S. Benzaria

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.

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.

Nm 283, an efficient prodrug of the potent anti-HCV agent 2'-C-methylcytidine.

In order to improve the oral bioavailability of 2′-C-methylcytidine, a potent anti-HCV agent, the corresponding 3′-O-L-valinyl ester derivative (NM 283) has been synthesized. Based on its ease of synthesis and its physicochemical properties, NM 283 has emerged as a promising antiviral drug for treatment of chronic HCV infection.

2'-C-Methyl branched pyrimidine ribonucleoside analogues : potent inhibitors of RNA virus replication

RNA viruses are the agents of numerous widespread and often severe diseases. Their unique RNA-dependent RNA polymerase (RDRP) is essential for replication and, thus, constitutes a valid target for the development of selective chemotherapeutic agents. In this regard, we have investigated sugar-modified ribonucleoside analogues as potential inhibitors of the RDRP. Title compounds retain ‘natural’ pyrimidine bases, but possess a β-methyl substituent at the 2′-position of the D- or L-ribose moiety. Evaluation against a broad range of RNA viruses, either single-stranded positive (ssRNA), single-stranded negative (ssRNA−) or double-stranded (dsRNA), revealed potent activities for D-2′-C-methyl-cytidine and -uridine against ssRNA+, and dsRNA viruses. None of the L-enantiomers were active. Moreover, the 5′-triphosphates of the active D-enantiomers were found to inhibit the bovine virus diarrhoea virus polymerase. Thus, the 2′-methyl branching of natural pyrimidine ribonucleosides transforms physiological molecules into potent, broad-spectrum antiviral agents that merit further development.

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.

Anti-human immunodeficiency virus type 1 activities of dideoxynucleoside phosphotriester derivatives in primary monocytes/macrophages

Mononucleoside phosphotriester derivatives of dideoxynucleosides, following intracellular enzymatic activation, are likely to liberate their parent 5-nucleoside monophosphate. Prodrugs of 3-azido-2,3-dideoxythymidine (AZT), 2,3-didehydro-2,3- dideoxythymidine (d4T), 2,3-dideoxyinosine (ddl) and 2,3-dideoxyadenosine (ddA) were evaluated for their anti-HIV1 activities in monocyte-derived macrophages, cells which are known to have low levels of nucleoside kinases. Prodrugs were found to be much more active, or just as active, as the corresponding dideoxynucleoside. Furthermore, their selectivity index was enhanced by a factor of 2 to 200.

Monoval-LdC: Efficient Prodrug of 2′-Deoxy-β-L-cytidine (L-dC), A Potent and Selective Anti-HBV Agent

Abstract In order to improve the oral bioavailability of LdC, valinyl esters were prepared as prodrugs. We report here the syntheses of the 3′-mono-, 5′-mono, and 3′,5′-di-O-valinyl esters of LdC. The comparison of their ease of synthesis, their physicochemical properties, as well as their pharmacokinetic parameters in cynomologus monkeys has revealed 3′-mono-O-valinyl derivative as the most promising of the studied prodrugs. This compound is being developed as a new anti-HBV agent.

Synthesis, Physicochemical and Pharmacokinetic Studies of Potential Prodrugs of β-L-2′-Deoxycytidine, a Selective and Specific Anti-HBV Agent

β-L-2′-Deoxycytidine (β-L-dC) is a potent, selective and specific anti-hepatitis B virus (HBV) agent. To improve its oral bioavailability, several derivatives involving sugar or base acylation, as well as N4-derivatization with an N,N-(dimethyl-amino)methylene function, were synthesized. The physicochemical characteristics (including chemical stabilities, solubilities and distribution coefficient values) and pharmacokinetics of these compounds were determined and compared with those of the parent drug, β-L-dC. Presented in part at the 14th International Conference on Antiviral Research, Seattle, Washington, USA, 8–13 April 2001. Antiviral Reseach 2001; 50:A79.

Synthesis of 2',3',5'-trideoxyuridine-5'-methylphosphonic acid and its diphosphate derivative: study of the interaction with HIV-1 reverse transcriptase

2′,3′,5′-Trideoxyuridine-5′-methylphosphonate, [8], was synthesized from ddU. The 5′,6′ carbon-carbon bond was formed by condensing the 5′-aldehyde of ddU and a Wittig reagent. The binding interaction of the diphosphate derivative [10] of the phosphonate [8] with HIV-1 reverse transcriptase (RT) was studied using methods based primarily on fluorescence spectroscopy. From the quenching of intrinsic tryptophan fluorescence of RT during its titration against [10], a dissociation constant of 24 μm was calculated at 25°C. In the presence of a DNA/DNA template/primer of defined sequence and RT, [10] and a fluorescent derivative of ddTTP competed for binding to RT without incorporation of ddU-5′-methylphosphonate. In the presence of a 0.5 mm concentration of [10], the RT activity measured with Poly(rA)/(dT)15 and [3H] dTTP was lowered to 65%. All our observations are consistent with suppression of the catalysis of bond formation between the OH at the primer 3′-end and α-P of [10] after formation of the complex between RT, template/primer and [10].