Asymmetric Synthesis and Biological Evaluation of β-L-(2R,5S)- and α-L-(2R,5R)-1,3-Oxathiolane-Pyrimidine and -Purine Nucleosides as Potential Anti-HIV Agents

Article abstract of DOI:10.1021/jm00054a001

In order to study the structure-acivity relationships of L-oxathiolanyl nucleosides as potential anti-HIV agents, a series of enantiomerically pure L-oxathiolanyl pyrimidine and purine nucleosides were synthesized and evaluated for anti-HIV-1 activity in human peripheral blood mononuclear (PBM) cells.The key intermediate 8 was synthesized starting from L-gulose via 1,6-thiaanhydro-L-gulopyranose.The acetate 8 was condensed with thymine, 5-substituted uracils and cytosines, 6-chloropurine, and 6-chloro-2-fluoropurine to give pyrimidine and purine nucleosides.Upon evaluation of these final nucleosides, the 5-fluorocytosine derivative 51 was found to be the most potent compound among those tested.In the case of 5-substituted cytosine analogues, the antiviral potency was found to be in the following decreasing order: cytosine (β-isomer) > 5-iodocytosine (β-isomer) > 5-fluorocytosine (α-isomer) > 5-methylcytosine (α-isomer) > 5-methylcytosine (β-isomer) > 5-bromocytosine (β-isomer) > 5-chlorocytosine (β-isomer).Among the thymine, uracil, and 5-substituted uracil derivatives, thymine (α-isomer) and uracil (β-isomer) derivatives exhibited moderate anti-HIV activity.In the purine series, the antiviral potency is found to be in the following decreasing order: adenine (β-isomer) > 6-chloropurine (β-isomer) > 6-chloropurine (α-isomer) > 2-NH2-6-Cl-purine (β-isomer) > guanine (β-isomer) > N⁶-methyladenine (α-isomer) > N⁶-methyladenine (β-isomer).The cytotoxicity was also determined in human PBM cells as well as Vero cells.None of the synthesized nucleosides was toxic up to 100 μ in PBM cells.