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Adenosine Deaminases Acting on RNA (ADARs) are enzymes that catalyze the conversion of adenosine to inosine in RNA duplexes. These enzymes can be harnessed to correct disease-causing G-to-A mutations in the transcriptome because inosine is translated as guanosine. Guide RNAs (gRNAs) can be used to direct the ADAR reaction to specific sites. Chemical modification of ADAR guide strands is required to facilitate delivery, increase metabolic stability, and increase the efficiency and selectivity of the editing reaction. Here, we show the ADAR reaction is highly sensitive to ribose modifications (e.g. 4'-C-methylation and Locked Nucleic Acid (LNA) substitution) at specific positions within the guide strand. Our studies were enabled by the synthesis of RNA containing a new, ribose-modified nucleoside analog (4'-C-methyladenosine). Importantly, the ADAR reaction is potently inhibited by LNA or 4'-C-methylation at different positions in the ADAR guide. While LNA at guide strand positions -1 and -2 block the ADAR reaction, 4'-C-methylation only inhibits at the -2 position. These effects are rationalized using high-resolution structures of ADAR-RNA complexes. This work sheds additional light on the mechanism of ADAR deamination and aids in the design of highly selective ADAR guide strands for therapeutic editing using chemically modified RNA.

ConspectusIn 1960, Weber prophesied that There are many ways in which the properties of the excited state can be utilized to study points of ignorance of the structure and function of proteins. This has been realized, illustrating that an intrinsic and highly responsive fluorophore such as tryptophan can alter the course of an entire scientific discipline. But what about RNA and DNA? Adapting Webers protein photophysics prophecy to nucleic acids requires the development of intrinsically emissive nucleoside surrogates as, unlike Trp, the canonical nucleobases display unusually low emission quantum yields, which render nucleosides, nucleotides, and oligonucleotides practically dark for most fluorescence-based applications.Over the past decades, we have developed emissive nucleoside surrogates that facilitate the monitoring of nucleoside-, nucleotide-, and nucleic acid-based transformations at a nucleobase resolution in real time. The premise underlying our approach is the identification of minimal atomic/structural perturbations that endow the synthetic analogs with favorable photophysical features while maintaining native conformations and pairing. As illuminating probes, the photophysical parameters of such isomorphic nucleosides display sensitivity to microenvironmental factors. Responsive isomorphic analogs that function similarly to their native counterparts in biochemical contexts are defined as isofunctional.Early analogs included pyrimidines substituted with five-membered aromatic heterocycles at their 5 position and have been used to assess the polarity of the major groove in duplexes. Polarized quinazolines have proven useful in assembling FRET pairs with established fluorophores and have been used to study RNA-protein and RNA-small-molecule binding. Completing a fluorescent ribonucleoside alphabet, composed of visibly emissive purine (thA, thG) and pyrimidine (thU, thC) analogs, all derived from thieno[3,4-d]pyrimidine as the heterocyclic nucleus, was a major breakthrough. To further augment functionality, a second-generation emissive RNA alphabet based on an isothiazolo[4,3-d]pyrimidine core (thA, tzG, tzU, and tzC) was fabricated. This single-atom mutagenesis restored the basic/coordinating nitrogen corresponding to N7 in the purine skeleton and elevated biological recognition.The isomorphic emissive nucleosides and nucleotides, particularly the purine analogs, serve as substrates for diverse enzymes. Beyond polymerases, we have challenged the emissive analogs with metabolic and catabolic enzymes, opening optical windows into the biochemistry of nucleosides and nucleotides as metabolites as well as coenzymes and second messengers. Real-time fluorescence-based assays for adenosine deaminase, guanine deaminase, and cytidine deaminase have been fabricated and used for inhibitor discovery. Emissive cofactors (e.g., SthAM), coenzymes (e.g., NtzAD+), and second messengers (e.g., c-di-tzGMP) have been enzymatically synthesized, using xyNTPs and native enzymes. Both their biosynthesis and their transformations can be fluorescently monitored in real time.Highly isomorphic and isofunctional emissive surrogates can therefore be fabricated and judiciously implemented. Beyond their utility, side-by-side comparison to established analogs, particularly to 2-aminopurine, the workhorse of nucleic acid biophysics over 5 decades, has proven prudent as they refined the scope and limitations of both the new analogs and their predecessors. Challenges, however, remain. Associated with such small heterocycles are relatively short emission wavelengths and limited brightness. Recent advances in multiphoton spectroscopy and further structural modifications have shown promise for overcoming such barriers.

We disclose herein a novel and general radical approach to alkylthiopurines, encompassing 4 types of thiopurines, as well as their corresponding ribosides. This strategy is achieved through visible light‐mediated late‐stage functionalization of the sulfur atoms of mercaptopurines. The in situ‐generated disulfide was proposed as the pivotal neutral intermediate for this transformation. We present herein a novel photo‐mediated homolytic C−S bond formation for the preparation of alkylthiopurines and alkylthiopurine nucleosides. Despite the presence of reactive sites for the Minisci reaction, chemoselective S‐alkylation remained the predominant pathway. This method allows for the late‐stage introduction of a broad spectrum of alkyl groups onto the sulfur atom of unprotective mercaptopurine derivatives, encompassing 2‐, 6‐, and 8‐mercaptopurine rings. Organoborons serve as efficient and eco‐friendly alkylating reagents, providing advantages in terms of readily availability, stability, and reduced toxicity. Further derivatization of the thioetherified nucleosides, together with anti‐tumor assays, led to the discovery of potent anti‐tumor agents with an IC50 value reaching 6.1 μM (Comp. 31 for Jurkat). [ABSTRACT FROM AUTHOR]

ABSTRACT Synthesis of 5‐alkynyl furopyrimidine nucleoside analogs, with free‐ribose groups, was carried out, and their biological activity was evaluated. The substituents introduced at the C‐5 included propargyl and homopropargyl alcohols, 4‐methylphenyl (p‐tolyl), and 4‐pentylphenyl substituted alkynyl groups (56%–88%). Subsequently, alkyne function was coordinated to dicobalt hexacarbonyl unit, yielding the corresponding dicobalt hexacarbonyl 5‐alkynyl furopyrimidine nucleosides (51%–75%). All compounds contained 4‐pentylphenyl group attached at the C‐6 position of the bicyclic base, in line with most active antiviral structures. The antiproliferative effect of these modified nucleosides on cancer cells of different phenotypes was determined using in vitro studies. The tested compounds show antiproliferative effects with median inhibitory concentration (IC50) values of 16–23 and 9–15 μM for HeLa and K562 cells. The determination of reactive oxygen species (ROS) formation in K562 cells in the presence of modified nucleosides may suggest that the mode of action of the examined compounds may be attributed to the induction of oxidative stress. [ABSTRACT FROM AUTHOR]

A regiospecific synthesis of N9‐alkylated purines as novel acyclic nucleosides was developed. This approach is based on reconstructive methodology involving the construction of a target heterocyclic scaffold on a readily available 5‐aminotetrazole moiety, which is subsequently cleaved under reductive conditions due to azido‐tetrazole tautomerism. It appeared that the rate of reduction for the azide fragment in 6‐nitro‐7‐alkylaminotetrazolo[1,5‐a]pyrimidines is much greater than the rate of nitro group reduction. Treatment of these heterocycles with hydrogen over a palladium catalyst resulted in the formation of triaminopyrimidines in excellent yields through the reduction of both the azide and nitro group. Triaminopyrimidines were transformed into the desired N9‐alkylated purines, and an analog of the marketed drug penciclovir was synthesized by the developed method. [ABSTRACT FROM AUTHOR]

Catalysis has been at the forefront of the developments that has revolutionised synthesis and provided the impetus in the discovery of platform technologies for efficient C−C or C−X bond formation. Current environmental situation however, demands a change in strategy with catalysis being promoted more in solvents that are benign (Water) and for that the development of hydrophilic ligands (especially phosphines) is a necessity which could promote catalytic reactions in water, allow recyclability of the catalytic solutions and make it possible to isolate products using column‐free techniques that involve lesser usage of hazardous organic solvents. In this review, we therefore critically analyse such catalytic processes providing examples that do follow the above‐mentioned parameter. [ABSTRACT FROM AUTHOR]

Nucleosides, nucleotides, and their analogues are an important class of molecules that are used as substrates in research of enzymes and nucleic acid, or as antiviral and antineoplastic agents. Nucleoside phosphorylation is usually achieved with chemical methods; however, enzymatic phosphorylation is a viable alternative. Here, we present a chemoenzymatic synthesis of modified cytidine monophosphates, where a chemical synthesis of novel N4-modified cytidines is followed by an enzymatic phosphorylation of the nucleosides by nucleoside kinases. To enlarge the substrate scope, multiple mutant variants of Drosophila melanogaster deoxynucleoside kinase (DmdNK) (EC:2.7.1.145) and Bacillus subtilis deoxycytidine kinase (BsdCK) (EC:2.7.1.74) have been created and tested. It has been determined that certain point mutations in the active sites of the kinases alter their substrate specificities noticeably and allow phosphorylation of compounds that had been otherwise not phosphorylated by the wild-type DmdNK or BsdCK. [ABSTRACT FROM AUTHOR]

The reagent system based on the combined use of Et3SiH/I2 acts as an efficient N-glycosidation promoter for the synthesis of natural and sugar-modified nucleosides. An analysis of reaction stereoselectivity in the absence of C2-positioned stereodirecting groups revealed high selectivity with six-membered substrates, depending on the nucleophilic character of the nucleobase or based on anomerization reactions. The synthetic utility of the Et3SiH/I2-mediated N-glycosidation reaction was highlighted by its use in the synthesis of the investigational drug apricitabine. [ABSTRACT FROM AUTHOR]

APOBEC proteins are cytidine deaminases that restrict the replication of viruses and transposable elements. Several members of the APOBEC3 family, APOBEC3A, APOBEC3B, and APOBEC3H-I, can access the nucleus and cause what is thought to be indiscriminate deamination of the genome, resulting in mutagenesis and genome instability. Although APOBEC3C is also present in the nucleus, the full scope of its deamination target preferences is unknown. By expressing human APOBEC3C in a yeast model system, I have defined the APOBEC3C mutation signature, as well as the preferred genome features of APOBEC3C targets. The APOBEC3C mutation signature is distinct from those of the known cancer genome mutators APOBEC3A and APOBEC3B. APOBEC3C produces DNA strand-coordinated mutation clusters, and APOBEC3C mutations are enriched near the transcription start sites of active genes. Surprisingly, APOBEC3C lacks the bias for the lagging strand of DNA replication that is seen for APOBEC3A and APOBEC3B. The unique preferences of APOBEC3C constitute a mutation profile that will be useful in defining sites of APOBEC3C mutagenesis in human genomes. [ABSTRACT FROM AUTHOR]

Glaesserella parasuis (G. parasuis) induces vascular damage and systemic inflammation. However, the mechanism by which it causes vascular damage is currently unclear. Baicalin has important anti-inflammatory, antibacterial and immunomodulatory functions. In this study, we explored the ability of baicalin and probenecid to protect against G. parasuis challenge in a piglet model. Sixty piglets were randomly divided into a control group; an infection group; a probenecid group; and 25 mg/kg, 50 mg/kg and 100 mg/kg baicalin groups. The probenecid group and the 25 mg/kg, 50 mg/kg and 100 mg/kg baicalin groups were injected intramuscularly with 20 mg/kg body weight (BW) probenecid and 25 mg/kg BW, 50 mg/kg BW and 100 mg/kg BW baicalin, respectively. All piglets except those from the control group were injected intraperitoneally with 1 × 108 CFU of G. parasuis. The control group was injected intraperitoneally with TSB. The results showed baicalin and probenecid protected piglets against G. parasuis challenge, improved body weight and decreased temperature changes in piglets. Baicalin and probenecid attenuated IL-1β, IL-10, IL-18, TNF-α and IFN-γ mRNA levels in the blood for 48 h, inhibited the production of the nucleosides ATP, ADP, AMP and UMP from 24 to 72 h, reduced Panx-1/P2Y6/P2X7 expression, weakened NF-kB, AP-1, NLRP3/Caspase-1 and ROCK/MLCK/MLC signalling activation, and upregulated VE-cadherin expression in the blood vessels of piglets challenged with G. parasuis. Baicalin and probenecid alleviated pathological tissue damage in piglets induced by G. parasuis. Our results might provide a promising strategy to control and treat G. parasuis infection in the clinical setting. [ABSTRACT FROM AUTHOR]

Nucleosides find applications in medicinal chemistry, chemical biology and diagnostics. Among the nucleosides, C‐nucleosides have attracted particular attention because their carbon‐carbon bond between nucleobase and ribose provides stability against degradation. While several well‐established methods exist for the synthesis of 2′‐deoxy‐C‐nucleosides, the preparation of their ribofuranosyl counterparts is more challenging. Established methods for their synthesis give mixtures of anomers and require harsh reagents or conditions. Here we report a diastereoselective glycosylation method involving a Heck reaction between a glycal and an aryl iodide, followed by oxidation of the silyl enol ether with methyl(trifluoromethyl)dioxirane (TFDO). The resulting ketone is then diastereoselectively reduced to the ribonucleoside. The new route has been applied to pyridones and is expected to also yield other ribo‐C‐nucleosides in diastereoselective fashion. [ABSTRACT FROM AUTHOR]

In this report, we show that a very common modification (especially in tRNA), dihydrouridine, was efficiently produced by photoreduction of the canonical pyrimidine ribonucleoside, uridine in formamide. Formamide not only acts as a solvent in this reaction, but also as the reductant. The other three components of the canonical alphabet (C, A, G) remained intact under the same conditions, suggesting that dihydrouridine might have coexisted with all four canonical RNA nucleosides (C, U, A, G) at the dawn of life. [ABSTRACT FROM AUTHOR]

AbstractNucleosides and nucleobases in edible mushrooms collected from the Tekirdağ region of Turkey were determined by high performance liquid chromatography (HPLC). Separation of compounds was accomplished by gradient elution on a C18 column. A mixture of methanol (MeOH):50 mM sodium phosphate buffer (1:99, v/v) at pH 3.70 and methanol:50 mM sodium phosphate buffer (20:80) at pH 6.20 was used as the solvent. Two methods were used to treat the lyophilized mushrooms: ultrasound-assisted solid-liquid extraction (US-SLE) and pressurized (accelerated) solid-liquid extraction (PSLE). Deionized water was used as the extraction solvent. The extraction temperature and time were optimized. Fourteen nucleosides and nucleobases were simultaneously monitored at 254 nm within 25 min. Ultrasound-assisted solid-liquid was demonstrated to be more effective, perhaps because the pressurized liquid extraction system is a closed system and the matrix-solvent interaction may be insufficient. Adenosine, guanosine and uridine were the most abundant compounds in all studied mushrooms. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Yeast culture (YC) is a product fermented on a specific medium, which is a type of postbiotic of anaerobic solid‐state fermentation. Although YC has positive effects on the animal growth and health, it contains a variety of beneficial metabolites as dark matter, which have not been quantified. In the present study, liquid chromatography‐tandem mass spectrometry is employed to identify the unknown metabolites. Following their identification, the important chemicals are quantified using HPLC‐diode array detection methods.Non‐targeted metabolomics studies showed that 670 metabolites in total were identified in YC, of which 23 metabolites significantly increased, including organic acids, amino acids, nucleosides and purines, isoflavones, and other substances. The chemical quantitative analysis showed that the contents of succinic acid, aminobutyric acid, glutamine, purine and daidzein increased by 84.42%, 51.07%, 100%, 68.85% and 4.60%, respectively.Therefore, the use of non‐targeted metabolomics combined with chemical quantitative analysis to reveal the nutritional and functional substances of YC could help to elucidate the postbiotic mechanism and provide theoretical support for the regulation of the directional accumulation of beneficial metabolites. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Oral health problems have increased among older adults. Oral hypofunction is characterized by seven signs and symptoms: oral uncleanness, oral dryness, decline in occlusal force, decline in the movement function of the tongue and lips, decline in tongue pressure, decline in masticatory function, and decline in swallowing function, the latter being a significant risk factors for oral frailty. Recent research has suggested that salivary biomarkers can be used to assess not only oral diseases, including dental caries and periodontitis, but also systemic diseases, such as cancer and diabetes mellitus. This cross-sectional study investigated the relationship between oral hypofunction and the levels of salivary biomarkers. Methods: In total, 116 patients, aged 65 years or older, were included in this cross-sectional study. If three or more signs or symptoms in seven kinds of tests met the criteria of each test, oral hypofunction was diagnosed. The levels of biomarkers in the saliva collected from the patients were analyzed using an enzyme-linked immunosorbent assay. Results: In total, 63.8% of patients were diagnosed with oral hypofunction. Multivariable linear regression analysis showed that calprotectin levels in the saliva were significantly related to oral moisture and masticatory function. Furthermore, 8-OHdG levels in saliva were associated with the movement function of the tongue and lips and oral hygiene level, and salivary AGE correlated only with the movement function of the tongue and lips. Multiple logistic regression analysis revealed that calprotectin levels in the saliva were significantly correlated with the prevalence of oral hypofunction, even after adjusting for age, sex, and periodontal status. However, none of the biomarker levels in the saliva had a significant relationship with the number of examinations outside the reference range. Conclusions: Calprotectin, 8-OHdG, and AGE levels are associated with oral hypofunction in older adults. [ABSTRACT FROM AUTHOR]

Enzymatic transglycosylation of the fleximer base 4-(4-aminopyridine-3-yl)-1H-pyrazole using recombinant E. coli purine nucleoside phosphorylase (PNP) resulted in the formation of "non-typical" minor products of the reaction. In addition to "typical" N1-pyrazole nucleosides, a 4-imino-pyridinium riboside and a N1-pyridinium-N1-pyrazole bis-ribose derivative were formed. N1-Pyrazole 2′-deoxyribonucleosides and a N1-pyridinium-N1-pyrazole bis-2′-deoxyriboside were formed. But 4-imino-pyridinium deoxyriboside was not formed in the reaction mixture. The role of thermodynamic parameters of key intermediates in the formation of reaction products was elucidated. To determine the mechanism of binding and activation of heterocyclic substrates in the E. coli PNP active site, molecular modeling of the fleximer base and reaction products in the enzyme active site was carried out. As for N1-pyridinium riboside, there are two possible locations for it in the PNP active site. The presence of a relatively large space in the area of amino acid residues Phe159, Val178, and Asp204 allows the ribose residue to fit into that space, and the heterocyclic base can occupy a position that is suitable for subsequent glycosylation. Perhaps it is this "upside down" arrangement that promotes secondary glycosylation and the formation of minor bis-riboside products. [ABSTRACT FROM AUTHOR]

1,2,4-Triazole derivatives have a wide range of biological activities. The most well-known drug that contains 1,2,4-triazole as part of its structure is the nucleoside analogue ribavirin, an antiviral drug. Finding new nucleosides based on 1,2,4-triazole is a topical task. The aim of this study was to synthesize ribosides and deoxyribosides of 1,2,4-triazole-3-thione derivatives and test their antiviral activity against herpes simplex viruses. Three compounds from a series of synthesized mono- and disubstituted 1,2,4-triazole-3-thione derivatives were found to be substrates for E. coli purine nucleoside phosphorylase. Of six prepared nucleosides, the riboside and deoxyriboside of 3-phenacylthio-1,2,4-triazole were obtained at good yields. The yields of the disubstituted 1,2,4-triazol-3-thiones were low due to the effect of bulky substituents at the C3 and C5 positions on the selectivity of enzymatic glycosylation for one particular nitrogen atom in the triazole ring. The results of cytotoxic and antiviral studies on acyclovir-sensitive wild-type strain HSV-1/L2(TK+) and acyclovir-resistant strain (HSV-1/L2/RACV) in Vero E6 cell culture showed that the incorporation of a thiobutyl substituent into the C5 position of 3-phenyl-1,2,4-triazole results in a significant increase in the cytotoxicity of the base and antiviral activity. The highest antiviral activity was observed in the 3-phenacylthio-1-(β-D-ribofuranosyl)-1,2,4-triazole and 5-butylthio-1-(2-deoxy-β-D-ribofuranosyl)-3-phenyl-1,2,4-triazole nucleosides, with their selectivity indexes being significantly higher than that of ribavirin. It was also found that with the increasing lipophilicity of the nucleosides, the activity and toxicity of the tested compounds increased. [ABSTRACT FROM AUTHOR]

Purpose: To study the correlations of genetic variants of telbivudine phosphorylase kinases and telbivudine plasma concentration with creatine kinase elevation in chronic hepatitis B patients who received telbivudine. Methods: An observational study was performed in China chronic hepatitis B patients receiving telbivudine therapy at 600 mg once daily. Plasma concentration was measured 12 h after taking telbivudine using ultra-performance liquid chromatography–tandem mass spectrometry and SNPs located in RRM2B, TK2, and NME4 was detected by MALDI-TOF mass spectrometry. All statistical analyses were performed with R 4.3.1 and all graphs were drawn by Origin 2023b and P value < 0.05 was considered statistically significant. Results: A total of 140 patients receiving telbivudine therapy were recruited with a median plasma concentration of 952.49 (781.07–1238.98) ng/mL. The value of plasma concentration was proportional to the grade of creatine kinase elevation and the best telbivudine plasma concentration threshold to discriminate the grade 3/4 CK elevation was 1336.61 ng/mL. Multivariate analysis revealed that plasma concentration and rs3826160 were the independent risk factor of telbivudine-induced creatine kinase elevation. Patients with TC and CC genotype in rs3826160 not only had a higher incidence of creatine kinase elevation but also a higher plasma concentration than TT genotype carriers. Conclusion: Chronic hepatitis B patients with TC and CC genotype in rs3826160 have high telbivudine plasma concentration are at risk of elevated creatine kinase. [ABSTRACT FROM AUTHOR]

The abiotic formation of nucleotides from small, simple molecules is of large interest in the context of elucidating the origin of life scenario. In what follows, it is shown that nucleosides and nucleotides can be formed from formamide in a one-pot reaction utilizing the mineral cerium phosphate (CePO4) as a photocatalyst, a catalyst and a reactant that supplies the necessary phosphate groups. While the most abundant RNA/DNA building blocks were thymidine and thymidine monophosphate, considerable yields of other building blocks such as cytidine, cytidine monophosphate, and adenosine cyclic monophosphate were found. Comparing the yield of nucleosides and nucleotides under light conditions to that in the dark suggests that in the presence of cerium phosphate, light promotes the formation of nucleobases, whereas the formation of nucleotides from nucleosides take place even in the absence of light. The scenario described herein is considerably simpler than other scenarios involving several steps and several reactants. Therefore, by virtue of the principle of Occam's razor, it should be of large interest for the community. [ABSTRACT FROM AUTHOR]

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Broad spectrum oral antivirals are urgently needed for the early treatment of many RNA viruses of clinical concern. We previously described the synthesis of 1-O-octadecyl-2-O-benzyl-glycero-3-phospho-RVn (V2043), an orally bioavailable lipid prodrug of remdesivir nucleoside (RVn, GS-441524) with broad spectrum antiviral activity against viruses with pandemic potential. Here we compared the relative activity of V2043 with new RVn lipid prodrugs containing sn-1 alkyl ether or sn-2 glycerol modifications. We found that 3-F-4-MeO-Bn, 3-CN-Bn, and 4-CN-Bn sn-2 glycerol modifications improved antiviral activity compared to V2043 when tested in vitro against clinically important RNA viruses from 5 virus families. These results support the continued development of V2043 and sn-2 glycerol modified RVn lipid prodrugs for the treatment of a broad range of RNA viruses for which there are limited therapies.

Comprehensive Summary: HpnG plays a crucial role in the production of ribosylhopane, a key intermediate in the biosynthesis of bacteriohopanepolyol. Despite early extensive studies, the precise function of HpnG has remained elusive. Here, we report functional characterization of HpnG as a purine nucleoside phosphorylase, which converts adenosylhopane to phosphoribosylhopane in the presence of phosphate. HpnG demonstrates broad substrate specificity and impressive stability, making it a valuable enzymatic tool for applications in nucleoside processing and related biotechnology. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: HpnG plays a crucial role in the production of ribosylhopane, a key intermediate in the biosynthesis of bacteriohopanepolyol. Despite early extensive studies, the precise function of HpnG has remained elusive. Here, we report functional characterization of HpnG as a purine nucleoside phosphorylase, which converts adenosylhopane to phosphoribosylhopane in the presence of phosphate. HpnG demonstrates broad substrate specificity and impressive stability, making it a valuable enzymatic tool for applications in nucleoside processing and related biotechnology. [ABSTRACT FROM AUTHOR]

Hyperuricemia is a metabolic disease caused by uric acid metabolism disorder. Lactic acid bacteria as an important probiotic could ameliorate hyperuricemia in multiple ways. The study aimed to isolate lactic acid bacteria with capable to degrade nucleosides efficiently from pickles. The nucleoside degradation ability of the screened strains was analysed by using high performance liquid chromatography (HPLC), then the xanthine oxidase inhibition by strains, environmental tolerance in vitro and antibiotic susceptibility were also tested. Results showed that the degradation rate of inosine and guanosine by lactobacillus brevis SLlac-18 were 97.81% and 97.89%, respectively, and xanthine oxidase inhibition of strains were also existed. In addition, the survival rate of SLlac-18 was 96% at pH 2.0, 96.33% at 3 g/L bile salt for 5 h, and 96.33% at gastrointestinal fluid for 5 h. SLlac-18 was also highly tolerant to the treatment of gastrointestinal fluids with a survival rate of more than 90%, and was susceptible to four common antibiotics such as erythromycin and ampicillin. lactobacillus brevis SLlac-18 has the potential function to degrade uric acid, which can be applied to the prevention and treatment of hyperuricemia, that has certain application value. [ABSTRACT FROM AUTHOR]

In this study, we have developed a metal‐mediated synthetic method for incorporating the 1,1,2,2‐tetrafluoroethyl (CF2CF2H) motif into unactivated, electron‐rich alkenyl iodides using cross‐coupling reactions. We discovered that the stable Cu(CF2CF2H)(PPh2Me)3 complex, while unreactive with these substrates, serves as a P‐ligated reservoir for the formation of solvent‐stabilized "ligandless" and reactive CuCF2CF2H species. This transformation occurs upon addition of CuBr, which partially scavenges the P‐ligand in the form of CuBr(PPh2Me)3. The resulting in situ generated solvent stabilized "ligandless" system significantly enhances the reactivity of the complex, particularly towards challenging electron‐rich substrates. This advancement enables the synthesis of HCF2CF2‐glycals, as well as nucleosides/nucleobases and arenes. [ABSTRACT FROM AUTHOR]

Herein, we report an in‐situ mild and metal‐free protocol for thiomethylation of heteroarenes in high yields. The thiomethylation of various chloropurines, nucleosides, and chloroheteroarenes has been accomplished offering easy access to agrochemicals and synthetic molecules useful for drug discovery. [ABSTRACT FROM AUTHOR]

Background Bemnifosbuvir (AT-527) is a novel oral guanosine nucleotide antiviral drug for the treatment of persons with COVID-19. Direct assessment of drug disposition in the lungs, via bronchoalveolar lavage, is necessary to ensure antiviral drug levels at the primary site of SARS-CoV-2 infection are achieved. Objectives This Phase 1 study in healthy subjects aimed to assess the bronchopulmonary pharmacokinetics, safety and tolerability of repeated doses of bemnifosbuvir. Methods A total of 24 subjects were assigned to receive bemnifosbuvir twice daily at doses of 275, 550 or 825 mg for up to 3.5 days. Results AT-511, the free base of bemnifosbuvir, was largely eliminated from the plasma within 6 h post dose in all dosing groups. Antiviral drug levels of bemnifosbuvir were consistently achieved in the lungs with bemnifosbuvir 550 mg twice daily. The mean level of the guanosine nucleoside metabolite AT-273, the surrogate of the active triphosphate metabolite of the drug, measured in the epithelial lining fluid of the lungs was 0.62 µM at 4–5 h post dose. This exceeded the target in vitro 90% effective concentration (EC90) of 0.5 µM for antiviral drug exposure against SARS-CoV-2 replication in human airway epithelial cells. Bemnifosbuvir was well tolerated across all doses tested, and most treatment-emergent adverse events reported were mild in severity and resolved. Conclusions The favourable pharmacokinetics and safety profile of bemnifosbuvir demonstrates its potential as an oral antiviral treatment for COVID-19, with 550 mg bemnifosbuvir twice daily currently under further clinical evaluation in persons with COVID-19. [ABSTRACT FROM AUTHOR]

Nucleoside analogs (NAs) have been extensively examined as plausible antiviral agents in recent years, in particular since the outbreak of the global pandemic of COVID-19 in 2019. In this review, the structures and antiviral properties of over 450 NAs are collected according to the type of virus, namely SARS-CoV, SARS-CoV-2, MERS-CoV, HCoV-OC43, HCoV-229E, and HCoV-NL63. The activity of the NAs against HCoV-related enzymes is also presented. Selected studies dealing with the mode of action of the NAs are discussed in detail. The repurposing of known NAs appears to be the most extensively investigated scientific approach towards efficacious anti-HCoV agents. The recently reported de novo-designed NAs seem to open up additional approaches to new drug candidates. [ABSTRACT FROM AUTHOR]

New homodimers of 1,2,3-triazolyl nucleoside analogs based on 6-methyluracil, which are linked by the polymethylene linker at the N(1) or N(3) atoms, were synthesized. Screening of in vitro antiviral activity against influenza A virus (H1N1) and Coxsackievirus B3 revealed the lead compound that in vitro inhibited the replication of Coxsackievirus B3 with a half-maximal inhibitory concentration (IC50) and a half-maximal cytotoxic concentration (CC50) of 30.1 and >374 µmol L−1, respectively. A dependence of the antiviral activity on the length of the polymethylene linker connecting the 6-methyluracil and 1,2,3-triazolyl-β-d-ribofuranosyl fragments was found. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has been a major reason behind the increased research aimed at the identification of effective antiviral agents. Among these, Nucleoside analogs have shown a promising effect on the inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus replication, the pathogen of COVID-19. Nucleoside analogs are synthetic compounds designed to mimic natural nucleosides, the building blocks of RNA and DNA. This review provides a comprehensive examination of the pivotal role nucleoside analogs play in combating SARS-CoV-2 infections. These analogs function by incorporating into the viral RNA during replication, disrupting the synthesis process and preventing the virus from proliferating. Researchers have identified multiple nucleoside analogs exhibiting robust antiviral efficacy against SARS-CoV-2, including remdesivir, favipiravir, and molnupiravir. This review explores the mechanisms of action, pharmacokinetics, and safety profiles of these nucleoside analogs. Furthermore, it discusses the challenges and limitations associated with their use, including the emergence of resistant viral strains and potential side effects. Additionally, the review delves into ongoing research efforts to optimize nucleoside analogs for enhanced efficacy and reduced adverse effects. In summary, the article aims to enhance our overall understanding of nucleoside-based treatments by combining information about their chemistry, mechanisms of action, and activation pathways. The goal is to contribute to advancements in addressing emerging viral threats in the future. [ABSTRACT FROM AUTHOR]

The bacterial communities related to seaweed can vary considerably across different locations, and these variations influence the seaweed's nutrition, growth, and development. To study this further, we evaluated the bacteria found on the green marine seaweed Ulva prolifera from Garorim Bay and Muan Bay, two key locations on Republic of Korea's west coast. Our analysis found notable differences in the bacterial communities between the two locations. Garorim Bay hosted a more diverse bacterial population, with the highest number of ASVs (871) compared to Muan Bay's 156 ASVs. In Muan Bay, more than 50% of the bacterial community was dominated by Pseudomonadota. On the other hand, Garorim Bay had a more balanced distribution between Bacteroidota and Pseudomonadota (37% and 35.5%, respectively). Additionally, Cyanobacteria, particularly Cyanothece aeruginosa, were found in significant numbers in Garorim Bay, making up 8% of the community. Mineral analysis indicated that Garorim Bay had higher levels of S, Na, Mg, Ca, and Fe. Function-wise, both locations exhibited bacterial enrichment in amino acid production, nucleosides, and nucleotide pathways. In conclusion, this study broadens our understanding of the bacterial communities associated with Ulva prolifera in Korean waters and provides a foundation for future research on the relationships between U. prolifera and its bacteria. [ABSTRACT FROM AUTHOR]

Cordyceps cicadae, as a new food ingredient, is a valuable edible and medicinal fungi. However, its resources are severely depleted due to environmental limitations and excessive harvesting practices. N6-(2-hydroxyethyl) adenosine (HEA), as an important product of Cordyceps cicadae, has the potential to be used in medical industry due to its diverse disease curing potential. However, the disclosure of HEA synthesis still severely limited its application until now. In this study, the kinetic curves for adenosine and HEA under shaker fermentation were explored. The kinetics of HEA and adenosine production exhibited a competitive pattern, implicating a possibility of sharing a same step during their synthesis. Due to HEA as a derivative of nitrogen metabolism, the effect of different nitrogen sources (peptone, yeast extract, ammonium sulfate, diammonium oxalate monohydrate, ammonium citrate dibasic, and ammonium citrate tribasic) on HEA production in Cordyceps cicadae strain AH 10-4 had been explored under different incubation conditions (shaker fermentation, stationary fermentation, and submerged fermentation). Our results indicated that the complex organic nitrogen sources were found to improve the accumulation of HEA content under shaker fermentation. In contrast, the optimal nitrogen source for the accumulation of HEA under stationary fermentation and submerged fermentation was ammonium citrate tribasic. But submerged fermentation obviously shortened the incubation time and had a comparable capacity of HEA accumulation by 2.578 mg/g compared with stationary fermentation of 2.535 mg/g, implicating a possibility of scaled-up production of HEA in industry by submerged fermentation. Based on the dramatic HEA production by ammonium sulfate as nitrogen resources between stationary and shaker fermentations, alanine, aspartate and glutamate as well as arginine metabolic pathway were related to the production of HEA by comparative transcriptome. Further investigation indicated that glutamic acid, which is an analog of Asp, showed an optimum production of HEA in comparison with other amino acids. [ABSTRACT FROM AUTHOR]

Ribonucleic acids (RNAs) play a vital role in living organisms. Many of their cellular functions depend critically on chemical modification. Methods to modify RNA in a controlled manner—both in vitro and in vivo—are thus essential to evaluate and understand RNA biology at the molecular and mechanistic levels. The diversity of modifications, combined with the size and uniformity of RNA (made up of only 4 nucleotides) makes its site‐specific modification a challenging task that needs to be addressed by complementary approaches. One such approach is solid‐phase RNA synthesis. We discuss recent developments in this field, starting with new protection concepts in the ongoing effort to overcome current size limitations. We continue with selected modifications that have posed significant challenges for their incorporation into RNA. These include deazapurine bases required for atomic mutagenesis to elucidate mechanistic aspects of catalytic RNAs, and RNA containing xanthosine, N4‐acetylcytidine, 5‐hydroxymethylcytidine, 3‐methylcytidine, 2′‐OCF3, and 2′‐N3 ribose modifications. We also discuss the all‐chemical synthesis of 5′‐capped mRNAs and the enzymatic ligation of chemically synthesized oligoribonucleotides to obtain long RNA with multiple distinct modifications, such as those needed for single‐molecule FRET studies. Finally, we highlight promising developments in RNA‐catalyzed RNA modification using cofactors that transfer bioorthogonal functionalities. [ABSTRACT FROM AUTHOR]

The rhizosphere is a complex ecosystem, consisting of a narrow soil zone influenced by plant roots and inhabited by soil-bornemicroorganisms. Plants actively shape the rhizosphere microbiome through root exudates. Some metabolites are signaling molecules specifically functioning as chemoattractants rather than nutrients. These elusive signaling molecules have been sought for several decades, and yet little progress has been made. Root-secreted nucleosides and deoxynucleosides were detected in exudates of various plants by targeted ultra-performance liquid chromatography-mass spectrometry/mass spectrometry. Rhizobacteria were isolated from the roots of Helianthemum sessiliflorum carrying the mycorrhizal desert truffle Terfezia boudieri. Chemotaxis was determined by a glass capillary assay or plate assays on semisolid agar and through a soil plate assay. Nucleosides were identified in root exudates of plants that inhabit diverse ecological niches. Nucleosides induced positive chemotaxis in plant beneficial bacteria Bacillus pumilus, Bacillus subtilis, Pseudomonas turukhanskensis spp., Serratia marcescens, and the pathogenic rhizobacterium Xanthomonas campestris and E coli. In a soil plate assay, nucleosides diffused to substantial distances and evoked chemotaxis under conditions as close as possible to natural environments. This study implies that root-secreted nucleosides are involved in the assembly of the rhizosphere bacterial community by inducing chemotaxis toward plant roots. In animals, nucleoside secretion known as "purinergic signaling" is involved in communication between cells, physiological processes, diseases, phagocytic cell migration, and bacterial activity. The coliform bacterium E. coli that inhabits the lower intestine of warmblooded organisms also attracted to nucleosides, implying that nucleosides may serve as a common signal for bacterial species inhabiting distinct habitats. Taken together, all these may indicate that chemotaxis signaling by nucleosides is a conserved universal mechanism that encompasses living kingdoms and environments and should be given further attention in plant rhizosphere microbiome research. [ABSTRACT FROM AUTHOR]

The FDA has approved several drugs based on the fluorinated nucleoside pharmacophore, and numerous drugs are currently in clinical trials. Fluorine-containing nucleos(t)ides offer significant antiviral and anticancer activity. The insertion of a fluorine atom, either in the base or sugar of nucleos(t)ides, alters its electronic and steric parameters and transforms the lipophilicity, pharmacodynamic, and pharmacokinetic properties of these moieties. The fluorine atom restricts the oxidative metabolism of drugs and provides enzymatic metabolic stability towards the glycosidic bond of the nucleos(t)ide. The incorporation of fluorine also demonstrates additional hydrogen bonding interactions in receptors with enhanced biological profiles. The present article discusses the synthetic methodology and antiviral activities of FDA-approved drugs and ongoing fluoro-containing nucleos(t)ide drug candidates in clinical trials. [ABSTRACT FROM AUTHOR]

Azido-modified nucleosides have been extensively explored as substrates for click chemistry and the metabolic labeling of DNA and RNA. These compounds are also of interest as precursors for further synthetic elaboration and as therapeutic agents. This review discusses the chemistry of azidonucleosides related to the generation of nitrogen-centered radicals (NCRs) from the azido groups that are selectively inserted into the nucleoside frame along with the subsequent chemistry and biological implications of NCRs. For instance, the critical role of the sulfinylimine radical generated during inhibition of ribonucleotide reductases by 2′-azido-2′-deoxy pyrimidine nucleotides as well as the NCRs generated from azidonucleosides by radiation-produced (prehydrated and aqueous) electrons are discussed. Regio and stereoselectivity of incorporation of an azido group ("radical arm") into the frame of nucleoside and selective generation of NCRs under reductive conditions, which often produce the same radical species that are observed upon ionization events due to radiation and/or other oxidative conditions that are emphasized. NCRs generated from nucleoside-modified precursors other than azidonucleosides are also discussed but only with the direct relation to the same/similar NCRs derived from azidonucleosides. [ABSTRACT FROM AUTHOR]

Inherited deficiency of thymidine phosphorylase (TP), encoded by TYMP, leads to a rare disease with multiple mitochondrial DNA (mtDNA) abnormalities, mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). However, the impact of TP deficiency on lysosomes remains unclear, which are important for mitochondrial quality control and nucleic acid metabolism. Muscle biopsy tissue and skin fibroblasts from MNGIE patients, patients with m.3243 A > G mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and healthy controls (HC) were collected to perform mitochondrial and lysosomal functional analyses. In addition to mtDNA abnormalities, compared to controls distinctively reduced expression of LAMP1 and increased mitochondrial content were detected in the muscle tissue of MNGIE patients. Skin fibroblasts from MNGIE patients showed decreased expression of LAMP2, lowered lysosomal acidity, reduced enzyme activity and impaired protein degradation ability. TYMP knockout or TP inhibition in cells can also induce the similar lysosomal dysfunction. Using lysosome immunoprecipitation (Lyso- IP), increased mitochondrial proteins, decreased vesicular proteins and V-ATPase enzymes, and accumulation of various nucleosides were detected in lysosomes with TP deficiency. Treatment of cells with high concentrations of dThd and dUrd also triggers lysosomal dysfunction and disruption of mitochondrial homeostasis. Therefore, the results provided evidence that TP deficiency leads to nucleoside accumulation in lysosomes and lysosomal dysfunction, revealing the widespread disruption of organelles underlying MNGIE. [ABSTRACT FROM AUTHOR]

Brain astrocytes are well known for their broad metabolic potential. After glucose deprivation, cultured primary astrocytes maintain a high cellular ATP content for many hours by mobilizing endogenous substrates, but within 24 h the specific cellular ATP content was lowered to around 30% of the initial ATP content. This experimental setting was used to test for the potential of various exogenous substrates to prevent a loss in cellular ATP in glucose deprived astrocytes. The presence of various extracellular monocarboxylates, purine nucleosides or fatty acids prevented the loss of ATP from glucose-deprived astrocytes. Of the 20 proteinogenic amino acids, only alanine, aspartate, glutamate, glutamine, lysine or proline maintained high ATP levels in starved astrocytes. Among these amino acids, proline was found to be the most potent one to prevent the ATP loss. The astrocytic consumption of proline as well as the ability of proline to maintain a high cellular ATP content was prevented in a concentration-dependent manner by the proline dehydrogenase inhibitor tetrahydro-2-furoic acid. Analysis of the concentration-dependencies obtained by considering the different carbon content of the applied substrates revealed that fatty acids and proline are more potent than glucose and monocarboxylates as exogenous substrates to prevent ATP depletion in glucose-deprived astrocytes. These data demonstrate that cultured astrocytes can utilise a wide range of extracellular substrates as fuels to support mitochondrial ATP regeneration and identify proline as potent exogenous substrate for the energy metabolism of starved astrocytes. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to reveal the effect of apocynin (APO) on the factors involved in obesity-related endothelial dysfunction (ED) and atherosclerosis (AS). Materials and Methods: Male Wistar albino rats were divided into control (CNT), high-fat diet (HFD) and HFD+APO groups. HFD and HFD+APO groups were fed HFD for sixteen weeks. APO (25 mg/kg) was administered to the HFD+APO group for the last four weeks. The effects of APO on: AS-related metabolic parameters (triglyceride, total cholesterol, high-density lipoprotein-cholesterol, insulin and leptin), oxidative stress (OS), [ malondialdehyde, glutathione, nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase-2, oxidised-low-density lipoprotein (ox-LDL) and 8-hydroxy-2-deoxyguanosine], low-density lipoprotein and ox-LDL uptake potential (activin receptor-like kinase-1 and lectin-like oxidized low-density lipoprotein receptor-1, respectively), tissue inflammation (myeloperoxidase, monocyte-chemoattractant-protein-1, tumor necrosis factor-alpha), ED (endothelial-nitric oxide synthase, inducible-nitric oxide synthase, nitric oxide), programmed cell death (terminal deoxynucleotidyl-transferase-dUTP-nick-end labeling, cleaved-poly-ADP-ribose-polymerase, gasdermin-D N-terminal fragment, caspase-1), smooth muscle cell transformation (alpha-smooth muscle actin), histology and ultrastructure of thoracic aorta were evaluated. Results: In obesity, APO had an ameliorative effect on metabolic parameters, OS, inflammation, ED, programmed cell death and ox-LDL uptake potential, but not on foam cell formation and LDL uptake potential. Conclusion: Apocynin may improve ED and AS in obesity by suppressing OS-linked factors involved in the early stage of AS. [ABSTRACT FROM AUTHOR]

Highly effective oral antiviral therapy with low drug resistance can strongly inhibit HBV replication；however, some patients may still have low-level viremia (LLV) after receiving entecavir, tenofovir disoproxil fumarate, tenofovir alafenamide, or tenofovir amibufenamide for 48 weeks or more. Multiple studies in China and globally show that LLV after antiviral therapy is closely associated with the progression of chronic hepatitis B liver fibrosis, the risk of decompensated liver cirrhosis and hepatocellular carcinoma, and the reduction in long-term survival rate. Therefore, this article reviews the development, risk factors, and clinical harm of LLV after first-line treatment with nucleos (t) ide analogues, as well as different treatment regimens, in order to provide a reference for the treatment of LLV in chronic hepatitis B patients in the future. [ABSTRACT FROM AUTHOR]

Simple Summary: Acute T-lymphoblastic leukemia is a disease with a very low survival rate after relapse, and the search for new therapeutic agents is important for the clinical benefit of patients with acute T-lymphoblastic leukemia. Our study developed YLS010, a small molecule that is more sensitive to acute T-lymphoblastic leukemia cells, based on the structure of the invented small molecule YLS004. This novel small molecule demonstrated good antitumor activity in vivo and in vitro with acceptable toxicity. These findings provide a new avenue for the development of clinical drugs for patients with acute T-lymphoblastic leukemia. (1) Background: The research group has developed a new small molecule, 6-Isopropyldithio-2′-deoxyguanosine analogs-YLS004, which has been shown to be the most sensitive in acute T-lymphoblastic leukemia cells. Moreover, it was found that the structure of Nelarabine, a drug used to treat acute T-lymphoblastic leukemia, is highly similar to that of YLS004. Consequently, the structure of YLS004 was altered to produce a new small molecule inhibitor for this study, named YLS010. (2) Results: YLS010 has exhibited potent anti-tumor effects by inducing cell apoptosis and ferroptosis. A dose gradient was designed for in vivo experiments based on tentative estimates of the toxicity dose using acute toxicity in mice and long-term toxicity in rats. The study found that YLS010 at a dose of 8 mg/kg prolonged the survival of late-stage acute T-lymphoblastic leukemia mice in the mouse model study. (3) Conclusions: YLS010 has demonstrated specific killing effects against acute T-lymphoblastic leukemia both in vivo and in vitro. Preclinical studies of YLS010 offer a new opportunity for the treatment of patients with acute T-lymphoblastic leukemia in clinical settings. [ABSTRACT FROM AUTHOR]

Ectonucleotidases play an important role in regulating the level of extracellular nucleotides and nucleosides and are an important part of the regulation of the effects of adenosine and ATP on adenosine and P2 receptors, respectively. We have previously established the ambiguous effect of P2 receptor agonists on the contractile activity of smooth muscle tissue in rats with the valproate model of autism. In this work, HPLC was used to evaluate the activity of ectonucleotidases in the smooth muscle tissues of the internal organs of rats with a valproate model of autism. The activity of ectonucleotidases was significantly higher in the smooth muscle tissues of the duodenum, vas deferens, and bladder, but lower in the ileum and uterus. The results obtained make it possible to compare the activity of ectonucleotidases identified here with changes in P2 receptor-mediated contractility of smooth muscle tissues revealed in our previous experiments. [ABSTRACT FROM AUTHOR]

Azido nucleosides have been utilized for click reactions, metabolic incorporation into cellular DNA, and fluorescent imaging of live cells. Two classes of 6-azido modified uracil nucleosides; one with azido group directly attached to uracil ring and second with azido group attached via methylene linker are described. The 6-azido-2'-deoxyuridine (6-AdU) was prepared in 55% overall yield by lithiation-based regioselective C6-iodination of silyl protected 2'-deoxyuridine followed by treatment with sodium azide and deprotection with TBAF. Lithiation-based C6-alkylation of the protected uridine with methyl iodide followed by the oxidation of the 6-methyl product with selenium dioxide and the subsequent mesylation and azidation of the resulting 6-hydroxymethyl group gave after deprotection 6-azidomethyluridine (6-AmU) in 61% overall yield. Direct lithiation-based C6-hydroxymethylation followed by mesylation/azidation sequence and deprotection provided 6-AmU or 6-azidomethyl-2'-deoxyuridine (6-AmdU). Yields for the lithiation-based regioselective C6-iodination and alkylation were higher for uridine than 2'-deoxyuridine derivatives and they appear to be less dependent on the sugar protection group used. Strain promoted click reactions of 6-AdU and 6-AmdU with symmetrically fused cyclopropyl cyclooctyne (OCT) provided fluorescent triazoles. DFT-calculated dihedral angles and energy differences for the favored anti and syn conformation of 6-AdU and 6-AmdU versus their C5 azido counterparts are discussed. [ABSTRACT FROM AUTHOR]

Here we report the short synthesis of "reversed" halogenated C-nucleoside (benzimidazole) analogs. Initially, 1,2; 3,4 vicinal diols of D -galactose were acetylated with two different ketones, acetone and cyclohexanone, to furnish acetylated galacto pyranose 1a and 1b, respectively. Subsequently, pyridinium chlorochromate (PCC) was used for the oxidation of C-6 hydroxy- of 1a and 1b to aldehyde 2a and 2b in good yields. Subsequently, the acetylated β- D -galactopyranosyl C-6 aldehydes were reacted with halogen-substituted O-phenylenediamine to furnish reverse C-galactopyranosyl nucleosides 3a to 7a; 3b to 7b. Hitherto, this is the first report on the synthesis of pyranose-based reverse-position C-nucleosides. These newly synthesized C-nucleosides were identified as an anti-leishmanial agent, in vitro, against Leishmania major and Leishmania tropica. The halogen substitution on the benzimidazole moiety and lipophilicity of the acetylated group of C-nucleosides were found to be the key factors for anti-leishmanial activity. For instance, compound 3a, a non-halogenated analogue, was inactive while its bromine-substituted analogue 6a was considerably active against L. major and L. tropica with IC50 = 8.60 ± 0.04 μM and 8.3 ± 0.4 μM, respectively. Moreover, fluorinated nucleoside 4a with low lipophilicity was inactive but its analogue 4b was active against both strains L. major and L. tropica with IC50 = 24.7 ± 0.3 μM and 20.9 ± 0.4 μM, respectively. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis and evaluation of the anti-hepatitis B virus (HBV) activity of novel nucleoside derivatives. Hepatitis B is a prevalent viral disease that affects millions of people worldwide and can lead to chronic disease and liver cancer. The article describes the synthesis of a 2'-deoxy-4'-thioguanosine derivative with a cyano group at the 4'-position, which exhibited significantly more potent anti-HBV activity than the parent nucleoside. This finding could guide the development of new anti-HBV agents. [Extracted from the article]

This article provides an overview of the current strategies for the enantioselective synthesis of modified nucleosides, which have been used in the treatment of various diseases, including viruses. The focus is on the modifications that can be made to different parts of the nucleoside structure to create therapeutically useful compounds. The article discusses the latest developments in the synthesis of cyclic and acyclic nucleosides, highlighting various methods and reactions that can be used to achieve high yields and enantioselectivities. The authors also acknowledge the institutions that supported their research. [Extracted from the article]

This article discusses recent advances in the synthesis of 5-(hetero)aryl uracil derivatives, which are important compounds in the field of life sciences. The article focuses on various synthesis strategies for these derivatives, including selective coupling of pre-functionalized uracils, transition-metal-catalyzed or photo-prompted modification of uracil moieties, substitution of unactivated uracils with (hetero)aromatic components, and oxidative coupling of un-functionalized uracils. The article also discusses specific coupling reactions, such as Negishi coupling and Suzuki-Miyaura coupling, that have been used to synthesize these compounds. The development of new derivatives and synthesis strategies for these compounds is of great interest due to their wide-ranging biological potential. [Extracted from the article]

This article discusses the synthesis of 5-Hydroxyuridine (5-OHU) and its formation in bacterial tRNA. The authors explore the reaction mechanism and the impact of different parameters on the yield of the desired compounds. They also discuss the conformation of nucleosides, specifically focusing on the sugar geometry and its influence on the overall structure. The study utilizes various techniques to analyze the sugar conformation and its impact on the nucleoside structure. Overall, this research provides insights into the synthesis and properties of 5-hydroxuridine, an important RNA lesion. [Extracted from the article]

This article provides a concise overview of the synthesis and significance of modified C-nucleosides in medicinal chemistry. C-nucleosides, which are more resistant to hydrolysis than N-nucleosides, have various applications in drug design and chemical biology. The article discusses the development of synthetic methodologies for C-nucleoside analogues and their role as inhibitors of purine nucleoside phosphorylase or IMP dehydrogenase. It also highlights the use of nucleoside analogues in chemotherapy, gene expression inhibition, and other therapeutic strategies. The article concludes with a discussion of different synthetic strategies and the importance of C-nucleoside scaffolds in biology and medicine. The text explores various methods for the synthesis of C-nucleoside analogues, including the use of carbon nucleophiles and intermolecular cyclization. Specific compounds, such as showdomycin and pseudouridimycin, are mentioned for their potential applications in medicinal chemistry and chemical biology. The development of efficient and selective techniques for C-glycosidation processes is still ongoing, but these methods show promise for the synthesis of new molecules and the discovery of new properties and modes of action. [Extracted from the article]