The present disclosure relates to compounds, compositions and methods for the treatment of hepatitis C virus (HCV) infection. Also disclosed are pharmaceutical compositions containing such compounds and methods for using these compounds in the treatment of HCV infection.

Hepatitis C virus inhibitors

Cytochrome P450 14α-sterol demethylases (CYP51) are essential enzymes in sterol biosynthesis in eukaryotes. CYP51 removes the 14α-methyl group from sterol precursors such as lanosterol, obtusifoliol, dihydrolanosterol, and 24(28)-methylene-24,25-dihydrolanosterol. Inhibitors of CYP51 include triazole antifungal agents fluconazole and itraconazole, drugs used in treatment of topical and systemic mycoses. The 2.1- and 2.2-Å crystal structures reported here for 4-phenylimidazole- and fluconazole-bound CYP51 from Mycobacterium tuberculosis (MTCYP51) are the first structures of an authentic P450 drug target. MTCYP51 exhibits the P450 fold with the exception of two striking differences—a bent I helix and an open conformation of BC loop—that define an active site-access channel running along the heme plane perpendicular to the direction observed for the substrate entry in P450BM3. Although a channel analogous to that in P450BM3 is evident also in MTCYP51, it is not open at the surface. The presence of two different channels, with one being open to the surface, suggests the possibility of conformationally regulated substrate-in/product-out openings in CYP51. Mapping mutations identified in Candida albicans azole-resistant isolates indicates that azole resistance in fungi develops in protein regions involved in orchestrating passage of CYP51 through different conformational stages along the catalytic cycle rather than in residues directly contacting fluconazole. These new structures provide a basis for rational design of new, more efficacious antifungal agents as well as insight into the molecular mechanism of P450 catalysis.

https://www.pnas.org/content/pnas/98/6/3068.full.pdf

Crystal structure of cytochrome P450 14α-sterol demethylase (CYP51) from Mycobacterium tuberculosis in complex with azole inhibitors

The present invention provides nucleoside compounds and certain derivatives thereof which are inhibitors of RNA-dependent RNA viral polymerase. These compounds are inhibitors of RNA-dependent RNA viral replication and are useful for the treatment of RNA-dependent RNA viral infection. They are particularly useful as inhibitors of hepatitis C virus (HCV) NS5B polymerase, as inhibitors of HCV replication, and/or for the treatment of hepatitis C infection. The invention also describes pharmaceutical compositions containing such nucleoside compounds alone or in combination with other agents active against RNA-dependent RNA viral infection, in particular HCV infection. Also disclosed are methods of inhibiting RNA-dependent RNA polymerase, inhibiting RNA-dependent RNA viral replication, and/or treating RNA-dependent RNA viral infection with the nucleoside compounds of the present invention.

Nucleoside derivatives as inhibitors of rna-dependent rna viral polymerase

An enantiomer, diastereoisomer or tautomer of a compound, represented by formula I: wherein A, B, R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are as defined herein, or a salt or ester thereof, as an inhibitor of HCV NS5B polymerase.

Viral Polymerase Inhibitors

The cytochrome P450 sterol 14alpha-demethylase enzyme (CYP51) is the target of azole antifungals. Azoles block ergosterol synthesis, and thereby fungal growth, by binding in the active-site cavity of the enzyme and ligating the iron atom of the heme cofactor through a nitrogen atom of the azole. Mutations in and around the CYP51 active site have resulted in azole resistance. In this work, homology models of the CYP51 enzymes from Aspergillus fumigatus and Candida albicans were constructed based on the X-ray crystal structure of CYP51 from Mycobacterium tuberculosis. Using these models, binding modes for voriconazole (VOR), fluconazole (FLZ), itraconazole (ITZ), and posaconazole (POS) were predicted from docking calculations. Previous work had demonstrated that mutations in the vicinity of the heme cofactor had a greater impact on the binding of FLZ and VOR than on the binding of POS and ITZ. Our modeling data suggest that the long side chains of POS and ITZ occupy a specific channel within CYP51 and that this additional interaction, which is not available to VOR and FLZ, serves to stabilize the binding of these azoles to the mutated CYP51 proteins. The model also predicts that mutations that were previously shown to specifically impact POS susceptibility in A. fumigatus and C. albicans act by interfering with the binding of the long side chain.

Three-Dimensional Models of Wild-Type and Mutated Forms of Cytochrome P450 14α-Sterol Demethylases from Aspergillus fumigatus and Candida albicans Provide Insights into Posaconazole Binding

Use of compounds of formula (I), wherein R1 is hydrogen, hydroxy, alkyl, hydroxyalkyl, alkoxy, halogen, cyano, isocyano or azido; R2 is hydrogen, hydroxy, alkoxy, chlorine, bromine or iodine; R3 is hydrogen; or R?2 and R3? together represent =CH?2?; or R?2 and R3? represent fluorine; X is O, s or CH?2?; a, b, c, d denoting asymmetric carbon atoms each of which is substituted with 4 different substituents; and B signifies a purine base B1 which is connected through the 9-nitrogen of formula (B1), wherein R?4? is hydrogen, hydroxyl, alkyl, alkoxy, alkylthio, aryloxy, arylthio, heterocyclyl, NR7R8, halogen or SH; R5 is hydrogen, hydroxy, alkyl, haloalkyl, cycloalkyl, alkoxy, alkylthio, aryl, aryloxy, arylthio, heterocyclyl, heterocyclylamino, halogen, NR?7R8, NHOR9, NHNR7R8? or SH; R6 is hydrogen, hydroxy, alkyl, alkoxy, alkylthio, aryloxy, arylthio, heterocyclyl, NR7R8, halogen, SH or cyano; R?7 and R8? are independently of each other hydrogen, alkyl, aryl, hydroxyalkyl, alkenylalkyl, alkynylalkyl, cycloalkyl or acyl; R9 is hydrogen, alkyl or aryl; or B signifies an oxidised purine base B2 which is connected through the 9-nitrogen of formula (B2), wherein R?4, R5 and R6? are as defined above; or B signifies a purine base B3 which is connected through the 9-nitrogen of formula (B3), wherein R?4 and R6? are as defined above; R10 is hydrogen, alkyl or aryl; Y is O, S or NR11; R11 is hydrogen, hydroxy, alkyl, OR9, heterocyclyl or NR?7R8; R7, R8 and R9? are as defined above; or B signifies a pyrimidine base B4 which is connected through the 1-nitrogen of formula (B4), wherein Z is O or S; R12 is hydrogen, hydroxy, alkyl, alkoxy, haloalkyl, alkylthio, aryl, aryloxy, arylthio, heterocyclyl, heterocyclylamino, halogen, NR?7R8, NHOR9, NHNR7R8? or SH; R13 is hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, haloalkyl, cycloalkyl or halogen; R?7, R8 and R9? are as defined above; or B signifies a pyrimidine base B5 which is connected through the 1-nitrogen of formula (B5), wherein Y, Z, R10 are as defined above for the treatment of diseases mediated by the Hepatitis C Virus (HIV) or for the preparation of a medicament for such treatment. The invention is concerned with novel and known purine and pyrimidine nucleoside derivatives, their use as inhibitors of subgenomic Hepatitis C Virus (HCV) RNA replication and pharmaceutical compositions of such compounds.

Nucleoside derivatives for the treatment of hepatitis c

The present invention relates to the use of nucleoside derivatives of Formula (I) wherein B signifies a 9-purinyl residue B1 of Formula (B1) or a 1-pyrimidyl residue B2 of Formula (B2) wherein the symbols are as defined in the specification, and of pharmaceutically acceptable salts thereof; for the treatment of diseases mediated by the Hepatitis C Virus (HCV), for the preparation of a medicament for such treatment and to pharmaceutical compositions containing such compounds.

4'-substituted nucleosides for the treatment of diseases mediated by the hepatitis C virus

Modeling, synthesis and biological activity of novel antifungal agents (1)

Restrictinol 2 and 9, 10, 11, 12-tetrahydro-7-desmethylrestricticin (Ro 09-1571) have been synthesized from L-glucose. Ro 09-1571 showed improved in vitro antifungal activity and chemical stability as compared with Restricticin 1.

Takuo Tsukuda

Papers

Nucleoside derivatives for the treatment of hepatitis c

4'-substituted nucleosides for the treatment of diseases mediated by the hepatitis C virus

Modeling, synthesis and biological activity of novel antifungal agents (1)

Synthesis of restrictinol and 9,10,11,12-tetrahydro-7-desmethylrestricticin

Synthesis of cyclohexyl analogs of restricticin