Microwave Synthesis of Arylphosphonium Salts Bound to Flourescent Markers, Antibiotic Polymers, and DNA and Protein Binders (2009 - Present)

Investigator:  John Williams, Rhode Island College

Abstract:  Arylphosphonium salts (APS) are cytotoxic. They exhibit structure-activity relationships (SARs) as antibiotics, in DNA binding, enzyme inhibition and in lethality to malignant cells. These lipophilic cations easily pass across cell membranes. They preferentially accumulate in the mitochondria of malignant cells in response to the larger charge gradient relative to normal cell mitochondria. This property has been exploited to deliver DNA alkylating agents into mitochondria of malignant cells. APS exhibit SARs for in vitro and in vivo inhibition of acetylcholinesterase. They are competitive inhibitors of bovine serum amine oxidase, protein kinase C and HIV integrase, among others. Thus their lethal effect on malignant and normal cells has a number of possible mechanisms; from disruption of metabolism to inhibition of enzymes and binding to proteins to interference with DNA function. APS have been shown to modulate DNA toxicity in a collaborative project underway for which preliminary results have been published. DNA binding is also evidenced by melting curve shifts, electrophoresis mobility and in silico binding studies done in our laboratories.  All of these show strong SARs. We will do collaborative experiments to explore the specific mechanisms for toxicity of APS. I We will synthesize APS bound to fluorescent molecules, polymers containing covalently bound antibiotic APS,  APS for new DNA binding and toxicity experiments, and novel APS ionic liquids. AutoDock and HyperChem will be used to calculate APS-DNA interactions. The syntheses will be done by wet and dry bench methods and by microwave acceleration in the solid, melt and solution phases with attention to "green" methodology. The fluorescent-labeled compounds will be used to observe localization and dispersion of APS into cells using fluorescent microscopy. Polymeric APS will be tested for antibacterial activity and incorporated into plastics suitable for the fabrication of medical tubing, bagging and containers. New monomer APS will be screened in a continuation of DNA-replication toxicity studies and in melting and electrophoresis experiments. In conjunction with the synthesis of compounds for these experiments, a library of the new APS will be kept to be used in future studies of enzyme inhibition, binding to transmembrane proteins, and interaction with signaling proteins like the aryl hydrocarbon receptor.  All of the bench and computational chemistry will be done in our laboratories by undergraduates.