Convenient approaches to the synthesis of oligonucleotide macrocycles containing non-nucleotide linkers.

Two convenient, practical routes to the synthesis of non-nucleotide bridged cyclic oligonucleotides have been developed. The first procedure included circularization of oligonucleotides by template-directed ligation on solid phase, while the second procedure involved preparation of a circular oligomer by non-template chemical ligation of a linear precursor in solution. Using these approaches, a series of single- and double-stranded cyclic oligonucleotides with non-nucleotide bridges has been synthesized.

Synthesis and evaluation of some properties of chimeric oligomers containing PNA and phosphono-PNA residues.

In an attempt to improve physico-chemical and biological properties of peptide nucleic acids (PNAs), particularly water solubility and cellular uptake, the synthesis of chimeric oligomers consisted of PNA and phosphono-PNA analogues (pPNAs) bearing the four natural nucleobases has been accomplished. To produce these chimeras, pPNA monomers of two types containing N-(2-hydroxyethyl)phosphonoglycine, or N-(2-aminoethyl)phosphonoglycine backbone, were used in conjunction with PNA monomers representing derivatives of N-(2-aminoethyl)glycine, or N-(2-hydroxyethyl)glycine. The oligomers obtained were composed of either PNA and pPNA stretches or alternating PNA and pPNA monomers. The examination of hybridization properties of PNA-pPNA chimeras to DNA and RNA complementary strands in comparison with pure PNAs, and pPNAs as well as DNA-pPNA hybrids and DNA fragments confirmed that these chimeras form stable complexes with complementary DNA and RNA fragments. They were found to be resistant to degradation by nucleases. All these properties together with good solubility in water make PNA-pPNA hybrids promising for further evaluation as potential therapeutic agents.