Monitoring the intracellular metabolism of nucleoside phosphoramidate pronucleotides by 31P NMR

The intracellular metabolism of 3'-azido-3'-deoxythymidine (AZT)-(L)-tryptophan methyl ester phosphoramidate (L-ATO) and AZT-(L)-phenylalanine methyl ester phosphoramidate (L-APO) by the human T-lymphoblastoid cell line CCRF-CEM (CEM-1.3) and peripheral blood mononuclear cell line (PBMC) was investigated with high field 31P NMR spectroscopy. The AZT amino acid phosphoramidates were shown to accumulate intracellularly and to be readily converted into AZT-MP by both tissues types. Thus, the efficient delivery of nucleoside monophosphates to cells can be facilitated by nucleoside phosphoramidate pronucleotides.