Georges Maury

Equal inhibition of the replication of human immunodeficiency virus in human T-cell culture by ddA BIS(SATE)phosphotriester and 3′-azido-2′,3′-dideoxythymidine

It is shown that ddA bis(SATE)phosphotriester is one of the most potent anti-HIV agents in cell culture. Compared with the parent nucleoside, ddA, an increase of 3 orders of magnitude was observed in the EC50, which makes this compound as active as AZT. This can be tentatively explained if one considers that direct ddAMP intracellular delivery shunts the well established ddA/ddI metabolism pathway.

The enantioselectivity of enzymes involved in current antiviral therapy using nucleoside analogues: a new strategy?

This review is primarily intended for synthetic bio-organic chemists and enzymologists who are interested in new strategies in the design of virus inhibitors. It is an attempt to assess the importance of the enzymatic properties of L-nucleosides and their analogues, particularly those that are active against viruses such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), herpes simplex virus (HSV), etc. Only data obtained with purified enzymes have been considered and discussed. The examined enzymes include nucleoside- or nucleotide-phosphorylating enzymes, catabolic enzymes, viral target enzymes and cellular polymerases. The enantioselectivities of these enzymes were determined from existing data and are significant only when a sufficient number of enantiomeric pairs of substrates could be examined. The reported data emphasize the weak enantioselectivities of cellular or viral nucleoside kinases and some viral DNA polymerases. Thus, cellular deoxycytidine kinase has a considerably relaxed enantioselectivity with respect to a large number of nucleosides or their analogues, and it occupies a strategic position in the intracellular activation of the compounds. Similarly, HIV-1 reverse transcriptase often has a relatively weak enantioselectivity and can be inhibited by the 5-triphosphates of a large series of L-nucleosides and analogues. In contrast, degradation enzymes, such as adenosine or cytidine deaminases, generally demonstrate strict enantioselectivities favouring D-enantiomers and are used by chemists in asymmetric syntheses. The weak enantioselectivities of some enzymes involved in nucleoside metabolism are more or less pronounced, and one enantiomer or the other is favoured depending on the substrate. This suggests that the low enantioselectivity is fortuitous and does not result from evolutionary pressure, since these enzymes do not create or modify asymmetric centres in substrates. The combined enantioselectivities of the enzymes examined in this review strongly suggest that the field of L-nucleosides and their analogues should be systematically explored in the search for new virus inhibitors.

Template. Phosphorothioate oligonucleotides duplexes as inhibitors of HIV-1 reverse transcriptase

We have investigated the interaction between a number of 14 mers phosphorothioate oligonucleotides and HIV-1 reverse transcriptase. Two methods were used to measure the affinity of the analogs for the enzyme. In the first, the oligonucleotide or its duplex with Poly(rl) were used as inhibitors of the enzyme using Poly(rA).(dT)14 as template primer. In the second, the oligonucleotides or their duplexes were used to displace a fluorescent template primer complex of known affinity from its binding site on reverse transcriptase. The two methods gave the same relative order of affinity. Phosphorothioate oligodeoxyribonucleotides had a much higher affinity than oligo(dC)14 and it was increased on hybridization. Quantitatively similar results were obtained for S(dC)14 or its analog with bases in the alpha-configuration. Of the analogs tested, only S(dC)14 showed priming activity.

UNNATURAL ENANTIOMERS OF 5-AZACYTIDINE ANALOGUES: SYNTHESES AND ENZYMATIC PROPERTIES

2′-Deoxy-β-L-5-azacytidine (L-Decitabine), β-L-5-azacytidine, and derivatives were stereospecifically prepared starting from L-ribose or L-xylose. D- and L-enantiomers of 2′-deoxy-β-5-azacytidine were weak substrates of human recombinant deoxycytidine kinase (dCK), whereas both enantiomers of β-5-azacytidine or the L-xylo-analogues were not substrates of the enzyme. None of the reported derivatives of β-L-5-azacytidine was a substrate of human recombinant cytidine deaminase (CDA).

bis(S-Acyl-2-thioethyl)esters of 2′,3′-Dideoxyadenosine 5′-Monophosphate Are Potent Anti-HIV Agents in Cell Culture

Abstract It is shown that ddA bis(SATE)phosphotriesters have potent anti-HIV activity in cell culture. Thus, compared with the parent nucleoside, a decrease of 3 or 4 orders of magnitude was observed in the EC50 values for the bis(S-acetyl-2-thioethyl)phosphotriester derivative, which makes this compound as active as AZT.

Inhibition and Substrate Specificity of Adenosine Deaminase. Interaction with 2′-, 3′- and/or 5′-Substituted Adenine Nucleoside Derivatives

Abstract A series of adenine nucleoside derivatives, most of them prepared for the first time, have been evaluated as substrates or inhibitors of adenosine deaminase. The best inhibitory results were obtained with the 3′, 5′-di-O-benzoyl esters of 9-β-D-pentofuranosyladenines.

Study of the Enantioselectivity of Enzymes Involved in Nucleoside Analogue Metabolism: Deoxycytidine Kinase

Abstract The substrate properties of recombinant human deoxycytidine kinase (dCK) with regard to a series of D- or L-enantiomers of cytidine, 2′-deoxycytidine, and 2′,3′-dideoxycytidine analogues were studied using HPLC analysis. Our results suggest that dCK has a remarkably relaxed enantioselectivity with respect to a large number of cytidine derivatives in the β configuration.

Synthesis and HIV-1 reverse transcriptase inhibition properties of two new methylenephosphonate analogues of 3′-azido-3′-deoxythymidine-5′-triphosphate

Abstract Two new 5′-phosphorylated derivatives of 3′-azido-3′-deoxythymidine (AZT), namely α,β;β,γ-bis (methylene) AZT-5′-triphosphate 1 and α,β-propylene AZT 5′-diphosphate 2 , were synthesized. When evaluated for their inhibitory effects on human immunodeficiency virus (HIV) reverse transcriptase, these compounds were about 1000-fold less active than AZT-5′-triphosphate (AZTTP) as competitive inhibitors of this enzyme.

Rapid determination of the affinity of 28- and 14-mer phosphorothioate oligonucleotides for HIV-1 reverse transcriptase by fluorescence spectroscopy

Intrinsic fluorescence of human immunodeficiency virus type 1 reverse transcriptase (E.C. 2.7.7.49) and displacement experiments of a fluorescent template.primer probe were used to study the interaction of the enzyme with several types of 28- and 14-mer normal or phosphorothioate oligodeoxycytidinylates and their duplexes with poly(rI). The two methods gave convergent results and allowed in each case fast determinations of ligand affinities for the enzyme. The dissociation constants (Kd) obtained from intrinsic fluorescence changes were slightly lower than those determined from the less direct competitive displacement experiments. In all cases, the enzyme displayed better recognition of the hybrid than of the unannealed oligonucleotide. The Kd values of phosphorothioate oligomers and their hybrids were lower than those of the corresponding normal oligomers and hybrids, but the difference was not as significant as in the case of the Ki constants for (dC)28 and S(dC)28 (Majumdar et al. (1989) Biochemistry 28, 1340). The affinities of the annealed phosphorothioate oligodeoxycytidinylates for the enzyme were found to be larger than for any other compounds in this series (Kd of poly(rI).S(dC)28: 0.28 nM at 25 degrees C). Changing the beta stereochemistry of the oligomer bases to alpha did not alter the affinity of the oligodeoxycytidinylate and its hybrids for the enzyme.

Synthesis of New Fluorescent Nucleoside Analogues and Application to the Study of Human Deoxycytidine Kinase

We have determined the affinity of human deoxycytidine kinase with respect to new fluorescent N-methylanthraniloyl cytidine derivatives or non fluorescent enantiomeric cytidine analogues. New results regarding the enantioselectivity and the mechanism of the enzyme are presented.