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The pandemic caused by the novel betacoronavirus SARS-CoV-2 has already claimed more than 3.5 million lives. Despite the development and use of anti-COVID-19 vaccines, the disease remains a major public health challenge throughout the world. Large-scale screening of the drugs already approved for the treatment of other viral, bacterial, and parasitic infections, as well as autoimmune, oncological, and other diseases is currently underway as part of their repurposing for development of effective therapeutic agents against SARS-CoV-2. In this work, we present the results of a phenotypic screening of libraries of modified heterocyclic bases and 5-norcarbocyclic nucleoside analogs previously synthesized by us. We identified two leading compounds with apparent potential to inhibit SARS-CoV-2 replication and EC50 values in a range of 2070 M. The structures of these compounds can be further optimized to develop an antiviral drug.

Analogues and derivatives of nucleic acid components have been used as key drugs in different areas of medicine over the past decades. The replacement of one or more nitrogen atoms of the heterocyclic base with a CH group affords deazapurine nucleoside analogues, and the replacement of the methine group with a nitrogen atom gives azapurine derivatives. A combination of aza and deaza moieties in the purine base leads to aza(deaza)-modified bases. Some nucleoside analogues were found to exhibit pronounced anticancer and antiviral activity. The synthesis and evaluation of biological activity of aza- and deazapurine nucleoside analogues have attracted interest from researchers four decades ago. This review describes and integrates the studies concerning certain aspects of the synthesis and(or) activity of various representatives of this class of compounds. The structure–biological activity relationships are analyzed. The successful approaches to the design of aza- and deazapurine nucleoside analogues are considered. A comparison is given for the methods of chemical and enzymatic synthesis of these compounds. The bibliography includes 161 references.

Despite the development of efficient anti–human immunodeficiency virus-1 (HIV-1) therapy, HIV-1 associated pathogens remain a major clinical problem. Human cytomegalovirus (CMV) is among the most common HIV-1 copathogens and one of the main causes of persistent immune activation associated with dysregulation of the immune system, cerebrovascular and cardiovascular pathologies, and premature aging. Here, we report on the development of dual-targeted drugs with activity against both HIV-1 and CMV. We synthesized seven compounds that constitute conjugates of molecules that suppress both pathogens. We showed that all seven compounds exhibit low cytotoxicity and efficiently inhibited both viruses in cell lines. Furthermore, we chose a representative compound and demonstrated that it efficiently suppressed replication of HIV-1 and CMV in human lymphoid tissue ex vivo coinfected with both viruses. Further development of such compounds may lead to the development of dual-targeted anti-CMV/HIV-1 drugs.

The data of transmission electron microscopy (TEM) on morphology of M. tuberculosis H37Rv bacterial cells treated with four analogues of pyrimidine nucleosides with different substituents at 5 position of base are presented. We showed that the growth of M. tuberculosis H37Rv cells effectively inhibited by each of these compounds. This process is accompanied with the accumulation of lipid intracellular vacuole-like inclusions in the cells, appearance of deep protrusions and indentations on the surface, partial and/or complete destruction of the three-layered cell envelope. The exact molecular mechanism of action of 5-substituted pyrimidine nucleosides on M. tuberculosis cells remains to be proved. However, one can suggest that mechanism of action for these compounds is related either to their direct interactions with bacteria cell walls or to interactions with enzymes participating in the process of cell wall formation.

Emerging and re-emerging viruses periodically cause outbreaks and epidemics all over the world, eventually leading to global events such as the current pandemic of the novel SARS-CoV-2 coronavirus infection COVID-19. Therefore, an urgent need for novel antivirals is crystal clear. Here we present the synthesis and evaluation of an antiviral activity of phenoxazine-based nucleoside analogs divided into three groups: (1) 8-alkoxy-substituted, (2) acyclic, and (3) carbocyclic. The antiviral activity was assessed against a structurally and phylogenetically diverse panel of RNA and DNA viruses from 25 species. Four compounds (11a-c, 12c) inhibited 4 DNA/RNA viruses with EC50 ≤ 20 μM. Toxicity of the compounds for the cell lines used for virus cultivation was negligible in most cases. In addition, previously reported and newly synthesized phenoxazine derivatives were evaluated against SARS-CoV-2, and some of them showed promising inhibition of reproduction with EC50 values in low micromolar range, although accompanied by commensurate cytotoxicity., Graphical abstract Image 1

Nucleoside analogues have long served as key chemotherapeutic drugs for the treatment of viral infections and cancers. Problems associated with the development of drug resistance have led to a search for the design of nucleosides capable of bypassing point mutations in the target enzyme's binding site. As a possible answer to this, the Seley-Radtke group developed a flexible nucleoside scaffold (fleximers), where the heterocyclic purine base is split into its two components, i.e. pyrimidine and imidazole. Herein, we present a series of new pyrazole-containing flex-bases and the corresponding fleximer analogues of 8-aza-7-deaza nucleosides. Subsequent studies found that pyrazole-containing flex-bases are substrates of purine nucleoside phosphorylase (PNP). We have compared the chemical synthesis of fleximers and enzymatic approaches with both isolated enzymes and the use of E. coli cells overproducing PNP. The latter provided stereochemically pure pyrazole-containing β-D-ribo- and β-D-2′-deoxyribo-fleximers and are beneficial in terms of environmental issues, are more economical, and streamline the steps required from a chemical approach. The reaction is carried out in water, avoiding hazardous chemicals, and the products are isolated by ion-exchange chromatography using water/ethanol mixtures for elution. Moreover, the target nucleosides were obtained on a multi-milligram scale with >97–99% purity, and the reactions can be easily scaled up.

Viral infections are one of the important factors that influence the development of mankind. In recent decades, there has been a steady increase in the number of infectious diseases of viral etiology. This is due to the peculiarities of demography and human behavior, uncontrolled urbanization in developing countries, intensification of international travel and trade, lack of effective sanitation, environmental pollution, lack of programs to combat vectors of various diseases, adaptation of viruses themselves to new conditions, the emergence of a large number of refugees, and the shortcomings of public health measures. Such a tense situation is seen as a new challenge not only to modern medicine, but also to humanity as a whole. One of the ways to overcome this problem is the search and development of new highly effective antiviral drugs to combat socially significant diseases. This chapter summarizes the literature data on the study of uracil derivatives, acting as non-nucleoside inhibitors against various RNA and DNA viruses.

Widespread latent herpes viral infections within a population can lead to the development of co-infections in HIV-infected patients. These infections are not particularly dangerous for healthy individuals and often occur with minimal symptoms, but for those who are immunocompromised, these infections can accelerate the acute phase of HIV infection and AIDS. Thus, the idea of designing compounds that could combine activity against HIV and co-infections would seem promising. In that regard, eleven compounds were synthesized that represent conjugates of non-nucleoside HIV reverse transcriptase inhibitors and nucleoside inhibitors of the herpes family viruses with the hope that these novel heterodimers will result in dual activity against HIV and concomitant herpes virus infections. ispartof: MOLECULES vol:25 issue:15 ispartof: location:Switzerland status: published

Graphical abstract, 1-[tert-Butyl(diphenyl)silyl]pyrrol-3-ylboronic acid was obtained from pyrrole in three steps. Its Suzuki–Miyaura cross-coupling with functionalized pyridinyl and pyrimidinyl bromides afforded new promising 3-hetaryl-1H-pyrroles.

Carbocyclic nucleosides have long played a role in antiviral, antiparasitic, and antibacterial therapies. Recent results from our laboratories from two structurally related scaffolds have shown promising activity against both Mycobacterium tuberculosis and several parasitic strains. As a result, a small structure activity relationship study was designed to further probe their activity and potential. Their synthesis and the results of the subsequent biological activity are reported herein.

The phenoxazine scaffold is widely used to stabilize nucleic acid duplexes, as a part of fluorescent probes for the study of nucleic acid structure, recognition, and metabolism, etc. Here we present the synthesis of phenoxazine-based nucleoside derivatives and their antiviral activity against a panel of structurally diverse viruses: enveloped DNA herpesviruses varicella zoster virus (VZV) and human cytomegalovirus, enveloped RNA tick-borne encephalitis virus (TBEV), and non-enveloped RNA enteroviruses. Studied compounds were effective against DNA and RNA viruses reproduction in cell culture. 3-(2′-Deoxy-β-D-ribofuranosyl)-1,3-diaza-2-oxophenoxazine proved to be a potent inhibitor of VZV replication with superior activity against wild type than thymidine kinase deficient strains (EC50 0.06 and 10 μM, respectively). This compound did not show cytotoxicity on all the studied cell lines. Several compounds showed promising activity against TBEV (EC50 0.35–0.91 μM), but the activity was accompanied by pronounced cytotoxicity. These compounds may be considered as a good starting point for further structure optimization as antiherpesviral or antiflaviviral compounds.

New well-soluble in 10% DMSO phosphonate derivatives of substituted benzophenone have been synthesized using different methods. Preliminary computer modeling of proposed structures in the reverse transcriptase HIV-1 hydrophobic pocket suggested these molecules as potential non-nucleoside inhibitors of this enzyme.

Here we report the synthesis and biological activity of new 5&prime, norcarbocyclic derivatives of bicyclic pyrrolo- and furano[2,3-d]pyrimidines with different substituents in the heterocyclic ring. Lead compound 3i, containing 6-pentylphenyl substituent, displays inhibitory activity with respect to a number of tumor cells with a moderate selectivity index value. Compound 3i induces cell death by the apoptosis pathway with the dissipation of mitochondrial potential.

A series of novel 5&prime, norcarbocyclic derivatives of 5-alkoxymethyl or 5-alkyltriazolyl-methyl uracil were synthesized and the activity of the compounds evaluated against both Gram-positive and Gram-negative bacteria. The growth of Mycobacterium smegmatis was completely inhibited by the most active compounds at a MIC99 of 67 &mu, g/mL (mc2155) and a MIC99 of 6.7&ndash, 67 &mu, g/mL (VKPM Ac 1339). Several compounds also showed the ability to inhibit the growth of attenuated strains of Mycobacterium tuberculosis ATCC 25177 (MIC99 28&ndash, 61 &mu, g/mL) and Mycobacterium bovis ATCC 35737 (MIC99 50&ndash, 60 &mu, g/mL), as well as two virulent strains of M. tuberculosis, a laboratory strain H37Rv (MIC99 20&ndash, 50 &mu, g/mL) and a clinical strain with multiple drug resistance MS-115 (MIC99 20&ndash, g/mL). Transmission electron microscopy (TEM) evaluation of M. tuberculosis H37Rv bacterial cells treated with one of the compounds demonstrated destruction of the bacterial cell wall, suggesting that the mechanism of action for these compounds may be related to their interactions with bacteria cell walls.

5′-Norcarbocyclic analogues of furano[2,3-d]pyrimidine nucleosides as well as 5-bromo and 5-iodouracil derivatives were synthesized to evaluate their potential antitumor activity. The halogenated derivatives display no cytotoxicity with respect to all tested cells: KB-3-1 (human epidermoid carcinoma), HeLa (human cervical epithelioid carcinoma), HuTu-80 (human duodenal cancer), B16 (mouse melanoma), and MDCK (normal epithelial). The cytotoxicity of the non-halogenated furano[2,3-d]pyrimidine derivatives increases with the lengthening of the alkyl chain of the substituent from 45 to 60 μm for octyl to from 3 to 10 μm for dodecyl.

HIV and M. tuberculosis are two intersecting epidemics making the search for new dual action drugs against both pathogens extremely important. Here, we report on the synthesis and suppressive activities of five dual-targeted HIV/TB compounds. These compounds constitute heterodimers of AZT, as anti-HIV molecules, and 5-arylaminouracil derivatives or 2′-deoxyuridine monophosphates analogs, as anti-TB molecules. We found that these compounds inhibit the growth of M. tuberculosis and suppress the replication of HIV in human cell cultures and human lymphoid tissues ex vivo. We identified one particular heterodimer that inhibited most potently both HIV and the drug-resistant TB strain MS −115. This compound demonstrated low toxicity and had no cytostatic effect on cells in culture. This is a leading candidate for future development and further in vivo testing.

Carbocyclic nucleoside analogues have a distinguished history as anti-infectious agents, including key antiviral agents. Toxicity was initially a concern but this was reduced by the introduction of 5′-nor variants. Here, we report the result of our preliminary screening of a series of 5′-norcarbocyclic uridine analogues against protozoan parasites, specifically the major pathogens Leishmania mexicana and Trypanosoma brucei. The series displayed antiparasite activity in the low to mid-micromolar range and establishes a preliminary structure-activity relationship, with the 4′,N3-di-(3,5-dimethylbenzoyl)-substituted analogues showing the most prominent activity. Utilizing an array of specially adapted cell lines, it was established that this series of analogues likely act through a common target. Moreover, the strong correlation between the trypanocidal and anti-leishmanial activities indicates that this mechanism is likely shared between the two species. EC50 values were unaffected by the disabling of pyrimidine biosynthesis in T. brucei, showing that these uridine analogues do not act directly on the enzymes of pyrimidine nucleotide metabolism. The lack of cross-resistance with 5-fluorouracil, also establishes that the carbocyclic analogues are not imported through the known uracil transporters, thus offering forth new insights for this class of nucleosides. The lack of cross-resistance with current trypanocides makes this compound class interesting for further exploration.

Several 5-aminouracil derivatives that have previously been shown to inhibit Mycobacterium tuberculosis growth at concentrations of 5-40 g/mL are demonstrated to act also as noncompetitive non-nucleoside inhibitors of HIV-1 reverse transcriptase without causing toxicity in vitro (МT-4 cells) and ex vivo (human tonsillar tissue).

Key biological targets (S-adenosyl-L-homocysteine hydrolase, telomerase, human immunodeficiency virus reverse transcriptase, herpes virus DNA polymerase and hepatitis B virus DNA polymerase) and the mechanisms of action of carbocyclic nucleoside analogues are considered. Structural types of analogues are discussed. Methods of synthesis for the most promising compounds and the spectrum of their biological activities are described. The bibliography includes 126 references.

A new group of terminal deoxynucleotidyltransferase (TDT) substrates, namely, non-nucleoside triphosphates (NNTP) bearing 5-substituted 2,4-dinitrophenyl fragments instead of nucleoside residues was synthesized.

Three series of 5-arylaminouracil derivatives, including 5-(phenylamino)uracils, 1-(4′-hydroxy-2′-cyclopenten-1′-yl)-5-(phenylamino)uracils, and 1,3-di-(4′-hydroxy-2′-cyclopenten-1′-yl)-5-(phenylamino)uracils, were synthesized and screened for potential antimicrobial activity. Most of compounds had a negative effect on the growth of the Mycobacterium tuberculosis H37Rv strain, with 100% inhibition observed at concentrations between 5 and 40 μg/mL. Of those, 1-(4′-hydroxy-2′-cyclopenten-1′-yl)-3-(4‴-hydroxy-2‴-cyclopenten-1‴-yl)-5-(4″-butyloxyphenylamino)uracil proved to be the most active among tested compounds against the M. tuberculosis multidrug-resistant strain MS-115 (MIC90 5 μg/mL). In addition, the thymidylate kinase of M. tuberculosis was evaluated as a possible enzymatic target.

A series of new carbocyclic uracil derivatives were synthesized and evaluated as potential antituberculosis agents. Racemic 1-[4'-hydroxy-2'-cyclopenten-1'-yl]-5-tetradecynyluracil completely inhibited the growth of Mycobacterium tuberculosis H37Rv in vitro at a concentration of 10 μg/ml. Individual (+) and (-) isomers of the above uracil derivative were isolated and showed the same level of activity against two strains of Mycobacterium tuberculosis: laboratory sensitive (H37Rv) and clinical resistant to five top antituberculosis drugs (MS-115).

9-(4-Phosphonomethoxy-2-cyclopenten-1-yl)hypoxanthine and 9-(4-phosphonomethoxy-2,3-dihydroxycyclopenten-1-yl)hypoxanthine were synthesized as isosteric carbocyclic analogues of inosine-5-monophosphate. The synthesized compounds were shown to be capable of inhibiting the activity of human type II inosine-5-monophosphate dehydrogenase (IMPDH II) (IC50 = 500 M) and to have no significant effects on the growth of Mycobacterium tuberculosis.

A new series of potential nonnucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs) based on the carbocyclic 5′-nor-uracil scaffold were designed and synthesized. Binding modes in the active site of the enzyme were studied computationally to provide insight on potential interactions. Several of the 2′,3′-dideoxy-2′,3′-didehydro-5′-nor-uridine analogues showed inhibitory activity against wild-type and mutant (L100I) HIV-RT with Ki 13–18 μM and 1–11 μM, respectively.

A new series of potential nonnucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs) based on the carbocyclic 5′-nor-uracil scaffold were designed and synthesized. Three different aspects of the scaffold were investigated: the effects of adding a linker between the carbocyclic and phenyl fragments, introduction of different substituents on the benzoyl residue and replacing the central carbocyclic ring with a benzyl group. Analogues of 2′,3′-dideoxy-2′,3′-didehydro-5′-nor-uridine, bearing 3,5-dichloro- or 3,5-dimethylbenzoyl groups, showed inhibitory activity against HIV-RT wild-type (IC50 5–10 μM) and mutants L100I (IC50 1.2–2.1 μM) and K103N (IC50 8–17 μM).