Publications

Bicyclams are a novel class of antiviral compounds which act as potent and selective inhibitors of the replication of human immunodeficiency virus type 1 (HIV-1) and HIV-2. They block an early step in the viral life cycle following adsorption to the CD4 receptor and preceding reverse transcription. To identify the molecular target of these compounds, we genetically analyzed variants of the HIV-1 molecular clone NL4-3, which developed resistance against two structurally related bicyclams, JM2763 and the more potent SID791. The resistant strains were obtained after long-term passaging in MT-4 cells in the presence of progressively increasing compound concentrations. Recombinants between selected genes of the resistant strains and the parental NL4-3 provirus were generated by adapting the marker rescue technique to MT-4 cells. The bicyclam-resistant phenotype was rescued by transferring the envelope gp120 gene of bicyclam-resistant virus into the NL4-3 parental genetic background. In the gp120 genes of the resistant strains, we identified several mutations leading to amino acid substitutions in the V3 loop. Furthermore, two substitutions of highly conserved amino acids in close proximity to the disulfide bridges of the V3 and V4 loops were found in both SID791- and JM2763-resistant strains. Additional mutations in regions encoding V3, C4, V5, and C5 were present in SID791-resistant viruses. Recombination experiments with overlapping parts of the envelope gene indicated that most, if not all, of the mutations were necessary to develop the fully SID791 resistant phenotype. The mutations in the C-terminal part of gp120 downstream of the V3 loop sequence conferred partial resistance to JM2763 but did not significantly decrease susceptibility to SID791. The genetic data and the biological properties of the resistant viruses point to inhibition of entry and fusion as the mode of action of the HIV-inhibitory bicyclams. A possible mechanism of binding of bicyclams to gp120 leading to inhibition of unfolding of gp120 and its shedding from the gp41 fusion domain is discussed.

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Abstract We report our strategies to prepare TSAO compounds carrying at 5′-position groups, such as amines, that may be positively charged at physiological conditions, unexpectedly, cyclic TSAO-derivatives were obtained. A possible mechanism for the formation of these unexpected compounds is advanced.

Synthesis of Z and E ethenyl acyclonucleosides (6a-e and 7a-e) via Michael addition of nucleobases with the diethyl acetylenedicarboxylate is described. The structures of compounds have been confirmed by spectral data. New compounds were found to be inactive against DNA and RNA viruses.

The inhibitory effects of 20 selected antiviral compounds on the replication of adenoviruses (types 1 to 8) in vitro were investigated. While 18 compounds were ineffective, 2 compounds, namely (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine [(S)-HPMPA] and 9-[(2-hydroxy-1,3,2-dioxaphosphorinan-5-yl)oxymethyl]guanine P-oxide (2'-nor-cyclic GMP), were highly effective against all adenovirus types assayed in human embryonic fibroblast cultures. Their 50% inhibitory doses were 1.1 microgram/ml for (S)-HPMPA and 4.1 micrograms/ml for 2'-nor-cyclic GMP. They were nontoxic for the host cells at the effective antiviral doses.

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.

Negatively charged albumins (NCAs) have been identified as potent inhibitors of HIV-1 replication in vitro. Time of addition studies suggest that succinylated and aconitylated human serum albumin (Suc-HSA and Aco-HSA) act at an early stage of the virus life cycle, and surface plasmon resonance (BIAcore) experiments have confirmed a direct interaction of NCAs with HIV-1 gp120. Resistance to Suc-HSA and Aco-HSA was analyzed by characterizing HIV-1 variants that were selected in cell culture after serial passage of the NL4-3 strain in the presence of the compounds. After 24 passages (126 days) we isolated variants that were resistant to Suc-HSA (>27-fold) and Aco-HSA (37-fold), as compared with the wild-type NL4-3 virus. The binding of the NCA-resistant HIV strains to CD4+ MT-4 cells could no longer be inhibited by either Suc- or Aco-HSA. The emergence of mutations in the envelope gp120 of the resistant virus paralleled the emergence of the resistant phenotype. The Suc-HSA-resistant strain was 100-fold cross-resistant to the G quartet-containing oligonucleotide AR177 (Zintevir, an HIV-binding inhibitor), and partially cross-resistant to dextran sulfate, but remained sensitive to the bicyclam AMD3100 and the chemokine SDF-1alpha, which block HIV replication by interaction with the chemokine receptor CXCR4. Furthermore, neither Suc-HSA nor Aco-HSA inhibited the binding of monoclonal antibodies 12G5 and 2D7 (directed to CXCR4 and CCR5, respectively) in SUPT-1 cells or THP-1 cells. These results confirm that NCAs bind primarily to gp120 and do not interact directly with the HIV chemokine receptor but block the binding of the virus particles (through gp120) with CD4+ cells.

This work investigates the influence of powder size/shape on selective laser sintering (SLS) of a thermoplastic polyurethane (TPU) elastomer. It examines a TPU powder which had been cryogenically milled in two different sizes; coarse powder (D50∼200μm) with rough surfaces in comparison with a fine powder (D50∼63μm) with extremely fine flow additives. It is found that the coarse powder coalesces at lower temperatures and excessively smokes during the SLS processing. In comparison, the fine powder with flow additives is better processable at significantly higher powder bed temperatures, allowing a lower optimum laser energy input which minimizes smoking and degradation of the polymer. In terms of mechanical properties, good coalescence of both powders lead to parts with acceptable shear-punch strengths compared to injection molded parts. However, porosity and degradation from the optimum SLS parameters of the coarse powder drastically reduce the tensile properties to about one-third of the parts made from the fine powders as well as those made by injection molding (IM).

Methyl 2,5-anhydro-3-O-(2-methoxyethyl)-2-thio-beta-D-arabinofuranoside and methyl 2,5-anhydro-3-O-(2-fluorobenzyl)-2-thio-alpha-D-lyxofuranoside were transformed into the corresponding uridine, thymidine, cytidine and adenosine analogues, which exclusively exhibited the alpha-configuration irrespective of the anomeric configuration of the donor. The structure, configuration, and conformation of the products was elucidated by X-ray structure analyses. The nucleoside analogues were tested for antiviral activities.