Synthesis and characterisation of polyamine-poly(ethylene glycol) constructs for DNA binding and gene delivery

Article abstract of DOI:10.1016/S0968-0896(00)00113-9

Improved non-viral vector systems are needed for efficient delivery of DNA to target cell nuclei in gene therapy. A series of linear polyamine-poly(ethylene glycol) (PEG) constructs has been synthesised by reaction of appropriately Boc-protected thermine derivatives with ω-methoxyPEG oxiranylmethyl ethers. Constructs carrying 1-3 MeOPEG units and 0, 2 or 4 N-methyl groups have been prepared by this method. H₂N(CH₂)₃NBoc(CH₂)₃NBoc(CH₂)₃NHBoc was prepared efficiently by mono-trifluoroacetylation of thermine, attachment of Boc and removal of the trifluoroacetyl group in one pot. A similar process gave H₂N(CH₂)₃NBoc(CH₂)₃NBoc(CH₂)₃NH₂. BocMeN(CH₂)₃NHMe was alkylated by 1,3-dibromopropane to give BocMeN(CH₂)₃NMe(CH₂)₃NMe(CH₂)₃NMeBoc. A cyanoethylation/reduction sequence extended H₂N(CH₂)₃NBoc(CH₂)₃NBoc(CH₂)₃NH₂ to give H₂N(CH₂)₃NBoc(CH₂)₃NBoc(CH₂)₃NBoc(CH₂)₃NBoc(CH₂)₃NH₂, which was converted to its mono- and di-MeOPEG550 derivatives. Deprotection gave the linear polyamine-MeOPEG constructs. A branched triamine-poly(ethylene glycol) construct was prepared by acylation of (BocHN(CH₂)₃)₂N(CH₂)₃NH₂ with ω-methoxyPEG 550 chloroformate, followed by deprotection. A cyanoethylation/reduction/protection sequence from (H₂N(CH₂)₃)₂N(CH₂)₃NHBoc gave a protected pentamine. Alkylation with Br(CH₂)₅CONH(CH₂)₂NHBoc, deprotection, acylation with MeOPEG chloroformate and deprotection gave a pentamine-MeOPEG construct in which the MeOPEG is attached through a linker to the central amine. The linear hexamine construct carrying MeOPEG550 at only one terminus was the most effective DNA-interactive member of the two series in an ethidium displacement assay and was effective in delivering a reporter gene to RIF-1 tumours. Copyright (C) 2000 Elsevier Science Ltd.