Inhibition of Hepatitis B Virus Replication by Nucleoside Enantiomers of β-2′,3′-Dideoxypurine Analogues

Various purine β-L-2′,3′-dideoxynucleoside analogues with both sugar and base modifications including β-L-ddG, β-L-ddl, β-L-ddA, 2′-azido-β-L-araddA, 2′-amino-β-L-araddA, 2′,5′-anhydro-β-L-araddA, 2′-azido-β-L-ddA, 2′-amino-β-L-ddA, 2′-fluoro-β-L-ddA, 3′-azido-β-L-ddA, 3′-amino-β-L-ddA, 3′-fluoro-β-L-ddA, 2,6-diamino-β-L-2′,3′-dideoxyfuranosylpurine, 6-cyclopropylamino-β-L-ddA, 2′-azido-6-N-triphenylphosphine-β-L-araddA, 2-amino-6-methylamino-β-L-2′,3′-dideoxyfuranosylpurine, 2-amino-6-cyclopropylamino-β-L-2′,3′-dideoxyfuranosylpurine, 2-amino-6-cyclopentylamino-β-L-2′,3′-dideoxyfuranosylpurine, 2′,3′-didehydro-β-L-ddA and 2′,3′-didehydro-6-N-triphenyl phosphine-β-L-ddA were synthesized and evaluated as potential inhibitors of hepatitis B virus (HBV) replication in HBV DNA-transfected human hepatoblastoma-derived Hep-G2 cells (2.2.15 cells). β-L-ddA, 2′-azido-β-L-ddA, 3′-azido-β-L-ddA, 2″,3′-didehydro-β-L-ddA (β-L-D4A) and a modified base of β-L-D4A, inhibited HBV replication in vitro. β-L-D4A was the more potent and selective antiHBV agent with a 50% effective concentration value of 0.1 μM and a selectivity index of 1800. On the basis of this finding, studies are in progress to synthesize new purine derivatives with the β-L unnatural configuration which hopefully will lead to identifying additional potent and highly selective anti-HBV agents.