Bis(carbamoyloxymethyl) esters of 2',3'-dideoxyuridine 5'-monophosphate (ddUMP) as potential ddUMP prodrugs

A strategy for addicting transgene-free bacteria to synthetic modified metabolites

Biological containment is a safeguard technology to prevent uncontrolled proliferation of "useful but dangerous" microbes. Addiction to synthetic chemicals is ideal for biological containment, but this currently requires introduction of transgenes containing synthetic genetic elements for which environmental diffusion has to be prevented. Here, I designed a strategy for addicting transgene-free bacteria to synthetic modified metabolites, in which the target organism that can neither produce an essential metabolite nor use the extracellularly supplied metabolite, is rescued by a synthetic derivative that is taken up from a medium and converted into the metabolite in the cell. Because design of the synthetic modified metabolite is the key technology, our strategy differs distinctly from conventional biological containment, which mainly depends on genetic manipulation of the target microorganisms. Our strategy is particularly promising for containment of non-genetically modified organisms such as pathogens and live vaccines.

Nucleoside mono- and diphosphate prodrugs of 2',3'-dideoxyuridine and 2',3'-dideoxy-2',3'-didehydrouridine

Despite their close structural similarity to nucleoside analogues such as the anti-HIV drugs AZT and d4T, 2',3'-dideoxyuridine (ddU) and 2',3'-dideoxy-2',3'-didehydrouridine (d4U) are entirely inactive against HIV in their nucleoside form. However, it has been shown that the corresponding triphosphates of these two nucleosides can effectively block HIV reverse transcriptase. Herein we report on two types of nucleotide prodrugs (cycloSal and DiPPro nucleotides) of ddU and d4U to investigate their ability to overcome insufficient intracellular phosphorylation, which may be the reason behind their low anti-HIV activity. The release of the corresponding mono- and diphosphates from these compounds was demonstrated by hydrolysis studies in phosphate buffer (pH 7.3) and human CD4 (+) T-lymphocyte CEM cell extracts. Surprisingly, however, these compounds showed low or no anti-HIV activity in tests with human CD4 (+) T-lymphocyte CEM cells. Studies of the conversion of ddUDP and d4UDP into their triphosphate metabolites by nucleoside diphosphate kinase (NDPK) showed nearly no conversion of either diphosphate, which may be the reason for low intracellular triphosphate levels that result in low antiviral activity.