Selective Photodynamic Activity of Tetrakis(4‐aminophenyl)porphyrins with and without Acetyl Protecting Groups on Cancer and Normal Cells

Abstract

Tetrakis(4‐aminophenyl)porphyrin (1) and tetrakis(4‐acetamidophenyl)porphyrin (2) were dissolved in water with the incorporation of a polysaccharide (λ‐carrageenan (CGN)) as a water‐solubilizing agent. Although the photodynamic activity of the CGN‐2 complex was considerably lower than that of the CGN‐1 complex, the selectivity index (SI; IC50 in a normal cell/IC50 in a cancer cell) of the CGN‐2 complex was considerably higher than that of the CGN‐1 complex. This is because the photodynamic activity of the CGN‐2 complex was significantly affected by the intracellular uptakes by the normal and cancer cells. During in vivo experiments, the CGN‐2 complex inhibited tumor growth under light irradiation with high blood retention compared with the CGN‐1 complex and Photofrin, which exhibited lower blood retention. This study showed that the photodynamic activity and SI are influenced by substituent groups of arene in the meso‐positions of porphyrin analogs.