Synthesis of poly(propyl ether imine) dendrimers and evaluation of their cytotoxic properties

In this paper, we report the synthesis of several poly(propyl ether imine) dendrons and dendrimers. These dendrons and dendrimers were constructed by involving an ether as the linker component and an imine as the branching component. The divergent syntheses of dendrons and dendrimers were established with the aid of two alternate Michael addition reactions and two alternate reduction reactions in a four-step iterative synthetic sequence. Dendrons up to three generations were synthesized and some of the dendrons were attached to a benzenoid core so as to obtain dendrimers up to two generations containing 12 carboxylic acids at the periphery. Divergent synthesis involving ether as the core was found to be more facile, and dendrimers up to three generations having 16 carboxylic acids at the periphery were achieved in good to excellent yields in each individual step. The adopted synthetic sequence allows us to install either alcohol, an amine, or a carboxylic acid at their peripheries. The carboxylic acid-terminated dendrons and dendrimers were evaluated as to their cytotoxic properties, and while most dendrons and dendrimers did not exhibit any measurable cytotoxicity, even up to 100 microg/mL, the second-generation dendrimer with the benzenoid core exhibited a mild toxicity at concentrations above 30 microg/mL.