Solid-Phase Synthesis of Thermolytic DNA Oligonucleotides Functionalized with a Single 4-Hydroxy-1-butyl or 4-Phosphato-/Thiophosphato-1-butyl Thiophosphate Protecting Group
作者:Andrzej Grajkowski、Cristina Ausín、Jon S. Kauffman、John Snyder、Sonja Hess、John R. Lloyd、Serge L. Beaucage
DOI:10.1021/jo062087y
日期:2007.2.1
Several thermolytic CpG-containing DNA oligonucleotides analogous to 1 have been synthesized to serve as potential immunotherapeutic oligonucleotide prodrug formulations for the treatment of infectious diseases in animal models. Specifically, the CpG motif (GACGTT) of each DNA oligonucleotide has been functionalized with either the thermolabile 4-hydroxy-1-butyl or the 4-phosphato-/thiophosphato-1-butyl thiophosphate protecting group. This functionalization was achieved through incorporation of activated deoxyribonucleoside phosphoramidite 8b into the oligonucleotide chain during solid-phase synthesis and, optionally, through subsequent phosphorylation effected by phosphoramidite 9. Complete conversion of CpG ODNs hbu1555, psb1555, and pob1555 to CpG ODN 1555 (homologous to 2) occurred under elevated temperature conditions, thereby validating the function of these diastereomeric oligonucleotides as prodrugs in vitro. Noteworthy is the significant increase in solubility of CpG ODN psb1555 and CpG pob1555 in water when compared to that of neutral CpG ODN fma1555 (homologous to 1).