MIC values of these isoquinoline compounds with analogous 2-(1-benzyl-1,2,3-triazol-4-yl)pyridine compounds shows a 2.5- to 40-fold improvement in potency. This study establishes that increased hydrophobicity introduced at the central chelating units of Ru(II) coordination compounds can be a useful means by which to optimize antimicrobial activity that is complimentary to the variation of peripheral substituent identity at the chelator's N1 triazole position.

Synthesis and biological evaluation of new benzimidazole-1,2,3-triazole hybrids as potential α-glucosidase inhibitors

In this study, a series of benzimidazole-1,2,3-triazole hybrids 8a-n as new α-glucosidase inhibitors were designed and synthesized. In vitro α-glucosidase inhibition activity results indicated that all the synthesized compounds (IC₅₀ values ranging from 25.2 ± 0.9 to 176.5 ± 6.7 μM) exhibited more inhibitory activity in comparison to standard drug acarbose (IC₅₀ = 750.0 ± 12.5 μM). Enzyme kinetic study on the most potent compound 8c revealed that this compound was a competitive inhibitor into α-glucosidase. Moreover, the docking study was performed in order to evaluation of interaction modes of the synthesized compounds in the active site of α-glucosidase and to explain structure-activity relationships of the most potent compounds and their corresponding analogs.

Continued exploration and tail approach synthesis of benzenesulfonamides containing triazole and dual triazole moieties as carbonic anhydrase I, II, IV and IX inhibitors

A library of twenty two novel 1,2,3-triazole benzenesulfonamides incorporating thiosemicarbazide, 5(4H)-thione-1,2,4-triazole and variously substituted phenacyl appended 1,2,4-triazole as tail were designed, synthesized and assessed for their efficacy as inhibitors against carbonic anhydrase human (h) isoforms hCA I, II, IV and IX. The physiologically important and off-target cytosolic isoform hCA I was weakly inhibited by most of the newly synthesized sulfonamides while the glaucoma associated isoform hCA II was moderately inhibited with KIs spanning in low nanomolar range (KI = 8.0 nM-0.903 μM). The membrane bound isoform hCA IV, which is known to be involved in glaucoma and retinitis pigmentosa among others, was strongly inhibited by all newly synthesized sulfonamides out of which nine compounds inhibited isoform hCA IV even more effectively as compared to standard drug acetazolamide (AAZ). The membrane bound isoform hCA IX, associated with growth of tumor cells, was moderately inhibited with KIs ranging between 51 nM-3.198 μM. The effect of appending variously substituted tails on heterocyclic moieties over inhibition potential of synthesized sulfonamides is also disclosed which can be of further interest in pharmacological studies for exploring synthesis of isoform selective inhibitors.

Antitumor and antiviral activities of 4-substituted 1,2,3-triazolyl-2,3-dibenzyl-L-ascorbic acid derivatives

Two series of 6-(1,2,3-triazolyl)-2,3-dibenzyl-l-ascorbic acid derivatives with the hydroxyethylene (8a−8u) and ethylidene linkers (10c−10p) were synthesized and evaluated for their antiproliferative activity against seven malignant tumor cell lines and antiviral activity against a broad range of viruses. Conformationally unrestricted spacer between the lactone and 1,2,3-triazole units in 8a−8u series had a profound effect on antitumor activity. Besides, the introduction of a long side chain at C-4 of 1,2,3-triazole that led to the synthesis of decyl-substituted 2,3-dibenzyl-l-ascorbic acid 8m accounted for a selective and potent antiproliferative activity on breast cancer MCF-7 cells cells in the nM range. Further analysis showed that compound 8m strongly enhanced expression of hypoxia inducible transcription factor 1 α (HIF-1α) and to some extent decreased expression of nitric oxide synthase 2 (NOS2) suggesting its role in regulating HIF-1α signalling pathway. The p-methoxyphenyl-substituted derivative 10g displayed specific anti-cytomegalovirus (CMV) potential, whereas aliphatic-substituted derivatives 8l and 8m had the most potent, yet relatively non-specific, anti-varicella-zoster (VZV) activity.

•

Two series of 1,2,3-triazolyl 2,3-dibenzyl-l-ascorbic acid conjugates were synthesized.

•

Conformationally unrestricted spacer had a major effect on antitumor activities.

•

Decyl-substituted l-ascorbic acid 8m caused inhibition of breast cancer MCF-7 cells in the nM range.

•

8m increased the expression of hypoxia inducible transcription factor HIF-1α.

•

p-Methoxyphenyl-substituted derivative 10g had specific anti-CMV activity.