Publications

The acyclic nucleoside phosphonate (ANP) family of drugs shows promise as therapeutics for treating poxvirus infections. However, it has been questioned whether the utility of these compounds could be compromised through the intentional genetic modification of viral sequences by bioterrorists or the selection of drug resistance viruses during the course of antiviral therapy. To address these concerns, vaccinia virus (strain Lederle) was passaged 40 times in medium containing an escalating dose of (S)-1-[3-hydroxy-2-(phosphonomethoxypropyl)-2,6-diaminopurine [(S)-HPMPDAP], which selected for mutant viruses exhibiting a approximately 15-fold-increased resistance to the drug. (S)-HPMPDAP-resistant viruses were generated because this compound was shown to be one of the most highly selective and effective ANPs for the treatment of poxvirus infections. DNA sequence analysis revealed that these viruses encoded mutations in the E9L (DNA polymerase) gene, and marker rescue studies showed that the phenotype was produced by a combination of two (A684V and S851Y) substitution mutations. The effects of these mutations on drug resistance were tested against various ANPs, both separately and collectively, and compared with E9L A314T and A684V mutations previously isolated using selection for resistance to cidofovir, i.e., (S)-1-[3-hydroxy-2-(phosphonomethoxypropyl)cytosine]. These studies demonstrated a complex pattern of resistance, although as a general rule, the double-mutant viruses exhibited greater resistance to the deoxyadenosine than to deoxycytidine nucleotide analogs. The S851Y mutant virus exhibited a low level of resistance to dCMP analogues but high-level resistance to dAMP analogues and to 6-[3-hydroxy-2-(phosphonomethoxy)propoxy]-2,4-diaminopyrimidine, which is considered to mimic the purine ring system. Notably, (S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]-3-deazaadenine retained marked activity against most of these mutant viruses. In vitro studies showed that the A684V mutation partially suppressed a virus growth defect and mutator phenotype created by the S851Y mutation, but all of the mutant viruses still exhibited a variable degree of reduced virulence in a mouse intranasal challenge model. Infections caused by these drug-resistant viruses in mice were still treatable with higher concentrations of the ANPs. These studies have identified a novel mechanism for the development of mutator DNA polymerases and provide further evidence that antipoxviral therapeutic strategies would not readily be undermined by selection for resistance to ANP drugs.

In order to obtain compounds which would give 2′-deoxy-5-vinyluridine (VdUrd) by elimination under basic conditions, a series of 5-(1-substituted ethyl)uracil derivatives has been made. Attempts to obtain 5-(1-alkyl- or -aryl-sulphonyloxy) derivatives were unsuccessful because elimination to give the 5-vinyl derivatives was extremely easy. 5-(1-Acyloxyethyl) derivatives did not eliminate, but with aqueous alkali gave 5-(1-hydroxyethyl)uracil derivatives. Reaction of VdUrd with a series of arenethiols gave 5-(1-arylthioethyl)-2′-deoxyuridines. In the absence of radical inhibitors 5-(2-arylthioethyl)-2′deoxyuridines were the major products. The arylthio compounds were oxidized to the corresponding sulphoxides and sulphones. Treatment of these 5-(1-substituted) derivatives with potassium t-butoxide in dimethylformamide gave VdUrd. As expected the reaction rate was greatest with the compound which had the best leaving group. However, with aqueous alkali the compounds gave 2′-deoxy-5-(1-hydroxyethyl)uridine and at pH 7.6 at 37 °C they were stable. When N-3 of the uracil ring was alkylated the elimination was faster. The implication of this result for the mechanism of the elimination is discussed. Two of the compounds synthesized, namely 2′-deoxy-5-[1-(2,4,5-trichlorophenylthio)ethyl]uridine and 2′-deoxy-3-methyl-5-[1-(2,4,5-trich lorophenylthio)ethyl]uridine, showed activity against vaccinia virus and murine L1210 leukaemia cells at a concentration. of 30–40 µg/ml, and 2′-deoxy-5-[(2-phenylthio)ethyl]uridine, had activity against different strains of herpes simplex viruses types 1 and 2 at a concentration of 20 µg/ml.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Abstract For Abstract see ChemInform Abstract in Full Text.

Cidofovir [(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC)] is recognized as a promising drug for the treatment of poxvirus infections, but drug resistance can arise by a mechanism that is poorly understood. We show here that in vitro selection for high levels of resistance to HPMPC produces viruses encoding two substitution mutations in the virus DNA polymerase (E9L) gene. These mutations are located within the regions of the gene encoding the 3'-5' exonuclease (A314T) and polymerase (A684V) catalytic domains. These mutant viruses exhibited cross-resistance to other nucleoside phosphonate drugs, while they remained sensitive to other unrelated DNA polymerase inhibitors. Marker rescue experiments were used to transfer A314T and/or A684V alleles into a vaccinia virus Western Reserve strain. Either mutation alone could confer a drug resistance phenotype, although the degree of resistance was significantly lower than when virus encoded both mutations. The A684V substitution, but not the A314T change, also conferred a spontaneous mutator phenotype. All of the HPMPC-resistant recombinant viruses exhibited reduced virulence in mice, demonstrating that these E9L mutations are inextricably linked to reduced fitness in vivo. HPMPC, at a dose of 50 mg/kg of body weight/day for 5 days, still protected mice against intranasal challenge with the drug-resistant virus with A314T and A684V mutations. Our studies show that proposed drug therapies offer a reasonable likelihood of controlling orthopoxvirus infections, even if the viruses encode drug resistance markers.

New purinyl 2′,3′-dihomo-xylo-carbocyclic pentafuranosides and carbocyclic nucleosides fused with tetrahydrofuran ring were synthesized from (±)-c-4-amino-r-1,c-2,t-3-cyclopentanetrimethanol (8). The strongly acid medium in which the purine system was completed on pyrimidine derivative 9 caused condensation of the cis-hydroxymethyl groups, giving rise to a 3-oxabicyclo[3.3.0]octane structure. None of the new compounds exhibited more than very modest antiviral or antitumor activity.

Abstract D-Allo/D-altro 2-(2,4:3, 5-di-O-benzylidenepentitol-1-y1)-4-(4,4-dimethyloxazolin-2-y1)pyridine was synthesized from 2-lithio-4-(4,4-dimethyloxazolin-2-y1)pyridine and 2, 4:3,5-di-O-benzylidenealdehydo-D-ribose. After mesylation and subsequent treatment of the adduct with CF3COOH/H2O and then ammonia, 4-carbamoyl-2-D-ribofuranosylpyridine was formed. The α- and β-anomers were separated by semipreparative hplc on a LICHROSORB 10 DIOL column. The β-anomer had no antiviral activity, but it had modest cytostatic activity against tumor cells.

Tat is a regulatory HIV‐1 protein, which has the particularity to be secreted very early by HIV‐infected cells. The extra cellular roles of Tat are suspected to be the main cause of the maintenance of reservoirs of HIV‐infected cells and the failure of actual AIDS therapies to eradicate HIV. This study describes the rationale used to design molecules that bind to a target area containing an hydrophobic pocket identified in the 2D‐NMR structure of Tat. Molecules were synthesized and the derivative named TDS2 was shown to be a Tat inhibitor. Fluorescence revealed that TDS2 binds in the target area, which is conserved across five different Tat variants representative of the main HIV‐1 subtypes. TDS2 inhibited in vitro HIV‐1 replication in human T‐cells. Further chemical modifications remain necessary to enhance affinity to Tat and reduce cytotoxicity.

Abstract For Abstract see ChemInform Abstract in Full Text.

Selective Laser Melting (SLM) is a promising technique for the production of biometallic scaffolds for orthopaedic applications. To produce successful scaffolds, the laser parameters should be care ...