Gilles Sauvé

HIGHLY SELECTIVE SILVER(I) OXIDE MEDIATED MONOPROTECTION OF SYMMETRICAL DIOLS

Abstract Treatment of symmetrical diol with Ag 2 O and alkyl halide gave the monoprotected derivative in good to excellent yield.

Is Antisense an Appropriate Nomenclature or Design for Oligodeoxynucleotides Aimed at the Inhibition of HIV-1 Replication?

We have evaluated the specificity and the variation in activity against human immunodeficiency virus (HIV) infection of antisense oligodeoxynucleotides (ODNs) with regard to factors such as dose-response range, number and choice of experimental controls, backbone modifications of the ODNs, type of cell infection, length of assays, and delivery approach. The highest level of inhibition was achieved in our long-term assay with MOLT-3 cells acutely infected with HIV-1 (IIIB0 and treated with free phosphorothioate-modified ODNs (PS-ODNs). The highest level of specificity was observed in our short-term assay with MOLT-3 cells acutely infected with HIV-1 (IIIB) and treated with free PS-ODNs. the highest potency (IC50 level) was observed in our short-term chronic-infection model with (DLS)-delivered ODNs in which the DLS delivery improved the ODN activity up to 106 times compared to the activity of free ODNs. Thus, the near blocking of HIV replication obtained when using PS-ODNs appears because of the addition of extracellular and/or membranar effects. The higher efficacy of PS-ODNs compared to unmodified ODNs, when both are delivered with the DLS system, was demonstrated solely in our short-term assay with MOLT-3 cells. Important variations in the level of sequence specificity were observed and depended on the type of control used and the type of cell assay employed. It seems that all 3 groups of control-tested, random, sense sequence, and non-antisense T30177 ODNs might have distinct activity and, consequently, different modes of action in inhibiting HIV replication. Our data buttress the notion that the contribution of the sequence-specific mediated mode of action is minor compared to the other mechanisms involved in ODN antiviral activity.

Regioselective deprotection of p-methoxybenzyl ethers of furanose derivatives

Abstract Reaction of per-p-methoxybenzylated hexofuranoses and pentofuranoses with either a catalytic amount of tin chloride dihydrate (SnCl 2 ·2H 2 O) or 0.5–10% solution of trifluoroacetic acid in dichloromethane afforded regioselectively the corresponding monosaccharide derivatives having a single free hydroxyl group at C(5) in good yields.

Synthesis of novel inhibitors of the HIV-1 protease: Difunctional enols of simple N-protected amino acids

A series of enol HIV-1 protease inhibitors which show competitive inhibition and the structure-activity relationship study which led to the design of these compounds are reported. By systematically modifying simple amino acids, Boc-Phe enol and Boc-Tyr enol derivatives yield nanomolar Kiapp values (Kiapp = 0.485 microM and Kiapp = 0.425 microM, respectively). These enols are of low molecular weight (< 500 g/mol) and of non-peptidic nature. The enols are synthesized in a one step chemical synthesis and modifications to increase their potency could easily be performed. Boc-Phe enol and Boc-Tyr enol showed low inhibitory effect on pepsin, Kiapps of 23 and 149 microM, respectively, and Boc-Phe enol showed a Kiapp of 20 microM for cathepsin D. Neither of these two compounds inhibited renin (< 10% inhibition at 200 microM).

NMR and molecular modeling characterization of HIV-1 protease inhibitors: Difunctional enols of N-protected phenylalanine

Abstract The three-dimensional structure of five HIV protease inhibitors of the N- tert -butoxycarbonylphenylalanyl enol family have been investigated by NMR and molecular modeling. Complete 1 H and 13 C chemical shift assignments were obtained. Both the E and Z forms were observable, the percentage of Z form being of the order of 20–30%. Coupling constant measurements indicated that the NH-CHα dihedral angles are different for the E and Z forms. Docking calculations with the HIV protease yield minimal energies which correlate with their experimental inhibition constants.

Solution Structure of the HIV Protease Inhibitor Acetyl-pepstatin as Determined by NMR and Molecular Modeling

The structure of acetyl-pepstatin has been investigated in solution by two-dimensional NMR spectroscopy and molecular modeling. The analysis of DQFCOSY, TOCSY and NOESY spectra lead to a full assignment of the -NMR signals both in DMSO-d6 and in TFE-d3:H2O 1:1. Interproton distances, dihedral angles and exchanger regimes of NH or OH protons were derived from ROESY connectivities, coupling constants and temperature dependences of the chemical shifts, respectively. Molecular modeling using the NMR distance and dihedral angle constraints obtained in DMSO-d6 yielded a model showing a well-defined structure for the N-terminal segment Ac-1 to Sta-4, but a flexible structure for the C-terminal segment. The structure was less defined in TFE-d3:H2O 1:1 and 13C T1 measurements are indicative of higher mobility. Comparison of the NMR-determined solution structure of acetyl-pepstatin with its crystal structure when bound to HIV-1 protease shows that the conformation is more extended in the complex as a result of intermolecular interactions.

Characterization of Dynamic State Inhibitors of HIV-1 Protease

The inhibitory behavior of simple N-protected amino acids containing a dysfunctional enol group was analyzed. Pseudo-Hill coefficients below 0.5 were obtained for the enol compounds. The active moiety of the enols described herein is involved in an equilibrium between keto and enol forms. The enol in its E form interacts strongly with the enzyme and we suggest that the Z form is expelled from the active site, as suggested by molecular modeling studies using the docking technique. Also, tetrahedral intermediate mimicry is achieved by the enol form, but not by the corresponding keto form. A pseudo-Hill coefficient of 0.25 has been determined for the Boc-phenylalanine enol, and by multiplying the concentration of inhibitor by its pseudo-Hill coefficient, a Ki of 0.82 microM has been determined for the inhibitory E-enol form. Boc-tyrosine enol generated a Ki of 0.39 microM. The requirements at the P1 position to achieve good inhibition are also described.

Antiviral properties of simple difunctionalized enols targeted to the HIV-1 protease

The human immunodeficiency virus type 1 (HIV-1) protease catalyses the specific cleavage of the virion structural polyproteins p55gag and p160gag-pol and is, therefore, essential for viral maturation. We have previously reported a series of low molecular weight non-peptidic enol-based compounds that inhibit the HIV-1 protease activity in a competitive fashion (Vaillancourt et al., Bioorg. Med. Chem., 2 (1994) 343-355). Here we demonstrate that VS-215 and VS-261, two of these non-peptidic inhibitors, impair viral polyprotein maturation and exhibit antiviral activity in infected MT4 cells. The ID50 for these two compounds ranged between 24 and 50 microM whereas their TD50 ranged between 60 and 200 microM depending on the cell lines used. The calculated therapeutic index of these two inhibitors both had values of 2.5 even though they were shown to be non cytotoxic at their ID50. Their calculated permeability index ranged between 0.09 and 0.79 suggesting that these enol-based inhibitors efficiently reach the site of protease activity. These results provide new information on the therapeutic potential of this new class of protease inhibitors and emphasize the usefulness of enol chemistry in the development of anti-HIV-1 protease inhibitors.