The UltraMILD set of methyl phosphoramidites, in conjunction with UltraMILD deprotection conditions, can be used to prepare the interesting, nuclease resistant methyl phosphotriester linkage. These have potential therapeutic applications.

We also produce a range of ethyl phosphoramidites with classical nucleobase protection. Nuclease resistant P-ethoxy oligonucleotides (a hydrophobic analogue of phosphodiesters) have been shown, through incorporation into liposomes, to be effective in the inhibition of protein expression and cell growth in therapeutic applications.⁽¹⁾ The neutral charge and slight lipophilic character appears to improve the delivery of the oligonucleotide into a cell.

Ref:

1. (a) Cellular pharmacology of P-ethoxy antisense oligonucleotides targeted to Bcl-2 in a follicular lymphoma cell line, Y. Gutiérrez-Puente, A.M. Tari, R.J. Ford, R. Tamez-Guerra, R. Mercado-Hernandez, M. Santoyo-Stephano, and G. Lopez-Berestein, Leuk. Lymphoma., 44, 1979-85, 2003. (b) Safety, pharmacokinetics, and tissue distribution of liposomal P-ethoxy antisense oligonucleotides targeted to Bcl-2, Y. Gutiérrez-Puente, A.M. Tari, C. Stephens, M. Rosenblum, R.T. Guerra, G. Lopez-Berestein, J. Pharmacol. Exp. Ther., 291, 865-9, 1999.