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The synthesis of new 2,6-disubstituted purine 2',3'-dideoxy-2',3'-difluoro-D-arabino nucleosides is reported. Their ability to block HIV and HCV replication along with their cytotoxicity toward Huh-7 cells, human lymphocyte, CEM and Vero cells was also assessed. Among them, β-2,6-diaminopurine nucleoside 25 and guanosine derivative 27 demonstrate potent anti-HIV-1 activity (EC50 = 0.56 and 0.65 µm; EC90 = 4.2 and 3.1 µm) while displaying only moderate cytotoxicity in primary human lymphocytes. [ABSTRACT FROM AUTHOR]

One in five of the world's plant species is threatened with extinction according to the 2010 first global analysis of extinction risk. Tilman et al. predicted a massive ecological change to terrestrial plants within the next 50-100 y, accompanied by an increase in the number of global plant species facing extinction [Tilman D, et al. (2001) Proc Natl Acad Sci USA 98(10):5433-5440]. Most of the drugproducing plant families contain endangered species never previously studied for their utility to human health, which strongly validates the need to prioritize protection and assessment of these fragile and endangered groups [Zhu F, et al. (2011) Proc Natl Acad Sci USA 108(31):12943-12948]. With little prior attention given to endangered and rare plant species, this report provides strong justification for conservation of the rare plant Diplostephium rhododendroides Hieron., as well as other potential drug-producing endangered species in this and other groups. [ABSTRACT FROM AUTHOR]

9-(2',3'-Dideoxy-2',3'-difluoro-β-D-arabinofuranosyl)adenine (20), 2-chloro-9-(2',3'-dideoxy-2,3-difluoro-β-D-arabinofuranosyl)adenine (22), as well as their respective α-anomers 21 and 23, were synthesized by the nucleobase anion glycosylation of intermediate 5-O-benzoyl-2,3-dideoxy-2,3-difluoro-α-D-arabinofuranosyl bromide (13) starting from methyl 5-O-benzyl-3-deoxy-3-fluoro-α-D-ribofuranoside (3) and methyl 5-O-benzoyl-α-D-xylofuranoside (10). These compounds were evaluated as potential inhibitors of HIV-1 and hepatitis C virus in human PBM and Huh-7 Replicon cells, respectively. The adenosine analog 20 demonstrated potent activity against HIV-1 in primary human lymphocytes with no apparent cytotoxicity. Conformation of pentofuranose ring of nucleoside 20 in solution was studied by PSEUROT calculations. [ABSTRACT FROM AUTHOR]

We recently discovered a novel compound, identified as N 3 ,5′-cyclo-4-(β-d-ribofuranosyl)- vic -triazolo[4,5- b ]pyridinin-5-one, with anti-hepatitis C virus (HCV) activity in vitro. The structure was confirmed by chemical synthesis from 2-hydroxy-5-nitropyridine. It showed anti-HCV activity with EC 50 =19.7 µM in replicon cells. Its 3′-deoxy sugar analogue was also synthesized, but was inactive against HCV in vitro. [ABSTRACT FROM AUTHOR]