Phosphonodithioester-Amine Coupling as a Key Reaction Step for the Design of Cationic Amphiphiles Used for Gene Delivery.

Montassar Khalil,Tristan Montier,Mathieu Berchel,Alexis Hocquigny,Paul-Alain Jaffrès

doi:10.3390/molecules26247507

Abstract

A convergent synthesis of cationic amphiphilic compounds is reported here with the use of the phosphonodithioester–amine coupling (PAC) reaction. This versatile reaction occurs at room temperature without any catalyst, allowing binding of the lipid moiety to a polar head group. This strategy is illustrated with the use of two lipid units featuring either two oleyl chains or two-branched saturated lipid chains. The final cationic amphiphiles were evaluated as carriers for plasmid DNA delivery in four cell lines (A549, Calu3, CFBE and 16HBE) and were compared to standards (BSV36 and KLN47). These new amphiphilic derivatives, which were formulated with DOPE or DOPE-cholesterol as helper lipids, feature high transfection efficacies when associated with DOPE. The highest transfection efficacies were observed in the four cell lines at low charge ratios (CR = 0.7, 1 or 2). At these CRs, no toxic effects were detected. Altogether, this new synthesis scheme using the PAC reaction opens up new possibilities for investigating the effects of lipid or polar head groups on transfection efficacies.

Highlights

Previous publications have observed that oleyl chains inthe fluidity of self-assemblies thanks to the presence of their carbon–carbon double bond crease the fluidity of self-assemblies thanks to the presence of their carbon–carbon double possessing a Z-configuration. This structural feature introduces a kink in the lipid chain bond possessing structural feature introduces a kink in theIn lipid that disturbs the alipid packing and This increases fluidity, as previously reported the chain that disturbs the lipid packing and increases fluidity, as previously reported
In case of branched lipid chains, the ramification results in a larger volume of hydrophobic the case of branched lipid chains, the ramification results in a larger volume of hydrophochains that contribute to the formation of a cone-shaped amphiphilic structure that favors bic chains that contribute toand the produces formationefficient of a cone-shaped structurestarts that non-lamellar self-assemblies gene carriersamphiphilic
The final cationic amphiphilic compounds 4a–b were isolated in a four-step synthesis scheme in sufficient quantities for their evaluation as plasmid DNA carriers

Summary

Introduction

Cationic amphiphilic compounds form liposomes in water and can interact with nucleic acids (e.g., pDNA, siRNA, mRNA) to produce lipoplexes after full reorganization of the liposomal supramolecular assemblies [1]. This self-reorganization occurs thanks to both ionic interactions and the self-assembly of their lipid chains, limiting their interactions with water [2]. The final goal of all these cationic amphiphiles consists of producing supramolecular assemblies featuring tunable stability in order to be sufficiently stable during the carrying process, while permitting cargo release in the cytosol after cell internalization, which usually occurs via an endocytosis pathway [8]

Methods

Results

Conclusion