siRNA activity of 5′-A, 5′-6-mCEPh-purine, and 5′-6-PBuS-purine siRNAs (A) Chemical structure of 6-PBuS-purine. (B) Comparison of RNAi activity of luciferase-targeting siRNAs, each bearing A, 6-mCEPh-purine or 5′-6-PBuS-purine at the 5′-end of the guide strand. Relative levels of luciferase luminescence in luciferase-expressing HeLa cells after treatment with various concentrations of transfected siRNA. Data are represented as the means ± SD, n = 5. The 6-mCEPh-purine P-value was calculated by comparison with 5′-A. P-value (a) Two-way ANOVA, (##)P < 0.05 (b), (###)P < 0.001 (b): unpaired t-test. (C) Knockdown activity of ApoB-targeting siRNAs with adenine, 6-mCEPh-purine, and 6-PBuS-purine at the guide strand 5′-end. Relative levels of ApoB mRNA in mouse primary cells after treatment with various concentrations of transfected siRNA. Data are represented as the means ± SD, n = 5; P = 0.001 (a): two-way ANOVA; (##) P < 0.05(b), (###) P < 0.001 (b): one-way ANOVA; (*) P < 0.05, (**) P < 0.01: unpaired t-test and Bonferroni correction.
