Oligonucleotide analogues with cationic backbone linkages

Area of Science:

• Medicinal Chemistry
• Molecular Biology
• Biotechnology

Background:

• Oligonucleotides show promise as bioactive agents due to their sequence-specific binding.
• Their oligoanionic backbone hinders penetration of biological barriers like cell membranes.
• Structural modifications are crucial for in vivo and in cellulo applications.

Purpose of the Study:

• To review strategies for modifying oligonucleotide backbones to reduce negative charges.
• To explore artificial backbone linkages that impart zwitterionic or oligocationic properties.
• To summarize research on specific alternative backbone structures.

Main Methods:

• Site-specific replacement of phosphate diester linkages with positively charged motifs.
• Synthesis and characterization of oligonucleotide analogues with novel backbones.
• Review of existing research on four classes of artificial backbone linkages.

Main Results:

• Development of oligonucleotide analogues with reduced negative charge density.
• Introduction of zwitterionic or oligocationic properties via backbone modification.
• Detailed description of synthesis and properties for aminoalkylated phosphoramidates, guanidinium groups, S-methylthiourea motifs, and nucleosyl amino acid (NAA)-derived modifications.

Conclusions:

• Artificial backbone modifications can overcome charge-related barriers for oligonucleotide delivery.
• Novel linkages offer potential for enhanced cellular uptake and therapeutic efficacy.
• This approach is key to advancing nucleic acid-based therapies.