Ten paths to the discovery of antivirally active nucleoside and nucleotide analogues

Recent medicinal approaches of novel pyrimidine analogs: A review

Pyrimidine derivatives attract researchers due to their versatile scaffold & their medicinal significance. Pyrimidine associated analogs are majorly contributed to the field of medicinal chemistry. In this review article, the recent new structural design and development of active agent studies and biological approaches are highlighted. In addition, the biological potency and the structure-activity relationship of pyrimidines such as antimicrobial, anticancer, anti-inflammatory, analgesic, anti-diabetic, anti-HIV, anthelmintic, CNS depressants, and cardiac agents are discussed. Finally, this review article may attract the researchers for new structural design and development of novel active pyrimidine scaffolds with more active and less harmful.

Design, synthesis, and biological evaluation of piperidinyl-substituted [1,2,4]triazolo[1,5-a]pyrimidine derivatives as potential anti-HIV-1 agents with reduced cytotoxicity

Taking the previously reported compound BH-7d as the lead, we designed and synthesized a series of piperidinyl-substituted [1,2,4]triazolo[1,5-a]pyrimidines, and their anti-HIV activities as well as cytotoxicities were evaluated. Several compounds exhibited moderate anti-HIV (IIIB) potency, among which 2b was the most active one (EC₅₀  = 4.29 μM). Structure-activity relationships derived from the antiretroviral results were analyzed. Additionally, most compounds demonstrated reduced cytotoxicity (CC₅₀  > 200 μM) compared with those of BH-7d and etravirine. Molecular docking study further revealed the binding conformation of 2b in the binding pocket of HIV-1 reverse transcriptase.

6-Chloropurine Ribonucleosides from Chloropyrimidines: One-Pot Synthesis

A one-pot glycosylation and cyclization procedure is described for the synthesis of 6-chloropurine ribonucleosides from chloropyrimidines. From such a procedure and modification of the obtained chloropurine ribonucleosides, many drug candidates or molecular tools for biological study designed from their similarity to naturally occurring nucleosides could be obtained. The synthesis begins by preparation of several amidinoaminochloropyrimidines as precursors for the one-pot procedure. Then, by adding trimethylsilyl trifluoromethanesulfonate (TMSOTf) to a mixture of a pyrimidine and 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribose, different 6-chloropurine ribonucleosides are obtained. This methodology allows the straightforward introduction of an alkyl substituent at position 8 of purine ribonucleosides, which then can be functionalized at positions 2 and 6. © 2018 by John Wiley & Sons, Inc.

Design, Synthesis, and Evaluation of Anti-HBV Activity of Hybrid Molecules of Entecavir and Adefovir: Exomethylene Acycloguanine Nucleosides and Their Monophosphate Derivatives

Exomethylene acycloguanine nucleosides 4, 6 and its monophosphate derivatives 5, 7, and 8 have been synthesized. Mitsunobu-type coupling of 2-N-acetyl-6-O-diphenylcarbamoylguanine (11) with primary alcohols proceeded regioselectively to furnish the desired N(9)-substituted products in moderate yield. Evaluation of 4-8 for anti-HBV activity in HepG2 cells revealed that the phosphonate derivative 8 was found to exhibit moderated activity (EC50 value of 0.29 μM), but cytotoxicity (CC50 value of 39 μM) against the host cells was also observed.

Aminomethylnaphthoquinones and HSV-1: in vitro and in silico evaluations of potential antivirals

BACKGROUND

Herpes simplex viruses (HSV) are leading causes of human infections which result in severe manifestations, especially in neonates, immunocompromised and/or transplanted individuals. Current HSV type-1 (HSV-1) resistance to standard antiviral agents is a therapeutic challenge, especially for treating immunocompromised patients.

METHODS

Herein we describe the promising antiviral profile of three 2-aminomethyl-3-hydroxy-1,4-naphthoquinones against HSV-1 using Vero cells.

RESULTS

The in silico theoretical analysis indicated that the lowest unoccupied molecular orbital (LUMO) and the conformational features of these molecules are important structural features for modulating their biological activity. Our in vitro results showed that these compounds have significant anti-HSV-1 activity comparable to acyclovir, the antiviral currently used clinically. Importantly two of them showed a lower cytotoxicity profile against Vero cells than acyclovir. The inhibitory mechanism analysis using a time-of-addition assay revealed that all compounds inhibit the late phase of lytic replication. Finally, the highest selectivity index of the first tested compound was almost twice as high as that of acyclovir.

CONCLUSIONS

Since resistance is still a problem for treating HSV infections, these compounds present a promising profile toward the development of new strategies for anti-HSV-1 therapy.

Enzymatic synthesis of 2'-ara and 2'-deoxy analogues of c-di-GMP

The substrate specificity of recombinant full-length diguanylate cyclase (DGC) of Thermotoga maritima with mutant allosteric site was investigated. It has been originally shown that the enzyme could use GTP closest analogues - 2'-deoxyguanosine-5'-triphosphate (dGTP) and 9-β-D-arabinofuranosyl-guanine-5'-triphosphate (araGTP) as the substrates. The first demonstrations of an enzymatic synthesis of bis-(3'-5')-cyclic dimeric deoxyguanosine monophosphate (c-di-dGMP) and the previously unknown bis-(3'-5')-cyclic dimeric araguanosine monophosphate (c-di-araGMP) using DGC of T. maritima in the form of inclusion bodies have been provided.

Design, synthesis, and biological evaluation of unconventional aminopyrimidine, aminopurine, and amino-1,3,5-triazine methyloxynucleosides

Herein we describe a class of unconventional nucleosides (methyloxynucleosides) that combine unconventional nucleobases such as substituted aminopyrimidines, aminopurines, or aminotriazines with unusual sugars in their structures. The allitollyl or altritollyl derivatives were pursued as ribonucleoside mimics, whereas the tetrahydrofuran analogues were pursued as their dideoxynucleoside analogues. The compounds showed poor, if any, activity against a broad range of RNA and DNA viruses, including human immunodeficiency virus (HIV). This inactivity may be due to lack of an efficient metabolic conversion into their corresponding 5'-triphosphates and poor affinity for their target enzymes (DNA/RNA polymerases). Several compounds showed cytostatic activity against proliferating human CD4(+) T-lymphocyte CEM cells and against several other tumor cell lines, including murine leukemia L1210 and human prostate PC3, kidney CAKI-1, and cervical carcinoma HeLa cells. A few compounds were inhibitory to Moloney murine sarcoma virus (MSV) in C3H/3T3 cell cultures, with the 2,6-diaminotri-O-benzyl-D-allitolyl- and -D-altritolyl pyrimidine analogues being the most potent among them. This series of unconventional nucleosides may represent a novel family of potential antiproliferative agents.

Palladium-catalyzed Suzuki reaction in aqueous solvents applied to unprotected nucleosides and nucleotides

Nucleoside analogues have attracted much attention due to their potential biological activities.

A genetic screen identifies interferon-α effector genes required to suppress hepatitis C virus replication

BACKGROUND & AIMS

Hepatitis C virus (HCV) infection is a leading cause of end-stage liver disease. Interferon-α (IFNα) is an important component of anti-HCV therapy; it up-regulates transcription of IFN-stimulated genes, many of which have been investigated for their antiviral effects. However, all of the genes required for the antiviral function of IFNα (IFN effector genes [IEGs]) are not known. IEGs include not only IFN-stimulated genes, but other nontranscriptionally induced genes that are required for the antiviral effect of IFNα. In contrast to candidate approaches based on analyses of messenger RNA (mRNA) expression, identification of IEGs requires a broad functional approach.

METHODS

We performed an unbiased genome-wide small interfering RNA screen to identify IEGs that inhibit HCV. Huh7.5.1 hepatoma cells were transfected with small interfering RNAs incubated with IFNα and then infected with JFH1 HCV. Cells were stained using HCV core antibody, imaged, and analyzed to determine the percent infection. Candidate IEGs detected in the screen were validated and analyzed further.

RESULTS

The screen identified 120 previously unreported IEGs. From these, we more fully evaluated the following: asparagine-linked glycosylation 10 homolog (yeast, α-1,2-glucosyltransferase); butyrylcholinesterase; dipeptidyl-peptidase 4 (CD26, adenosine deaminase complexing protein 2); glucokinase (hexokinase 4) regulator; guanylate cyclase 1, soluble, β 3; MYST histone acetyltransferase 1; protein phosphatase 3 (formerly 2B), catalytic subunit, β isoform; peroxisomal proliferator-activated receptor-γ-DBD-interacting protein 1; and solute carrier family 27 (fatty acid transporter), member 2; and demonstrated that they enabled IFNα-mediated suppression of HCV at multiple steps of its life cycle. Expression of these genes had more potent effects against flaviviridae because a subset was required for IFNα to suppress dengue virus but not influenza A virus. In addition, many of the host genes detected in this screen (92%) were not transcriptionally stimulated by IFNα; these genes represent a heretofore unknown class of non-IFN-stimulated gene IEGs.

CONCLUSIONS

We performed a whole-genome loss-of-function screen to identify genes that mediate the effects of IFNα against human pathogenic viruses. We found that IFNα restricts HCV via actions of general and specific IEGs.

A cutting-edge view on the current state of antiviral drug development

Prominent in the current stage of antiviral drug development are: (i) for human immunodeficiency virus (HIV), the use of fixed-dose combinations (FDCs), the most recent example being Stribild(TM); (ii) for hepatitis C virus (HCV), the pleiade of direct-acting antivirals (DAAs) that should be formulated in the most appropriate combinations so as to obtain a cure of the infection; (iii)-(v) new strategies (i.e., AIC316, AIC246, and FV-100) for the treatment of herpesvirus infections: herpes simplex virus (HSV), cytomegalovirus (CMV), and varicella-zoster virus (VZV), respectively; (vi) the role of a new tenofovir prodrug, tenofovir alafenamide (TAF) (GS-7340) for the treatment of HIV infections; (vii) the potential use of poxvirus inhibitors (CMX001 and ST-246); (viii) the usefulness of new influenza virus inhibitors (peramivir and laninamivir octanoate); (ix) the position of the hepatitis B virus (HBV) inhibitors [lamivudine, adefovir dipivoxil, entecavir, telbivudine, and tenofovir disoproxil fumarate (TDF)]; and (x) the potential of new compounds such as FGI-103, FGI-104, FGI-106, dUY11, and LJ-001 for the treatment of filoviruses (i.e., Ebola). Whereas for HIV and HCV therapy is aimed at multiple-drug combinations, for all other viruses, HSV, CMV, VZV, pox, influenza, HBV, and filoviruses, current strategies are based on the use of single compounds.

Fast and efficient microwave synthetic methods for some new 2(1H)-pyridone arabinosides

Two series of novel 3-cyano-2-(2′′,3′′,4′′-tri-