Copper-catalyzed Azide-alkyne Cycloaddition Reaction Research Articles

Synthesis, Docking, and Machine Learning Studies of Some Novel Quinolinesulfonamides-Triazole Hybrids with Anticancer Activity.

In the presented work, a series of 22 hybrids of 8-quinolinesulfonamide and 1,4-disubstituted triazole with antiproliferative activity were designed and synthesised. The title compounds were designed using molecular modelling techniques. For this purpose, machine-learning, molecular docking, and molecular dynamics methods were used. Calculations of the pharmacokinetic parameters (connected with absorption, distribution, metabolism, excretion, and toxicity) of the hybrids were also performed. The new compounds were synthesised via a copper-catalysed azide-alkyne cycloaddition reaction (CuAAC). 8-N-Methyl-N-{[1-(7-chloroquinolin-4-yl)-1H-1,2,3-triazol-4-yl]methyl}quinolinesulfonamide was identified in in silico studies as a potential strong inhibitor of Rho-associated protein kinase and as a compound that has an appropriate pharmacokinetic profile. The results obtained from in vitro experiments confirm the cytotoxicity of derivative 9b in four selected cancer cell lines and the lack of cytotoxicity of this derivative towards normal cells. The results obtained from silico and in vitro experiments indicate that the introduction of another quinolinyl fragment into the inhibitor molecule may have a significant impact on increasing the level of cytotoxicity toward cancer cells and indicate a further direction for future research in order to find new substances suitable for clinical applications in cancer treatment.

Synthesis of 1, 2, 3-triazole linked 5 fluorouracil - carbon dots -folate conjugates for target specific anticancer activity and cell imaging applications

This work provides a unique strategy to anchor the individual properties of fluorophores, pharmacophores and receptors in a single platform using a copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC). Notably, this approach counters the long-term dispute associated with the target-specific drug delivery of 5 fluorouracil and its intracellular tracing. Significantly, the luminescence property of the carbon dots (CDs) and the anticancer activity of the 5 fluorouracil drug are well preserved, even after their structural modification. The resulting nano-hybrid conjugate shows good thermal stability, photo-stability and can selectively guide the drug molecule toward cancer cells and remain nontoxic to noncancerous (hFB) cells. The conjugation of folic acid to the nanohybrid surface promoted the folate receptor-facilitated endocytosis to the folate-positive (HeLa) cell lines over the folate-negative (MCF-7) cells, which enhanced cellular uptake and corresponding better cell apoptosis results. Around 18.2% of cell apoptosis (late + early) values were recorded for the folate-conjugated formulation compared to the folate-less formulation (12.3%) and pure 5 FU drug (7.9%) by a flow cytometry study. Cell cycle analysis confirmed that the populations of HeLa cells in the S phase were around 18.20% and 29.8% for the folate-less formulation and the folate-conjugated formulation, indicating all the formulations can hinder the DNA replication and thymidylate synthesis by introducing cell cycle arrest in the S phase, just like the pure 5 FU drug. Also, the location of the drug molecule can be simultaneously traced because of the luminescent nature of the CDs. Therefore, the developed system has potential in target-specific drug delivery and long-term drug molecule tracking applications.

Conjugated molecularly imprinted polymers based on covalent organic frameworks: Fluorescent sensing platform for specific capture of urea and elimination of ethyl carbamate

This study described the preparation of an azide covalent organic framework-embedded molecularly imprinted polymers (COFs(azide)@MIPs) platform for urea adsorption and indirect ethyl carbamate (EC) removal from Chinese yellow rice wine (Huangjiu). By modifying the pore surface of COFs using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, COFs(azide) with a high fluorescence quantum yield and particular recognition ability were inventively produced. In order to selectively trap urea, the COFs(azide) were encased in an imprinted shell layer via imprinting technology. With a detection limit (LOD) of 0.016 μg L-1 (R2 = 0.9874), the COFs(azides)@MIPs demonstrated a good linear relationship with urea in the linear range of 0–5 μg L-1. Using real Huangjiu samples, the spiking recovery trials showed the viability of this sensing platform with recoveries ranging from 88.44 % to 109.26 % and an RSD of less than 3.40 %. The Huangjiu processing model system achieved 38.93 % EC reduction by COFs(azides)@MIPs. This research will open up new avenues for the treatment of health problems associated with fermented alcoholic beverages, particularly Huangjiu, while also capturing and removing hazards coming from food.

Synthesis of block macro-CTAs by HNTs@Cu-catalyzed click reaction: Suitable CTAs for synthesizing multiblock polymers via RAFT polymerization

Multiblock copolymer macrochain-transfer agents (MBP-CTAs) can be used to synthesize MBPs in one pot via reversible addition-fragmentation chain-transfer (RAFT) polymerization. MBP-CTAs can be efficiently synthesized via a copper-catalyzed azide-alkyne cycloaddition reaction. However, traditional purification methods cannot sufficiently purify MBP-CTAs, resulting in the failure of RAFT. In this study, it was discovered that using a supported catalytic system, namely, Cu@A-HNTs, inhibited the connection between Cu and S. The residual Cu content in the MBP-CTA was successfully reduced to a low level (7.88 µg/mg). Then, hydrophilic and hydrophobic MBPs were synthesized through RAFT polymerization using the MBP-CTAs. Subsequently, multiblock copoly(methyl methacrylate-b-butyl methacrylate-CTA)s (PMMA-b-PBMA-c-CTA)s were successfully prepared. The MBP-CTAs and MBPs were characterized using ultraviolet–visible spectroscopy, 1H nuclear magnetic resonance, size-exclusion chromatography, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, differential scanning calorimetry measurements and uniaxial tensile tests. The results of performance testing of PMMA-b-PBMA-c-CTAs demonstrated that their fracture stress and strain significantly increased comparing with that of PMMA-b-CTAs.

MOFs Modulate Copper Trafficking in Tumor Cells for Bioorthogonal Therapy.

In situ drug synthesis using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has attracted considerable attention in tumor therapy because of its satisfactory effectiveness and reduced side-effects. However, the exogenous addition of copper catalysts can cause cytotoxicity and has hampered biomedical applications in vivo. Here, we design and synthesize a metal-organic framework (MOF) to mimic copper chaperone, which can selectively modulate copper trafficking for bioorthogonal synthesis with no need of exogenous addition of copper catalysts. Like copper chaperones, the prepared ZIF-8 copper chaperone mimics specifically bind copper ions through the formation of coordination bonds. Moreover, the copper is unloaded under the acidic environment due to the dissipation of the coordination interactions between metal ions and ligands. In this way, the cancer cell-targeted copper chaperone mimics can selectively transport copper ions into cells. Regulation of intracellular copper trafficking may inspire constructing bioorthogonal catalysis system with reduced metal cytotoxicity in live cells.

Cyclic Peptide Conjugate Vaccines and Physically Mixed Cyclic Peptide Vaccines for Subcutaneous Immunization.

Immune stimulants (adjuvants) enhance immune system recognition to provide an effective and individualized immune response when delivered with an antigen. Synthetic cyclic deca-peptides, co-administered with a toll-like receptor targeting lipopeptide, have shown self-adjuvant properties, dramatically boosting the immune response in a murine model as a subunit peptide-based vaccine containing group A Streptococcus peptide antigens.Here, we designed a novel peptide and lipid adjuvant system for the delivery of group A Streptococcus peptide antigen and a T helper peptide epitope. Following linear peptide synthesis on 2-chlorotrityl chloride resin, the linear peptide was cleaved and head-to-tail cyclized in solution. The selective arrangement of amino acids in the deca-peptide allowed for selective conjugation of lipids and/or peptide antigens following cyclisation. Using both solution-phase peptide chemistry and copper-catalyzed azide-alkyne cycloaddition reaction were covalently (and selectively) ligated lipid and/or peptide antigens onto the cyclic deca-peptide core. Subcutaneous administration of the vaccine design to mice resulted in the generation of a large number of serum immunoglobulin (Ig) G antibodies.

Novel isatin-triazole based thiosemicarbazones as potential anticancer agents: synthesis, DFT and molecular docking studies.

Thiosemicarbazones of isatin have been found to exhibit versatile bioactivities. In this study, two distinct types of isatin-triazole hybrids 3a and 3b were accessed via copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC), together with their mono and bis-thiosemicarbazone derivatives 4a-h and 5a-h. In addition to the characterization by physical, spectral and analytical data, a DFT study was carried out to obtain the optimized geometries of all thiosemicarbazones. The global reactivity values showed that among the synthesized derivatives, 4c, 4g and 5c having nitro substituents are the most soft compounds, with compound 5c having the highest electronegativity and electrophilicity index values among the synthesized series, thus possessing strong binding ability with biomolecules. Molecular docking studies were performed to explore the inhibitory ability of the selected compounds against the active sites of the anticancer protein of phosphoinositide 3-kinase (PI3K). Among the synthesized derivatives, 4-nitro substituted bisthiosemicarbazone 5c showed the highest binding energy of -10.3 kcal mol-1. These findings demonstrated that compound 5c could be used as a favored anticancer scaffold via the mechanism of inhibition against the PI3K signaling pathways.

Coumarin-azasugar-benzyl conjugates as non-neurotoxic dual inhibitors of butyrylcholinesterase and cancer cell growth.

We have applied the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to prepare a library of ten coumarin-azasugar-benzyl conjugates and two phthalimide-azasugar-benzyl conjugates with potential anti-Alzheimer and anti-cancer properties. The compounds were evaluated as cholinesterase inhibitors, demonstrating a general preference, of up to 676-fold, for the inhibition of butyrylcholinesterase (BuChE) over acetylcholinesterase (AChE). Nine of the compounds behaved as stronger BuChE inhibitors than galantamine, one of the few drugs in clinical use against Alzheimer's disease. The most potent BuChE inhibitor (IC50 = 74 nM) was found to exhibit dual activities, as it also showed high activity (GI50 = 5.6 ± 1.1 μM) for inhibiting the growth of WiDr (colon cancer cells). In vitro studies on this dual-activity compound on Cerebellar Granule Neurons (CGNs) demonstrated that it displays no neurotoxicity.

Real-time Visualization of Transcribed mRNA via Click Chemistry in a Liposomal Space.

We present a CuAAC (Copper-Catalyzed Azide-Alkyne Cycloaddition) reaction protocol designed for the visualization of mRNA. To achieve this, we synthesized stable mRNA molecules incorporating the modified nucleoside analog, EU, a crucial element for fluorophore attachment. Leveraging this modified mRNA, we successfully executed the CuAAC reaction, wherein the pro-fluorophore, coumarin, was conjugated to EU on the mRNA through our meticulously designed CuAAC process. This innovative approach resulted in the emission of fluorescence, enabling both precise quantification and visual observation of mRNA. Furthermore, we demonstrated the feasibility of concurrent mRNA synthesis and visualization by seamlessly integrating the CuAAC reaction mix into the mRNA transcription process. Additionally, our novel methodology opens avenues for prospective real-time monitoring of mRNA transcription within artificial cells. These advancements hold significant promise for expanding our comprehension of fundamental cellular processes and finding applications across diverse biological contexts in the future.

Highly efficient functionalization of hydroxypropyl cellulose with glucuronic acid through click chemistry under microwave irradiation as potential biomaterial with therapeutic properties

A straightforward and effective method to chemically conjugate hydroxypropyl cellulose (HPC) to GlcA is described via microwave assisted copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) between the azide functionalized HPC and the alkynyl functionalized GlcA, reducing reaction times from 24 h to 2 h. Two types of HPC azide derivatives, including an ester (ES) or a carbamate (CB) functional group, were synthesized and characterized by FT-IR and NMR spectroscopy that revealed the efficiency in the incorporation of the azide moieties in the cellulose backbone. These compounds were then conjugated with the alkynyl GlcA by CuAAC, affording the desired glycopolymers, HPA-ES-GlcA and HPA-CB-GlcA in excellent yields. The whole process involved rapid and effective reactions as well as easy purification techniques, using mostly non-toxic solvents, contributing to the sustainability of the synthesis These glycopolymers were characterized by FT-IR, NMR, TGA, DTA and SEM. Furthermore, the cytotoxicity, anti-inflammatory and antibacterial properties of the new glycopolymers were tested and it was found that these new HPC-GlcA conjugates presented low cytotoxicity, good anti-inflammatory and antibacterial properties. Overall, our results showed that HPC-GlcA polymers are suitable as potential GAG mimics for biomedical applications, therefore further investigations will be carried out.

Copper phosphorylated cellulose nanofibers mediated azide-alkyne cycloaddition click reaction in water

Heterogenous copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) was performed by using the phosphorylated carbohydrate-based cellulose nanofibers loaded with copper(II) ions. The copper-containing phosphorylated cellulose nanofibers (here after noted Cu(II)-PCNFs) were prepared in two different morphologies, namely the paper and foam ones and characterized by different techniques, including Scanning Electronic Microscopy (SEM), Energy Dispersive X-ray (EDX), Brauner-Emmett-Teller (BET), FT-IR spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), X-ray Photoelectron spectroscopy (XPS) and Atomic Force Microscopy (AFM). Cu(II)-PCNFs showed high activity in the CuAAC reaction when applied to the ligation of various organic azides and terminal alkynes without any reducing agent, resulting in the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles in water at room temperature. These nanofibers were recovered and reused with no significant loss of catalytic activity or selectivity. A carbohydrate-based bio-support cellulose as reliable heterogenous catalyst was efficiently developed in view of taking the click chemistry concept to sustainable chemistry.

Expanding the synthesis of a library of potent glucuronic acid glycodendrons for Dengue virus inhibition

Multivalent glycodendrons are valuable tools to mimic many structural and functional features of cell-surface glycoconjugates and its focal position scaffolds represent important components to increase specificity and affinity. Previous work in our group described the preparation of a tetravalent glucuronic acid dendron that binds with good affinity to Dengue virus envelope protein (KD = 22 μM). Herein, the chemical synthesis and binding analysis of a new library of potent glucuronic acid dendrons bearing different functional group at the focal position and different level of multivalency are described. Their chemical synthesis was performed sequentially in three stages and with good yields. Namely a) the chemical synthesis of the oligo and polyalkynyl scaffolds, b) assembling with fully protected glucuronic acid-based azide units by using a microwave assisted copper-catalysed azide-alkyne cycloaddition reaction and c) sequential deprotection of hydroxyl and carboxylic acid groups.Surface Plasmon Resonance studies have demonstrated that the valency and the focal position functional group exert influence on the interaction with Dengue virus envelope protein. Molecular modelling studies were carried out in order to understand the binding observed. This work reports an efficient glycodendrons chemical synthesis that provides appropriate focal position functional group and multivalence, that offer an easy and versatile strategy to find new active compounds against Dengue virus.

Synthesis of a Series of Trimeric Branched Glycoconjugates and Their Applications for Supramolecular Gels and Catalysis.

Carbohydrate-derived molecular gelators have found many practical applications as soft materials. To better understand the structure and molecular gelation relationship and further explore the applications of sugar-based gelators, we designed and synthesized eight trimeric branched sugar triazole derivatives and studied their self-assembling properties. These included glucose, glucosamine, galactose, and maltose derivatives. Interestingly, the gelation properties of these compounds exhibited correlations with the peripheral sugar structures. The maltose derivative did not form gels in the tested solvents, but all other compounds exhibited gelation properties in at least one of the solvents. Glucose derivatives showed superior performance, followed by glucosamine derivatives. They typically formed gels in toluene and alcohols; some formed gels in ethanol-water mixtures or DMSO water mixtures. The glycoclusters 9 and 10 demonstrated rate acceleration for the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. These were further studied for their metallogels formation properties, and the copper metallogels from compound 9 were successfully utilized to catalyze click reactions. These metallogels were able to form a gel column, which was effective in converting the reactants into the triazole products in multiple cycles. Moreover, the same gel column was used to transform a second click reaction using different reactants. The synthesis and characterization of these compounds and their applications for catalytic reactions were discussed.

Enolate-Azide [3 + 2]-Cycloaddition Reaction Suitable for DNA-Encoded Library Synthesis.

The DNA-encoded chemical library (DEL) is a powerful hit selection technique in either basic science or innovative drug discovery. With the aim to circumvent the issue concerning DNA barcode damage in a conventional on-DNA copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC), we have successfully developed the first DNA-compatible enolate-azide [3 + 2] cycloaddition reaction. The merits of this DEL chemistry include metal-free reaction and high DNA fidelity, high conversions and easy operation, broad substrate scope, and ready access to the highly substituted 1,4,5-trisubstituted triazoles. Thus, it will not only further enrich the DEL chemistry toolbox but also will have great potential in practical DEL synthesis.

A Polyoxometalate-Based Pathologically Activated Assay for Efficient Bioorthogonal Catalytic Selective Therapy.

Since polyoxometalates (POMs) can undergo reversible multi-electron redox transformations, they have been used to modulate the electronic environment of metal nanoparticles for catalysis. Besides, POMs possess unique electronic structures and acid-responsive self-assembly ability. These properties inspire us to tackle the drawbacks of the well-known copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction when applied in biomedical applications, such as low catalytic efficiency and unsatisfactory disease selectivity in living systems. Herein, we construct the molybdenum (Mo)-based POM nanoclusters doped with Cu (Cu-POM NCs) as a highly efficient bioorthogonal catalyst, which is responsive to pathologically acid and H2S for selective antibiofilm therapy. Leveraging the merits of POM, the Cu-POM NCs exhibit biofilm-responsive self-assemble behavior, efficient CuAAC reactions-mediated in situ synthesis of antibacterial molecules, and NIR-II photothermal effect selectively triggered by H2S in pathogens. It should be noted that the consumption of bacterial H2S at the pathological site by Cu-POM NCs extremely decreases the number of persister bacteria, which is conducive to the inhibition of bacterial tolerance and elimination of biofilms. Unlocked at pathological sites and endowed with NIR-II photothermal property, the constructed POM-based bioorthogonal catalytic platform provides new insights into the design of efficient and selective bioorthogonal catalysts for disease therapy.

Synthesis and biological evaluation of carbohydrate-Coumarin/vanillic acid hybrid as a promising antiparasitic agent

Leishmaniasis is caused by infection with the protozoan parasites Leishmania. It is classified as one of the most significant neglected tropical diseases. It remains a significant global public health concern. Current treatments include the use of pentavalent antimonial, amphotericin B, pentamidine, miltefosine, and paromomycin. However, several limitations such as toxicity, side effect, and resistance to these drugs of certain species are of concern. To combat this disease, effective chemotherapy is urgently required for its treatment and management. In this study, we synthesized a series of carbohydrate-coumarin/vanillic acid hybrids linked through triazole moiety via CuACC (Copper-catalysed azide-alkyne cycloaddition) reaction. These compounds were evaluated for their in vitro antiparasitic activity using MTT assay against Leishmania donovani whereas, all compounds show IC50 value in the range of 65–74 μM.

Two-Step Validation Approach for Tools To Study the DNA Repair Enzyme SNM1A.

We report a two-step validation approach to evaluate the suitability of metal-binding groups for targeting DNA damage-repair metalloenzymes using model enzyme SNM1A. A fragment-based screening approach was first used to identify metal-binding fragments suitable for targeting the enzyme. Effective fragments were then incorporated into oligonucleotides using the copper-catalysed azide-alkyne cycloaddition reaction. These modified oligonucleotides were recognised by SNM1A at >1000-fold lower concentrations than their fragment counterparts. The exonuclease SNM1A is a key enzyme involved in the repair of interstrand crosslinks, a highly cytotoxic form of DNA damage. However, SNM1A and other enzymes of this class are poorly understood, as there is a lack of tools available to facilitate their study. Our novel approach of incorporating functional fragments into oligonucleotides is broadly applicable to generating modified oligonucleotide structures with high affinity for DNA damage-repair enzymes.

Cellulose Acetate-Supported Copper as an Efficient Sustainable Heterogenous Catalyst for Azide-Alkyne Cycloaddition Click Reactions in Water.

A new sustainable heterogeneous catalyst for copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) was investigated. The preparation of the sustainable catalyst was carried out through the complexation reaction between the polysaccharide cellulose acetate backbone (CA) and copper(II) ions. The resulting complex [Cu(II)-CA] was fully characterized by using different spectroscopic methods such as Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Ultraviolet-visible (UV-vis), and Inductively Coupled Plasma (ICP) analyses. The Cu(II)-CA complex exhibits high activity in the CuAAC reaction for substituted alkynes and organic azides, leading to a selective synthesis of the corresponding 1,4-isomer 1,2,3-triazoles in water as a solvent and working at room temperature. It is worth noting that this catalyst has several advantages from the sustainable chemistry point of view including no use of additives, biopolymer support, reactions carried out in water at room temperature, and easy recovery of the catalyst. These characteristics make it a potential candidate not only for the CuAAC reaction but also for other catalytic organic reactions.

Immunostimulation with chemotherapy of a ruthenium-arene complex via blockading CD47 signal in chronic myelogenous leukemia cells

Combination of novel immunomodulation and traditional chemotherapy has become a new tendency in cancer treatment. Increasing evidence suggests that blocking the “don't eat me” signal transmitted by the CD47 can promote the phagocytic ability of macrophages to cancer cells, which might be promising for improved cancer chemoimmunotherapy. In this work, we conjugated CPI-alkyne modified by Devimistat (CPI-613) with ruthenium-arene azide precursor Ru-N3 by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to construct Ru complex CPI-Ru. CPI-Ru exhibited satisfactory cytotoxicity towards the K562 cells while nearly non-toxic towards the normal HLF cells. CPI-Ru has been demonstrated to cause severe damage to mitochondria and DNA, ultimately inducing cancer cell death through the autophagic pathway. Moreover, CPI-Ru could significantly downregulate the expression of CD47 on the surface of K562 accompanied by the enhanced immune response by targeting the blockade of CD47. This work provides a new strategy for utilizing metal-based anticancer agents to block CD47 signal to achieve chemoimmunotherapy in chronic myeloid leukemia treatment.

Design, Synthesis and Biological Evaluation of Quinoline-8-Sulfonamides as Inhibitors of the Tumor Cell-Specific M2 Isoform of Pyruvate Kinase: Preliminary Study.

Cancer cells need to carefully regulate their metabolism to keep them growing and dividing under the influence of different nutrients and oxygen levels. Muscle isoform 2 of pyruvate kinase (PKM2) is a key glycolytic enzyme involved in the generation of ATP and is critical for cancer metabolism. PKM2 is expressed in many human tumors and is regulated by complex mechanisms that promote tumor growth and proliferation. Therefore, it is considered an attractive therapeutic target for modulating tumor metabolism. Various modulators regulate PKM2, shifting it between highly active and less active states. In the presented work, a series of 8-quinolinesulfonamide derivatives of PKM2 modulators were designed using molecular docking and molecular dynamics techniques. New compounds were synthesized using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Compound 9a was identified in in silico studies as a potent modulator of muscle isoform 2 of pyruvate kinase. The results obtained from in vitro experiments confirmed the ability of compound 9a to reduce the intracellular pyruvate level in A549 lung cancer cells with simultaneous impact on cancer cell viability and cell-cycle phase distribution. Moreover, compound 9a exhibited more cytotoxicity on cancer cells than normal cells, pointing to high selectivity in the mode of action. These findings indicate that the introduction of another quinolinyl fragment to the modulator molecule may have a significant impact on pyruvate levels in cancer cells and provides further directions for future research to find novel analogs suitable for clinical applications in cancer treatment.