Neutral and polyanionic carboranylporphyrazines: synthesis and physico-chemical properties

Among the challenges precluding the widespread use of boron neutron capture therapy (BNCT) has been the difficulty in achieving selective delivery of large quantities of boron to malignant cells. In an attempt to address this issue we have recently developed an effective strategy to synthesize a new family of boronated porphyrazines to be delivered through the membrane of cancerous tissues as such or with the help of liposomes. Herein we describe the synthesis and the basic physico-chemical properties of neutral octa-closo-carboranyl-alkylthio-porphyrazines as well as of their water-soluble counterparts obtained by mild deboronation of the closo-polyedra. Preliminary studies indicate that these compounds show negligible cell toxicity and, compared with BPA, good cellular uptake. This encourages further studies for their evaluation as potential BNCT agents.