bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of HIV-1 RNase H Activity by Nucleotide Dimers and Monomers
Authors: Allen S. J. W. , Krawczyk S. H. , McGee L. R. , Bischofberger N. , Mulato A. S. , Cherrington J. M.
Published: May 2015

Nucleotide dimers and monomers were shown to inhibit human immunodeficiency virus type 1 (HIV) RNase H activity. Several effective inhibitors were identified and placed into three general groups based on biochemical characterization of their inhibition, The first group (group A) inhibited HIV RNase H and the closely related feline immunodeficiency virus (FIV) RNase H, but did not inhibit less related retroviral or cellular RNases H or HIV reverse transcriptase (RT). The second group (group B) inhibited the RNase H activity of several retroviruses as well as the reverse transcriptase function of HIV RT. The third group (group C) inhibited RNases H from retroviral and cellular sources but did not inhibit HIV RT. Kinetic analyses of HIV RNase H inhibition were conducted and all three types of inhibitors exhibited a competitive mode of inhibition with regard to substrate. The small nucleotides described here represent the most potent (Ki values from 0.57 to 16 μM) and selective inhibitors of HIV RNase H reported to date. Further structure - function analyses of these molecules may lead to the discovery of unique, potent antiretroviral therapeutics.
Inhibition of Varicella-Zoster Virus by Penciclovir in Cell Culture and Mechanism of Action
Authors: Bacon T. H. , Gilbart J. , Howard B. A. , Standring-Cox R.
Published: May 2015

The effect of penciclovir (BRL 39123) on the replication of varicella-zoster virus (VZV) in human embryonic lung fibroblasts (MRC-5 cells) was similar to aciclovir when the compounds were present continuously. However, when the compounds were withdrawn the antiviral activity of penciclovir was maintained more effectively than that of aciclovir. In the plaque reduction assay, median 50% effective concentrations (EC50s) were 3.8 μg ml−1 for penciclovir and 4.2 μg ml−1 for aciclovir ( n = 29 clinical isolates). Similarly, penciclovir and aciclovir were equally effective in reducing the numbers of VZV-infected MRC-5 cells and in reducing VZV DNA synthesis within infected cells following continuous treatment. Within VZV-infected cells (S)-penciclovir-triphosphate was formed from penciclovir with >95% enantiomeric purity, and the concentration of penciclovir-triphosphate was 360-fold greater than aciclovir-triphosphate immediately after treatment. This phosphorylation ratio compensates for the lower affinity of VZV DNA polymerase for penciclovir-triphosphate compared with aciclovir-triphosphate (Kis = 7.5 μM and 0.2 μM, respectively). When VZV-infected cultures were treated for 3 days, followed by withdrawal of the compound, inhibition of viral DNA synthesis by penciclovir was maintained for 24 h, whereas viral DNA synthesis resumed more readily after removal of aciclovir. Furthermore, following 8 h daily pulse treatment for 5 days, penciclovir was significantly more active than aciclovir in reducing VZV DNA synthesis ( p = 0.006, n = 10 clinical isolates). The long intracellular half-life of penciclovir-triphosphate (9.1 h) compared with that of aciclovir-triphosphate (0.8 h) accounts for the sustained inhibition of virus replication by penciclovir. This property may contribute to the clinical efficacy of famciclovir, the oral form of penciclovir.
Synthesis of Various 5-(5″-Substituted-3″-Bromophenyl)-2′-β-Deoxyuridines
Authors: Persson T. , Hörnfeldt A.-B. , Gronowitz S. , Johansson N. G.
Published: May 2015

A series of 5-(5″-substituted-3″-bromophenyl)-2′-β-deoxyuridines were prepared and investigated for their activity against HCMV and HIV. None of the compounds exhibited any activity against HIV at the highest concentration, 100μgml−1. In the HCMV ELISA assay the ED50 and CD50 values of the 5-(5″-substituted-3″-bromophenyl)-2′-deoxyuridines were about 60μg ml−1 150μg ml−1, respectively.
Cidofovir, a New Agent with Potent Anti-Herpesvirus Activity
Authors: Hitchcock M. J. M. , Jaffe H. S. , Martin J. C. , Stagg R. J.
Published: May 2015

Cidofovir is a potent, broad spectrum antiviral agent with activity in vitro and in vivo against cytomegalovirus and other members of the herpesvirus family, as well as certain other DNA viruses. After uptake into cells it is converted enzymatically to cidofovir diphosphate, a structural analogue of deoxycytidine triphosphate, which selectively inhibits viral DNA polymerases relative to host cell polymerases. Cross-resistance to cidofovir is not usually seen with human cytomegalovirus isolates that are foscarnet-resistant, or isolates that are ganciclovir-resistant due to a deficiency in ganciclovir phosphorylation. Cross-resistance is seen, however, with isolates that are ganciclovir resistant due to polymerase mutations. A prolonged elimination phase seen in vivo, correlates with a long intracellular half-life seen in vitro and allows for efficacy in animal models of virus infection with infrequent dosing or prophylaxis. Clinical studies of intravenous cidofovir in cytomegalovirus retinitis in patients with AIDS are claimed to show delay of retinitis progression with maintenance doses given once every 2 weeks.
Side-Chain Derivatives of Biologically Active Nucleosides. Part 2: Synthesis and anti-HIV Activity of 5′-C-Methyl Derivatives of 3′-Fluoro-3′-Deoxythymidine
Authors: Hiebl J. , Zbiral E. , von Janta-Lipinski M. , Balzarini J. , De Clercq E.
Published: May 2015

1-(3′-Fluoro-2′,3′,6′-trideoxy-β-D-allofuranosyl)thymine [7] and 1-(3′-fluoro-2′,3′,6′-trideoxy-α-L-talofuranosyl) thymine [8] were synthesized starting from the corresponding 2,3′-anhydro nucleoside derivatives. The fluorine was introduced stereoselectively by opening of the anhydro bridge in the presence of HF/AIF3. The 5′-C-methyl derivatives, [7] and [8], of 3′-fluoro-3′-deoxythymidine (FLT) were evaluated for their inhibitory effect against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2). The compounds [7] and [8] had antiviral activity which was three orders of magnitude lower than the reference compound 3′-fluoro-3′-deoxythymidine. None of the compounds showed appreciable activity against other RNA or DNA viruses at subtoxic concentrations.
Novel Nucleoside Phosphoramidates as Inhibitors of HIV: Studies on the Stereochemical Requirements of the Phosphoramidate Amino Acid
Authors: McGuigan C. , Salgado A. , Yarnold C. , Harries T.Y. , De Clercq E. , Balzarini J.
Published: May 2015

Novel phosphoramidate derivatives of the anti-HIV nucleoside analogue d4T were designed to act as labile membrane-soluble prodrugs of the bio-active free nucleotide d4TMP. We herein reveal the very marked dependence of the antiviral activity of these phosphoramidates upon the stereochemistry of the amino acid attached to the phosphate centre; with a strong preference for the L-stereochemistry. These phosphate triesters were shown to liberate amino acid derivatives of the nucleotide intracellularly. These novel analogues, typified by alaninyl d4T monophosphate, may act as intracellular sources of the free nucleotides. The alaninyl d4T adducts themselves exert an antiviral effect when administered extracellularly, but again with clear distinctions between the L- and D-series. This evidence indicates that extracellularly administered blocked triesters derived from L-amino acids can generate d4TMP intracellularly, by a new pathway which is highly dependent on the amino acid stereochemistry.
Methyl-2-Thienylketopolymethyleneoxyphenyl Derivatives of Alkyl-Substituted 4,5-Dihydro-Oxazoles with Anti-Human Picornavirus Activity
Authors: Mai A. , Artico M. , Massa S. , Ragno R. , De Montis A. , Comas S. , Spiga M.G. , La Colla P.
Published: May 2015

The synthesis of 5-methyl-2-thienylketopolymethylene oxyphenyl 4,5-dihydro-2-(alkyl)oxazoles was accomplished by the assembly of two synthones, namely 1-(5-methyl-2-thienyl)-7-hydroxy-1-heptanone (or 1-(5-methyl-2-thienyl)-5-chloro-1-pentanone) and 4-[4,5-dihydro(alkyl)oxazol-2-yl]phenol, in the presence of diethyl azodicarboxylate(DEAD)-triphenyl phosphine (or sodium iodide and anhydrous potassium carbonate). Eighteen new disoxaril analogues were synthesized by the above procedure and tested in vitro against several rhino and enteroviruses. With a few exceptions, all test derivatives were more potent than WIN 51711 when assayed against HRV-14, and as potent as WIN 51711 against HRV-2, but none of them inhibited the other HRV serotypes. Among the various derivatives, two compounds showed the same wide spectrum activity of WIN 51711 against several rhino, and enteroviruses, but were at least 10-fold less toxic.
Isolation and Characterization of HIV-1 Isolates Resistant to Oxathiin Carboxanilide Analogues: Evaluation of Variables in the Drug Resistance Selection Process
Authors: Kinjerski T.L. , Pallansch L.A. , Buckheit R.W.
Published: May 2015

Virus isolates resistant to a variety of structural analogues of oxathiin carboxanilide (UC84) were selected in cell culture and phenotypically and mo!ecularly characterized in order to evaluate the effects of variables in the resistance selection process. The rate of appearance of the resistant viruses and the net loss of sensitivity of the virus isolates to the selecting compound were not dependent on the selective pressure employed against wild-type virus, but were associated with structural features of the compound. Although each of the compounds rapidly selected for resistant viruses, the isolates obtained varied in their overall level of resistance, in their cross-resistance to other non-nucleoside reverse transcriptase inhibitors (NNRTIs) and in the amino acid changes present in the reverse transcriptase (RT). The mutation Y181C was most commonly observed, often with a second mutation, such as K101E or V-106A. The amino acid change L100I was also observed upon selection. In order to determine the reproducibility of the in-vitro resistance selection process, 10 isolates resistant to UC84 were independently selected in parallel cultures. Mutations detected in the RT of these isolates were varied but included the commonly reported Y181C and V106A amino acid changes, as well as unique changes K101I, K101N, K103Q, G190A, T139I and A98S. These results demonstrate that from the heterogeneous wild-type population, antiviral agents, such as the UC compounds, may select a wide variety of virus isolates with resistance-engendering amino acid changes in the RT. In addition, the results also suggest that antiviral agents may select for resistant viruses at different rates and to different extents, offering the possibility that compounds might be identified which do not readily result in high level drug resistance.
Synthesis and Pharmacological Evaluation of CGP 57813 and CGP 61755, HIV-1 Protease Inhibitors from the Phe-c-Phe Peptidomimetic Class
Authors: Cozens R.M. , Bold G. , Capraro H-G. , Fässler A. , Mestan J. , Lang M. , Poncioni B. , Stover D. , Rösel J.L.
Published: May 2015

In this report we describe the enzyme inhibitory, antiviral and pharmacokinetic properties of CGP 57813 and CGP 61755, structural analogues of CGP 53437 that were synthesized in an attempt to obtain human immunodeficiency virus type 1 (HIV-1) protease inhibitors with improved selectivity and oral bioavailability. CGP 57813 inhibited HIV-1 protease with an IC50 of 11 nM (similar to CGP 53437). CGP 61755, on the other hand, was c.a. 10-fold more potent (IC50 = 1 nM; similar to saquinavir and indinavir). The selectivity profile of CGP 57813 was comparable to that of CGP 53437 while CGP 61755 clearly had improved selectivity for HIV-1 protease over human aspartic proteases. All three compounds had similar antiviral activity in HIV-1/MN infected MT-2 cells; ED50s were c.a. 5 nM and ED90s were 30 nM. Compared to CGP 53437, both CGP 57813 and CGP 61755 had markedly better bioavailability in mice after oral administration in a DMSO-hydroxypropyl-β-cyclodextrin formulation. However, when CGP 57813 was administered in a sesame oil-based formulation to either mice or dogs no useful plasma concentrations could be measured. In contrast, CGP 61755 was clearly bioavailable in dogs after oral administration of the compound in the same formulation; 1.2 g per dog resulted in a mean AUC0-8 h = 21.06 ± 3.53 μM.h, a mean Cmax = 4.8 ± 0.52 μM and compound was detectable for at least 8 h after administration. The potent antiviral activity of CGP 61755 together with improved selectivity and oral bioavailability holds promise for efficacy in AIDS therapy.
Comparison of Cytotoxicity of Mononucleoside Phosphotriester Derivatives Bearing Biolabile Phosphate Protecting Groups in Normal Human Bone Marrow Progenitor Cells
Authors: Périgaud C. , Girardet J.-L. , Lefebvre I. , Xie M.-Y. , Aubertin A.-M. , Kirn A. , Gosselin G. , Imbach J.-L. , Sommadossi J.-P.
Published: May 2015

The effects of three mononucleoside phosphotriester derivatives of 3′-azido-2′,3′-dideoxythymidine (AZT) which incorporate biolabile phosphate protecting groups, namely S-acetyl-2-thioethyl (MeSATE), S-(2-hydroxyethylsulfidyl)-2-thioethyl (DTE), and pivaloyloxymethyl (POM) were studied and compared to their nucleoside parent in human myeloid colony-forming cells. Moreover, the relative antiviral potency of these three pronucleotides were determined in primary human peripheral blood mononuclear cells infected with human immunodeficiency virus type 1. The results indicate that the SATE and DTE pro-moieties, as well as their degradation products, do not induce additional toxicity. The bis(MeSATE) phosphotriester derivative of AZT emerged as the most selective inhibitor with an in-vitro therapeutic index of the same order of magnitude as observed for AZT. This study has been extended to the corresponding bis(MeSATE) and bis(DTE) phosphotriester derivatives of 2′,3′-dideoxyuridine (ddU).
Ex Vivo anti-HIV Activity of Human Serum Obtained from Normal Volunteers Following Oral Administration of the HIV-1 Protease Inhibitor CGP 53437: Value as Predictor of Antiviral Efficacy
Authors: Lazdins JK , Walker JK , Cozens RM , Flesch G , Czendlik C , Howald H , Kremers W , Alteri E
Published: May 2015

The aim of the study was to determine whether the concentration of CGP 53437 measured in the sera of normal volunteers following oral administration of a single dose, had retained its anti-HIV activity; and whether such results could be of predictive value for future clinical antiviral efficacy studies. CGP 53437 is an inhibitor of HIV-1 protease that suppresses HIV-1 replication in human lymphocytes in vitro at 100 nM. The in vitro anti-HIV activity of human sera obtained from CGP 53437-treated individuals was compared with that of sera spiked with known concentrations of CGP 53437 (in the presence or absence of α-1 acid glycoprotein). It was found that the concentration of the compound measured in the sera from treated individuals provided the expected in vitro anti-HIV activity. These results not only validate our analytical method for detection of CGP 53437, but also support the notion that interaction of CGP 53437 with plasma proteins does not significantly affect its antiviral activity (shift of the ED90 by a factor of three). In conclusion, ex vivo anti-HIV activity determinations of sera containing an HIV protease inhibitor, in conjunction with the pharmacokinetic evaluation during Phase I clinical studies, can provide valuable information regarding the suitability of such inhibitors for further clinical studies.
Anti-HIV Activities of Anionic Metalloporphyrins and Related Compounds
Authors: Song R , Witvrouw M , Schols D , Robert A , Balzarini J , De Clercq E , Bemadou J , Meunier B
Published: May 2015

Various water-soluble polysulphonated and polycarboxylated porphyrins and some of their metallated derivatives have been prepared and their antiviral properties against human immunodeficiency virus (HIV-1, HIV-2), simian immunodeficiency virus and other viruses are reported. Besides these polyanionic compounds, two new series of porphyrins were included and studied from the perspective of bio-availability modulation: (i) acefylsulphonamido derivatives endowed with weak acidity properties (deprotonation gives the corresponding anionic derivatives in a pH range 4.5-8.5) and (ii) compounds with the anionic charge transiently masked by esterification (acetoxymethyl- and pivaloyloxymethylesters). Among the more active compounds in inhibiting HIV-induced cytopathic effects, the sulphonated and carboxylated porphyrin complexes were found to interact directly with the HIV protein gp 120 and not with the CD4 cellular receptor.
3-Hydroxyphthaloyl-β-Lactoglobulin. I. Optimization of Production and Comparison with other Compounds Considered for Chemoprophylaxis of Mucosally Transmitted Human Immunodeficiency Virus Type 1
Authors: Neurath AR , Debnath AK , Strick N , Li Y-Y , Lin K , Jiang S
Published: May 2015

Modification of the major bovine whey protein, β-lactoglobulin (β-LG) by 3-hydroxyphthalic anhydride (3HP) leads to the generation of a potent inhibitor of infection by human immunodeficiency virus (HIV) types 1 and 2, designated 3HP-β-LG. 3HP-β-LG also has antiviral activity against herpesviruses, albeit at concentrations exceeding those required for inhibition of HIV-1 infection. The topical application of 3HP-β-LG to decrease the rate of sexual transmission of HIV and other sexually transmitted viruses worldwide is being considered. Results presented here: (i) define the conditions for chemical modification of β-LG by 3HP, resulting in 3HP-β-LG with optimum anti-HIV-1 activity; (ii) show that β-LG, prior to chemical modification, or 3HP-β-LG can be exposed to the elevated temperatures used to pasteurize milk without adversely affecting anti-HIV-1 activity; (iii) provide evidence that 3HP-β-LG is a more potent anti-HIV-1 compound than sulphated polysaccharides, other candidate compounds considered as prophylactic agents to prevent sexual transmission of HIV-1; and (iv) confirm that the primary target for 3HP-β-LG is CD4, although binding to the HIV-1 envelope protein gp120 was also observed and contributed to the antiviral activity of 3HP-β-LG.
3-Hydroxyphthaloyl-β-Lactoglobulin. II. Anti-Human Immunodeficiency Virus Type 1 Activity in in Vitro Environments Relevant to Prevention of Sexual Transmission of the Virus
Authors: Neurath AR , Debnath AK , Strick N , Li Y-Y , Lin K , Jiang S
Published: May 2015

It is anticipated that the rate of sexual transmission of viruses could be substantially decreased by the use of topical chemical barrier methods. Chemical modification of bovine (β-lactoglobulin (β-LG), the major protein of whey, led to the generation of a potent inhibitor (designated 3HP-β-LG) of human immunodeficiency virus type 1 (HIV-1) infection which was also active against herpesviruses. Compounds intended for topical application to prevent sexual transmission of viruses need to maintain their antiviral activity at pH <<7, corresponding to an acidic vaginal environment, and in the presence of seminal fluid. Results presented here show that the binding of 3HP-β-LG to the CD4 receptor for HIV, involved in the anti-HIV-1 activity of this compound, decreases with decreasing pH. The presence of seminal fluid also decreased the binding of 3HP-β-LG to CD4 and diminished the inhibitory effect of the compound on CD4-gp120 binding. 3HP-β-LG was shown to bind Zn++, and the inhibitory effect of seminal fluid could be substantially diminished by chelating Zn++ with ethylenediaminetetraacetate. Saliva had no effect on 3HP-β-LG binding to CD4 or on its interference with gp120-CD4 binding. The decreased 3HP-β-LG-CD4 binding and the concomitant reduction of gp120-CD4 binding inhibition by 3HP-β-LG at low pH and in the presence of seminal fluid could be compensated for by an increase of the 3HP-β-LG concentration and by adding Zn++ chelators to 3HP-β-LG. These results provide a background for the design of 3HP-β-LG formulations for topical use.
Acyclic Phosphonomethylether Nucleoside Inhibitors of Respiratory Viruses
Authors: Barnard DL , Bischofberger N , Kim CU , Huffman JH , Sidwell RW , Dougherty JP , Lew W , Williams AAA , Yang W
Published: May 2015

A series of acyclic phosphonomethylether nucleosides were synthesized and then evaluated for inhibitory activity against respiratory viruses of clinical significance using CPE inhibition, neutral red uptake and virus yield reduction assays. Of the 20 compounds synthesized, none significantly inhibited influenza A or B viruses or respiratory syncytial virus strains A2, Long or 18537; the selective indices (SI) were less than 10. A new compound, GS-2128 (2R, 5R-9-[2,5-dihydro-5-(phosphonomethoxy)-2-furanyl]adenine; D4API), selectively inhibited adenovirus 5 (SI>10) as did GS-0577 (9-(3-hydroxy-2-phosphonylmethoxypropyl)-adenine; HPMPA) and GS-0504 [(S)-1-[3-hydroxy-2-(phosphonylmethoxypropyl)]-cytosine; HPMPC]. The 50% effective concentrations (EC50) ranged from 8–100 μg mL−1 and 50% cell inhibitory concentrations (CC50) from 40–1000 μg mL−1. All three compounds were also found to be active against laboratory strains and clinical isolates of adenovirus types 1, 2, 8 and 41 with EC50 values ranging from 0.2 to 10 μg mL−1. Two compounds, GS-438 (9-(2-phosphonylmethoxyethyl)guanine, PMEG) and GS-2542 (9-[3-phosphonomethoxy)methoxymethyl]guanine) inhibited parainfluenza virus 3 strain C243, with SI of 52 and >333, respectively. PMEG also inhibited measles virus strains CC, Halonen and Chicago with EC50 values ranging from 0.03–9 μg mL−1. These data suggest that these compounds should be considered for possible development as therapeutic agents for respiratory virus infections.
Inhibition of Human Cytomegalovirus DNA Replication with a Phosphorothioate Cholesteryl-Modified Oligonucleotide is Mediated by Rapid Cellular Association and Virus-Facilitated Nuclear Localization
Authors: Zhang Z , Smith JA , Smyth AP , Tang J-Y , Eisenberg W , Pari GS
Published: May 2015

We have previously shown that an antisense phosphorothioate (PS) oligodeoxynucleotide has potent anti-human cytomegalovirus (HCMV) activity (GS Pari, AK Field & JA Smith, Antimicrobial Agents and Chemotherapy 1995, 39: 1157–1161). We have now used a modified PS oligonucleotide having three 2′-O-methyl nucleotides at the 3′ end and four 2′-O-methyl nucleotides at the 5′ end, containing a cholesteryl moiety linked to the 3′ end by a novel thiono-triester linkage. This compound, UL36ANTI-M, is superior to the PS (UL36ANTI) version with respect to antiviral potency, melting temperature and nuclease resistance. Also, we show that cellular association for this oligonucleotide is rapid, occurring within 15 min after treatment and is about 12-fold higher when compared to UL36ANTI. This increased rate of cellular association also correlates with antiviral properties in that a 15 min incubation with UL36ANTI-M was sufficient to achieve 75% inhibition of viral DNA replication and complete inhibition was achieved after only a 1 h pretreatment. In addition confocal microscopic examination showed a change in subcellular distribution from perinuclear to nuclear for oligonucleotides in HCMV-infected human fibroblasts. However, the total amount of cell-associated oligonucleotide was unchanged in infected cells.
Molecular Targets in Inhibition of Hepatitis C Virus Replication
Authors: Bartenschlager R
Published: May 2015

Hepatitis C virus (HCV) is the major cause of transfusion-associated hepatitis and accounts for a significant proportion of hepatitis cases worldwide. Most, if not all, infections become persistent and about 60% of cases develop chronic liver disease with various outcomes ranging from an asymptomatic carrier state to chronic active hepatitis and liver cirrhosis, which is strongly associated with the development of hepatocellular carcinoma. Since the initial cloning of the viral genome in 1989, our knowledge of the molecular biology of HCV has increased rapidly and led to the identification of several potential targets for antiviral intervention. In contrast, the low replication of the virus in cell culture, the lack of convenient animal models and the high genome variability present major challenges for drug development. This review will describe candidate drug targets and summarize ‘classical’ and ‘novel’ approaches currently being pursued to develop efficient HCV-specific therapies.
The Influence of Cyclosporin Immunosuppression on the Efficacy of Famciclovir or Valaciclovir Chemotherapy Studied in a Murine Herpes Simplex Virus Type 1 Infection Model
Authors: Thackray AM , Field HJ
Published: May 2015

Mice with or without immunosuppression by cyclosporin (Cy) were inoculated with herpes simplex virus type 1 in the ear pinna. Without immunosuppression, 20% of the mice died; clinical signs resolved in survivors and infectious virus was cleared by 7 to 10 days post-inoculation (p.i.). With Cy, mortality was 50%, clinical signs increased and infectious virus persisted. Mice were treated with either valaciclovir (VACV) or famciclovir (FCV) from days 1–5 or 5–10 p.i. and both compounds moderated the disease, but only FCV led to rapid restoration of body weight and complete protection from mortality. Resolution of clinical signs was more marked with immunosuppression. On cessation of VACV therapy, infectious virus recurred on individual days. Without immunosuppression, recurrence was detected in neural tissues only, but with Cy, infectious virus also recurred in skin. No recurrences of infectious virus were observed in any FCV-treated mice.
Intra-Individual Variation in Serum AZT Concentration is Not Related to Intestinal Absorption or Small Intestinal Inflammatory Changes in Human Immunodeficiency Virus-Infected Subjects
Authors: Sherwood RA , Marsden JT , Stein CA , Somasundaram S , Aitken C , Oxford JS , Menzies IS , Bjarnason I
Published: May 2015

3′-Azido-3′-deoxythymidine (AZT; zidovudine) either alone or in combination with didanosine or another nucleoside analogue is the first-line treatment for patients with human immunodeficiency virus (HIV) infection, many of whom have concurrent gastrointestinal (GI) disease. This study assessed whether the absorption of AZT was affected by GI disease. The absorption and pharmacokinetics of AZT in 23 HIV-infected individuals was measured after a single dose of AZT and was related in 12 patients to small intestinal function. Levels of AZT and its metabolite 5′-glucopyranuronosylthymidine (G-AZT) were measured by radioimmunoassay. Intestinal permeability was assessed by differential urinary excretion of orally administered lactulose/1-rhamnose; absorptive capacity was measured simultaneously by the urinary excretion of 3-o-methyl-D-glucose, d-xylose and 1-rhamnose. Small intestinal inflammation was assessed by faecal excretion of indium-labelled neutrophils. Peak levels of AZT in serum varied between 170 and 1820 ng mL−1. The metabolite G-AZT was present in serum at peak concentrations varying from 1020 to 9930 ng mL−1. There was up to a sevenfold variation in the area under the curve (AUC). The time to maximum serum concentration for AZT was between 30 and 120 min, with an absorption half-life of between 2 and 38 min. The median elimination half-life was 57 min (range 46–72 min), close to the predicted half-life of 60 min. Intestinal permeability was increased in six of the 12 subjects studied and eight had evidence of reduced absorptive capacity. Ten of the 12 patients had evidence of small intestinal inflammation. We concluded that neither changes in permeability nor absorptive capacity influenced the absorption of AZT. There was no relationship between the presence of intestinal inflammation and AZT absorption. This study showed a significant intra-individual variation of serum AZT levels which cannot be explained on the basis of altered intestinal absorptive capacity or intestinal inflammatory changes.
Structural Features and Anti-Human Immunodeficiency Virus (HIV) Activity of the Isomers of 1-(2′,6′-Difluorophenyl)-1H,3H-Thiazolo[3,4-a]Benzimidazole, a Potent Non-Nucleoside HIV-1 Reverse Transcriptase Inhibitor
Authors: Chimirri A , Grasso S , Molica C , Monforte A-M , Monforte P , Zappalà M , Bruno G , Nicolò F , Witvrouw M , Jonckeere H , Balzarini J , De Clercq E
Published: May 2015

The structural features, including the absolute configuration, of the enantiomers of 1-(2′,6′-difluorophenyl)-1 H,3 H-thiazolo[3,4- a]benzimidazole (TBZ; NSC 625487), the lead compound of a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs), are described. Diffractometric analysis revealed that TBZ, like other NNRTIs, assumes a butterfly-like conformation in which the phenyl ring at C1 is in an orthogonal orientation relative to the thiazolobenzimidazole system, and the 2′,6′-fluorine atoms form two intramolecular hydrogen bonds with H1 and one of the methylene protons at C3, respectively. The stereochemistry in solution, as confirmed by lanthanide shift reagent-assisted ‘H NMR, paralleled the situation present in the solid state. The in vitro anti-HIV activity of the two enantiomers was also evaluated and the results obtained showed that the R-(+) is more active than the S-(−) isomer in inhibiting HIV-1 replication. Resistance and cross-resistance to other NNRTIs as well as inhibitory effects on HIV-1 reverse transcriptase activity are also reported.
Pyridazino[3,4-b][1,5]Benzodiazepin-5-Ones: Synthesis and Biological Evaluation
Authors: Heinisch G , Huber E , Leitner C , Matuszczak B , Maurer A , Pachler S , Prillinger U
Published: May 2015

Starting from 3,6-dichloropyridazine-4-carboxylic acid chloride, a series of pyridazino[3,4- b][1,5]benzodiazepin-5-ones bearing various substituents in positions 3, 6, 8 and 11 was prepared via N-alkyl-3-alkylamino-6-chloro- N-(2-chloro-5-nitrophenyl)-pyridazine-4-carboxamides. The latter were smoothly accessible by treatment of N-alkyl-3,6-dichloro-N-(2-fluorophenyl)-pyridazine-4-carboxamides with primary aliphatic amines. The new tricyclic compounds, which are structurally related to nevirapine and congeners were screened as human immunodeficiency virus type 1 reverse transcriptase inhibitors; the influence of the substitution pattern on inhibitory potency is discussed.
Lymphatic Targeting of Anti-Human Immunodeficiency Virus Nucleosides: Pharmacokinetics of G′-Deoxy-2′,3′-Didehydrothymidine after Intravenous and Oral Administration of Dipalmitoylphosphatidyl Prodrug to Mice
Authors: Manouilov KK , Xu Z-S , Manouilova LS , Boudinot FD , Schinazi RF , Chu CK
Published: May 2015

The lymphatic system is a primary target for early anti-human immunodeficiency virus drug therapy. Strategies are currently being sought to enhance the delivery of nucleoside analogues such as 3′-deoxy-2′,3′-didehydrothymidine (stavudine; d4T) toward the lymph and lymph nodes. The purpose of this study was to synthesize dipalmitoylphosphatidyl-d4T (DPP-d4T) as a lipophilic prodrug of d4T and to evaluate the lymphatic distribution of d4T following administration of d4T and DPP-d4T to mice. The pharmacokinetics of d4T were characterized following administration of a single intravenous or oral dose of 50 mg kg−1 d4T and an equimolar dose (214 mg kg−1) of DPP-d4T. Concentrations of d4T in serum and lymph nodes were determined by HPLC. Following administration of d4T, the distribution of d4T into lymph nodes was rapid with maximum concentrations observed within 5 min after dosing. The AUC and half-life values of d4T in three groups of lymph nodes were similar to those in serum. Administration of DPP-d4T resulted in significantly lower concentrations of d4T in serum and lymph nodes. Approximately 67% of the intravenously administered DPP-d4T was biotransformed to parent compound. The apparent oral bioavailability of DPP-d4T was low. While the phospholipid prodrug did not increase d4T concentrations in the lymph nodes, it did provide an extended release of the parent nucleoside, resulting in sustained concentrations of d4T.
Acute and Delayed Toxicity Studies on the Antiherpesvirus Agents 5-Methoxymethyl-2′-Deoxycytidine and 5-Methoxymethyl-2′-Deoxyuridine
Authors: Shi R , Gupta SV , Kukhanova M , Kumar SVP , Stuart AL , Cheng YC
Published: May 2015

5-Methoxymethyl-2′-deoxycytidine (MMdCyd) and the corresponding deoxyuridine analogue, 5-methoxymethyl-2′-deoxyuridine (MMdUrd) are selective antiherpesvirus agents. MMdCyd (ED50 1.5 μM) is a more potent inhibitor of herpes simplex virus replication than MMdUrd (ED50 30 μM) when maintained in the deoxycytidine form (deamination prevented). The 5′-triphos-phates, MMdCTP and MMdUTP, were synthesized, and incorporation into DNA by mitochondrial DNA polymerase γ was investigated. MMdCTP and MMdUTP were incorporated into DNA in place of dCTP and dTTP, respectively. The effect of MMdCyd and MMdUrd on cell growth (acute toxicity) and prolonged exposure (delayed cytotoxicity) in CEM cells was investigated. The two analogues did not exhibit acute or delayed toxicity (2 weeks exposure) up to 1000 μM. In contrast, at a concentration as low as 0.125 μM of 2′,3′-dideoxycytidine (ddC; control drug), the doubling time of the cells increased after 10 days. At higher concentrations, a very marked increase in doubling time was observed from 6 days onward with ddC treatment. The data suggest that in uninfected cells neither MMdUrd nor MMdCyd are anabolized to the triphosphate form in significant amounts. As a result, little or no MMdCTP or MMdUTP builds up in the mitochondria and thus delayed toxicity is not observed.
Antiviral Therapy in Herpes Zoster: A Review
Authors: Marley J
Published: May 2015

Herpes zoster is a disease caused by reactivation of the latent form of the varicella zoster virus (VZV). It is usually seen in adults, occurring mainly in the elderly. The acute phase of the disease is characterized by a rash, which is typically accompanied by pain. In some patients the pain may persist after the rash has healed, and may last for many months or years. Three antiviral agents are currently available to treat herpes zoster: aciclovir, its prodrug valaciclovir, and famciclovir. All three are effective in accelerating healing of the rash, and reducing the patient's period of infectivity. These antiviral agents also impact on the chronic pain associated with herpes zoster but appear to differ in their efficacy. Two different measures of chronic pain have been used in clinical studies: post-herpetic neuralgia (PHN) which refers to the pain occurring after the rash has healed, and zoster-associated pain (ZAP), defined as the continuum of pain occurring after the onset of herpes zoster (i.e. making no distinction between acute pain and PHN). Famciclovir has been shown to significantly reduce the risk and duration of PHN in patients over 50 years old. In another study famciclovir was shown to be significantly more effective than aciclovir in relieving ZAP when treatment was taken within 48 h of the onset of herpes zoster. Valaciclovir was also found to be better than aciclovir in reducing the duration of ZAP, but it is unclear whether this improvement over aciclovir also applied to PHN. Elderly patients therefore benefit from antiviral therapy, which should be initiated as early as possible, and can significantly reduce the risk and duration of the chronic pain associated with herpes zoster.
Alkylthioglycerol Prodrugs of Foscarnet: Synthesis, Oral Bioavailability and Structure–Activity Studies in Human Cytomegalovirus-, Herpes Simplex Virus Type 1- and Human Immunodeficiency Virus Type 1-Infected Cells
Authors: Beadle JR , Kini GD , Aldern KA , Gardner MF , Wright KN , Richman DD , Hostetler KY
Published: May 2015

In a previous study, we reported that 1- O-octadecyl- sn-glycero-3-foscarnet (ODG-PFA) was 40 to 93 times more potent than free foscarnet (PFA) in human cytomegalovirus (HCMV)-, herpes simplex virus type 1 (HSV-1)- and human immunodeficiency virus type 1 (HIV-1)-infected cells. To evaluate the effect of substituting a 1- S-alkyl thioether for a 1- O-alkyl ether, we synthesized a series of PFA conjugates of 1- S-alkyl- sn-thioglycerols with varied 1- S-alkyl chain lengths. To establish structure–activity relationships we measured the in vitro antiviral activity of liposomal formulations of the drugs in cells infected with HCMV, HSV-1 or HIV-1. The optimum 1- S-alkyl chain length in the series was 16 to 18 carbon atoms. We compared the antiviral activity of 16- and 18-carbon alkyl thioglycerol versus alkylglycerol prodrugs and did not observe any significant differences in their antiviral activities. The series' most active member, 1- S-octadecyl- sn-glycero-3-foscarnet (ODSG-PFA) was 56-, eight- and 45-fold more active than PFA in HCMV-, HSV-1- and HIV-1-infected cells in vitro. The oral absorption of PFA and 1-S-octadecyl-sn-thioglycero-3-PFA was compared in mice by measuring plasma levels of 14C after oral administration of radiolabelled compounds. The peak plasma level of 14C was sevenfold higher following administration of [14C]ODSG-PFA than following an equimolar dose of [14C]PFA. Area-under-the-curve was 23-fold greater for ODSG-PFA than for PFA. Like previously reported alkyloxyether–lipid PFA conjugates, alkylthioether conjugates provided enhanced antiviral activity and oral bioavailability. However, S-ether conjugates may be metabolized differently than O-ether conjugates. More detailed in vivo pharmacokinetic evaluation of the alkyl-thioether–PFA conjugates is required.
Targeting RNase L to Human Immunodeficiency Virus RNA with 2-5A-Antisense
Authors: Player  , Maitra RK , Silverman RH , Torrence PF
Published: May 2015

In an attempt to develop a lead for the application of 2–5A-antisense to the targeted destruction of human immunodeficiency virus (HIV) RNA, specific target sequences within the HIV mRNAs were identified by analysis of the theoretical secondary structure. 2-5A-antisense chimeras were chosen against a total of 11 different sequences: three in the gag mRNA, three in the rev mRNA and five in the tat mRNA. 2-5A-antisense chimera synthesis was accomplished using solid-phase phosphoramidite chemistry. These chimeras were evaluated for their activity in a cell-free assay system using purified recombinant human RNase L to effect cleavage of 32P-labelled RNA transcripts of plasmids derived from HIV NL4-3. This screening revealed that of the three 2-5A-antisense chimeras targeted against gag mRNA, only one had significant HIV RNA cleavage activity, approximately10-fold-reduced compared to the parent 2-5A tetramer and comparable to that reported for the prototypical 2-5A-anti-PKR chimera, targeted against PKR mRNA. The cleavage activity of this chimera was specific, since a scrambled antisense domain chimera and a chimera without the key 5′-monophosphate moiety were both inactive. The 10 other 2-5A-antisense chimeras against tat and rev had significantly less activity. These results imply that HIV gag RNA, like PKR RNA and a model HIV tat-oligoA- vif RNA, can be cleaved using the 2-5A-antisense approach. The results further imply that not all regions of a potential RNA target are accessible to the 2-5A-antisense approach.
Synthesis and Evaluation of Some Masked Phosphate Esters of the Anti-Herpesvirus Drug 882C (Netivudine) as Potential Antiviral Agents
Authors: McGuigan C , Perry A , Yarnold CJ , Sutton PW , Lowe D , Miller W , Rahim SG , Slater MJ
Published: May 2015

A number of symmetric and asymmetric 5′-phosphate esters of the potent anti-varicellazoster virus (VZV) agent 1–(β-d-arabinofuranosyl)-5-prop-1-ynyluracil (882C; netivudine) were prepared as potential lipophilic, membrane-soluble prodrugs of the bioactive phosphate forms. The compounds were prepared by the base-catalysed coupling of various phosphorochloridates with the free nucleoside analogue. Compounds were fully characterized by a range of spectroscopic and analytical methods and were studied for their inhibition of several viruses in tissue culture. All of the phosphate esters were inactive against human cytomegalovirus, herpes simplex virus type 2, VZV, human immunodeficiency virus type 1 and influenza A virus (EC50 >100 μM) except the 5′-(4–nitrophenyl phenyl) phosphate, which inhibited influenza A virus. The relative rate of esterase-mediated hydrolysis of one of the lead target structures was measured in order to rationalize the poor antiviral action, and data were collected on possible metabolites in support of this analysis. Cell-specific esterases are implicated as key determinants of the antiviral potency of prodrugs of this type.
Inhibitory Effects of Podophyllotoxin Derivatives on Herpes Simplex Virus Replication
Authors: Sudo K , Konno K , Shigeta S , Yokota T
Published: May 2015

Podophyllotoxin and its derivatives were examined for inhibitory effects on the replication of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), including acyclovir-resistant virus and clinical isolates. Deoxypodophyllotoxin (RD4–6266) proved to be a highly potent and selective inhibitor of all HSV strains in MRC-5 cells. EC50 values of RD4–6283 (in which the methylenedioxy ring A is modified) for HSV-1 and -2 were inferior to those of deoxypodophyllotoxin. However, podorhizol (RD4–6277) and 5′-methoxy-podorhizol (RD4–6276), in which ring C is absent, did notinhibit HSV replication. Moreover, RD4–6266 also inhibited the production of infectious virus particles of HSV-1 KOS strain and HSV-2 G strain. In contrast, none of the podophyllotoxin derivatives were found to have an antiviral effect against influenza A virus, respiratory syncytial virus or human cytomegalovirus in doses not toxic to the cells.
Inhibitory Effects of Novel Nucleoside and Nucleotide Analogues on Epstein—Barr Virus Replication
Authors: Meerbach A , Holý A , Wutzler P , De Clercq E , Neyts J
Published: May 2015

The anti-Epstein–Barr virus (EBV) activity of different classes of compounds was assessed by means of an EBV DNA hybridization assay using a digoxigenin-labelled probe specific for the BamHI W fragment of the EBV genome, as well as by measuring viral capsid antigen (VCA) expression after a 7 day incubation period of P3HR-1 producer cells with the test substances. Acyclovir, ganciclovir, cidofovir and zidovudine were included as reference compounds. Several compounds proved to be potent and selective inhibitors of EBV DNA synthesis and VCA expression. Of the new compounds that were evaluated for their anti-EBV activity, the highest efficacy (lowest EC50) and highest selectivity index (SI) were shown by the purine nucleoside analogue 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (S2242) (EC50 0.6 ng/ml; SI 600), the acyclic nucleoside phosphonate analogues 9-(2-phosphonomethoxyethyl)-6-dimethylaminopurine (EC50 1.1 μg/ml; SI 91), 9-(2-phosphonomethoxyethyl)-2-amino-6-benzhydrylaminopurine (EC501.3 μg/ml; SI 29), 7-(2-phosphonomethoxyethyl)-6-dimethylaminopurine (EC50 0.8 μg/ml; SI 56), 9-( R)-(2-phosphonomethoxypropyl)-6-(2-dimethylaminoethyl)-aminopurine (EC50 0.5 μg/ml; SI 42), the 2′,3′-dideoxythymidine derivative 3′-oximino-2′,3′-dideoxythymidine (EC501.5 μg/ml; SI 65), and 1-(2,3-dideoxy-3- N-hydroxyamino-β-d-threo-pentafuran yl)pentafuranosyl)thymine (EC50 4.1 μg/ml; SI >24).
Potent β-Lactam Inhibitors of Human Cytomegalovirus Protease
Authors: Yoakim C , Ogilvie WW , Cameron DR , Chabot C , Grand-Maître C , Guse I , Haché B , Kawai S , Naud J , O'Meara JA , Plante R , Déziel R
Published: May 2015

A series of novel monobactam inhibitors of human cytomegalovirus (HCMV) protease has been described that possess a heterocyclic thiomethyl side chain at C-4. Changes to the heterocycle did not significantly change the inhibitory activity of these compounds in an enzymatic assay, although improvements in solubility and cell culture activity were noted. A number of permutations between C-4 substitutions and N-1 derivatives led to the identification of several β-lactams with antiviral activity in a plaque reduction assay. N-methyl thiotetrazole-containing compounds were found to be the most potent inhibitors in the enzymatic assay.
3-(5-Dimethylamino-1-Naphthalenesulphonyl)-2-(3-Pyridyl)Thiazolidine (YHI-1) Selectively Inhibits Human Immunodeficiency virus Type 1
Authors: Premanathan M , Arakaki R , Ramanan S , Jinno S , Baba M , Yamashita S , Nakashima H
Published: May 2015

3-(5-Dimethylamino-1-naphthalenesulphonyl)-2-(3-pyridyl)thiazolidine (YHI-1), a synthetic analogue of D-cysteinolic acid isolated from sardines ( Sardinops melanostictus), was found to be a specific inhibitor of human immunodeficiency virus type 1 (HIV-1) replication in various cell cultures. YHI-1 inhibited HIV-1IIIB replication with a 50% effective concentration (EC50) of 3.35, 10.23 and 4.61 μM in MT-4 cells, peripheral blood mononuclear cells and MAGI-CCR5 cells, respectively. However, no antiviral activity was observed with non-nucleoside reverse transcriptase inhibitor (NNRTI)-resistant HIV-1 strains, such as nevirapine-resistant HIV-1HE/NEV and MKC-442-resistant HIV-1IIIB-R, or with HIV-2ROD or SIVMAC. YHI-1 failed to inhibit reverse transcriptase (RT) activity in vitro with different template–primer systems. Time-of-addition experiments, the failure to inhibit NNRTI-resistant strains and the failure to show in vitro activity against RT suggest that a metabolite of YHI-1 inside the cell acts like an NNRTI. Thus, YHI-1 seems to belong to a new class of HIV-1 inhibitor and is a good candidate for further development.
When narrative takes over: The representation of embedded mindstates in Shakespeare’s Othello
Authors: van Duijn Max J , Sluiter Ineke , Verhagen Arie
Published: May 2015

In recent times, researchers across a variety of disciplines in the humanities and social sciences have been interested in the human ability to process embedded mindstates, also known as ‘multiple-order intentionality’ (MOI): A believes that B thinks that C intends (etc.). This task is considered increasingly cognitively demanding with every order of embedding added. However, we argue that the way in which the information relevant to the task is represented in language (in particular, using a narrative) greatly influences how well people are able to deal with MOI cognitively. This effect can be illustrated by paraphrasing situations presented by a play such as Shakespeare’s Othello: by the end of Act II the audience has to understand that Iago intends that Cassio believes that Desdemona intends that Othello believes that Cassio did not intend to disturb the peace. Formulated this way, using sentence embedding to express the intentional relationships, this is highly opaque. At the same time, we know that Othello has been understood and appreciated by innumerable different audiences for ages. What is it that the play’s text does to make the audience understand all these embedded mindstates without undue cognitive strain? In this article we discuss six ‘expository strategies’ relevant to the representation of MOI and illustrate their working with examples from Shakespeare’s Othello.
Assessing the sociology of sport: On sport and the city
Authors: Schimmel Kimberly S
Published: May 2015

On the 50th anniversary of the ISSA and IRSS, Kimberly Schimmel, one of the leading scholars on sport, urban policy and the political economy of development reviews the trajectory of research into the relationship between cities and sport. Three principal themes are identified: city-building – politics and profits; city-life – culture and community; and city-space – semblance and spectacle. The current challenges are then outlined: for example, the emergence of new relationships between sport cultures and transforming urban developments; how urban spaces are increasingly viewed as terrain on which military tactics and weaponry are deemed necessary to protect capital investments, control crowds and prevent and respond to terrorist attacks; and the experiences of those who live and work in, and visit, urban areas. Future directions of the sociology of sport with regard to sport and the city are considered, with the reminder that sociologists of sport across the globe view with informed scepticism any notion that sports can act as a solution to general urban problems: the city is not a unitary entity that benefits uniformly from sport-related policy, as recent events in Brazil have amply illustrated.