Synthesis, RNAi activity and nuclease-resistant properties of apolar carbohydrates siRNA conjugates.

Oligoribonucleotide conjugates carrying apolar carbohydrates at the 5'-end and the corresponding siRNA duplexes have been prepared using phosphoramidite chemistry. All the carbohydrate-siRNA derivatives were compatible with RNA interference machinery if transfected with oligofectamine. In the absence of a transfection agent, some of them exerted certain reduction of gene expression. Double-tailed permethylated glucose conjugated to siRNA through a long spacer inhibited gene expression up to 26% compared to the scrambled duplex. Such modifications contribute positively to the stability of oligoribonucleotides against 5'-exonuclease degradation.