In our search for new therapeutic agents against chronic hepatitis C, a ribonucleoside analogue, 2'-C-methylcytidine, was discovered to be a potent and selective inhibitor in cell culture of a number of RNA viruses, including the pestivirus bovine viral diarrhea virus, a surrogate model for hepatitis C virus (HCV), and three flaviviruses, namely, yellow fever virus, West Nile virus, and dengue-2 virus. However, pharmacokinetic studies revealed that 2'-C-methylcytidine suffers from a low oral bioavailability. To overcome this limitation, we have synthesized the 3'-O-l-valinyl ester derivative (dihydrochloride form, valopicitabine, NM283) of 2'-C-methylcytidine. We detail herein for the first time the chemical synthesis and physicochemical characteristics of this anti-HCV prodrug candidate, as well as a comparative study of its pharmacokinetic parameters with those of its parent nucleoside analogue, 2'-C-methylcytidine.

A novel series of 3-aryl-phospho-indole (API) non-nucleoside reverse transcriptase inhibitors of HIV-1 was developed. Chemical variation in the phosphorus linker led to the discovery of 3-phenyl-methyl-phosphinate-2-carboxamide 14, which possessed excellent potency against wild-type HIV-1 as well as viruses bearing K103N and Y181C single mutants in the reverse transcriptase gene. Chiral separation of the enantiomers showed that only R enantiomer retained the activity. The pharmacokinetic, solubility, and metabolic properties of 14 were assessed.

In order to improve the oral bioavailability of 2-C-methylcytidine, a potent anti-HCV agent, the corresponding 3'-O-L-valinyl ester derivative (NM 283) has been synthesized Based on its ease of synthesis and its physicochemical properties, NM 283 has emerged as a promising antiviral drug for treatment of chronic HCV infection.