Norbert Bischofberger

Synthesis, hybridization properties and antiviral activity of lipid-oligodeoxynucleotide conjugates

Triethylammonium 1,2-di-O-hexadecyl-rac-glycero-3-H-phosphonate (2) was coupled to the 5 terminus of oligodeoxynucleotides via hydrogen phosphonate solid support DNA synthesis methodology. Duplex DNA oligomers with a single 5-phospholipid melted at lower temperatures than the corresponding unmodified duplex, but duplexes bearing lipids at each 5 end had higher Tms. In uptake experiments with L929 cells, 8-10 times more lipid-DNA became cell-associated than did unmodified DNA. Unmodified antisense diesters were inactive in a VSV antiviral assay in L929 cells (at up to 200 microM). Attachment of a lipid to the oligomer, however, led to a greater than 90% at 150 microM (greater than 80% at 100 microM) reduction in viral protein synthesis. The antiviral activity depended on the sequence of the oligodeoxynucleotide, but some compounds having little or no base complementarity to the viral target were also effective. Phosphorothioate derivatives reduced viral protein synthesis by 20-30% at 100 microM in the VSV assay. The lipid-DNA compounds were not toxic to the cells at up to 100 microM.

Minireview: nucleotide prodrugs

Nucleotides have shown interesting biological activities in a wide variety of antiviral, antiproliferative, immunomodulatory and other biological assays, and they present promising drug candidates. Because of their negative charge(s) nucleotides suffer from some disadvantages which can be successfully overcome by the utilization of nucleotide prodrugs. Nucleotide prodrugs were successfully used to increase oral absorption of nucleotides in vivo. By taking advantage of intracellular triggers (reducing potential, enzyme activity, pH), nucleotide prodrugs can be used in vitro for the intracellular delivery of the nucleotide resulting in enhanced potency and in some cases enhanced selectivity. Nucleotide prodrugs have also been utilized for tissue specific delivery of the nucleotides in vivo resulting in altered selectivity and reduced toxicity. For nucleotide prodrugs, their ultimate intended use is (in most cases) in vivo for the treatment of a disease. Thus, it is important to incorporate adequate assays and design criteria into any prodrug effort. In vivo systems are complicated because of metabolism, excretion and tissue distribution of the prodrug and the parent. Thus, results of in vitro assays have to be interpreted cautiously because they may be unsuitable predictors of the in vivo situation.

SYNTHESIS AND INFLUENZA NEURAMINIDASE INHIBITORY ACTIVITY OF AROMATIC ANALOGUES OF SIALIC ACID

Abstract Aromatic analogues of sialic acid ( 2 and 3 ) have been synthesized as potential influenza neuraminidase inhibitors. Whereas compound 2 exhibited good neuraminidase inhibitory activity, compound 3 , possessing the glycerol side chain at the C 5 position, was not a neuraminidase inhibitor.

Synthesis of 4-C substituted pyrimidine nucleosides

t-Butyldimethylsilyl protected uridine and thymidine were converted to the 4-0-triisopropylphenylsulfonyl derivatives 3 and 4, respectively. 3 and 4 underwent clean displacements with malonate-type nucleophiles yielding the 4-C-substituted pyrimidine nucleosides in good yield.

Oligodeoxynucleotides containing 5-(1-propynyl)-2'-deoxyuridine formacetal and thioformacetal dimer synthons

Abstract Oligodeoxynucleotides containing the C-5 propyne 2′-deoxyuridine analog in conjunction with the formacetal and 3′-thioformacetal linkage are described. Thermal denaturation analysis demonstrates that these analogs have enhanced binding affinity to both single-strand RNA and DNA and double-strand DNA.

Structure-Activity Study of Oligodeoxynucleotides Which Inhibit Thrombin

Abstract The 15-mer oligodeoxynucleotide GGTTGGTGTGGTTGG is a potent inhibitor of thrombin and it forms a stable, highly compact structure in solution. Deletions and substitutions by abasic residues, 2′-deoxyinosine, 7-deaza-2′-deoxyguanosine and 8-methyl-2′-deoxyguanosine show that the structural features of the oligodeoxynucleotide are important for its biological activity.

Chapter 30. Sequence-defined Oligonucleotides as Potential Therapeutics

Publisher Summary The sequence-specific modulation of gene expression within a cell using oligodeoxynucleotide (ODN) analogs is a significant approach to potential therapeutics called antisense RNA because of the intent to down-regulate the expression of a disease-causing protein by inhibiting the translation of its precursor messenger RNA (mRNA). This chapter discusses recent work on the inhibition of gene expression using ODNs by mRNA hybridization through Watson Crick base pairing and the inhibition by triple helix formation with duplex genomic DNA. The antisense RNA and duplex targeting triple helix approaches share common features not usually required of drugs in an absolute sense such as stability in serum and tissue, access to intracellular targets, and ability to attain significant concentration levels in the cytoplasm and nucleus. These stringent pharmacokinetic and pharmacodynamic requirements are discussed in the chapter in the context of the antisense approach. ODN-mediated modulation of gene expression shows therapeutic potential. Preliminary studies have demonstrated the titration of transcription factors from their genomic DNA by using double-stranded ODN sequences identical to the genomic sequences bound by these factors. The approach for using sequence-defined ODNs as potential therapeutics is through binding to proteins and to small molecules.

Chapter 16. Recent developments in antiretroviral therapies

Publisher Summary This chapter discusses developments happening in antiretroviral therapies. Clinical use of novel potent inhibitors of human immunodeficiency virus (HIV) in the past marked a new era in the treatment of HIV infection and for the first time in the history of the disease reverted the AIDS-related death rate. To date, fourteen antiretroviral agents belonging to three distinct classes—nucleoside and non-nucleoside reverse transcriptase inhibitors, and protease inhibitors—have been licensed in USA. Combination therapy of at least three potent drugs became the standard of care. The treatments, however, suffer from limitations such as resistance development, frequent cross-resistance within classes, long-term toxicity, difficult dosing regimens, and adverse drug-drug interactions, which all may lead to long-term treatment failure. The chapter reviews the progress in the discovery and development of new antiretroviral agents. An overview of nucleoside reverse transcriptase inhibitors (NRTIs) is presented and non-nucleoside reverse transcriptase inhibitors (NNRTIs) are discussed. An overview of HIV protease inhibitors (PIs) is presented and inhibitors of HIV transcription are also discussed.

Preparation of formacetal-linked purine-purine dinucleotide analogs

Abstract Protected formacetal-linked purine-purine dinucleotide analogs, including dG-f-dG, dG-f-dA, dA-f-dG, and dA-f-dA, were synthesized for the first time in 40 – 60% yields by condensation of the 5′-OH group with the 3′-OCH 2 SCH 3 group of the two corresponding deoxynucleoside units using N -iodosuccinimide in the presence of 2.5 eq of trifluoromethanesulfonic acid at −30°C.

A convenient preparation of protected 3′-deoxyguanosine from guanosine

Protected 3′-deoxyguanosine was synthesized from guanosine in five steps and 50% overall yield through reaction of the 2′,3′-diol with a-acetoxyisobutyryl bromide followed by base treatment to form 2′,3′-anhydroguanosine and subsequent selective reduction of the epoxide with LiHBEt3.