The discovery of IDX21437: Design, synthesis and antiviral evaluation of 2'-α-chloro-2'-ß-C-methyl branched uridine pronucleotides as potent liver-targeted HCV polymerase inhibitors.

Herein we describe the discovery of IDX21437 35b, a novel RPd-aminoacid-based phosphoramidate prodrug of 2'-α-chloro-2'-ß-C-methyluridine monophosphate. Its corresponding triphosphate 6 is a potent inhibitor of the HCV NS5B RNA-dependent RNA polymerase (RdRp). Despite showing very weak activity in the in vitro Huh-7 cell based HCV replicon assay, 35b demonstrated high levels of active triphosphate 6 in mouse liver and human hepatocytes. A biochemical study revealed that the metabolism of 35b was mainly attributed to carboxyesterase 1 (CES1), an enzyme which is underexpressed in HCV Huh-7-derived replicon cells. Furthermore, due to its metabolic activation, 35b was efficiently processed in liver cells compared to other cell types, including human cardiomyocytes. The selected RP diastereoisomeric configuration of 35b was assigned by X-ray structural determination. 35b is currently in Phase II clinical trials for the treatment of HCV infection.

Discovery of benzophosphadiazine drug candidate IDX375: A novel hepatitis C allosteric NS5B RdRp inhibitor.

Hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells, and as a consequence is an attractive target for selective inhibition. This paper describes the discovery of a novel family of HCV NS5B non-nucleoside inhibitors inspired by the bioisosterism between sulfonamide and phosphonamide. Systematic structural optimization in this new series led to the identification of IDX375, a potent non-nucleoside inhibitor that is selective for genotypes 1a and 1b. The structure and binding domain of IDX375 were confirmed by X-ray co-crystalisation study.

Synthesis of potent and broad genotypically active NS5B HCV non-nucleoside inhibitors binding to the thumb domain allosteric site 2 of the viral polymerase.

The hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells and, as a consequence, is an attractive target for selective inhibition. This Letter describes the discovery of a new family of HCV NS5B non-nucleoside inhibitors, based on the bioisosterism between amide and phosphonamidate functions. As part of this program, SAR in this new series led to the identification of IDX17119, a potent non-nucleoside inhibitor, active on the genotypes 1b, 2a, 3a and 4a. The structure and binding domain of IDX17119 were confirmed by X-ray co-crystallization study.

Synthesis of the first example of a nucleoside analogue bearing a 5'-deoxy-beta-D-allo-septanose as a seven-membered ring sugar moiety.

The first example of a nucleoside analogue bearing a 5'-deoxy-beta-D-allo-septanose as a seven-membered ring sugar moiety, namely 9-(5-deoxy-beta-D-allo-septanosyl)-adenine, is reported. This compound was synthesized in 14 steps from the commercially available D-glycero-D-gulo-1,4-lactone. When evaluated in cell culture experiments against a broad range of viruses, it did not exhibit any significant antiviral effect or cytotoxicity.

Synthesis and antiviral evaluation of 7-fluoro-7-deaza-2-aminopurine nucleoside derivatives.

Three 7-fluoro-7-deaza-2-aminopurine nucleoside derivatives were synthesized and evaluated as potential inhibitors of RNA virus replication, including hepatitis C virus (HCV).

Synthesis and antiviral evaluation of a seven-membered sugar ring nucleoside analog, 9-(5-deoxy-beta-D-allo-septanosyl)-adenine.

The first example of a nucleoside analogue bearing a 5'-deoxy-beta-D-allo-septanose as the sugar moiety was synthesized and evaluated as a potential inhibitor of several virus replication.

Synthesis and antiviral evaluation of 4-fluoropyrazole-3-carboxamide nucleoside derivatives.

A series of novel 4-fluoro-1H-pyrazole-3-carboxamide nucleoside analogues were synthesized and evaluated as potential inhibitors of RNA virus replication, including hepatitis C virus (HCV).

Synthesis of 1'-C-fluoromethyladenosine.

In search for new antiviral agents, we have been interested in 1'-C-fluoromethyl branched ribonucleosides. In this paper, we describe the synthesis of 1'-C-fluoromethyladenosine via electrophilic fluorination of exo-glycal.

Synthesis of beta-L-2'-deoxythymidine (L-dT).

The "unnatural" l-nucleoside beta-l-2'-deoxythymidine (L-dT) is a potent, specific, and selective inhibitor of the replication of hepatitis B virus (HBV), which is currently in Phase III clinical trials. This unit describes, in detail, a semi-large-scale synthesis of l-dT. This convenient methodology produces l-dT in six steps starting with l-ribose and ending with a satisfactory overall yield of l-dT, and may be applied to other 2'-deoxynucleosides, incorporating different heterocyclic bases.

Synthesis, physicochemical and pharmacokinetic studies of potential prodrugs of beta-L-2'-deoxycytidine, a selective and specific anti-HBV agent.

beta-L-2'-Deoxycytidine (beta-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 N4-derivatization with an N,N-(dimethylamino)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, beta-L-dC.