Synthesis and Antisense Properties of 2-O-(2S-Methoxy-propyl)-RNA-Modified Gapmer Antisense Oligonucleotides

摘要

To ascertain whether increasing hydrophobicity can enhance the activity of second-generation antisense oligonucleotides (ASOs) in muscle, we investigated the antisense properties of 2'-O-(2S-methoxypropyl)-RNA (2S-MOP)-modified ASOs. Synthesis of the 25-MOP 5-methyl uridine phosphoramidite was accomplished on a multi-gram scale by Lewis-acid-catalyzed ring opening of 5-O-fert-butyldiphenylsilyl ether-protected 2,2'-an-hydro-5-methyl uridine with 2S-methoxy-1-propanol. Synthesis of the 2S-MOP 5-methyl cytidine nucleoside from the corresponding 5-methyl uridine nucleoside was accomplished by formation and displacement of a 4-triazolide intermediate with aqueous ammonia. 2S-MOP-modified oligonucleotides were prepared on an automated DNA synthesizer and showed similar enhancements in duplex thermal stability as 2'-O-methoxy-ethyl RNA (MOE)-modified oligonucleotides. 2S-MOP-contain-ing antisense oligonucleotides were evaluated in Balb-c mice and showed good activity for decreasing the expression levels of scavenger receptor Bl (Srb1) and phosphatase and tensin homologue (PTEN) mRNA in liver and muscle tissue.