Antisense oligodeoxynucleotides: synthesis, biophysical and biological evaluation of oligodeoxynucleotides containing modified pyrimidines

摘要: Abstract 6-Azathymidine, 6-aza-2'-deoxycytidine, 6-methyl-2'-deoxyuridine, and 5,6-dimethyl-2'-deoxyuridine nucleosides have been converted to phosphoramidite synthons incorporated into oligodeoxynucleotides (ODNs). ODNs containing from 1 5 of these modified pyrimidines were compared with known 2'-deoxyuridine, 5-iodo-2'-deoxyuridine, 5-bromo-2'-deoxyuridine, 5-fluoro-2'-deoxyuridine, 5-bromo-2'-deoxycytidine, 5-methyl-2'-deoxycytidine nucleoside modifications. Stability in 10% heat inactivated fetal calf serum, binding affinities RNA DNA complements, ability support RNase H degradation targeted DNA-RNA heteroduplexes measured determine structure-activity relationships. 6-Azathymidine capped show an enhanced stability serum (7- 12-fold increase over unmodified ODN) while maintaining hybridization properties similar the ODNs. A 22-mer ODN having its eight thymine bases replaced by 6-azathymines or 5-bromouracils hybridized a target did not inhibit mediated degradation.