title: Conjugated PDT drug: photosensitizing activity and tissue distribution of PEGylated pheophorbide a.
abstract: The design of new photosensitizers with enhanced phototoxicity and pharmacokinetic properties remains a central challenge for cancer photodynamic therapy (PDT). In this study, Pheophorbide a (Pba) has been pegylated to methoxypolyethylene glycol (mPE G-Pba) to produce a soluble photosensitizer that exhibits a higher tissue distribution than free Pba. In vitro studies have shown that mPE G-Pba promotes a fairly strong photosensitizing effect in cancer cells, as previously observed for the unpegylated molecule. mPE G-Pba targets the mitochondria where, following photoactivation, ROS are produced which cause a cellular injury by lipid peroxidation. The effect of pegylation on the photosensitizer biodistribution has been examined in different selected organs of female mice, at different time points after intraperitoneal administration of the drug (50 μmol/Kg body weight). Other than free Pba, which showed a low tissue accumulation, mPE G-Pba has been detected in significant amounts (8 to 16 μg/ml) in liver, spleen, duodenum and kidney and, 3-5 hours after intraperitoneal injection, in moderate amounts (3 to 8 μg/ml) in brain and lung. In vivo optical imaging performed on living female C57/BL6 mice bearing a subcutaneous melanoma mass, showed that injected mPEG-Pba distributes all over the body, with an higher uptake in the tumor respect to free Pba. Our results indicate that although pegylation somewhat decreases the phototoxicity, it significantly increases the drug solubility and tissue distribution and tumor uptake of mPE G-Pba, making the conjugate an interesting photosensitizer for PDT.
authors.affiliation: Department of Biomedical Science and Technology, School of Medicine, University of Udine, Udine, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Rapozzi
authors.forename: Marina
authors.initials: M
authors.lastname: Zacchigna
authors.forename: Stefania
authors.initials: S
authors.lastname: Biffi
authors.forename: Chiara
authors.initials: C
authors.lastname: Garrovo
authors.forename: Francesca
authors.initials: F
authors.lastname: Cateni
authors.forename: Marco
authors.initials: M
authors.lastname: Stebel
authors.forename: Sonia
authors.initials: S
authors.lastname: Zorzet
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Bonora
authors.forename: Sara
authors.initials: S
authors.lastname: Drioli
authors.forename: Luigi E
authors.initials: LE
authors.lastname: Xodo
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D002734:Chlorophyll / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D007274:Injections, Intraperitoneal; D008315:Malondialdehyde / Q000032:analysis; D051379:Mice; D051336:Mitochondrial Membranes / Q000378:metabolism; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry* / Q000493:pharmacokinetics* / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D011092:Polyethylene Glycols; D008315:Malondialdehyde