Cationic Porphyrin Basicity and Possible Implications in Photodynamic Therapy

Photodynamic therapy (PDT) is a cutting edge cancer treatment that is currently being researched with great interest. PDT uses an agent, commonly a porphyrin molecule, thatis activated when it is exposed to specific wavelenghths of light. Upon activation, the agent produceds a form of oxygen that causes cellular apoptosis or tissue necrosis. Some of our current results indicate that cationic porphyrins at certain wavelengtths can produce differente outcomes depending on the type of cancer. For example, while cationic porphyrins such as meso-Tetra (N-methyl-2-pyridyl) porphyine and meso-Tetra (N-methyl-3-pyridyl) porphine seem to accelerate the growth of pancreatic cancer cells (Panc 28). It doesn't seem to affec the Mia Paca-w. This seems to confirm that differences in conformation and polaritiy makes a substantial difference in the outcome. Protonation enhances the excited state absorption of porphyrins probably because of changes to the expected saddle conformation. Therefore, further analysis of excitation, emission of several N-methyl substituted free base porphyrins and their respective dications would elucidate the connection between conformation, polarity and expected effect for different cancer lines.