Study of Different Substituted Cyclic and Acyclic Benzylpronucleotides of d4T Relative to Their Hydrolytic Stability and Antiviral Activity

CycloSal-d4TMP and two different bis(benzyl) phosphate triesters of the antivirally active nucleoside analog d4T were studied with regard to their chemical hydrolysis behavior at pH 7.3, in CEM/0 cell extracts, and their anti-HIV activity. In contrast to triesters 2-4, bis-(o-AB)-d4TMP 1 was found to be chemically exquisitely stable. All compounds led to the formation of d4TMP in cell extracts and all triesters achieved the TK-bypass.