Porphyrin with amino acid moieties: A tumor photosensitizer

A porphyrin with amino acid moieties was synthesized in this work, which may be a latent photosensitizer for photodynamic therapy (PDT). Adler's strategy was used to synthesize meso-tetra (4-nitrophenyl) porphyrin (TNPP) through cyclolization of 4-nitrobenzaldhyde and pyrrole in refluxed nitrobenzene. Reduction of TNPP yielded meso-tetra(4-aminophenyl) porphyrin (TAPP). The synthesis was improved by employing lactic acid as a catalyst. Based on TAPP, porphyrin with valine (TAPP-4Val) was obtained. The application of the resultant TAPP-4Val as tumor photosensitizer on human breast tumor cells for photodynamic therapy (PDT) was preliminarily explored. Dark-toxicity evaluations showed that, under a concentration at up to 6 × 10−6 M, the survival of MCF-7 cells was larger than 90%, which means TAPP-4Val is almost of non-cytotoxicity. However, TAPP-4Val showed remarkable phototoxicity after visible light irradiation. Effects of irradiation time on the survival of cells under typical concentrations of TAPP-4Val were also studied. The new porphyrin with amino acid moieties, TAPP-4Val, is of high phototoxicity but minimal or no dark-toxicity, which can be used as an effective photosensitizer for PDT.