Synthesis and Exon-Skipping Properties of a 3'-Ursodeoxycholic Acid-Conjugated Oligonucleotide Targeting DMD Pre-mRNA: Pre-Synthetic versus Post-Synthetic Approach

Molecules. 2021 Dec 17;26(24):7662. doi: 10.3390/molecules26247662.


Steric blocking antisense oligonucleotides (ASO) are promising tools for splice modulation such as exon-skipping, although their therapeutic effect may be compromised by insufficient delivery. To address this issue, we investigated the synthesis of a 20-mer 2'-OMe PS oligonucleotide conjugated at 3'-end with ursodeoxycholic acid (UDCA) involved in the targeting of human DMD exon 51, by exploiting both a pre-synthetic and a solution phase approach. The two approaches have been compared. Both strategies successfully provided the desired ASO 51 3'-UDC in good yield and purity. It should be pointed out that the pre-synthetic approach insured better yields and proved to be more cost-effective. The exon skipping efficiency of the conjugated oligonucleotide was evaluated in myogenic cell lines and compared to that of unconjugated one: a better performance was determined for ASO 51 3'-UDC with an average 9.5-fold increase with respect to ASO 51.

Keywords: antisense oligonucleotide; bile acid; conjugation; dystrophin; exon-skipping; solid phase synthesis; solid support; ursodeoxycholic acid.

MeSH terms

  • Cell Line, Transformed
  • Exons*
  • Humans
  • Muscular Dystrophy, Duchenne* / drug therapy
  • Muscular Dystrophy, Duchenne* / genetics
  • Muscular Dystrophy, Duchenne* / metabolism
  • Myoblasts, Skeletal / metabolism*
  • Oligonucleotides, Antisense* / chemical synthesis
  • Oligonucleotides, Antisense* / chemistry
  • Oligonucleotides, Antisense* / pharmacokinetics
  • Oligonucleotides, Antisense* / pharmacology
  • RNA Precursors* / genetics
  • RNA Precursors* / metabolism
  • Ursodeoxycholic Acid* / chemistry
  • Ursodeoxycholic Acid* / pharmacokinetics
  • Ursodeoxycholic Acid* / pharmacology


  • Oligonucleotides, Antisense
  • RNA Precursors
  • Ursodeoxycholic Acid