cycloSal-Pronucleotides - Design of Chemical Trojan Horses

Pronucleotides represent a promising alternative to improve the biological activity of nucleoside analogues against different viral diseases. The basic idea is to achieve nucleotide delivery into cells bypassing limitations encountered during the intracellular formation of nucleotides. The cycloSal-concept is one of several pronucleotide systems reported so far. For some nucleoside analogues, the cycloSal-approach improved antiviral potency thus broadening the applicability of nucleosides. The initial design, chemistry, the proof-of-principle and different applications of the cycloSal-strategy will be discussed in this review.