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

Coumarin-Triazole-Thiazole hybrids: A new avenue in Antitubercular agents

The present work reports the design and synthesis of a series of 2-(4-(((2-oxo-2H-chromen-4-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)-N-(thiazol-2-yl)acetamide derivatives (4a-4k), which were investigated for their potential against tubercular activities. The well-known click cycloaddition reaction of azido derivatives (3a-3k) and 4-(prop-2-yn-1-yloxy)-2H-chromen-2-one (2) in the presence of catalytic amount of CuSO4 in H2O and DMF was employed. Notably, compounds 4c, 4d, and 4g showed the most promising results with MIC values against tuberculosis are 7.81 μg/mL, 2.61 μg/mL, and 7.81 μg/mL, respectively. Compounds (4a-4k) exhibited moderate to excellent antioxidant activities and low cytotoxicities. In addition, molecular docking studies were performed to investigate the binding interaction modes of the compounds (4a-4k) with various proteins and ligand sites.

Design, synthesis and structure-activity relationships of novel HIV capsid inhibitors with potent antiviral activities

The HIV capsid (CA) protein is a highly promising target for anti-HIV treatment due to its critical role in viral replication. Based on the optimization of 11L guided by PF74, a series of novel HIV CA inhibitors targeting the NTD-CTD interface were identified, demonstrating potent inhibitory effects against both HIV-1 and HIV-2. Notably, compound IC-2b4 (EC50 = 0.08 ± 0.02 μM) exhibits twice the potency of 11L and three times that of PF74 against HIV-1. For HIV-2, IC-2a4 (EC50 = 0.01 ± 0.00 μM) demonstrates twice the efficacy of 11L and 221 times that of PF74. In mechanistic studies, IC-2b4 was shown to bind directly and stably to CA, exerting robust inhibitory effects during both the early and late stages of infection-a property also observed with IC-2b3. Molecular dynamics simulations revealed that IC-2b4 forms more extensive interactions with CA compared to PF74, thereby enhancing antiviral activity. These novel antiviral compounds collectively provide valuable insights into developing anti-HIV therapies and highlight the therapeutic potential of the CA protein as a drug target.

Sustainable Synthesis of 1,2,3-Triazoles using Cyrene as a Biodegradable Solvent in Click Chemistry

The first successful synthesis of 1,2,3-triazoles using CyreneTM as a biodegradable and non-toxic solvent in click chemistry has been developed. In contrast to previous methods, this sustainable approach allows product isolation by simple precipitation in water, eliminating the need for organic solvent extractions and column chromatography purifications, thus minimizing waste consumption while reducing operational costs. The protocol, performed also at gram scale, has broad applicability and versatility, as shown with complex substrates like biologically active coumarins or triazole-linked bifunctional molecules. Finally, this protocol is also amenable to a three-component reaction involving organic halides, terminal acetylenes and sodium azide, thus avoiding the isolation of organic azides, difficult-to-handle species known for their environmental sensitivity.

Design and synthesis of new 1,2,3-triazole derivatives as VEGFR-2/telomerase downregulatory candidates endowed with apoptotic potential for cancer treatment

In this current work, we dedicated efforts to designing and synthesizing new 1,2,3-triazole-analogues (5a-d), (6a-d), and (7a-c) to act as dual VEGFR-2 and telomerase inhibitors with promising apoptotic potential. The synthesized analogues were examined against eleven diverse types of cancer cells and two normal cells to assess their ability to inhibit cell growth (GI%). Obviously, compound 7b showed the best average GI% (75.69 %) surpassing the average GI% of Dox (65.79 %). Compound 5d showed the lowest IC50 values (25.86 and 51.91 µM) against HNO-97 and FaDu cancer cells, respectively. Besides, compound 5a exhibited the lowest IC50 value (15.46 µM) against HCT116, whereas compound 6b revealed the lowest IC50 value (31.14 µM) against HuH7. Besides, candidates 5a, 5b, 5d, and 7a showed prominent inhibitory results towards VEGFR-2 protein with decreasing its expression by 0.33, 0.42, 0.38 and 0.26-fold change, respectively. However, compounds 5a, 5b, 5d, and 7a showed promising inhibitory results towards telomerase protein and decreased its expression by 0.60, 0.50, 0.52, and 0.44-fold change, respectively. Additionally, it was clear that compound 5a was able to upregulate the expression of Caspases 3, 8, and 9 proteins by 2.19, 1.83, and 1.62-fold change, respectively. Besides, 5a was able to downregulate the expression of CDK-2, CDK-4, and CDK-6 proteins by 0.50, 0.43, and 0.13-fold change, respectively. Obviously, compound 5a halted the cell cycle at the G1, S, and G2-M phases in HCT116 cells. Subsequently, the synthesized 1,2,3-triazole analogues can be treated as lead VEGFR-2 and telomerase inhibitors with potential apoptotic activity for future optimization and cancer treatment.

An updated review on 1,2,3-/1,2,4-triazoles: synthesis and diverse range of biological potential

The synthesis of triazoles has attracted a lot of interest in the field of organic chemistry because of its versatile chemical characteristics and possible biological uses. This review offers an extensive overview of the different pathways used in the production of triazoles. A detailed analysis of recent research indicates that triazole compounds have a potential range of pharmacological activities, including the ability to inhibit enzymes, and have antibacterial, anticancer, and antifungal activities. The integration of computational and experimental methods provides a thorough understanding of the structure-activity connection, promoting sensible drug design and optimization. By including triazoles as essential components in drug discovery, researchers can further explore and innovate in the synthesis, biological assessment, and computational studies of triazoles as drugs, exploring the potential therapeutic significance of triazoles.

Drug Discovery and Exploration of Heterocycles for the Development of Anti-HIV Agents

It is a known fact that HIV infection remains a serious public health problem throughout the world, and the need to constantly develop new antiretroviral drugs to combat HIV emerges from the fact that repetitive mutations occurring in viral enzymes make this virus resistant to antiretroviral drugs. This resistance causes failure of treatment, and hence, for many years, extensive research has been to discover newer possibilities for fighting this disease at a molecular level, along with many long-standing and expensive clinical trials. Many scientific research programs have either been discarded or unsuccessful. However, the research has not stopped, and in the process, many heterocyclic scaffolds have been used to build up novel drug molecules to combat this disease. A literature survey reveals that many heterocycles have been explored and were found to be very useful in treating different types of viral infections. This concise and rigorous literature explains the journey and highlights the various strategies to develop new anti-HIV drug candidates.

Synthesis, Characterization, and antiviral evaluation of New Chalcone-Based Imidazo[1,2-a]pyridine Derivatives: Insights from in vitro and in silico Anti-HIV studies

Given the ease of synthetic accessibility and the promising biological profile demonstrated by both imidazo[1,2-a]pyridine and Chalcone derivatives, a series of Chalcone-based imidazo[1,2-a]pyridine derivatives were synthesized and characterized using 1H NMR, 13C NMR, Mass Spectrometry and FTIR techniques. Density functional theory (DFT) was employed to investigate the structural and electronic properties, providing insights into potential reactive sites. The synthesized compounds were evaluated in vitro for their antiviral properties against human immunodeficiency virus type-1 (HIV-1) and human immunodeficiency virus type-2 (HIV-2) in MT-4 cells. Furthermore, Molecular docking studies show strong binding affinities with HIV-1 reverse transcriptase and HIV-2 protease. To further understand the dynamic behavior and stability of these interactions, molecular dynamics (MD) simulations were conducted. The MD results indicated stable binding conformations of the ligands within the active sites, with low RMSD and RMSF values throughout the simulation, confirming the robustness of these interactions. ADME predictions suggested acceptable pharmacokinetic profiles, though solubility remains a limitation for these compounds. Although the in vitro antiviral activity was limited, the combination of in vitro and in silico approaches provided valuable insights, guiding further structural optimization to improve bioavailability and enhance the therapeutic potential of these derivatives.

Dual EGFR and telomerase inhibitory potential of new triazole tethered Schiff bases endowed with apoptosis: design, synthesis, and biological assessments

Many cancers have displayed resistance to chemotherapeutic drugs over the past few decades. EGFR has emerged as a leading target for cancer therapy via inhibiting tumor angiogenesis. Besides, studies strongly suggest that blocking telomerase activity could be an effective way to control the growth of certain cancer cells. Based on the fact that multi-target design rationale can afford candidates with greater treatment effectiveness. Besides, it was evidenced that inhibition of human telomerase enhances the effect of some tyrosine kinase inhibitors. So, in the current work, we aimed to design and synthesize novel 1,2,3-triazole-tethered Schiff bases (5a-l) to act as dual EGFR and telomerase inhibitors. Growth inhibition (GI)% was conducted for the synthesized compounds using a panel of eleven cancer cell lines as well as two normal cell lines. Interestingly, compound 5e displayed the highest mean GI% (76.78%) among the investigated compounds surpassing the mean GI% of the reference drug doxorubicin (65.79%). In addition, compound 5g displayed notably the lowest IC50 values (13.31, 13.31, 12.62, and 31.19 μM) for the four utilized cancer cell lines HNO97, HCT116, A375, and HEPG2, respectively. Interestingly, the investigated compounds exhibited significant inhibitory potential to EGFR and telomerase protein expression; in particular, compound 5g recorded inhibitory potentials of 3.45 and 1.31 ng mL-1, respectively. Hence, protein expression of the apoptosis-related proteins was carried out for compound 5g. Pro-apoptotic proteins (caspases 3, 8, and 9) were upregulated by 1.35, 1.55, and 1.51-fold change, respectively. Meanwhile, the anti-apoptotic proteins (CDK-2, CDK-4, and CDK-6) were downregulated by 2.91, 2.01, and 9.15-fold change, respectively, ensuring the apoptotic potential of compound 5g. Accordingly, compound 5g was selected for further investigation of its effects on cell cycle progression in A375 cancer cells. Obviously, compound 5g prompted cell cycle arrest at the G0-G1 phase. Additionally, the investigated compounds showed eligible pharmacokinetic profiles with feasible oral bioavailability. Consequently, the synthesized compounds can be treated as lead multi-target anticancer ligands for future optimization.

Divergent Regioselective Synthesis of Functionalized 1,2,3-1H-Triazoles from Nitriles and Arylazides Under Metal-Free and/or Solvent-Free Conditions

Highly selective and divergent syntheses, which are crucial in both organic synthesis and medicinal chemistry, involve significant advancements in compound accessibility. By modifying α-cyano esters into α-cyano ketones, the synthesis pathway broadens to include a diverse range of 4-CN, 5-amino, and 5-arylamino derivatives of 1,2,3-triazoles, which are achieved notably through the Dimroth rearrangement. This versatility extends further with the potential for a triple cascade reaction, leading to the production of carboximidamide compounds, which are facilitated by the Cornforth rearrangement. Advancements in compound accessibility not only expand the repertoire of synthesized molecules but also open new avenues for potential pharmacological agents. Building on these findings, we have developed an innovative and efficient method for the divergent synthesis of functionalized 1,2,3-triazoles. This method strategically utilizes α-cyanocarbonyls and arylazides by harnessing their reactivity and compatibility to orchestrate a variety of molecular transformations. By optimizing these substrates, our goal is to simplify synthetic routes, improve product yields, and accelerate the discovery and development of new chemical entities with promising biological activities.

Synthesis, crystal structure, and antiviral evaluation of new imidazopyridine-schiff base derivatives: in vitro and in silico anti-HIV studies

A series of Imidazo[1,2-a]pyridine-Schiff base derivatives were synthesized and characterized using 1H NMR, 13C NMR, Mass Spectrometry and FTIR techniques, and the structure of 4a was further confirmed through single-crystal X-ray diffraction analysis. Density Functional Theory (DFT) has been used to investigate the structural and electronic properties. The synthesized compounds were evaluated in vitro for their antiviral activity against human immunodeficiency virus type-1 (HIV-1) and human immunodeficiency virus type-2 (HIV-2) in MT-4 cells. Compound 4a displayed EC50 values of 82,02 and 47,72 μg ml-1 against HIV-1 and HIV-2, respectively. Molecular docking studies were conducted to gain insights into the interaction mechanism of the synthesized compounds with HIV-1 reverse transcriptase. ADME analysis suggested acceptable pharmacokinetic profiles, though solubility remains a limitation for these compounds, highlighting the need for further structural modifications to enhance bioavailability and therapeutic potential.

A microwave assisted tandem synthesis of quinazolinones using ionic liquid supported copper(II) catalyst with mechanistic insights

Quinazolinone is a preferred structural motif with notable pharmacological activity that is present in a wide range of naturally occurring compounds. A microwave assisted tandem cyclooxidative method has been developed to afford quinazolinones via a recyclable ionic liquid supported copper catalyst. This sustainable method exhibits operational simplicity through a rapid, clean, and energy-efficient route and a variety of 2-substituted quinazolinones are obtained in excellent yields. In addition, this innovative approach enables us to develop a library of nitriles in an environment-friendly synthetic protocol. Moreover, the catalyst can be recycled and reused up to three consecutive cycles without any significant loss of catalytic activity. Further organic transformation of the synthesized quinazolinones was carried out to afford reported as well as novel bioactive heterocyclic compounds.

A heterocyclic compound inhibits viral release by inducing cell surface BST2/Tetherin/CD317/HM1.24

The introduction of combined antiretroviral therapy (cART) has greatly improved the quality of life of human immunodeficiency virus type 1 (HIV-1)-infected individuals. Nonetheless, the ever-present desire to seek out a full remedy for HIV-1 infections makes the discovery of novel antiviral medication compelling. Owing to this, a new late-stage inhibitor, Lenacapavir/Sunlenca, an HIV multi-phase suppressor, was clinically authorized in 2022. Besides unveiling cutting-edge antivirals inhibiting late-stage proteins or processes, newer therapeutics targeting host restriction factors hold promise for the curative care of HIV-1 infections. Notwithstanding, bone marrow stromal antigen 2 (BST2)/Tetherin/CD317/HM1.24, which entraps progeny virions is an appealing HIV-1 therapeutic candidate. In this study, a novel drug screening system was established, using the Jurkat/Vpr-HiBiT T cells, to identify drugs that could obstruct HIV-1 release; the candidate compounds were selected from the Ono Pharmaceutical compound library. Jurkat T cells expressing Vpr-HiBiT were infected with NL4-3, and the amount of virus release was quantified indirectly by the amount of Vpr-HiBiT incorporated into the progeny virions. Subsequently, the candidate compounds that suppressed viral release were used to synthesize the heterocyclic compound, HT-7, which reduces HIV-1 release with less cellular toxicity. Notably, HT-7 increased cell surface BST2 coupled with HIV-1 release reduction in Jurkat cells but not Jurkat/KO-BST2 cells. Seemingly, HT-7 impeded simian immunodeficiency virus (SIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) release. Concisely, these results suggest that the reduction in viral release, following HT-7 treatment, resulted from the modulation of cell surface expression of BST2 by HT-7.

Application of an NMR/Crystallography Fragment Screening Platform for the Assessment and Rapid Discovery of New HIV-CA Binding Fragments

Identification and assessment of novel targets is essential to combat drug resistance in the treatment of HIV/AIDS. HIV Capsid (HIV-CA), the protein playing a major role in both the early and late stages of the viral life cycle, has emerged as an important target. We have applied an NMR fragment screening platform and identified molecules that bind to the N-terminal domain (NTD) of HIV-CA at a site close to the interface with the C-terminal domain (CTD). Using X-ray crystallography, we have been able to obtain crystal structures to identify the binding mode of these compounds. This allowed for rapid progression of the initial, weak binding, fragment starting points to compounds 37 and 38, which have 19F-pKi values of 5.3 and 5.4 respectively.

N-Heterocycles as Promising Antiviral Agents: A Comprehensive Overview

Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host's immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

Discovery of Dolutegravir Derivative against Liver Cancer via Inducing Autophagy and DNA Damage

We introduced a terminal alkyne into the core structure of dolutegravir, resulting in the synthesis of 34 novel dolutegravir-1,2,3-triazole compounds through click chemistry. These compounds exhibited remarkable inhibitory activities against two hepatocellular carcinoma cell lines, Huh7 and HepG2. Notably, compounds 5e and 5p demonstrated exceptional efficacy, particularly against Huh7 cells, with IC50 values of 2.64 and 5.42 μM. Additionally, both compounds induced apoptosis in Huh7 cells, suppressed tumor cell clone formation, and elevated reactive oxygen species (ROS) levels, further promoting tumor cell apoptosis. Furthermore, compounds 5e and 5p activated the LC3 signaling pathway, inducing autophagy, and triggered the γ-H2AX signaling pathway, resulting in DNA damage in tumor cells. Compound 5e exhibited low toxicity, highlighting its potential as a promising anti-tumor drug.

Design and Synthesis of New GS-6207 Subtypes for Targeting HIV-1 Capsid Protein

HIV-1 capsid protein (CA) is the molecular target of the recently FDA-approved long acting injectable (LAI) drug lenacapavir (GS-6207). The quick emergence of CA mutations resistant to GS-6207 necessitates the design and synthesis of novel sub-chemotypes. We have conducted the structure-based design of two new sub-chemotypes combining the scaffold of GS-6207 and the N-terminal cap of PF74 analogs, the other important CA-targeting chemotype. The design was validated via induced-fit molecular docking. More importantly, we have worked out a general synthetic route to allow the modular synthesis of novel GS-6207 subtypes. Significantly, the desired stereochemistry of the skeleton C2 was confirmed via an X-ray crystal structure of the key synthetic intermediate 22a. Although the newly synthesized analogs did not show significant potency, our efforts herein will facilitate the future design and synthesis of novel subtypes with improved potency.

Discovery of 1,2,3-triazole incorporated indole-piperazines as potent antitubercular agents: Design, synthesis, in vitro biological evaluation, molecular docking and ADME studies

In this report, a library consisting of three sets of indole-piperazine derivatives was designed through the molecular hybridization approach. In total, fifty new hybrid compounds (T1-T50) were synthesized and screened for antitubercular activity against Mycobacterium tuberculosis H37Rv strain (ATCC-27294). Five (T36, T43, T44, T48 and T49) among fifty compounds exhibited significant inhibitory potency with the MIC of 1.6 µg/mL, which is twofold more potent than the standard first-line TB drug Pyrazinamide and equipotent with Isoniazid. N-1,2,3-triazolyl indole-piperazine derivatives displayed improved inhibition activity as compared to the simple and N-benzyl indole-piperazine derivatives. In addition, the observed activity profile of indole-piperazines was similar to standard anti-TB drugs (isoniazid and pyrazinamide) against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa strains, demonstrating the compounds' selectivity towards the Mycobacterium tuberculosis H37Rv strain. All the active anti-TB compounds are proved to be non-toxic (with IC50 > 300 μg/mL) as verified through the toxicity evaluation against VERO cell lines. Additionally, molecular docking studies against two target enzymes (Inh A and CYP121) were performed to validate the activity profile of indole-piperazine derivatives. Further, in silico-ADME prediction and pharmacokinetic parameters indicated that these compounds have good oral bioavailability.

A Literature Review Focusing on the Antiviral Activity of [1,2,4] and [1,2,3]-triazoles

Out of a variety of heterocycles, triazole scaffolds have been shown to play a significant part in a wide array of biological functions. Many drug compounds containing a triazole moiety with important antimicrobial, anticancer and antidepressant properties have been commercialized. In addition, the triazole scaffold exhibits remarkable antiviral activity either incorporated into nucleoside analogs or non-nucleosides. Many synthetic techniques have been produced by scientists around the world as a result of their wide-ranging biological function. In this review, we have tried to summarize new synthetic methods produced by diverse research groups as well as provide a comprehensive description of the function of [1,2,4] and [1,2,3]-triazole derivatives as antiviral agents. Antiviral triazole compounds have been shown to target a wide variety of molecular proteins. In addition, several strains of viruses, including the human immunodeficiency virus, SARS virus, hepatitis B and C viruses, influenza virus, Hantavirus, and herpes virus, were discovered to be susceptible to triazole derivatives. This review article covered the reports for antiviral activity of both 1,2,3- and 1,2,4-triazole moieties up to 2022.

Novel Hybrid Triazoline - Triazole Glycosides: Synthesis, Characterization, Antimicrobial Activity study via In Vitro, and In Silico Means

Series of novel 1,2,3-triazole, and 1,2,3- triazoline glycosides (a-e) were efficiently synthesized starting from d-arabinose in an effort to synthesize a new type of hybrid molecules containing sugar azide. The key step involved is the introduction of a new group, ethylene glycol, to the anomeric site and protection of the hydroxyl groups with acetic anhydride. Following that, the acetyl group is converted into ethylene glycol to tosylate. Compound Azido ethyl-O-β-d-arabinofuranoside 4 was synthesized with good yield by treating the derivative 3 with sodium azide, which displaced the tosylate 3 and replaced it with the azide group. The new glycosides were synthesized via a 1,3-dipolar cycloaddition reaction between the intermediate compound 4 and several alkenes and alkynes. The triazole and triazoline compounds were characterized by FT-IR, 1H NMR, 13C NMR, LC/MS-IT-TOF spectral, and C·H.N. analysis. The antimicrobial screening was assayed using the disc diffusion technique revealed moderate to high potential inhibitory values against three test microorganisms compared to standard drugs. Their pharmacokinetics evaluation also showed promising drug-likeness and ADME properties. Furthermore, density functional theory (DFT) was utilized to obtain the molecular geometry of the title compounds utilizing B3LYP/6-311G++ (d, p), molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs) through the investigation of HOMO and LUMO orbitals, and energy gap value. A lower energy gap value denotes that electrons can be transported more easily, indicating that molecule (b) is more reactive than other compounds. Molecular docking analysis revealed that all the designed triazole and triazoline glycosides interacted strongly inside the active site of the enzyme (PDB ID: 2Q85). and exhibits high docking scores, higher than the standard drug. The range of docking scores is -7.99 kcal/mol compound (a) to -7.42 kcal/mol compound (e).

Modulation of HIV-1 capsid multimerization by sennoside A and sennoside B via interaction with the NTD/CTD interface in capsid hexamer

Small molecules that bind to the pocket targeted by a peptide, termed capsid assembly inhibitor (CAI), have shown antiviral effects with unique mechanisms of action. We report the discovery of two natural compounds, sennoside A (SA) and sennoside B (SB), derived from medicinal plants that bind to this pocket in the C-terminal domain of capsid (CA CTD). Both SA and SB were identified via a drug-screening campaign that utilized a time-resolved fluorescence resonance energy transfer assay. They inhibited the HIV-1 CA CTD/CAI interaction at sub-micromolar concentrations of 0.18 μM and 0.08 μM, respectively. Mutation of key residues (including Tyr 169, Leu 211, Asn 183, and Glu 187) in the CA CTD decreased their binding affinity to the CA monomer, from 1.35-fold to 4.17-fold. Furthermore, both compounds induced CA assembly in vitro and bound directly to the CA hexamer, suggesting that they interact with CA beyond the CA CTD. Molecular docking showed that both compounds were bound to the N-terminal domain (NTD)/CTD interface between adjacent protomers within the CA hexamer. SA established a hydrogen-bonding network with residues N57, V59, Q63, K70, and N74 of CA1-NTD and Q179 of CA2-CTD. SB formed hydrogen bonds with the N53, N70, and N74 residues of CA1-NTD, and the A177and Q179 residues of CA2-CTD. Both compounds, acting as glue, can bring αH4 in the NTD and αH9 in the CTD of the NTD/CTD interface close to each other. Collectively, our research indicates that SA and SB, which enhance CA assembly, could serve as novel chemical tools to identify agents that modulate HIV-1 CA assembly. These natural compounds may potentially lead to the development of new antiviral therapies with unique mechanisms of action.

Recent Advances in the Green Synthesis of Active N-Heterocycles and Their Biological Activities

N-heterocyclic scaffolds represent a privileged architecture in the process of drug design and development. It has widespread occurrence in synthetic and natural products, either those that are established or progressing as potent drug candidates. Additionally, numerous novel N-heterocyclic analogues with remarkable physiological significance and extended pharmaceutical applications are escalating progressively. Hence, the classical synthetic protocols need to be improvised according to modern requirements for efficient and eco-friendly approaches. Numerous methodologies and technologies emerged to address the green and sustainable production of various pharmaceutically and medicinally important N-heterocyclic compounds in last few years. In this context, the current review unveils greener alternatives for direct access to categorically differentiated N-heterocyclic derivatives and its application in the establishment of biologically active potent molecules for drug design. The green and sustainable methods accentuated in this review includes microwave-assisted reactions, solvent-free approaches, heterogeneous catalysis, ultrasound reactions, and biocatalysis.

Novel Oleanolic Acid-Phtalimidines Tethered 1,2,3 Triazole Hybrids as Promising Antibacterial Agents: Design, Synthesis, In Vitro Experiments and In Silico Docking Studies

As part of the valorization of agricultural waste into bioactive compounds, a series of structurally novel oleanolic acid ((3β-hydroxyolean-12-en-28-oic acid, OA-1)-phtalimidines (isoindolinones) conjugates 18a-u bearing 1,2,3-triazole moieties were designed and synthesized by treating an azide 4 previously prepared from OA-1 isolated from olive pomace (Olea europaea L.) with a wide range of propargylated phtalimidines using the Cu(I)-catalyzed click chemistry approach. OA-1 and its newly prepared analogues, 18a-u, were screened in vitro for their antibacterial activity against two Gram-positive bacteria, Staphylococcus aureus and Listeria monocytogenes, and two Gram-negative bacteria, Salmonella thyphimurium and Pseudomonas aeruginosa. Attractive results were obtained, notably against L. monocytogenes. Compounds 18d, 18g, and 18h exhibited the highest antibacterial activity when compared with OA-1 and other compounds in the series against tested pathogenic bacterial strains. A molecular docking study was performed to explore the binding mode of the most active derivatives into the active site of the ABC substrate-binding protein Lmo0181 from L. monocytogenes. Results showed the importance of both hydrogen bonding and hydrophobic interactions with the target protein and are in favor of the experimental data.

Synthesis, molecular docking and dynamics studies of pyridazino[4,5-b]quinoxalin-1(2H)-ones as targeting main protease of COVID-19

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a crisis in public health. Because, the 3CLpro, the main protease of SARS-CoV-2, possesses a critical role in coronavirus replication, many efforts have been devoted to developing various inhibitors to prevent the fast spread of COVID-19. In the current work, a number of various pyridazino[4,5-b]quinoxalin-1(2H)-one derivatives bearing thiadiazine and thiadiazole fragments has been prepared via a straightforward and practical strategy involving the reaction of 2-(ethoxycarbonyl)-3-formylquinoxaline 1,4-dioxide with thiocarbohydrazide under reflux conditions. To determine the bioavailability of pyridazino[4,5-b]quinoxalin-1(2H)-one derivatives, Lipinski's rule of five has been carried out. Regarding this rule, none of the synthesized compounds exhibit any deviation from Lipinski's rule of five. Furthermore, molecular docking and molecular dynamics approaches have been implemented to figure out the potential interactions of products with SARS-CoV-2 main protease. The outcomes of molecular docking studies demonstrate that the phenyl and nitrophenyl substituted pyridazino[4,5-b]quinoxalin-1(2H)-one show the lowest binding affinity among the other compounds, indicating a favorable orientation in the active site of the chymotrypsin-like cysteine protease. In addition, the MD simulation performed to evaluate the stability of the protein-ligand complex represents that the average binding energy of the nitrophenyl complex is less than that of the phenyl complex. Therefore, according to the in silico results, the inhibitory effect of the nitrophenyl complex is more significant than the phenyl complex.Communicated by Ramaswamy H. Sarma.

A Broad-Spectrum Antiviral Molecule, Protoporphyrin IX, Acts as a Moderator of HIV-1 Capsid Assembly by Targeting the Capsid Hexamer

The capsid protein (CA), an essential component of human immunodeficiency virus type 1 (HIV-1), represents an appealing target for antivirals. Small molecules targeting the CAI-binding cavity in the C-terminal domain of HIV-1 CA (CA CTD) confer potent antiviral activities. In this study, we report that a small molecule, protoporphyrin IX (PPIX), targets the HIV-1 CA by binding to this pocket. PPIX was identified via in vitro drug screening, using a homogeneous and time-resolved fluorescence-based assay. CA multimerization and a biolayer interferometry (BLI) assay showed that PPIX promoted CA multimerization and bound directly to CA. The binding model of PPIX to CA CTD revealed that PPIX forms hydrogen bonds with the L211and E212 residues in the CA CTD. Moreover, the BLI assay demonstrated that this compound preferentially binds to the CA hexamer versus the monomer. The superposition of the CAI CTD-PPIX complex and the hexameric CA structure suggests that PPIX binds to the interface formed by the NTD and the CTD between adjacent protomers in the CA hexamer via the T72 and E212 residues, serving as a glue to enhance the multimerization of CA. Taken together, our studies demonstrate that PPIX, a hexamer-targeted CA assembly enhancer, should be a new chemical probe for the discovery of modulators of the HIV-1 capsid assembly. IMPORTANCE CA and its assembled viral core play essential roles in distinct steps during HIV-1 replication, including reverse transcription, integration, nuclear entry, virus assembly, and maturation through CA-CA or CA-host factor interactions. These functions of CA are fundamental for HIV-1 pathogenesis, making it an appealing target for antiviral therapy. In the present study, we identified protoporphyrin IX (PPIX) as a candidate CA modulator that can promote CA assembly and prefers binding the CA hexamer versus the monomer. PPIX, like a glue, bound at the interfaces between CA subunits to accelerate CA multimerization. Therefore, PPIX could be used as a new lead for a CA modulator, and it holds potential research applications.

The discovery and design of novel HIV-1 capsid modulators and future perspectives

INTRODUCTION

Although combination antiretroviral therapy (cART) has achieved significant success in treating HIV, the emergence of multidrug-resistant viruses and cumulative medication toxicity make it necessary to find new classes of antiretroviral agents with novel mechanisms of action. With high sequence conservation, the HIV-1 capsid (CA) protein has attracted attention as a prospective therapeutic target due to its crucial structural and regulatory functions in the HIV-1 replication cycle.

AREA COVERED

Herein, the authors provide a cutting-edge overview of current advances in the design and discovery of CA modulators, PF74, GS-6207 and their derivativeswhich targets a therapeutically attractive NTD-CTD interprotomer pocket within the hexameric configuration of HIV-1 CA. The discovery and development of these compounds, and derivatives thereof, have provided valuable information for the design of second-generation CA-targeting antivirals.

EXPERT OPINION

Despite some successes in designing and discovering HIV-1 CA modulators, more studies are required to decipher which chemical groups confer specific desirable properties. The future of CA-modulating compounds may lie in covalent inhibition and the creation of proteolysis-targeting chimeras (PROTACs). Moreover, biological interrogation of the process of CA uncoating, virus-host interactions, and studies on the lattice-binding restriction factors may improve our knowledge of HIV-1 CA and support the design of new antiviral agents.

Discovery and Mechanistic Investigation of Piperazinone Phenylalanine Derivatives with Terminal Indole or Benzene Ring as Novel HIV-1 Capsid Modulators

HIV-1 capsid (CA) performs multiple roles in the viral life cycle and is a promising target for antiviral development. In this work, we describe the design, synthesis, assessment of antiviral activity, and mechanistic investigation of 20 piperazinone phenylalanine derivatives with a terminal indole or benzene ring. Among them, F₂-7f exhibited moderate anti-HIV-1 activity with an EC₅₀ value of 5.89 μM, which was slightly weaker than the lead compound PF74 (EC₅₀ = 0.75 μM). Interestingly, several compounds showed a preference for HIV-2 inhibitory activity, represented by 7f with an HIV-2 EC₅₀ value of 4.52 μM and nearly 5-fold increased potency over anti-HIV-1 (EC₅₀ = 21.81 μM), equivalent to PF74 (EC₅₀ = 4.16 μM). Furthermore, F₂-7f preferred to bind to the CA hexamer rather than to the monomer, similar to PF74, according to surface plasmon resonance results. Molecular dynamics simulation indicated that F₂-7f and PF74 bound at the same site. Additionally, we computationally analyzed the ADMET properties for 7f and F₂-7f. Based on this analysis, 7f and F₂-7f were predicted to have improved drug-like properties and metabolic stability over PF74, and no toxicities were predicted based on the chemotype of 7f and F₂-7f. Finally, the experimental metabolic stability results of F₂-7f in human liver microsomes and human plasma moderately correlated with our computational prediction. Our findings show that F₂-7f is a promising small molecule targeting the HIV-1 CA protein with considerable development potential.

Synthesis of Novel Ferrocene-Benzofuran Hybrids via Palladium- and Copper-Catalyzed Reactions

The combination of the ferrocene skeleton with pharmacophores often leads to molecules with interesting biological properties. Five ferrocene-benzofuran hybrids of different structures were synthesized by transition metal catalyzed reactions. The efficiency of both homogeneous and heterogeneous catalytic methods was tested. The products were characterized using 1H, 13C NMR and FTIR spectroscopy, HRMS and cyclic voltammetry. The structure of one of the new compounds was also proved with X-ray crystallography. The new hybrids showed moderate cytotoxicity on MCF-7 and MDA-MB-231 cell lines. It is remarkable that the less curable MDA-MB-231 cell line was more sensitive to treatment with three ferrocene derivatives.

Silver-Catalyzed Cascade Cyclization of Amino-NH-1,2,3-Triazoles with 2-Alkynylbenzaldehydes: An Access to Pentacyclic Fused Triazoles

An operationally simple Ag(I)-catalyzed approach for the synthesis of isoquinoline and quinazoline fused 1,2,3-triazoles was developed by a condensation and amination cyclization cascade of amino-NH-1,2,3-triazoles with 2-alkynylbenzaldehydes involving three new C-N bond formations in one manipulation, in which the group of -NH of the triazole ring serves as a nucleophile to form the quinazoline skeleton. The efficient protocol can be applied to a variety of substrates containing a range of functional groups, delivering novel pentacyclic fused 1,2,3-triazoles in good-to-excellent yields.

The 1,2,3-triazole 'all-in-one' ring system in drug discovery: a good bioisostere, a good pharmacophore, a good linker, and a versatile synthetic tool

INTRODUCTION

The 1,2,3-triazole ring occupies an important space in medicinal chemistry due to its unique structural properties, synthetic versatility and pharmacological potential making it a critical scaffold. Since it is readily available through click chemistry for creating compound collections against various diseases, it has become an emerging area of interest for medicinal chemists.

AREAS COVERED

This review article addresses the unique properties of the1,2,3-triazole nucleus as an intriguing ring system in drug discovery while focusing on the most recent medicinal chemistry strategies exploited for the design and development of 1,2,3-triazole analogs as inhibitors of various biological targets.

EXPERT OPINION

Evidently, the 1,2,3-triazole ring with unique structural features has enormous potential in drug design against various diseases as a pharmacophore, a bioisoster or a structural platform. The most recent evidence indicates that it may be more emerging in drug molecules in near future along with an increasing understanding of its prominent roles in drug structures. The synthetic feasibility and versatility of triazole chemistry make it certainly ideal for creating compound libraries for more constructive structure-activity relationship studies. However, more comparative and target-specific studies are needed to gain a deeper understanding of the roles of the 1,2,3-triazole ring in molecular recognition.[Figure: see text].

Design, Synthesis and Structure-Activity Relationships of Phenylalanine-Containing Peptidomimetics as Novel HIV-1 Capsid Binders Based on Ugi Four-Component Reaction

As a key structural protein, HIV capsid (CA) protein plays multiple roles in the HIV life cycle, and is considered a promising target for anti-HIV treatment. Based on the structural information of CA modulator PF-74 bound to HIV-1 CA hexamer, 18 novel phenylalanine derivatives were synthesized via the Ugi four-component reaction. In vitro anti-HIV activity assays showed that most compounds exhibited low-micromolar-inhibitory potency against HIV. Among them, compound I-19 exhibited the best anti-HIV-1 activity (EC50 = 2.53 ± 0.84 μM, CC50 = 107.61 ± 27.43 μM). In addition, I-14 displayed excellent HIV-2 inhibitory activity (EC50 = 2.30 ± 0.11 μM, CC50 > 189.32 μM) with relatively low cytotoxicity, being more potent than that of the approved drug nevirapine (EC50 > 15.02 μM, CC50 > 15.2 μM). Additionally, surface plasmon resonance (SPR) binding assays demonstrated direct binding to the HIV CA protein. Moreover, molecular docking and molecular dynamics simulations provided additional information on the binding mode of I-19 to HIV-1 CA. In summary, we further explored the structure—activity relationships (SARs) and selectivity of anti-HIV-1/HIV-2 of PF-74 derivatives, which is conducive to discovering efficient anti-HIV drugs.

Rational design of 1,2,3-triazole hybrid structures as novel anticancer agents: synthesis, biological evaluation and molecular docking studies

New hybrid compounds belonging to the class of 1,4-disubstituted 1,2,3-triazoles were synthesized. The structural characterization of the synthesized compounds was performed using IR, ¹H-NMR, ¹³C NMR and elemental analysis techniques. Diarylketones 1a and 1b were used as starting compounds for the synthesis of triazoles. The corresponding diarylmethanol derivatives (2a,b) were obtained from reduction of ketone units with NaBH₄. Oxyalkynes (3a,b) were obtained by treating the hydroxyl group with NaH in anhydrous THF and then with propargylbromide. The target hybrid structures 6a-n were obtained from the metal-catalyzed "click reaction" of the arylazide and alkyne units. The newly synthesized compounds were structurally analysed using ¹H-NMR, ¹³C-NMR, elemental analysis, LC-MS and FT-IR. The antioxidant and anticancer activities of all compounds were investigated. It has been determined that the new hybrid structures have very good antioxidant and anticancer activities according to the standards. In particular, compounds 6b, 6h, 6i and 6j (IC₅₀: 1.87, 12.5, 7.22, 8.04 µM) showed excellent activity compared to standard 5-Fu (IC₅₀: 40.89 µM). According to the results of molecular docking of compounds 6b and 6i with the highest cancer activity, MetAP-2 was found to have a high affinity through exposed polar and apolar contacts with fundemental residues in the binding pocket.Communicated by Ramaswamy H. Sarma.

Identification of 1,2,3-triazole-phthalimide derivatives as potential drugs against COVID-19: a virtual screening, docking and molecular dynamic study

In this work we aimed to perform an in silico predictive screening, docking and molecular dynamic study to identify 1,2,3-triazole-phthalimide derivatives as drug candidates against SARS-CoV-2. The in silico prediction of pharmacokinetic and toxicological properties of hundred one 1,2,3-triazole-phtalimide derivatives, obtained from SciFinder® library, were investigated. Compounds that did not show good gastrointestinal absorption, violated the Lipinski's rules, proved to be positive for the AMES test, and showed to be hepatotoxic or immunotoxic in our ADMET analysis, were filtered out of our study. The hit compounds were further subjected to molecular docking on SARS-CoV-2 target proteins. The ADMET analysis revealed that 43 derivatives violated the Lipinski's rules and 51 other compounds showed to be positive for the toxicity test. Seven 1,2,3-triazole-phthalimide derivatives (A7, A8, B05, E35, E38, E39, and E40) were selected for molecular docking and MFCC-ab initio analysis. The results of molecular docking pointed the derivative E40 as a promising compound interacting with multiple target proteins of SARS-CoV-2. The complex E40-Mpro was found to have minimum binding energy of -10.26 kcal/mol and a general energy balance, calculated by the quantum mechanical analysis, of -8.63 eV. MD simulation and MMGBSA calculations confirmed that the derivatives E38 and E40 have high binding energies of -63.47 ± 3 and -63.31 ± 7 kcal/mol against SARS-CoV-2 main protease. In addition, the derivative E40 exhibited excellent interaction values and inhibitory potential against SAR-Cov-2 main protease and viral nucleocapsid proteins, suggesting this derivative as a potent antiviral for the treatment and/or prophylaxis of COVID-19.Communicated by Ramaswamy H. Sarma.

GANAB and N-Glycans Substrates Are Relevant in Human Physiology, Polycystic Pathology and Multiple Sclerosis: A Review

Glycans are one of the four fundamental macromolecular components of living matter, and they are highly regulated in the cell. Their functions are metabolic, structural and modulatory. In particular, ER resident N-glycans participate with the Glc3Man9GlcNAc2 highly conserved sequence, in protein folding process, where the physiological balance between glycosylation/deglycosylation on the innermost glucose residue takes place, according GANAB/UGGT concentration ratio. However, under abnormal conditions, the cell adapts to the glucose availability by adopting an aerobic or anaerobic regimen of glycolysis, or to external stimuli through internal or external recognition patterns, so it responds to pathogenic noxa with unfolded protein response (UPR). UPR can affect Multiple Sclerosis (MS) and several neurological and metabolic diseases via the BiP stress sensor, resulting in ATF6, PERK and IRE1 activation. Furthermore, the abnormal GANAB expression has been observed in MS, systemic lupus erythematous, male germinal epithelium and predisposed highly replicating cells of the kidney tubules and bile ducts. The latter is the case of Polycystic Liver Disease (PCLD) and Polycystic Kidney Disease (PCKD), where genetically induced GANAB loss affects polycystin-1 (PC1) and polycystin-2 (PC2), resulting in altered protein quality control and cyst formation phenomenon. Our topics resume the role of glycans in cell physiology, highlighting the N-glycans one, as a substrate of GANAB, which is an emerging key molecule in MS and other human pathologies.

Uracil derivatives as HIV-1 capsid protein inhibitors: design, in silico, in vitro and cytotoxicity studies

A series of novel uracil derivatives such as bispyrimidine dione and tetrapyrimidine dione derivatives were designed based on the existing four-point pharmacophore model as effective HIV capsid protein inhibitors. The compounds were initially docked with an HIV capsid protein monomer to rationalize the ideas of design and to find the potential binding modes. The successful design and computational studies led to the synthesis of bispyrimidine dione and tetrapyrimidine dione derivatives from uracil and aromatic aldehydes in the presence of HCl using novel methodology. The in vitro evaluation in HIV p24 assay revealed five potential uracil derivatives with IC₅₀ values ranging from 191.5 μg ml⁻¹ to 62.5 μg ml⁻¹. The meta-chloro substituted uracil compound 9a showed promising activity with an IC₅₀ value of 62.5 μg ml⁻¹ which is well correlated with the computational studies. As expected, all the active compounds were noncytotoxic in BA/F3 and Mo7e cell lines highlighting the thoughtful design. The structure activity relationship indicates the position priority and lower log P values as the possible cause of inhibitory potential of the uracil compounds.

The paper describes the design, synthesis, computational and biological validation of a series of novel uracil derivatives as effective HIV capsid protein inhibitors.

Rotten to the core: antivirals targeting the HIV-1 capsid core

The capsid core of HIV-1 is a large macromolecular assembly that surrounds the viral genome and is an essential component of the infectious virus. In addition to its multiple roles throughout the viral life cycle, the capsid interacts with multiple host factors. Owing to its indispensable nature, the HIV-1 capsid has been the target of numerous antiretrovirals, though most capsid-targeting molecules have not had clinical success until recently. Lenacapavir, a long-acting drug that targets the HIV-1 capsid, is currently undergoing phase 2/3 clinical trials, making it the most successful capsid inhibitor to-date. In this review, we detail the role of the HIV-1 capsid protein in the virus life cycle, categorize antiviral compounds based on their targeting of five sites within the HIV-1 capsid, and discuss their molecular interactions and mechanisms of action. The diverse range of inhibition mechanisms provides insight into possible new strategies for designing novel HIV-1 drugs and furthers our understanding of HIV-1 biology.

Potency and metabolic stability: a molecular hybrid case in the design of novel PF74-like small molecules targeting HIV-1 capsid protein

PF74 (1) is a potent and well-characterized prototypical small molecule targeting human immunodeficiency virus type 1 (HIV-1) capsid protein (CA), but not a viable antiviral lead due to the lack of metabolic stability. We report herein our molecular hybridization-based medicinal chemistry efforts toward potent and metabolically stable PF74-like small molecules. The design of the new sub-chemotype 4 rationally combines binding features of two recently reported PF74-like compounds 2 and 3. The subsequent confirmation and structure-activity relationship (SAR) of hit 4a entailed the chemical synthesis of 37 novel analogs, most of which showed modest but meaningful thermal shift, and low μM antiviral activity. The most potent analogs (4a, 4d, 4o, and 4r) all exhibited noticeably improved metabolic stability over PF74. Molecular modeling suggests that these new analogs bind to the PF74 binding site. Overall, our work demonstrated that the molecular hybridization approach is suitable for designing compounds with balanced potency and metabolic stability.

Biological Evaluation of 4-(1H-triazol-1-yl)benzoic Acid Hybrids as Antioxidant Agents: In Vitro Screening and DFT Study

Fourteen triazole benzoic acid hybrids were previously characterized. This work aimed to screen their in vitro antioxidant activity using different assays, i.e., DPPH (1,1-diphenyl-1-picrylhydrazyl), reducing the power capability, FRAP (ferric reducing antioxidants power) and ABTS (2,2′-azino-bis(3-ethylben zothiazoline-6-sulfonate) radical scavenging. The 14 compounds showed antioxidant properties in relation to standard BHA (butylated hydroxylanisole) and Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid). Higher antioxidant activity was observed by the parent (1) at a concentration of 100 µg/mL (89.95 ± 0.34 and 88.59 ± 0.13%) when tested by DPPH and ABTS methods in relation to BHA at 100 µg/mL (95.02 ± 0.74 and 96.18 ± 0.33%). The parent (2) demonstrated remarkable scavenging activity when tested by ABTS (62.00 ± 0.24%), however, 3 was less active (29.98 ± 0.13%). Compounds 5, 6, 9, and 11 exhibited good scavenging activity compared to 1. DFT studies were performed using the B3LYP/6-311++g (2d,2p) level of theory to evaluate different antioxidant descriptors for the targets. Three antioxidant mechanisms, i.e., hydrogen atom transfer (HAT), sequential electron transfer proton transfer (SETPT) and sequential proton loss electron transfer (SPLET) were suggested to describe the antioxidant properties of 1–14. Out of the 14 triazole benzoic acid hybrids, 5, 9, 6, and 11 showed some good theoretical results, which were in agreement with some experimental outcomes. Based on the computed (PA and ETE) and (BDE and IP) values in (SPLET) and (HAT and SETPT) mechanisms, respectively, compound 9 emerged has having good antioxidant activity.

Electron Distribution in 1,2,3-Benzotriazole and 1,2,3-Triazole Anion Radical Isomers: An EPR and DFT Study

The anion radicals of N1- and N2-alkylbenzotriazoles and alkyltriazoles (alkyl = methyl or isopropyl) have been generated by low-temperature potassium metal reduction in tetrahydrofuran. Electron paramagnetic resonance (EPR) analysis and density functional theory calculations reveal that the electron spin distribution within the triazole ring of these systems is markedly different. The magnitude of the electron-nitrogen couplings along with the calculated spin densities reveals that the N2-alkylbenzotriazole and N2-alkyltriazole anion radicals have significantly greater electron spin residing within the N₃ portion of the triazole ring compared with that of the respective N1 isomers. These differences impact the overall geometry of the triazole ring where both N2-isomers lose planarity upon reduction. Experimental and computational results reveal that the N2-methyltriazole anion radical has the largest concentration of electron spin residing in the N₃ moiety compared to that of the other three anion radicals studied. Significant anisotropic line broadening is observed in the EPR spectrum of the N2-methyltriazole anion radical, which is a consequence of the large nitrogen hyperfine couplings and sufficiently slow rotational motion of this species in solution.

Synthesis and biological evaluation of 1,6-bis-triazole-2,3,4-tri-O-benzyl-α-d-glucopyranosides as a novel α-glucosidase inhibitor in the treatment of Type 2 diabetes

A novel series of 1,6-bis-triazole-benzyl-α-glucoside derivatives (7a-7ee) were designed, synthesized and evaluated for inhibitory activity against α-glucosidase. Most of the synthesized compounds exhibited good activity with IC₅₀ ranging from 3.73 µM to 53.34 µM and are more potent than the standard drug acarbose (IC₅₀ = 146.25 ± 0.40 µM). SARs study showed the ester and menthol moiety play an important role in the inhibitory activity. The molecular docking model of the potent compounds 7f, 7z, 7cc and 7dd showed good binding energy and interacts well with amino acid residues around the active site of the enzyme, which confirmed the in vitro activity results.