Pyrimidine Nucleoside Analogues Research Articles

Synthesis of Chiral Acyclic Pyrimidine Nucleoside Analogues from DHAP-Dependent Aldolases.

Dihydroxyacetone phosphate (DHAP)-dependent aldolases catalyze the aldol addition of DHAP to a variety of aldehydes and generate compounds with two stereocenters. This reaction is useful to synthesize chiral acyclic nucleosides, which constitute a well-known class of antiviral drugs currently used. In such compounds, the chirality of the aliphatic chain, which mimics the open pentose residue, is crucial for activity. In this work, three DHAP-dependent aldolases: fructose-1,6-biphosphate aldolase from rabbit muscle, rhanmulose-1-phosphate aldolase from Thermotoga maritima, and fuculose-1-phosphate aldolase from Escherichia coli, were used as biocatalysts. Aldehyde derivatives of thymine and cytosine were used as acceptor substrates, generating new acyclic nucleoside analogues containing two new stereocenters with conversion yields between 70% and 90%. Moreover, structural analyses by molecular docking were carried out to gain insights into the diasteromeric excess observed.

Development of novel pyrimidine nucleoside analogs as potential anticancer agents: Synthesis, characterization, and In-vitro evaluation against pancreatic cancer

The present study proposed modification of 5-FU by conjugation with an acyl chloride and a 5-membered heterocyclic ring to improve its in-vitro cytotoxicity and metabolic stability. XYZ-I-71 and XYZ-I-73 were synthesized by introducing a tetrahydrofuran ring on 5-fluorocytosine (a precursor of 5-FU) and conjugation with octanoyl chloride and lauroyl chloride, respectively. The structure of the synthesized compounds was validated using NMR and micro-elemental analysis. The antiproliferative activity of the analogs was determined against MiaPaCa-2, PANC-1, and BxPC-3 pancreatic cancer cells. The analog's stability in human liver microsomes was quantified by HPLC. We found that the XYZ-I-73 (IC50 3.6 ± 0.4 μM) analog was most effective against MiaPaCa-2 cells compared to XYZ-I-71(IC50 12.3 ± 1.7 μM), GemHCl (IC50 24.2 ± 1.3 μM), Irinotecan (IC50 10.1 ± 1.5 μM) and 5-FU (IC50 13.2 ± 1.1 μM). The antiproliferative effects of this analog in Miapaca-2 cells is evident based on it having a 7-fold,3-fold, and 4-fold increased cytotoxic effect over Gem-HCl, Irinotecan, and 5-FU, respectively. On the other hand, XYZ-I-71 exhibited a 2-fold increased cytotoxic effect over Gem-HCl but a comparable cytotoxic effect to 5-FU and Irinotecan in MiaPaCa-2 cells. A similar trend of higher XYZ-I-73 inhibition was observed in PANC-1 and BxPC-3 cultures. For 48-h MiaPaCa-2 cell migration studies, XYZ-I-73 (5 μM) significantly reduced migration (# of migrated cells, 168 ± 2.9), followed by XYZ-I-71(315±2.1), Gem-HCl (762±3.1) and 5-FU (710 ± 3.2). PARP absorbance studies demonstrated significant inhibition of PARP expression of XYZ-I-73 treated cells compared to 5-FU, GemHCl, and XYZ-I-71. Further, BAX and p53 expressions were significantly increased in cells treated with XYZ-I-73 compared to 5-FU, GemHCl, and XYZ-I-71. In-vitro, metabolic stability studies showed that 80 ± 5.9% of XYZ-I-71 and XYZ-I-73 remained intact after 2 h exposure in liver microsomal solution compared to 5-FU. The XYZ-I-73 analog demonstrated a remarkable cytotoxic effect and improved in-vitro metabolic stability over the selected standard drugs and may have potential anticancer activity against pancreatic cancer.

Serum exosomal miR-3662 down-regulates the expression of RBMS3 to promote malignant progression and gemcitabine resistance of breast cancer cells.

Breast cancer (BC) is a prevalent malignancy among women worldwide. As an anticancer drug of pyrimidine nucleoside analogs, gemcitabine can be used to treat BC, but its clinical application is restricted due to drug resistance. This study investigated the effect of serum exosomal microRNA-3662 (miR-3662) on gemcitabine resistance in BC cells bytargeting RNA-Binding Motif Single-Stranded Interacting Protein 3 (RBMS3) and related molecular mechanisms. We performed the bioinformatics analyses on the differential miRNAs in BC and predicted the downstream regulators. Quantitative real-time polymerase chain reaction was conducted to determine miR-3662 and RBMS3 expression, while dual luciferase was conducted to confirme the regulatory relationship between them. Flow cytometry, cell counting kit-8, and transwell assays were applied to assess apoptosis, cell viability, invasion, and migration. The expression of marker proteins (TSG101, CD63, and CD81) in patients' serum exosomes was evaluated through western blot, and exosomes were observed using transmission electron microscopy. miR-3662 expression was significantly upregulated in BC, and miR-3662 knockdown significantly reduced BC cell viability and gemcitabine resistance. As the downstream gene of miR-3662, RBMS3 was significantly downregulated in BC, and dual luciferase assay verified the binding of RBMS3-3'UTR to miR-3662. Rescue experiments revealed that silencing RBMS3 reversed the inhibitory effect of miR-3662 knockdown on BC cells. Besides, we also found that miR-3662 expression was significantly low in serum exosome samples from BC patients and could be transmitted to tumor cells. miR-3662 was upregulated in serum exosomes and promoted BC cell progression and gemcitabine resistance by targeting RBMS3.

Synthesis of 2′-Deoxy-2′-β-fluoro-4′-azido-5-fluorouridine as a Potential Anti-HIV Agent

Abstract2′-Deoxy-2′-β-fluoro-4′-azido-5-fluorouridine, a new pyrimidine nucleoside analogue of azvudine (FNC), was designed and synthesized. The synthesis of this nucleoside analogue was achieved by bromination of 1,3,5-O-tribenzoyl-2-deoxy-2-fluoro-d-arabinofuranoside, followed by reaction with silylated 5-fluorouracil and further modifications of the sugar moiety, in a 7.6% overall yield over nine steps. The product exhibited good antiviral activity against HIV-1 infection in HEK293T cells.

Novel β-L-1,3-thiazolidine pyrimidine nucleoside analogues: Design, synthesis, molecular docking, and anti-HIV activity

The remarkable activity of 1,3-thiazolidine pyrimidines against a variety of viruses has made them a viable class of antiviral medicines. These compounds exhibit a unique mechanism of action, targeting multiple stages of the viral life cycle, including viral entry, replication, and release. Moreover, their broad-spectrum antiviral activity and low cytotoxicity make them an attractive drug candidate for the treatment of viral infections. In this article, we detailed the synthesis of 1,3-thiazolidine pyrimidine derivatives substituted on the 5th position of the pyrimidine ring with different functional groups. The anti-HIV activity of the synthesized compounds was tested using the HIVRT assay. In comparison to the IC50 value of standard nevirapine (112.2 nM), the 1,3 thiazolidine pyrimidine compound substituted with Fluoro S4 (21.16 µM) and Bromo S5 (30.52 µM) only has moderate anti-HIV activity. Similarly, compounds S5 and S4 have a high affinity for the active site of HIV-1 reverse transcriptase, as evidenced by their docking scores of -89.5147 and -82.5556 kcal/mol, respectively.

In vitro and in vivo antiplasmodial evaluation of sugar-modified nucleoside analogues

Drug-resistant Plasmodium falciparum (Pf) infections are a major burden on the population and the healthcare system. The establishment of Pf resistance to most existing antimalarial therapies has complicated the problem, and the emergence of resistance to artemisinin derivatives is even more concerning. It is increasingly difficult to cure malaria patients due to the limited availability of effective antimalarial drugs, resulting in an urgent need for more efficacious and affordable treatments to eradicate this disease. Herein, new nucleoside analogues including morpholino-nucleoside hybrids and thio-substituted nucleoside derivatives were prepared and evaluated for in vitro and in vivo antiparasitic activity that led a few hits especially nucleoside-thiopyranoside conjugates, which are highly effective against Pf3D7 and PfRKL-9 strains in submicromolar concentration. One adenosine derivative and four pyrimidine nucleoside analogues significantly reduced the parasite burden in mouse models infected with Plasmodium berghei ANKA. Importantly, no significant hemolysis and cytotoxicity towards human cell line (RAW) was observed for the hits, suggesting their safety profile. Preliminary research suggested that these thiosugar-nucleoside conjugates could be used to accelerate the antimalarial drug development pipeline and thus deserve further investigation.

Increased renal elimination of endogenous and synthetic pyrimidine nucleosides in concentrative nucleoside transporter 1 deficient mice

Concentrative nucleoside transporters (CNTs) are active nucleoside influx systems, but their in vivo roles are poorly defined. By generating CNT1 knockout (KO) mice, here we identify a role of CNT1 in the renal reabsorption of nucleosides. Deletion of CNT1 in mice increases the urinary excretion of endogenous pyrimidine nucleosides with compensatory alterations in purine nucleoside metabolism. In addition, CNT1 KO mice exhibits high urinary excretion of the nucleoside analog gemcitabine (dFdC), which results in poor tumor growth control in CNT1 KO mice harboring syngeneic pancreatic tumors. Interestingly, increasing the dFdC dose to attain an area under the concentration-time curve level equivalent to that achieved by wild-type (WT) mice rescues antitumor efficacy. The findings provide new insights into how CNT1 regulates reabsorption of endogenous and synthetic nucleosides in murine kidneys and suggest that the functional status of CNTs may account for the optimal action of pyrimidine nucleoside analog therapeutics in humans.

Preparation of bicyclo[1.1.1]pentane-derived nucleoside analogues

Nucleoside analogues are prevalent in drug design and call for more diversified structures. Bicyclo[1.1.1]pentane (BCP) structure has recently found wide applications in drug discovery. However, incorporation of BCP fragment into nucleoside analogues is hitherto unknown. Thus, from readily available BCP-containing building blocks, six new compounds, including pyrimidine nucleoside analogues, purine nucleoside analogues, and C-nucleoside analogues were prepared in 1–4 steps, generally with good yields.

Seven-membered ring nucleobases as inhibitors of human cytidine deaminase and APOBEC3A.

The APOBEC3 (APOBEC3A-H) enzyme family as a part of the human innate immune system deaminates cytosine to uracil in single-stranded DNA (ssDNA) and thereby prevents the spread of pathogenic genetic information. However, APOBEC3-induced mutagenesis promotes viral and cancer evolution, thus enabling the progression of diseases and development of drug resistance. Therefore, APOBEC3 inhibition offers a possibility to complement existing antiviral and anticancer therapies and prevent the emergence of drug resistance, thus making such therapies effective for longer periods of time. Here, we synthesised nucleosides containing seven-membered nucleobases based on azepinone and compared their inhibitory potential against human cytidine deaminase (hCDA) and APOBEC3A with previously described 2'-deoxyzebularine (dZ) and 5-fluoro-2'-deoxyzebularine (FdZ). The nanomolar inhibitor of wild-type APOBEC3A was obtained by the incorporation of 1,3,4,7-tetrahydro-2H-1,3-diazepin-2-one in the TTC loop of a DNA hairpin instead of the target 2'-deoxycytidine providing a Ki of 290 ± 40 nM, which is only slightly weaker than the Ki of the FdZ-containing inhibitor (117 ± 15 nM). A less potent but notably different inhibition of human cytidine deaminase (CDA) and engineered C-terminal domain of APOBEC3B was observed for 2'-deoxyribosides of the S and R isomers of hexahydro-5-hydroxy-azepin-2-one: the S-isomer was more active than the R-isomer. The S-isomer shows resemblance in the position of the OH-group observed recently for the hydrated dZ and FdZ in the crystal structures with APOBEC3G and APOBEC3A, respectively. This shows that 7-membered ring analogues of pyrimidine nucleosides can serve as a platform for further development of modified ssDNAs as powerful A3 inhibitors.

060 The effect of topical 5-azacytidine in irritant and allergic contact dermatitis

DNA methylation is one of major epigenetic mechanisms by which regulate a panel of gene expressions. An old but a revisiting compound, 5-azacytidine, is a pyrimidine nucleoside analog of cytidine that can inhibit DNA methyltransferase, induce cell differentiation, and has direct cytotoxicity on abnormal bone marrow hematopoietic cells. Thus, systemic administration of 5-azacytidine has been approved for the treatment of myelodysplastic syndrome and acute myeloid leukemia. However, the effect of topical 5-azacytidine on skin inflammation is largely unknown.

A Pilot Study of Azacitidine As Epigenetic Priming for Chemotherapy in Infants Less Than 1 Year of Age with KMT2A-Rearranged Acute Lymphoblastic Leukemia (ALL); Results from the Children's Oncology Group (COG) Trial AALL15P1

Introduction Acute lymphoblastic leukemia (ALL) with KMT2A-rearrangement (KMT2A-r) in infants <1 year is a high-risk childhood ALL subtype, with consistently poor event-free survival (EFS) of approximately 35% when treated with intensive chemotherapy with or without hematopoietic stem cell transplant. Infant ALL blasts are characterized by DNA hypermethylation, which is hypothesized to contribute to chemoresistance by altering transcriptional regulation of gene expression. In preclinical studies of KMT2A-r blasts, epigenetic priming with DNA methyltransferase inhibitors improved the in vitro cytotoxicity of chemotherapy. Azacitidine, a pyrimidine nucleoside analog of cytidine and hypomethylating agent, has been used in combination with chemotherapy in children with leukemia. We previously reported that azacitidine was safe and well tolerated in AALL15P1 (ASPHO 2021) and herein we report survival outcomes. Methods The Children's Oncology Group (COG) trial AALL15P1 (NCT02828358) was a single arm, open label, groupwide pilot trial. The primary aim of the trial was to evaluate the tolerability of azacitidine in addition to Interfant-06 standard chemotherapy in infants with newly diagnosed KMT2A-r ALL. Estimation of 5-year EFS was an exploratory aim, given the small sample size. Eligibility criteria included B-ALL or acute leukemia of ambiguous lineage with ≥50% B-lymphoblasts, <366 days of age at diagnosis, and >36 weeks gestational age at enrollment. Exclusions included Down syndrome, secondary ALL, and prior cytotoxic therapy (except intrathecal chemotherapy or corticosteroids). Following an Interfant-based induction, infants with KMT2A-r received 4 courses of azacitidine, 2.5 mg/kg/dose intravenously over 10-40 minutes daily for 5 consecutive days in each course, immediately preceding the start of a chemotherapy course on day 6. Infants without KMT2A-r were removed from protocol following induction and did not receive azacitidine. Treatment failure was defined as failure to achieve M1 marrow status (<5% blasts by morphology) with resolution of extramedullary leukemia by the end of consolidation. EFS and overall survival (OS) were measured from the time of enrollment. Results The study accrued from March 2017 to December 2019 and all protocol-directed treatment concluded in December 2021. Of the 78 infants enrolled, 56 had KMT2A-r (72%), and 53 completed induction therapy and received at least 1 course of azacitidine. No patients were ineligible. Diagnostic clinical characteristics of infants with KMT2A-r included four infants age <7 days (7%), 13 age <90 days (23%), 18 with white blood cell count ≥300,000/µL (32%), 32 CNS2 (57%), and four CNS3 (7%). As of the data cutoff (06/30/2022), the median follow-up is 3.8 years, and the 3-year EFS (SE) and OS (SE) rates are 34.2% (+/- 0.08) and 63.8% (+/-0.08), respectively, for infants with KMT2A-r. Six infants experienced treatment failure. Minimal residual disease (MRD) levels of marrow blasts by flow cytometry in COG-approved laboratories were submitted for 49 KMT2A-r patients at the end of induction. Of those, 32 were MRD negative <0.01% (65%), eight MRD positive 0.01%-<1% (16%) and nine MRD positive ≥1% (18%). Event-free survival was significantly associated with MRD; the 3-year EFS of patients with any positive MRD was 20.6% (+/-0.13) vs. 40.1% (+/-0.09) (p=0.0185) for those without MRD. As previously reported, at no time did the trial meet or exceed the pre-determined dose limiting toxicity boundaries, and the rates and types of toxicities observed were within the expected range for infants receiving standard chemotherapy alone. Conclusions Epigenetic priming with azacitidine prior to standard chemotherapy was well tolerated in infants with KMT2A-r ALL, but the EFS was consistent with the poor survival of historical outcomes. Positive flow MRD at the end of induction predicted a higher risk of treatment failure, relapse, or death, in comparison to negative MRD, but EFS was still unacceptably low for MRD-negative patients. There remains an urgent need for improved therapies for infants with KMT2A-r ALL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

585 The effect of topical 5-azacytidine in irritant and allergic contact dermatitis

DNA methylation is one of major epigenetic mechanisms by which regulate a panel of gene expressions. An old but a revisiting compound, 5-azacytidine, is a pyrimidine nucleoside analog of cytidine that can inhibit DNA methyltransferase, induce cell differentiation, and has direct cytotoxicity on abnormal bone marrow hematopoietic cells. Thus, systemic administration of 5-azacytidine has been approved for the treatment of myelodysplastic syndrome and acute myeloid leukemia. However, the effect of topical 5-azacytidine on skin inflammation is largely unknown.

Lewis Acid Catalyzed (3+2)‐Cycloadditions of Chiral Pyrimidinyl‐Substituted Cyclopropanes with Nitrosoarenes or Silyl Enol Ethers

AbstractChiral isoxazole and carbocyclic pyrimidine nucleoside analogues were synthesized via (3+2)‐cycloadditions of chiral pyrimidinyl‐substituted dimethyl cyclopropanedicarboxylates. In the presence of MgI2, (3+2)‐cycloadditions of chiral pyrimidinyl‐substituted cyclopropanes with nitrosoarenes afforded diverse chiral isoxazole pyrimidine nucleoside analogues in up to 78 % yield and 88–96 % ee. Using Nd(OTf)3 as the catalyst, the annulation reaction with silyl enol ethers generated a series of chiral carbocyclic pyrimidine nucleoside analogues in up to 64 % yield, &gt;20 : 1 dr, and 87–96 % ee. The proposed methods either reduced or avoided partial racemization.

Analogues of Pyrimidine Nucleosides as Mycobacteria Growth Inhibitors.

Tuberculosis (TB) is the oldest human infection disease. Mortality from TB significantly decreased in the 20th century, because of vaccination and the widespread use of antibiotics. However, about a third of the world’s population is currently infected with Mycobacterium tuberculosis (Mtb) and the death rate from TB is about 1.4–2 million people per year. In the second half of the 20th century, new extensively multidrug-resistant strains of Mtb were identified, which are steadily increasing among TB patients. Therefore, there is an urgent need to develop new anti-TB drugs, which remains one of the priorities of pharmacology and medicinal chemistry. The antimycobacterial activity of nucleoside derivatives and analogues was revealed not so long ago, and a lot of studies on their antibacterial properties have been published. Despite the fact that there are no clinically used drugs based on nucleoside analogues, some progress has been made in this area. This review summarizes current research in the field of the design and study of inhibitors of mycobacteria, primarily Mtb.

A phase I study of duvelisib in combination with oral azacitidine (CC-486) in relapsed lymphoid malignancies.

TPS7594 Background: Phosphoinositide 3-kinase (PI3K) inhibitors have shown promising activity in lymphoid malignancies such as mature T cell lymphoma, diffuse large B cell lymphoma, and mantle cell lymphoma. Duvelisib’s PI3K-δ and PI3K-γ activity in T cell lymphoma is promising as a single agent (Horwitz, Koch et al. 2018). While the safety profile can generally be managed, certain autoimmune adverse events may limit its adaptation in clinical practice. Azacitidine, a pyrimidine nucleoside analog of cytidine, is active in T cell lymphoma (Saillard, Guermouche et al. 2017) as well as in DLBCL (Martin, Bartlett et al. 2018). Hypomethylators could enhance the activity of PI3K inhibitors through increasing PTEN expression (Spangle, Roberts et al. 2017), and upregulation of tumor suppressor genes (Zuo, Liu et al. 2011). Duvelisib’s immune mediated adverse events may be related to shifts in T cell differentiation towards Th17 phenotype and decreases in T reg differentiation that found to be more pronounced in patients with higher immune related toxicity (Gadi, Kasar et al. 2019). Studies have shown that T regs can be induced from Cd4+CD25- T cells using DNA methyltransferase inhibition with azacitidine (Fagone, Mazzon et al. 2018). Thus, the intermittent administration of azacytidine can potentially restore the balance by increasing T regs to decrease the autoimmune toxicity while maintaining Th17 phenotype that enhances tumor killing as shown in myelodysplastic syndrome (Jia, Yang et al. 2020). Methods: This is a 3+3 phase I dose escalation study designed to determine the maximum tolerated dose (MTD) of CC-486 in combination with duvelisib in patients with lymphoid malignancies. The MTD is defined as the highest dose with an observed incidence of dose limiting toxicity (DLT) in no more than one out of six patients treated at a particular dose level. Secondary endpoints include best overall response, disease control rate and duration of response. Exploratory end points will be biomarker driven with focus on the composition of different T cell compartments during the administration of the combination. Efficacy biomarkers will include measuring the phosphorylation of AKT in peripheral CD3+ T cells. Oral duvelisib will be given continuously with the dose escalation maintained during the first 2 cycles while CC-486 schedule will be 14 days on/14 days off. The first cohort of patients are enrolled, and are in the DLT testing period. Clinical trial information: NCT05065866.

New Derivatives of 5-Substituted Uracils: Potential Agents with a Wide Spectrum of Biological Activity.

Pyrimidine nucleoside analogues are widely used to treat infections caused by the human immunodeficiency virus (HIV) and DNA viruses from the herpes family. It has been shown that 5-substituted uracil derivatives can inhibit HIV-1, herpes family viruses, mycobacteria and other pathogens through various mechanisms. Among the 5-substituted pyrimidine nucleosides, there are not only the classical nucleoside inhibitors of the herpes family viruses, 2′-deoxy-5-iodocytidine and 5-bromovinyl-2′-deoxyuridine, but also derivatives of 1-(benzyl)-5-(phenylamino)uracil, which proved to be non-nucleoside inhibitors of HIV-1 and EBV. It made this modification of nucleoside analogues very promising in connection with the emergence of new viruses and the crisis of drug resistance when the task of creating effective antiviral agents of new types that act on other targets or exhibit activity by other mechanisms is very urgent. In this paper, we present the design, synthesis and primary screening of the biological activity of new nucleoside analogues, namely, 5′-norcarbocyclic derivatives of substituted 5-arylamino- and 5-aryloxyuracils, against RNA viruses.

Development of the electrochemical, spectroscopic and molecular docking approaches toward the investigation of interaction between DNA and anti-leukemic drug azacytidine

This study examines the interaction between pyrimidine nucleoside analogue azacytidine, an anti-leukemic drug, and DNA by employing electrochemical, UV–vis spectroscopy, fluorescence spectroscopy and molecular docking techniques. In the electrochemical technique, azacytidine and dsDNA interaction was investigated in two different ways: (1) in solution and (2) with a biosensor using differential pulse voltammetry (DPV) at a glassy carbon electrode. The interaction between azacytidine and dsDNA at increasing interaction times was investigated in line with the changes in adenine and guanine oxidation signals. In addition, interaction studies of polyguanine-azacytidine and polyadenine-azacytidine were performed with DPV. The binding constant values were calculated as 2.420 × 104 M−1 and 3.266 × 104 M−1 at 25 °C using UV and fluorescence spectroscopy, respectively. In conclusion, based on electrochemical and spectroscopic methods as well as molecular docking studies, it was predicted that azacytidine can bind to dsDNA via groove binding.

Physicochemical stability of azacitidine suspensions at 25 mg/mL in polypropylene syringes stored under different conditions of storage

Abstract Objectives Azacitidine is a pyrimidine nucleoside analogue whose stability is temperature dependent. Numerous publications have studied the stability of this drug with discordant results. The purpose of this work is to study the stability of azacitidine suspensions under different conditions to allow preparation in advance: vials stored at room temperature or between 2 and 8 °C, reconstituted with refrigerated water for injection (WFI) or frozen/thawed WFI, azacitidine suspensions stored at room temperature, 2–8 °C or at −20 °C. The feasibility of a vented ChemoClave® Spike vial was also tested to reconstitute and collect azacitidine to aid the preparation stage. Methods The stability study was performed by HPLC coupled to a photodiode array detector. The method was validated according to ICH Q2(R1). Two syringes were prepared for each analysis condition and two samples were realised for each syringe at each time of the analysis. For a storage at 2–8 °C, analyses were performed for up to 168 h. The stability was studied after 2 h at room temperature. For frozen storage, the stability was studied after 28 days. Results Azacitidine 25 mg/mL suspensions stored between 2 and 8 °C, prepared with refrigerated WFI or frozen/thawed WFI, retained more than 90% of the initial concentration for 96 h and then for 2 h at room temperature. Prepared with frozen/thawed WFI, azacitidine 25 mg/mL suspensions stored at −20 °C for 28 days and then 72 h between 2 and 8 °C after thawing, retained more than 90% of the initial concentration. When using a Spike system compared to using a needle for reconstitution and collection of the suspension, the results obtained by HPLC showed a decrease of 1.47% in the concentration of azacitidine. The comparisons of the volumes withdrawn after reconstitution were similar when using a Spike system or a needle. Conclusions Azacitidine 25 mg/mL suspensions reconstituted with refrigerated WFI were chemically stable for 4 days when stored at 2–8 °C whatever the storage of vials (refrigerator or room temperature), and 2 h at room temperature. A storage of azacitidine 25 mg/mL suspensions in syringes prepared with frozen/thawed WFI at −20 °C has been validated for up to 28 days, leading to the possibility to prepare in advance. A Spike device can be used to reconstitute and collect azacitidine.

Synthesis of fluorinated carbocyclic pyrimidine nucleoside analogues.

Analogues of the canonical nucleosides have a longstanding presence and proven capability within medicinal chemistry and drug discovery research. The synthesis reported herein successfully replaces furanose oxygen with CF2 and CHF in pyrimidine nucleosides, granting access to an alternative pharmacophore space. Key diastereoselective conjugate addition and fluorination methodologies are developed from chiral pool materials, establishing a robust gram-scale synthesis of 6'-(R)-monofluoro- and 6'-gem-difluorouridines. Vital intermediate stereochemistries are confirmed using X-ray crystallography and NMR analysis, providing an indicative conformational preference for these fluorinated carbanucleosides. Utilising these 6'-fluorocarbauridine scaffolds enables synthesis of related cytidine, ProTide and 2'-deoxy analogues alongside a preliminary exploration of their biological capabilities in cancer cell viability assays. This synthetic blueprint offers potential to explore fluorocarbanucleoside scaffolds, indicatively towards triphosphate analogues and as building blocks for oligonucleotide synthesis.

Chemical synthesis of 4'-thio and 4'-sulfinyl pyrimidine nucleoside analogues.

Analogues of the canonical nucleosides required for nucleic acid synthesis have a longstanding presence and proven capability within antiviral and anticancer research. 4'-Thionucleosides, that incorporate bioisosteric replacement of furanose oxygen with sulfur, represent an important chemotype within this field. Established herein is synthetic capability towards a common 4-thioribose building block that enables access to thio-ribo and thio-arabino pyrimidine nucleosides, alongside their 4'-sulfinyl derivatives. In addition, this building block methodology is templated to deliver 4'-thio and 4'-sulfinyl analogues of the established anticancer drug gemcitabine. Cytotoxic capability of these new analogues is evaluated against human pancreatic cancer and human primary glioblastoma cell lines, with observed activities ranging from low μM to >200 μM; explanation for this reduced activity, compared to established nucleoside analogues, is yet unclear. Access to these chemotypes, with thiohemiaminal linkages, will enable a wider exploration of purine and triphosphate analogues and the application of such materials for potential resistance towards relevant hydrolytic enzymes within nucleic acid biochemistries.