New base analogs for the formation of non-natural triplexes.

Novel nucleoside analogs have been designed for selective formation of antiparallel triplexes including a TA or a CG interrupting site. The new compounds are constructed of a W-shape bicyclic nucleic acid (WNA) bearing an aromatic ring as a stacking motif and a guanine for the formation of Hoogesteen hydrogen bonds, and are expected to effect triplex stabilization by both stacking and complementary hydrogen bonds. Purine-rich triplex-forming oligodeoxynucleotide (TFO) incorporating the new analog, WNA-7 beta G, formed a stable triplex with high selectivity to the AT site.