Jean-Luc Girardet

Rational design for cytosolic delivery of nucleoside monphosphates : “SATE” and “DTE” as enzyme-labile transient phosphate protecting groups

Abstract It was demonstrated that the use of neutral 2′,3′-dideoxyuridine phosphotriesters which incorporate enzyme mediated bioreversible protection such as S-acetylthioethanol (SATE) or dithiodiethanol (DTE) resulted in intracellular delivery of the parent mononucleotide. This point was corroborated by observation of an anti-HIV effect in various cell lines and decomposition data in cell extracts.

A Novel Nonnucleoside Analogue That Inhibits Human Immunodeficiency Virus Type 1 Isolates Resistant to Current Nonnucleoside Reverse Transcriptase Inhibitors

ABSTRACT Nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are important components of current combination therapies for human immunodeficiency virus type 1 (HIV-1) infection. However, their low genetic barriers against resistance development, cross-resistance, and serious side effects can compromise the benefits of the two current drugs in this class (efavirenz and nevirapine). In this study, we report a novel and potent NNRTI, VRX-480773, that inhibits viruses from efavirenz-resistant molecular clones and most NNRTI-resistant clinical HIV-1 isolates tested. In vitro mutation selection experiments revealed that longer times were required for viruses to develop resistance to VRX-480773 than to efavirenz. RT mutations selected by VRX-480773 after 3 months of cell culture in the presence of 1 nM VRX-480773 carried the Y181C mutation, resulting in a less-than-twofold increase in resistance to the compound. A virus containing the double mutation V106I-Y181C emerged after 4 months, causing a sixfold increase in resistance. Viruses containing additional mutations of D123G, F227L, and T369I emerged when the cultures were incubated with increasing concentrations of VRX-480773. Most of the resistant viruses selected by VRX-480773 are susceptible to efavirenz. Oral administration of VRX-480773 to dogs resulted in plasma concentrations that were significantly higher than those required for the inhibition of wild-type and mutant viruses. These results warrant further clinical development of VRX-480773 for the treatment of HIV infection in both NNRTI-naive and -experienced patients.

Increase of the anti-HIV activity of D4T in human T-cell culture by the use of the sate pronucleotide approach

Abstract The bis( S -acetyl-2-thioethyl) phosphotriester derivative of 2′,3′-didehydro-2′,3′-dideoxythymidine has been synthesized and evaluated for its inhibitory effects on the replication of HIV-1 in several cell culture systems. This pronucleotide showed potent anti-HIV activity and proved to be significantly superior to the parent nucleoside with regard to the antiviral efficiency.

Comments on nucleotide delivery forms

Publisher Summary A multitude of factors affect the biological activity of nucleoside analogs (Nu), which must be phosphorylated intracellularly by cellular or viral enzymes before exerting their effects. It follows that the intracellular metabolism of nucleosides is a key event for the appearance of their biological response. In all the nucleoside series with the same sugar modification, the biological responses differ greatly according to the type of nucleobase. Nucleosides may be first converted to their corresponding 5-mononucleotides (NuMP) by cellular or viral enzymes. Some nucleosides do not show a biological response only, because they are not enzymatically transformed to the corresponding NuMP. The presence and activity of the intracellular enzymes necessary for activation of nucleoside analogs are highly dependent on host species, cell type, and stage in the cell cycle. The emergence of resistance to nucleoside analogs has been frequently attributed to a decrease or loss of activity of the first phosphorylating enzyme. Nucleotides are readily dephosphorylated in extracellular fluids and on cell surfaces by nonspecific phosphohydrolases.

6-Benzylamino 4-oxo-1,4-dihydro-1,8-naphthyridines and 4-oxo-1,4-dihydroquinolines as HIV integrase inhibitors.

SAR studies on the quinolone carboxylic acid class of HIV-1 integrase inhibitors focused on improving the metabolic stability and led to the discovery of 27 and 38.

Comparison of cytotoxicity of mononucleoside phosphotriester derivatives bearing biolabile phosphate protecting groups in normal human bone marrow progenitor cells

The effects of three mononucleoside phosphotriester derivatives of 3′-azido-2′,3′-dideoxythymidine (AZT) which incorporate biolabile phosphate protecting groups, namely S-acetyl-2-thioethyl (MeSATE), S-(2-hydroxyethylsulfidyl)-2-thioethyl (DTE), and pivaloyloxymethyl (POM) were studied and compared to their nucleoside parent in human myeloid colony-forming cells. Moreover, the relative antiviral potency of these three pronucleotides were determined in primary human peripheral blood mononuclear cells infected with human immunodeficiency virus type 1. The results indicate that the SATE and DTE pro-moieties, as well as their degradation products, do not induce additional toxicity. The bis(MeSATE) phosphotriester derivative of AZT emerged as the most selective inhibitor with an in-vitro therapeutic index of the same order of magnitude as observed for AZT. This study has been extended to the corresponding bis(MeSATE) and bis(DTE) phosphotriester derivatives of 2′,3′-dideoxyuridine (ddU).

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.

Chapter Eleven – Urate Crystal Deposition Disease and Gout—New Therapies for an Old Problem

Abstract Gout is a chronic, inflammatory arthritic condition resulting from monosodium urate crystal deposition in joints and tissues, which develop because of high levels of serum uric acid. Gout treatment includes short-term approaches for acute gout attacks (gout flares) and long-term approaches for treating hyperuricemia. Acute gout therapy focuses on rapid inhibition of pain and inflammation resulting from the inflammatory response to monosodium urate crystal deposition. Most commonly prescribed acute gout therapies in the United States are NSAIDs, colchicine, and corticosteroids. Optimal treatment of gout also includes approaches to address chronically high uric acid levels. Therapeutic approaches to address gout-associated hyperuricemia include inhibiting production of uric acid using xanthine oxidase inhibitors, degrading uric acid with recombinant uricase, and increasing uric acid excretion using older uricosuric agents and newer selective uric acid reabsorption inhibitors. The recent surge of research in this area brings with it the potential for new targets and therapeutic combinations.

Synthesis of nucleoside libraries on solid support. I. N2, N6-disubstituted diaminopurine nucleosides

Starting with 2‐iodo‐6‐chloro‐9‐(β‐D‐ribofuranosyl)purine, a library of more than 1,300 N2,N6‐polysubstituted diaminopurine nucleosides was created. The starting material was condensed with a polystyrene monomethoxytrityl resin and a pool of primary and secondary amines was used to displace the 6‐chloro atom with high regio‐selectivity. The 2‐iodo was subsequently displaced by various primary amines. Nucleosides were cleaved from the resin with hexafluoroisopropanol solutions. A majority of compounds reached a purity of more than 80% without the need for any type of purification. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend.

Synthesis of Nucleoside Libraries on Solid Support. II. 2,6,8‐Trisubstituted Purine Nucleosides Using 8‐Bromoguanosine as Precursor

A series of 2,6,8‐trisubstituted purine nucleoside libraries was prepared by parallel solid‐phase synthesis using 8‐bromoguanosine as a common synthetic precursor. Polystyrene‐methoxytrityl chloride resin was linked to the N2 or O5′ position of the guanosine analogues. 8‐Bromoguanosine was derivatized at the C8 position via carbon‐carbon bond formation. Nucleophilic aromatic substitution at C2 and/or C6 positions with various amines produced two series of purine nucleoside libraries with very diverse substitution. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend.