Thioglycerol-porphyrin, -chlorin, and -phthalocyanine derivatives for photodynamic therapy of UM-UC-3 bladder cancer cells

Abstract

Photodynamic Therapy (PDT) has been successfully used to treat different tumour types since its approval. However, the search for more powerful and selective photosensitisers (PSs) is still a hot research area on porphyrin (Por), chlorin (Chl), and phthalocyanine (Pc) dyes. In this study, three new PSs of these three families of compounds were synthesized and characterized as thioglycerol derivatives (tetra-thioglycerolporphyrin 1, tetra-thioglycerol chlorin 2, and octa-thioglycerolphthalocyaninatozinc(II) 3). Their photophysical and photochemical properties were assessed, and in vitro studies using the human bladder cancer cell line UM-UC-3 were performed to evaluate their efficacy as PDT agents.The obtained results demonstrate that Por 1 has a higher uptake and singlet oxygen production than the other two PSs. However, its best PDT results were only obtained at the highest studied concentration (10 μM) and upon a light dose of 43.2 J.cm−2 (40 min under white light irradiation at an irradiance of 18 mW.cm−2). More interesting were the PDT results of Chl 2, which shows the highest PDT efficacy even at a lower PS concentration (2.5 μM). Crossing all data, this result may be related to the different PS subcellular localization. Unexpectedly, ZnPc 3 did not show any changes on metabolic activity of the cells under the studied conditions, most probably related to its very low uptake and singlet oxygen production.