Photodynamic activity of new photosensitizers obtained from 5,10,15,20-tetrapentafluorophenylporphyrin

The commercially available tetrapentafluorophenylporphyrin has been used as parent compounds for the synthesis of six new tetraarylporphyrins. These new porphyrins were obtained following aromatic nucleophilic substitution of the para-position fluorine atoms by means of molecules bearing an oxygen or sulphur anion, providing either tri- or tetra-substituted derivatives which were isolated as pure compounds after a single step of column chromatography purification. These new porphyrins, first analyzed to determine the photobleaching stability and the octanol/water repartition values, were studied as photosensitizers against the HCT116 cancer cell line with irradiation by a blue LED device. The intrinsic toxicity of these compounds was negligible, whereas the photodynamic efficacy was found to be directly related to the cellular uptake of the photosensitizer that was correlated with the hydrophilicity of the substituent. In fact, the PSs lacking of any polar groups were found to be poorly efficient while the photosensitizer bearing four hydroxyl groups showed the greatest photodynamic activity, thus confirming the importance of the presence of polar appendixes to properly interact with the cells, thus exerting the desired photo-killing effect.