Synthesis and silencing properties of siRNAs possessing lipophilic groups at their 3'-termini.

Short interfering RNAs (siRNAs) conjugated with lipophilic groups at their 3'-termini were synthesized. The silencing activities of these siRNAs were examined by a dual-luciferase assay. It was found that the '-end of the passenger strand (sense strand) was better than the guide strand (antisense strand) for connecting bulky lipophilic molecules, particularly a rigid molecule such as cholesterol.