Phosphonate Analogues Research Articles

Synthesis and Potent Anti-HCMV Activity of 2′,5′,5′-trifluoro-3′-hydroxy-apiosyl Nucleoside Phosphonic Acid Analogues

ABSTRACTAs antiviral nucleosides containing a fluorine atom at 2′-position are endowed with increased stabilization of glycosyl bond, it was of interest to investigate the influence of three fluorine atoms at 2′- and 5′-positions of apiosyl nucleoside phosphonate analogues. Various pyrimidine and purine 2′,5′,5′-trifluoro-3′-hydroxy-apiose nucleoside phosphonic acid analogues were synthesized from 1,3-dihydroxyacetone. Electrophilic fluorination of lactone was performed using N-fluorodibenzenesulfonimide. Difluorophosphonation was performed by direct displacement of triflate intermediate with diethyl(lithiodifluoromethyl) phosphonate to give the corresponding (α,α-difluoroalkyl) phosphonate. Condensation successfully proceeded from a glycosyl donor with persilylated bases to yield nucleoside phosphonate analogues. Deprotection of diethyl phosphonates provided the final phosphonic acid sodium salts. The synthesized nucleoside analogues were subjected to antiviral screening against various viruses.

Amidase activity of phosphonate analogue imprinted chymotrypsin mimics in shape-selective, substrate-specific and enantioselective amidolysis of l-phenylalanine-p-nitroanilides

Focusing on chymotrypsin mimics, highly crosslinked enzyme mimics are synthesized by molecular imprinting technique for the amidolysis of p-nitroanilide of phenylalanine, using phenyl-1-(N-benzyloxycarbonylamino)-2-(phenyl)ethyl phosphonate – the transition state analog of amidolysis – as the template, N-methacryloyl-l-histidine, N-methacryloyl-l-aspartic acid, and N-methacryloyl-l-serine as the functional monomers and EGDMA as the crosslinking agent. The amidase activity of the enzyme mimics follows pseudo first order kinetics. The transition state analog provides a tetrahedral geometry complementary to the transition state intermediate, which is responsible for the catalytic activity of the imprinted enzyme mimics. The enzyme mimics show stereospecificity and substrate selectivity in the amidolysis of phenylalanine p-nitroanilide. The proper orientation of the reactive functionalities in the super crosslinked macroporous polymer matrix for selective binding of the substrate through H-bonding is responsible for the high imprinting efficiency and substrate specificity of the imprinted polymer catalysts. Low cost, ease of preparation, high thermal stability, reusability and higher shelf life make the polymer catalysts better chymotrypsin mimics.

Antiviral activities of 2,6-diaminopurine-based acyclic nucleoside phosphonates against herpesviruses: In vitro study results with pseudorabies virus (PrV, SuHV-1)

Pseudorabies virus (PrV), a causative agent of Aujeszky’s disease, is deadly to most mammals with the exception of higher primates and men. This disease causes serious economic loses among farm animals, especially pigs, yet many European countries are today claimed to be Aujeszky’s disease free because of the discovery of an efficient vaccination for pigs. In reality, the virus is still present in wild boar. Current vaccines are neither suitable for dogs nor are there anti-PrV drugs approved for veterinary use. Therefore, the disease still represents a high threat, particularly for expensive hunting dogs that can come into close contact with infected boars. Here we report on the anti-PrV activities of a series of synthetic diaminopurine-based acyclic nucleoside phosphonate (DAP-ANP) analogues. Initially, all synthetic DAP-ANPs under investigation are shown to exhibit minimal cytotoxicity by MTT and XTT tests (1–100μM range). Thereafter in vitro infection models are established using PrV virus SuHV-1, optimized on PK-15 and RK-13 cell lines. Out of the six DAP-ANP analogues tested, analogue VI functionalized with a cyclopropyl group on the 6-amino position of the purine ring proves the most effective antiviral DAP-ANP analogue against PrV infection, aided by sufficient hydrophobic character to enhance bioavailability to its cellular target viral DNA-polymerase. Four other DAP-ANP analogues with functional groups introduced to the C2’position are shown ineffective against PrV infection, even with favourable hydrophobic properties. Cidofovir®, a drug approved against various herpesvirus infections, is found to exert only low activity against PrV in these same in vitro models.

Synthesis and comparison of the biological activity of monocyclic phosphonate, difluorophosphonate and phosphate analogs of the natural AChE inhibitor cyclophostin

New monocyclic phosphate, phosphonate and difluorophosphonate analogs of the natural AChE inhibitor cyclophostin were synthesized and their activity toward human AChE examined. Surprisingly, the phosphate, phosphonate, and difluorophosphonate analogs all showed diminished activity when compared with the natural product.

Synthesis and Antiviral Activity Evaluation of 5',5'-Difluoro-2'-methylapiosyl Nucleoside Phosphonic Acid Analogs

AbstractRacemic synthesis of novel 5',5'-difluoro-2'-methyl-apiose nucleoside phosphonic acid analogs was achieved as potentantiviral agents. Phosphonation was performed by direct displacement of triflate intermediate with diethyl(lithiodifluoromethyl) phosphonate to give the corresponding (α,α-difluoroalkyl) phosphonate. Condensation successfullyproceeded from a glycosyl donor with persilylated bases to yield the nucleoside phosphonate analogs. Deprotection ofdiethyl phosphonates provided the target nucleoside analogs. An antiviral evaluation of the synthesized compounds againstvarious viruses such as HIV, HSV-1, HSV-2 and HCMV revealed that the pyrimidine analogs (cytosine, uracil, andthymine) have weak anti-HIV or HCMV activity.Keywords: Antiviral Agents; 5',5'-Difluoro-2'-methyl-apiose Nucleoside Phosphonic Acid Analogues; VorbruggenReaction 1. Introduction The modification of the nucleosides and/or sugarmoiety of a natural nucleoside is an obvious choice fordeveloping new antiviral compounds, and apiose-basednucleoside could serve this purpose.Recently, apiose 5'-nor nucleoside phosphonate

Synthesis and Anti-HIV Activity of Novel 2′-Deoxy-2′-β-Fluoro-Threosyl Nucleoside Phosphonic Acid Analogues

Novel 2′-deoxy-2′-β-fluoro-threose purine phosphonic acid analogues were designed and racemically synthesized from 2-propanone-1,3-diacetate. Condensation successfully proceeded from a glycosyl donor 9 under Vorbrüggen conditions. Cross-metathesis of vinyl analogues 13 and 23 with diethyl vinylphosphonate yielded the desired nucleoside phosphonate analogues 14 and 24, respectively. Ammonolysis and hydrolysis of phosphonates yielded the nucleoside phosphonic acid analogues 16, 19, 26, and 29. The synthesized nucleoside analogues were subjected to antiviral screening against human immunodeficiency virus (HIV)-1. Adenine analogue 18 exhibited weak in vitro activities against human immunodeficiency virus (HIV)-1.

The Synthesis of Novel 5′‐Deoxy‐3′,5′,5′‐trifluoro‐apiosyl Nucleoside Phosphonic Acid Analogs as Antiviral Agents

Racemic syntheses of novel 5′‐deoxy‐3′,5′,5′‐trifluoro‐apiose nucleoside phosphonic acid analogs were carried out from 1,3‐dihydroxyacetone, to be used as antiviral agents. Nucleophilic displacement of the triflate intermediate with diethyl (lithiodifluoromethyl)phosphonate was performed to yield the corresponding (α,α‐difluoroalkyl) phosphonate. Condensation successfully proceeded from a glycosyl donor under Vorbrüggen conditions to yield the nucleoside phosphonate analogs. Ammonolysis and hydrolysis of the phosphonates yielded the corresponding nucleoside phosphonic acid analogs. Furthermore, the lipophilic prodrug of the adenine derivative was synthesized to increase cellular uptake. The synthesized nucleoside analogs were screened for their antiviral activity against human immunodeficiency virus (HIV)‐1. The bis(SATE) prodrug of the adenine analog exhibited significant in vitro activity against HIV‐1.

Design of phosphonate analogs of short peptides by “click” chemistry

Methods were developed for the first time for the modification of the natural neuropeptides Ile–Gly–Leu and Leu–Gly–Leu simultaneously with the phosphonate moiety and the triazole ring or solely with the triazole ring by means of click chemistry. All of the peptidomimetics synthesized were isolated as a mixture of diastereomers and were characterized by spectroscopic methods.

Mitochondrial Impairment May Increase Cellular NAD(P)H: Resazurin Oxidoreductase Activity, Perturbing the NAD(P)H-Based Viability Assays.

Cellular NAD(P)H-dependent oxidoreductase activity with artificial dyes (NAD(P)H-OR) is an indicator of viability, as the cellular redox state is important for biosynthesis and antioxidant defense. However, high NAD(P)H due to impaired mitochondrial oxidation, known as reductive stress, should increase NAD(P)H-OR yet perturb viability. To better understand this complex behavior, we assayed NAD(P)H-OR with resazurin (Alamar Blue) in glioblastoma cell lines U87 and T98G, treated with inhibitors of central metabolism, oxythiamin, and phosphonate analogs of 2-oxo acids. Targeting the thiamin diphosphate (ThDP)-dependent enzymes, the inhibitors are known to decrease the NAD(P)H production in the pentose phosphate shuttle and/or upon mitochondrial oxidation of 2-oxo acids. Nevertheless, the inhibitors elevated NAD(P)H-OR with resazurin in a time- and concentration-dependent manner, suggesting impaired NAD(P)H oxidation rather than increased viability. In particular, inhibition of the ThDP-dependent enzymes affects metabolism of malate, which mediates mitochondrial oxidation of cytosolic NAD(P)H. We showed that oxythiamin not only inhibited mitochondrial 2-oxo acid dehydrogenases, but also induced cell-specific changes in glutamate and malate dehydrogenases and/or malic enzyme. As a result, inhibition of the 2-oxo acid dehydrogenases compromises mitochondrial metabolism, with the dysregulated electron fluxes leading to increases in cellular NAD(P)H-OR. Perturbed mitochondrial oxidation of NAD(P)H may thus complicate the NAD(P)H-based viability assay.

Tenofovir Activating Kinases May Impact the Outcome of HIV Treatment and Prevention

Tenofovir Activating Kinases May Impact the Outcome of HIV Treatment and Prevention

Synthesis and Anti‐Retroviral Activity of Novel 5′‐Deoxy‐5′,5′‐difluoro‐threosyl Nucleoside Phosphonic Acid Analogs

Novel 5′‐deoxy‐5′,5′‐difluoro‐threose purine phosphonic acid analogs were designed and synthesized from 2‐propanone‐1,3‐diacetate. Direct displacement of the triflate intermediate 12 with diethyl (lithiodifluoromethyl)phosphonate provided the corresponding (α,α‐difluoroalkyl) phosphonate 13. Condensation successfully proceeded from a glycosyl donor 14 under Vorbrüggen conditions to provide the nucleoside phosphonate analogs 15α, 15β, 18α, and 18β, respectively. Ammonolysis and hydrolysis of the phosphonates 15β and 18β yielded the nucleoside phosphonic acid analogs 16, 17, 19b, and 20. Also, synthesis of prodrugs of adenine derivative was performed to increase cellular uptake. The synthesized nucleoside analogs were subjected to antiviral screening against human immunodeficiency virus (HIV)‐1. Bis(SATE) prodrug 22 of the adenine analog exhibited significant in vitro activity against HIV‐1.

Interplay of catalytic subsite residues in the positioning of α-d-glucose 1-phosphate in sucrose phosphorylase

Kinetic and molecular docking studies were performed to characterize the binding of α-d-glucose 1-phosphate (αGlc 1-P) at the catalytic subsite of a family GH-13 sucrose phosphorylase (from L. mesenteroides) in wild-type and mutated form. The best-fit binding mode of αGlc 1-P dianion had the phosphate group placed anti relative to the glucosyl moiety (adopting a relaxed 4C1 chair conformation) and was stabilized mainly by hydrogen bonds from residues of the enzyme׳s catalytic triad (Asp196, Glu237 and Asp295) and from Arg137. Additional feature of the αGlc 1-P docking pose was an intramolecular hydrogen bond (2.7Å) between the glucosyl C2-hydroxyl and the phosphate oxygen. An inactive phosphonate analog of αGlc 1-P did not show binding to sucrose phosphorylase in different experimental assays (saturation transfer difference NMR, steady-state reversible inhibition), consistent with evidence from molecular docking study that also suggested a completely different and strongly disfavored binding mode of the analog as compared to αGlc 1-P. Molecular docking results also support kinetic data in showing that mutation of Phe52, a key residue at the catalytic subsite involved in transition state stabilization, had little effect on the ground-state binding of αGlc 1-P by the phosphorylase. However, when combined with a second mutation involving one of the catalytic triad residues, the mutation of Phe52 by Ala caused complete (F52A_D196A; F52A_E237A) or very large (F52A_D295A) disruption of the proposed productive binding mode of αGlc 1-P with consequent effects on the enzyme activity. Effects of positioning of αGlc 1-P for efficient glucosyl transfer from phosphate to the catalytic nucleophile of the enzyme (Asp196) are suggested. High similarity between the αGlc 1-P conformers bound to sucrose phosphorylase (modeled) and the structurally and mechanistically unrelated maltodextrin phosphorylase (experimental) is revealed.

Sphingosine 1-phosphate enhances the excitability of rat sensory neurons through activation of sphingosine 1-phosphate receptors 1 and/or 3

BackgroundSphingosine-1-phosphate (S1P) is a bioactive sphingolipid that acts through a family of five G-protein-coupled receptors (S1PR1–5) and plays a key role in regulating the inflammatory response. Our previous studies demonstrated that rat sensory neurons express the mRNAs for all five S1PRs and that S1P increases neuronal excitability primarily, but not exclusively, through S1PR1. This raises the question as to which other S1PRs mediate the enhanced excitability.MethodsIsolated sensory neurons were treated with either short-interfering RNAs (siRNAs) or a variety of pharmacological agents targeted to S1PR1/R2/R3 to determine the role(s) of these receptors in regulating neuronal excitability. The excitability of isolated sensory neurons was assessed by using whole-cell patch-clamp recording to measure the capacity of these cells to fire action potentials (APs).ResultsAfter siRNA treatment, exposure to S1P failed to augment the excitability. Pooled siRNA targeted to S1PR1 and R3 also blocked the enhanced excitability produced by S1P. Consistent with the siRNA results, pretreatment with W146 and CAY10444, selective antagonists for S1PR1 and S1PR3, respectively, prevented the S1P-induced increase in neuronal excitability. Similarly, S1P failed to augment excitability after pretreatment with either VPC 23019, which is a S1PR1 and R3 antagonist, or VPC 44116, the phosphonate analog of VPC 23019. Acute exposure (10 to 15 min) to either of the well-established functional antagonists, FTY720 or CYM-5442, produced a significant increase in the excitability. Moreover, after a 1-h pretreatment with FTY720 (an agonist for S1PR1/R3/R4/R5), neither SEW2871 (S1PR1 selective agonist) nor S1P augmented the excitability. However, after pretreatment with CYM-5442 (selective for S1PR1), SEW2871 was ineffective, but S1P increased the excitability of some, but not all, sensory neurons.ConclusionsThese results demonstrate that the enhanced excitability produced by S1P is mediated by activation of S1PR1 and/or S1PR3.

Synthesis of Novel 2'(β)-Methyl-5'-deoxyapiose Nucleoside Phosphonic Acid Analogues as Antiviral Agents

AbstractNovel 2'(β)-methyl-5'-deoxyapiose purine phosphonic acid analogues were designed and synthesized from 2-propanone-1,3-diacetate. Condensation successfully proceeded from a glycosyl donor 9 under Vorbruggen conditions. Condensationof aldehyde 14 with Wittig reagent [(diethoxyphosphinyl)methylidene] triphenylphosphorane gave the desired nucleosidephosphonate analogues 15. Ammonolysis and hydrolysis of phosphonates gave the nucleoside phosphonic acid analogue17 and 19. The synthesized nucleoside analogues were subjected to antiviral screening against HIV-1. The adenineanalogue 19 exhibited weak in vitro activities against HIV-1.Key word: Anti-HIV Agents, 2'-Methyl-5'-deoxyphosphonic Acid Analogue, Vorbruggen Reaction 1. Introduction Nonclassical nucleosides continue to be a promisingchallenge for the development of new antiviral agentssince the discovery of lamivudine as anti-human immu-nodeficiency virus (HIV) and anti-hepatitis B virus(HBV) agent [1] . The apio dideoxynucleoside also belongto the class of nonclassical nucleoside in that 4-hydroxymethyl of the 2.3-dideoxyribose moves to theC3 position. This class of nucleosides like (1) (Figure1) showed not only the antiviral activity, but also met-abolic advantage such as resistance to adenosine deam-inase and glycosyl bond hydrolysis, when compared tothe classical 2,3-dideoxynucleosides

Synthesis of phosphonic analogues of AAZTA and relaxometric evaluation of the corresponding Gd(III) complexes as potential MRI contrast agents

AAZTA was developed in the last decade as an efficient chelating agent for lanthanides and other metal ions of diagnostic and therapeutic interest. Different derivatives of AAZTA were designed and synthesized in order to modulate the physico-chemical properties of the corresponding chelates or to conjugate them to carrier molecules for molecular imaging applications. In this work, three different analogues of AAZTA bearing one or two phosphonic acid residues were synthesized in three step procedures and moderate to good yields. The effects of this isofunctional substitution on the structure and properties of the corresponding Gd(III) complexes were preliminarily investigated by relaxometric techniques. The presence of phosphonic groups progressively reduces the number of coordinated water molecules on the metal center and increases the second-sphere contribution to the relaxivity.

The First Synthesis of 4′-Branched 5′-Deoxycarbocyclic 9-Deazaadenosine and Phosphonic Acids as Antiviral Agents

The first synthetic route to 4′-trifluoromethylated 5′-deoxycarbocyclic-9-deazaadenosine analog and its phosphonic acid derivatives was described from α-trifluoromethyl-α,β-unsaturated ester. The C–C bond connection between cyclopentane and base moiety was accomplished using Knoevenagel type condensation from ketone derivative 11. Synthesized nucleoside and phosphonic acid analogs were tested for anti-HIV activity as well as cytotoxicity.

ChemInform Abstract: Asymmetric Synthesis of Quaternary α‐Amino Acids and Their Phosphonate Analogues

AbstractReview: [117 refs.

The influence of α-aminophosphonic acids on the activity of aminopeptidase from barley seeds—an approach to determine the enzyme specificity

Inhibitory potencies of 24 α-aminophosphonic acids against barley seeds (Hordeum vulgare L.) metallo-aminopeptidase have been determined to evaluate structural requirements of this enzyme. The enzyme was sensitive mostly to the influence of phosphonic acid analogues of phenylalanine and its homologues, thus showing narrow specificity if compared with porcine aminopeptidases M1 and M17 and with Plasmodium aminopeptidase M17.

Rat hormone sensitive lipase inhibition by cyclipostins and their analogs

Cyclipostins are bicyclic lipophilic phosphate natural products. We report here that synthesized individual diastereomers of cyclipostins P and R have nanomolar IC50s toward hormone sensitive lipase (HSL). The less potent diastereomers of these compounds have 10-fold weaker IC50s. The monocyclic phosphate analog of cyclipostin P is nearly as potent as the bicyclic natural product. Bicyclic phosphonate analogs of both cyclipostins exhibit IC50s similar to those of the weaker diastereomer phosphates (about 400nM). The monocyclic phosphonate analog of cyclipostin P has similar potency. A series of monocyclic phosphonate analogs in which a hydrophobic tail extends from the lactone side of the ring are considerably poorer inhibitors, with IC50s around 50μM. Finally cyclophostin, a related natural product inhibitor of acetylcholinesterase (AChE) that lacks the hydrocarbon tail of cyclipostins, is not active against HSL. These results indicate a critical SAR for these compounds, the hydrophobic tail. The smaller lactone ring is not critical to activity, a similarity shared with cyclophostin and AChE. The HSL kinetics of inhibition for the cyclipostin P trans diastereomer were examined in detail. The reaction is irreversible with a KI of 40nM and a rate constant for inactivation of 0.2min−1. These results are similar to those observed for cyclophostin and AChE.

Design and Synthesis of α-Carboxy Nucleoside Phosphonate Analogues and Evaluation as HIV-1 Reverse Transcriptase-Targeting Agents

The synthesis of the first series of a new class of nucleoside phosphonate analogues is described. Addition of a carboxyl group at the α position of carbocyclic nucleoside phosphonate analogues leads to a novel class of potent HIV reverse transcriptase (RT) inhibitors, α-carboxy nucleoside phosphonates (α-CNPs). Key steps in the synthesis of the compounds are Rh-catalyzed O-H insertion and Pd-catalyzed allylation reactions. In cell-free assays, the final products are markedly inhibitory against HIV RT and do not require phosphorylation to exhibit anti-RT activity, which indicates that the α-carboxyphosphonate function is efficiently recognized by HIV RT as a triphosphate entity, an unprecedented property of nucleoside monophosph(on)ates.