Synthesis of nuclease-resistant siRNAs possessing benzene-phosphate backbones in their 3′-overhang regions

Abstract

We describe the synthesis and silencing activities of siRNA possessing N 1 -[3,5-bis(hydroxymethyl)phenyl]thymine ( b t ) in their 3′-overhang regions. We found that an siRNA possessing b t in the 3′-overhang region was more effective than an siRNA with natural nucleosides and the siRNA possessing 1,3-bis(hydroxymethyl)benzene ( b) without a nucleobase at the 3′-overhang region in in vitro experiment using HeLa cells system. Furthermore, the RNA possessing b t at its 3′-end was more resistant to nucleolytic hydrolysis by snake venom phosphodiesterase (a 3′-exonuclease) than the RNA possessing the natural nucleoside 2′-deoxythymidine at the 3′-end. Thus, the compound b t will be a novel 3′-overhang moiety that can enhance the silencing activity and nuclease-resistant property of siRNAs.