Pyrazole ribonucleoside analogues were prepared via a linear approach starting with the reaction of D-ribosylhydrazine with 1,3-dicarbonyl or acrylonitrile derivatives, thereby avoiding the regio- and stereoselectivity challenges typically encountered in N-glycosylation reactions. Three series of pyrazole nucleoside analogues, as along with selected corresponding pronucleotides, were prepared and their antiviral activity against Zika virus and Sars-Cov-2 is reported.

A one‐pot access to alkyl‐bisphosphonates and alkyl‐bisphosphinates was developed using affordable starting materials (terminal alkynes and low‐cost photoinitiator), no metal catalyst, neither ligand, and no or little amounts of solvents. The radical reaction proceeded smoothly under UV exposure, the reaction conditions were optimized and the scope of the reaction was explored.

The emergence of drug-resistant Plasmodium strains requires the development of novel antimalarial agents with original mechanisms of action. Here, we report the synthesis and biological evaluation of a new family of nucleotide analogues aiming to target an essential step of the development of the malaria parasite. Two series of acyclic nucleoside phosphonates were designed to incorporate strategic structural modifications either on the purine scaffold or on the acyclic chain. All synthesized compounds were evaluated against chloroquine-sensitive (3D7) Plasmodium falciparum strains. A few compounds demonstrated in vitro antimalarial activity with IC50 values ranging from 11.3 to38.8 µM. In addition, a molecular docking study revealed some crucial interactions with the putative target and supports the biological data. The present study establishes this novel family of nucleotide analogues as promising antimalarial scaffolds, warranting further optimization and evaluation.

Herein, we describe a new methodology for selective cephalosporin functionalization at the C3 position. First, an optimization study of the reaction conditions was performed and allowed favourable parameters for the Suzuki-Miyaura coupling reaction to be defined. Then, the scope of the reaction was evaluated using various boronic acids, and the reaction demonstrated a good functional-group tolerance profile. Finally, the formation of some side-products was also investigated, and the main limitations of the reaction were defined.

The urgent need for original antimalarial therapies arises from the alarming spread of malaria parasite resistance to existing drugs. A promising candidate, UA2239, an acyclic nucleoside phosphonate with a guanine as nucleobase, demonstrates rapid and irreversible inhibitory effects on Plasmodium parasites. It blocks the active exit process, named egress, of merozoites and gametes from infected erythrocytes. UA2239 disrupts the essential cyclic guanosine monophosphate (cGMP)–dependent egress pathway by decreasing cGMP levels in the parasite, strongly suggesting Plasmodium falciparum guanylyl cyclase α as its primary target. We also uncovered remarkable molecular mechanisms of resistance developed by parasites after prolonged exposure to the drug, which involve mutating not the target itself, but downstream effectors. The unique mechanism of action of UA2239 makes it a valuable first-in-class candidate for further development. Its ability to inhibit both parasite growth and transmission highlights its therapeutic potential as a dual-stage antimalarial agent.

Various series of 4,6-disubstituted-2-thiopyridine derivatives were synthesized and evaluated as potential ecto-5'-nucleotidase (CD73) inhibitors. Altogether, about ninety compounds were prepared using a general synthetic pathway involving one or two steps (eventually one-pot) procedures. Variation of the nature of the substituents in positions 4 and 6 (methyl, trifluoromethyl or phenyl) of the thiopurine ring, as well as on the thiol function, was examined and led to marked differences both in term of reactivity and ability to interfere with the putative target protein. Using a functional assay on immune cells, few compounds belonging to series 4 were shown to be able to antagonize the inhibition of the T-cell proliferation at both 100 mu M and 10 mu M (completely for 4 ab and partially for 4 ai), that is as potent as AOPCP which entirely reversed the inhibitory impact of exogenous ATP on T cell proliferation until 62.5 mu M. In addition, we have shown that both compounds (4 ab and 4 ai) were also capable of moderately inhibiting the hA2A receptor with Ki in the mu molar range in HEK-293 cells. Thus, with the aim to reduce the molecular size and the lipophilicity of our initial scaffold, we finally observed by serendipity a modification of the potential target of our compounds.

Since the discovery of penicillin, the forerunner of the most widely used class of antibiotics (i.e. β-lactams), natural compounds and their derivatives represented a major source of antibacterial therapeutic products whose availability enabled modern medical practices (invasive surgery, organ transplant, etc.). However, the relentless emergence of resistant bacteria is challenging the long-term efficacy of antibiotics, also decreasing their economic attractiveness for big pharma, leading to a significant decay in antibacterial development in the 21st century and an increased use of last-resort drugs such as carbapenems or colistin. Indeed, bacteria evolved an arsenal of resistance mechanisms, leading to the emergence of totally-drug resistant isolates, already sporadically isolated among Gram-negative bacterial species. To face this deadly peril, it is fundamental to explore new ground-breaking approaches. In view of the significance of both β-lactam antibiotics and the production of one or more β-lactamases as the major resistance mechanism (especially in Gram-negative bacteria), we implemented an original approach to selectively deliver antibacterial zidovudine (AZT) exploiting the β-lactamase-mediated hydrolysis of a β-lactam-conjugate prodrug. The synthesis of the targeted pronucleosides was performed in 5-7 steps and based on an original Pd-catalyzed cross-coupling reaction. Enzymatic and microbiological evaluations were performed to evaluate the synthesized pronucleosides, yielding new insights into molecular recognition of β-lactamase enzymes. This approach would potentially allow a targeted and selective eradication of antibiotic-resistant β-lactamase-producing (opportunistic) pathogens, as the inactive prodrug is unable to harm the commensal microbial flora.

Synthetic nucleoside mimics are re-emerging as crucial contenders for antiviral and anticancer medications. While, Ribavirin stands out for its unique antiviral properties, predominantly associated with its distinctive triazole heterocycle as a nucleobase, the exploration of alternative nitrogen-based aromatic heterocycles hold great promises for the discovery of novel bioactive nucleoside mimics. Although nucleoside derivatives synthesized from hydrazine-ribose units have been in development for many decades, they have been little evaluated biologically and even less for their antiviral properties. With the aim of taking a closer look at these under-explored derivatives and investigating their synthetic pathways, this review provides an overview of the molecular design, the chemical synthesis, and the biological activity, when available, of these nucleoside analogues. Overall, the entire body of work already done motivates further exploration of these analogues and encourages us of formulating structurally novel nucleoside drug candidates featuring innovative mode of action.

Herein, we report the design, the synthesis, and the study of novel triphenyl phosphonium-based nucleoside conjugates. 2'-Deoxycytidine was chosen as nucleosidic cargo, as it allows the introduction of fluorescein on the exocyclic amine of the nucleobase and grafting of the vector was envisaged through the formation of a biolabile ester bond with the hydroxyl function at the 5'-position. Compound 3 was identified as a potential nucleoside prodrug, showing ability to be internalized efficiently into cells and to be co-localized with mitochondria.

Dinucleoside 5’,5’‐polyphosphates (NpnNs) play essential roles in various biological processes. Access to these high value‐added compounds, while avoiding the many drawbacks of solution phase synthesis, is a challenge that has been overcome thanks to mechanochemistry. A straightforward solid‐state synthesis based on activation of phosphate or pyrophosphate sodium salts to their diimidazolides, followed by coupling with commercially available nucleotides, under air conditions, gave symmetrical NpnNs. The scope ranged from Np3Ns to highly challenging Np6Ns. The methodology has also been implemented using medronic acid and imidodiphosphate to obtain NpnNs analogues, some of which are unprecedented.

The nucleotidase ISN1 is a potential therapeutic target of the purine salvage pathway of the malaria parasite Plasmodium falciparum. We identified PfISN1 ligands by in silico screening of a small library of nucleos(t)ide analogues and by thermal shift assays. Starting from a racemic cyclopentyl carbocyclic phosphonate scaffold, we explored the diversity on the nucleobase moiety and also proposed a convenient synthetic pathway to access the pure enantiomers of our initial hit (compound (±)-2). 2,6-Disubstituted purine containing derivatives such as compounds 1, (±)-7e and β-L-(+)-2 showed the most potent inhibition of the parasite in vitro, with low micromolar IC50 values. These results are remarkable considering the anionic nature of nucleotide analogues, which are known to lack activity in cell culture experiments due to their scarce capacity to cross cell membranes. For the first time, we report the antimalarial activity of a carbocyclic methylphosphonate nucleoside with an L-like configuration.

Various series of 4,6-biaryl-2-thiopyridine derivatives were synthesized and evaluated as potential ecto-5 '-nucleotidase (CD73) inhibitors. Two synthetic routes were explored and the coupling of 4,6-disubstituted 3-cyano-2-chloro-pyridines with selected thiols allowed us to explore the structural diversity. Somehow divergent results were obtained in biological assays on CD73 inhibition using either the purified recombinant protein or cell-based assays, highlighting the difficulty to target protein-protein interface on proteins existing as soluble and membrane-bound forms. Among the 18 new derivatives obtained, three derivatives incorporating morpholino substituents on the 4,6-biaryl-2-thiopyridine core were shown to be able to reverse the adenosine-mediated immune suppression on human T cells. The higher blockade efficiency was observed for 2-((3-cyano-4,6-bis(4-morpholinophenyl)pyridin-2-yl)thio)-N-(isoxazol-3-yl)acetamide (with total reversion at 100 mu M) and methyl 2-((3-cyano-4,6-bis(4-morpholinophenyl)pyridin-2-yl)thio)acetate (with partial reversion at 10 mu M). Thus, this series of compounds illustrates a new chemotype of CD73 allosteric inhibitors.

Nucleoside analogues are widely used as anti-infectious and antitumoral agents. However, their clinical use may face limitations associated with their physico-chemical properties, pharmacokinetic parameters, and/or their peculiar mechanisms of action. Indeed, once inside the cells, nucleoside analogues require to be metabolized into their corresponding (poly-)phosphorylated derivatives, mediated by cellular and/or viral kinases, in order to interfere with nucleic acid biosynthesis. Within this activation process, the first-phosphorylation step is often the limiting one and to overcome this limitation, numerous prodrug approaches have been proposed. Herein, we will focus on recent literature data (from 2015 and onwards) related to new prodrug strategies, the development of original synthetic approaches and novel applications of nucleotide prodrugs (namely pronucleotides) leading to the intracellular delivery of 5'-monophosphate nucleoside analogues.

The ecto‐5′‐nucleotidase CD73 is involved in the production of immunosuppressive adenosine in the tumoral microenvironment and recently became a validated target in immuno‐oncology. To avoid formation of CD73‐produced adenosine, several series of potential inhibitors of the target enzyme based on a triazole scaffold were synthetized and evaluated on recombinant purified hCD73 and in cell‐based assays.

Treatment of N-carbamoyl aziridines by the diethyl phosphite anion affords either α-methylene-phosphonate or gem-bisphosphonate derivatives containing an aziridine motif depending on the nature of the base used.

The first soluble‐phase synthesis of adenosine nucleotides including α,β and β,γ‐methylene bisphosphonate analogues on a multi‐pod support is reported. Anchoring of a 2’,3’‐protected purine nucleoside to the tripodal support via the nucleobase was successfully achieved using a microwave assisted Cu(I)‐catalyzed azide‐alkyne cycloaddition. Then, phosphorylation was performed, followed by cleavage with aqueous ammonia to provide adenine derivatives, and finally deprotection. When using benzylamine instead of ammonia, a derivative with N6‐benzylamine adenine as nucleobase was obtained. This methodology allows to access adenosine 5’‐mono, di and triphosphates, as well as various analogues of pharmacological interest in modest to good yields.

We have focused our attention on alternative synthetic approaches for nucleotides and dinucleotides, that simplifies purification and/or improves sustainability. On one hand, we developed a liquid-phase synthesis using a benzene-centred tripodal support to prepare adenine nucleoside phosphoesters and methylenebisphosphonate derivatives. On the other hand, we used mechanochemistry, a technique that enables solid/solid reactions through mechanical grinding under solventless or solvent-free conditions, to get access to dinucleotides.

The synthesis and in vitro anti-HIV activity of a novel series of pronucleotides are reported. These prodrugs were characterized by a phosphorodithiolate structure, incorporating two O-pivaloyl-2- oxyethyl substituents as biolabile phosphate protections. The compounds were obtained following an original one-pot three-step procedure, involving the formation of a phosphorodithioite intermediate which is in situ oxidized. In vitro, comparative anti-HIV evaluations demonstrate that such original prodrugs are able to allow the efficient intracellular release of the corresponding 50-mononucleotide. The pronucleotide of 2',3'-dideoxyadenosine (ddA) 3 exhibited a very potent antiretroviral effect with 50% effective concentration (EC50) values in nanomolar concentration range in various cell lines. In primary monocytes/macrophages, this derivative was 500 times more potent in inhibiting HIV replication (EC50 0.23 pM) than ddA and the selectivity index of the prodrug is fifty times higher than the one of the parent nucleoside. (C) 2021 Elsevier Masson SAS. All rights reserved.

Background: The development of small molecules as cancer treatments is still of both interest and importance. Objective: Having synthesized and identified the initial cytotoxic activity of a series of chemically related N-(9H-purin-6-yl) benzamide derivatives, we continued their evaluation on cancer cell models. We also synthesized water-soluble prodrugs of the main compound and performed in vivo experiments. Method: We used organic chemistry to obtain compounds of interest and prodrugs. The biological evaluation included MTT assays, synergy experiments, proliferation assays by CFSE, cell cycle distribution and in vivo antitumoral activity Results: Our results show activities on cancer cell lines ranging from 3-39 μM for the best compounds, with both induction of apoptosis and decrease in cell proliferation. Two compounds evaluated in vivo showed weak antitumoral activity. In addition, the lead compound and its prodrug had a synergistic activity with the nucleoside analogue fludarabine in vitro and in vivo. Conclusion: Our work allowed us to gain better knowledge on the activity of N-(9H-purin-6-yl) benzamide derivatives and showed new examples of water-soluble prodrugs. More research is warranted to decipher the molecular mechanisms of the molecules.

The stereoselective synthesis of some 3'-deoxy-3'-C-methyl pyrimidine nucleosides is reported. The studied modifications concern the inversion of the configuration in 2'-position as well as the introduction of fluoro and azido substituents. The corresponding arabinonucleoside and 2'-substituted ribonucleoside analogs of uracil and cytosine have been obtained and fully characterized. Attempts to introduce fluoro and azido substituents with inversion at C-2' are also presented.