ALA Dipeptides derivatives for their use in Photodynamic Therapy

P. VALLECORSA, G. DI VENOSA, L. MAMONE, F. GIUNTINI, L. GÁNDARA, A. BATLLE, M.V. ROSSETTI, A.J. MACROBERT, I.EGGLESTON & A. CASAS

Düsseldorf

Congreso; international congress on Porphyrins and Porphyrias 2015; 2015

American Porphyria Foundation

Photodynamic therapy (PDT) involves theadministration of a photosensitizer (P) and subsequent irradiation with visible light, promotinghighly reactive oxygen species, which react with a variety of biomolecules leadingto cell dead. Here, four novel meso-subtitutedporphyrins derivatives have been tested as potential Ps in the mammaryadenocarcinoma LM3 tumor cell line. The 5,10,15,20-tetrakis[4-(3-N,N-dimethylammoniumpropoxy)phenyl]porphyrin(TAPP), the 5,15-di(4-[3-N,N-dimethylaminopropoxy]phenyl)-10,20-di(4-trifluoromethylphenyl)porphyrin (A2B2), the 5,10,15,20-tetrakis[3-(N-ethyl-N-methylcarbazoyl)]chlorin(TEMCC) and its porphyrin analogous (TEMCP) were used. These Ps showed thetypical Soret band at ~420 nm and the four Q-bands between515 and 650 nm. A more intense band at 650 nm was obtained for TEMCC comparedwith TEMCP. These compounds also produce singlet molecular oxygen with quantumyields of 0.40-0.53 inN,N-dimethylformamide.Cell dark toxicity after exposing the compounds for 3 h determined the maxima workconcentrations, these were 2.5 mM for TAPP and A2B2; and 5 mM for TEMCC and TEMCP. Testig the efficacy as Ps, LM3 cells were exposedto the compounds employing the above mentioned concentrations for 3 h and thenirradiated with a bank of fluorescent tubes (fluence rate of 0.5 mW/cm2). Lethal doses 50 (LD50) for eachporphyrin were as follows: TAPP: 135mJ/cm2, TEMCC: 360 mJ/cm2, TEMCP: 420 mJ/cm2, A2B2:600 mJ/cm2, showing that TAPP is the most photoactive porphyrin. So,we chose TAPP to further characterize the phototoxicity mechanisms. Uptakestudies suggested that TAPP is mainly transported by passive diffusion. TAPPcolocalization studies were performed using organelle trackers (LysoTrackerGreen for lysosomes, Mito Tracker Green for mitochondria and NBD C6-Ceramide forGolgi apparatus). By means of epifluorescence and confocal microscopy it wasfound that TAPP is mostly located in the vicinity of mitochondria.