Synthesis and antiviral evaluation of alkoxyalkyl-phosphate conjugates of cidofovir and adefovir.

Esterification of cidofovir (CDV), an antiviral nucleoside phosphonate, with alkyl or alkoxyalkyl groups increases antiviral activity by enhancing cell uptake and conversion to CDV diphosphate. Hexadecyloxypropyl-CDV (HDP-CDV) has been shown to be 40-100 times more active than CDV in vitro in cells infected with herpes group viruses, variola, cowpox, vaccinia or ectromelia viruses. Since the first phosphorylation of CDV may be rate limiting, we synthesized the hexadecyloxypropyl-phosphate (HDP-P-) and octadecyloxyethyl-phosphate (ODE-P-) conjugates of CDV and phosphonomethoxy-ethyl-adenine (PMEA, adefovir).

Synthesis and antiviral evaluation of alkoxyalkyl esters of phosphonopropoxymethyl-guanine and phosphonopropoxymethyl-diaminopurine.

Phosphonopropoxymethyl-guanine is the methylene phosphonate analogue of acyclovir. Although not highly active against HSV, 4-38 microM of phosphonopropoxymethyl-guanine has been reported to be active against human and murine cytomegalovirus. Recently we found that cidofovir, when esterified with alkoxyalkyl moieties, showed greatly increased antiviral activity against cytomegalovirus, herpes simplex virus and orthopoxviruses, in vitro.