Dimeric porphyrins are known to localize in tumor cells. Covalently attaching boron cages into porphyrin macrocyles provide a means of delivering high concentrations of boron into cancerous cells. The synthesized boronated porphyrins can then be utilized for boron neutron capture therapy, an experimental cancer therapy which depends on the ability of 10B to capture a thermal neutron. This nuclear reaction generates cytotoxic products that kill tumor cells, and if selectively concentrated in cancerous tissues can lead to specific tumor destruction. A semi-purified form of porphyrin derivative is currently in phase III clinical trials for photodynamic therapy, a related mode of cancer treatment which makes use of laser instead of neutrons as a means of cell destruction. Two diastereomers of diacetyl porphyrin dimer were synthesized and isolated in pure forms in our laboratory. NMR of the two diastereomers revealed dramatic differences between the two isomers. From known X-ray crystal structure data of related poprhyrins, models for the diastereomers were constructed and their minimized energy determined using the Tripos Sybyl 6.0 molecular modeling program. The two isomers either have RR, RS, SR or SS configuration, but one pair will be meso form. The two models are being analyzed and compared with results from low temperature and 2D NMR structural analyses. Results generated from Computer Graphics Laboratory greatly help us in understanding the structure of our molecules.
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