Synthesis and antitumor activities investigation of a C-nucleoside analogue of ribavirin

Developments in the chemistry and biology of 1,2,3-triazolyl-C-nucleosides

In the last 50 years, nucleoside analogs have been introduced to drug therapy as antivirals for different types of cancer due to their interference in cellular proliferation. Among the first line of nucleoside treatment drugs, ribavirin (RBV) is a synthetic N-nucleoside with a 1,2,4-triazole moiety that acts as a broad-spectrum antiviral. It is on the World Health Organization (WHO) list of essential medicines. However, this important drug therapy causes several side effects due to its nonspecific mechanism of action. There is thus a need for a continuous study of its scaffold. A particular approach consists of connecting  d-ribose to the nitrogen-containing base with a C-C bond. It provides more stability against enzymatic action and a better pharmacologic profile. The coronavirus disease (COVID) pandemic has increased the need for more solutions for the treatment of viral infections. Among these solutions, remdesivir, the first C-nucleoside, has been approved by the Food and Drug Administration (FDA) for clinical use against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It drew attention to the study of the C-nucleoside scaffold. Different C-nucleoside patterns have been synthesized over the years. They show many important activities against viruses and cancer cell lines. 1,2,3-Triazolyl-C-nucleoside derivatives are a prolific and efficient subclass of RBV analogs close to the already-known RBV with a C-C bond modification. These compounds are often prepared by alkynylation of the  d-ribose ring followed by azide-alkyne cycloaddition. They are reported to be active against the Crimean-Congo hemorrhagic fever virus and several tumoral cell lines, showing promising biological potential. In this review, we explore such approaches to 1,2,3-triazolyl-C-nucleosides and their evolution over the years.

Approaches to the synthesis of heterocyclic C-nucleosides

This review is focused on the synthetic strategies to heterocyclic C-nucleosides and covers the literature from 2011 to 2021. The main attention is paid to the following three approaches: the direct C-C coupling of a carbohydrate moiety with a preformed aglycon unit, the construction of a (pseudo)sugar residue on a pre-formed aglycon, and the construction of an aglycon on a pre-formed (pseudo)sugar. In each Section, the literature data are categorized in terms of the size of aglycon from simple to complex, the advantages and drawbacks of the reviewed approaches are discussed.

Integrated LC-MS and network pharmacology methods to screen quantitative indicators in the Hippocampus histrix Kaup and method transfer

Hippocampus histrix Kaup is a popular marine medicine with high medicinal and healthcare values. In this study, liquid chromatography-mass spectrometry (LC-MS) analysis combined with network pharmacological method was used to screen for suitable quantitative indicators for the quality control of H. histrix Kaup. Firstly, an LC-MS analytical method for the simultaneous determination of 12 nucleosides in extracts of H. histrix Kaup was established. And then, a network pharmacological method incorporated target prediction, protein-protein interaction network, components-targets network, and targets-pathways network was performed to screen for quantitative indicators. Finally, the developed LC-MS method was transferred to liquid chromatographs to improve the generalizability of the method. All 12 nucleotides were authenticated in extracts of H. histrix Kaup by comparing with the standards. The optimal chromatographic separation conditions are as follows: the chromatographic separation was achieved on an Acquire BEH-C18 column (2.1 mm * 100 mm, 1.7 µm) and gradient elution was performed using methanol solution and buffer (0.30% formic acid and 10 mmol/L ammonium acetate) as mobile phase at a flow rate of 0.15 mL/min and an acquisition wavelength of 260 nm. Network pharmacology results showed that adenosine, and uridine show excellent pharmacological activity. Integration the content, correlation, chromatographic separation, and pharmacological activity of each compound in H. histrix Kaup, uridine and adenosine were tentatively determined as quantitative indicators for quality control in H. histrix Kaup. The established LC-MS method was successfully transferred to liquid chromatographs, and the method is stable and reliable for the quality control of H. histrix Kaup. This developed integrated strategy was successfully used to screen quantitative indicators in the H. histrix Kaup.

Regioselective Synthesis and Molecular Docking Studies of 1,5-Disubstituted 1,2,3-Triazole Derivatives of Pyrimidine Nucleobases

1,2,3-triazoles are versatile building blocks with growing interest in medicinal chemistry. For this reason, organic chemistry focuses on the development of new synthetic pathways to obtain 1,2,3-triazole derivatives, especially with pyridine moieties. In this work, a novel series of 1,5-disubstituted-1,2,3-triazoles functionalized with pyrimidine nucleobases were prepared via 1,3-dipolar cycloaddition reaction in a regioselective manner for the first time. The N1-propargyl nucleobases, used as an alkyne intermediate, were obtained in high yields (87-92%) with a new two-step procedure that selectively led to the monoalkylated compounds. Then, FeCl₃ was employed as an efficient Lewis acid catalyst for 1,3-dipolar cycloaddition between different aryl and benzyl azides and the N1-propargyl nucleobases previously synthesized. This new protocol allows the synthesis of a series of new 1,2,3-triazole derivatives with good to excellent yields (82-92%). The ADME (Absorption, Distribution, Metabolism, and Excretion) analysis showed good pharmacokinetic properties and no violations of Lipinsky's rules, suggesting an appropriate drug likeness for these new compounds. Molecular docking simulations, conducted on different targets, revealed that two of these new hybrids could be potential ligands for viral and bacterial protein receptors such as human norovirus capsid protein, SARS-CoV-2 NSP13 helicase, and metallo-β-lactamase.

Studies on the synthesis of 1'-CN-triazolyl-C-ribosides

The search for broad-spectrum antiviral compounds is a continuous mandatory effort. The recent approval of the first C-nucleoside carrying a nitrile as a substituent at the C1' position of the ribose ring has raised interest in this underexplored substitution pattern. We have previously reported the development of different 1,2,3-triazolyl-C-ribonucleosides with anticancer and antiviral activities. Herein we report our results on the incorporation of a C1'-CN group in 1,2,3-triazolyl-C-ribonucleosides.

Anti-HCV and Zika activities of ribavirin C-nucleosides analogues

Ribavirin is an unnatural nucleoside exhibiting broad spectrum of antiviral and antitumor activities, still very widely studied particularly in a repositioning approach. C-triazolyl nucleoside analogues of ribavirin have been synthesized, as well as prodrugs and glycosylated or peptide conjugates to allow a better activity by vectorization into the liver or by facilitating uptake into the cells. The antiviral properties of all synthesized compounds have been evaluated in vitro against two important human viral pathogens belonging to the Flaviviridae family: hepatitis C virus (HCV) and Zika virus (ZIKV). There are no therapeutic options for Zika virus, whereas those available for HCV can be still improved. Our results indicated that compound 2 carrying an N-hydroxy carboxamide function exhibits the most inhibitory activities against both viruses. This compound moderately inhibited the propagation of HCV with an IC₅₀ value of 49.1 μM and Zika virus with an IC₅₀ of 33.2 μM comparable to ribavirin in the Vero cell line. The results suggest that compound 2 and its new derivatives may be candidates for further development of new anti-HCV and anti-ZIKV antiviral drugs.

Synthesis of ribavirin 1,2,3- and 1,2,4-triazolyl analogs with changes at the amide and cytotoxicity in breast cancer cell lines

We report the synthesis and cytotoxicity in MCF-7 and MDA-MB-231 breast cancer cells of novel 1,2,3- and 1,2,4-triazolyl analogs of ribavirin. We modified ribavirin's carboxamide moiety to test the effects of lipophilic groups. 1-β-D-Ribofuranosyl-1H-1,2,3-triazoles were prepared using Click Chemistry, whereas an unprecedented application of a prior 1,2,4-triazole ring synthesis was used for 1-β-D-ribofuranosyl-1H-1,2,4-triazole analogs. Though cytotoxicity was mediocre and there was no correlation with lipophilicity, we discovered that a structurally similar concentrative nucleoside transporter 2 (CNT2) inhibitor was modestly cytotoxic (MCF-7 IC₅₀ of 42 µM). These syntheses could be used to efficiently investigate variation in the nucleobase.

Synthesis of novel C-nucleoside analogues bearing an anomeric cyano and a 1,2,3-triazole nucleobase as potential antiviral agents

A linear sequence to access a novel series of C-nucleosides bearing a quaternary carbon at the anomeric position tethered to a 4-substituted 1,2,3-triazole ring is described. Most of the compounds were obtained from a C-1 alkynyl furanoside, by a tandem or two-step CuAAC/functionalisation sequence, along with a diastereoselective cyanation of the furanoside derivatives in acidic conditions.

1,2,3-Triazole hybrids as anticancer agents: A review

Despite the advancements in the development of anticancer agents, more effective and safer anticancer drugs still need to be developed as the current agents cause unwanted side effects and many patients have become drug resistant. 1,2,3-Triazoles, due to their remarkable biological potential, have received considerable attention in drug discovery for the development of anticancer agents. The present review article presents an overview of the recent advances in 1,2,3-triazole hybrids with anticancer potential over the last 2 years, their chemical structures, structure-activity relationships, and mechanisms of action, as well as insights into the docking studies.

Cu(I)-Catalyzed Click Chemistry in Glycoscience and Their Diverse Applications

Copper(I)-catalyzed 1,3-dipolar cycloaddition between organic azides and terminal alkynes, commonly known as CuAAC or click chemistry, has been identified as one of the most successful, versatile, reliable, and modular strategies for the rapid and regioselective construction of 1,4-disubstituted 1,2,3-triazoles as diversely functionalized molecules. Carbohydrates, an integral part of living cells, have several fascinating features, including their structural diversity, biocompatibility, bioavailability, hydrophilicity, and superior ADME properties with minimal toxicity, which support increased demand to explore them as versatile scaffolds for easy access to diverse glycohybrids and well-defined glycoconjugates for complete chemical, biochemical, and pharmacological investigations. This review highlights the successful development of CuAAC or click chemistry in emerging areas of glycoscience, including the synthesis of triazole appended carbohydrate-containing molecular architectures (mainly glycohybrids, glycoconjugates, glycopolymers, glycopeptides, glycoproteins, glycolipids, glycoclusters, and glycodendrimers through regioselective triazole forming modular and bio-orthogonal coupling protocols). It discusses the widespread applications of these glycoproducts as enzyme inhibitors in drug discovery and development, sensing, gelation, chelation, glycosylation, and catalysis. This review also covers the impact of click chemistry and provides future perspectives on its role in various emerging disciplines of science and technology.

Modified Nucleosides, Nucleotides and Nucleic Acids via Click Azide-Alkyne Cycloaddition for Pharmacological Applications

The click azide = alkyne 1,3-dipolar cycloaddition (click chemistry) has become the approach of choice for bioconjugations in medicinal chemistry, providing facile reaction conditions amenable to both small and biological molecules. Many nucleoside analogs are known for their marked impact in cancer therapy and for the treatment of virus diseases and new targeted oligonucleotides have been developed for different purposes. The click chemistry allowing the tolerated union between units with a wide diversity of functional groups represents a robust means of designing new hybrid compounds with an extraordinary diversity of applications. This review provides an overview of the most recent works related to the use of click chemistry methodology in the field of nucleosides, nucleotides and nucleic acids for pharmacological applications.

A One-Pot Approach to Novel Pyridazine C-Nucleosides

The synthesis of glycosides and modified nucleosides represents a wide research field in organic chemistry. The classical methodology is based on coupling reactions between a glycosyl donor and an acceptor. An alternative strategy for new C-nucleosides is used in this approach, which consists of modifying a pre-existent furyl aglycone. This approach is applied to obtain novel pyridazine C-nucleosides starting with 2- and 3-(ribofuranosyl)furans. It is based on singlet oxygen [4+2] cycloaddition followed by reduction and hydrazine cyclization under neutral conditions. The mild three-step one-pot procedure leads stereoselectively to novel pyridazine C-nucleosides of pharmacological interest. The use of acetyls as protecting groups provides an elegant direct route to a deprotected new pyridazine C-nucleoside.

Advance of structural modification of nucleosides scaffold

With Remdesivir being approved by FDA as a drug for the treatment of Corona Virus Disease 2019 (COVID-19), nucleoside drugs have once again received widespread attention in the medical community. Herein, we summarized modification of traditional nucleoside framework (sugar + base), traizole nucleosides, nucleoside analogues assembled by other drugs, macromolecule-modified nucleosides, and their bioactivity rules. 2′-“Ara”-substituted by –F or –CN group, and 3′-“ara” substituted by acetylenyl group can greatly influence their anti-tumor activities. Dideoxy dehydrogenation of 2′,3′-sites can enhance antiviral efficiencies. Acyclic nucleosides and L-type nucleosides mainly represented antiviral capabilities. 5-F Substituted uracil analogues exihibit anti-tumor effects, and the substrates substituted by –I, –CF₃, bromovinyl group usually show antiviral activities. The sugar coupled with 1-N of triazolid usually displays anti-tumor efficiencies, while the sugar coupled with 2-N of triazolid mainly represents antiviral activities. The nucleoside analogues assembled by cholesterol, polyethylene glycol, fatty acid and phospholipid would improve their bioavailabilities and bioactivities, or reduce their toxicities.

Novel aryltriazole acyclic C-azanucleosides as anticancer candidates

Nucleoside analogues represent an important class of drug candidates. With the aim of searching for novel bioactive nucleosides, we developed an efficient synthetic way to construct a series of aryl 1,2,3-triazole acyclic C-azanucleosides via Huisgen 1,3-dipolar cycloaddition. The aryl 1,2,3-triazole motifs within these azanucleosides showed coplanar features, suggesting they could act as surrogates for large planar aromatic systems or nucleobases. Moreover, several aryltriazole acyclic C-azanucleosides bearing long alkyl chains exhibited potent antiproliferative activity against various cancer cell lines via induction of apoptosis. Most interestingly, the lead compound significantly down-regulated the key proteins involved in the heat shock response pathway, representing the first anticancer acyclic azanucleoside with such a mode of action. These novel aryl 1,2,3-triazole cyclic C-azanucleosides therefore serve as promising paradigms for further exploring anticancer drug candidates.