title: Interaction of cationic meso-porphyrins with liposomes, mitochondria and erythrocytes.
abstract: Two series of cationic porphyrins meso-(3N-methylpyridinium)phenylporphyrin (3P1, 3P2c, 3P2t, 3P3 and 3P4) and meso-(4N-methylpyridinium)phenylporphyrin (4P1, 4P2c, 4P2t, 4P3 and 4P4) were studied to obtain a comprehensive understanding of factors that influence the binding of cationic porphyrins to liposomes and mitochondria, as well as their photodynamic efficiencies in erythrocytes. Binding and photodynamic efficiency were found to be inversely proportional to the number of positively charged groups and directly proportional to n-octanol/water partition coefficients (log P(OW)), except for the cis molecules 3P2c and 4P2c. In the cis molecules, binding and photodynamic efficiency were much higher than expected, indicating that specific interactions not accounted by log P(OW) enhance photodynamic efficiency. The effect of mitochondrial transmembrane electrochemical potentials on cationic porphyrin binding constants was estimated to be as large as 15%, and may be useful to selectively target this organelle when promoting photodynamic therapy to induce apoptosis.
authors: Instituto de Química, Universidade de São Paulo, C. Postal 26077, CEP 05513-970, São Paulo, Brazil.
authors: Fabio M
authors: FM
authors: Engelmann
authors: Ildemar
authors: I
authors: Mayer
authors: Dino S
authors: DS
authors: Gabrielli
authors: Henrique E
authors: HE
authors: Toma
authors: Alicia J
authors: AJ
authors: Kowaltowski
authors: Koiti
authors: K
authors: Araki
authors: Mauricio S
authors: MS
authors: Baptista
mesh_terms: D020003:1-Octanol / Q000737:chemistry; D000818:Animals; D002412:Cations; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008081:Liposomes / Q000737:chemistry*; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D011166:Porphyrins / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D026082:Singlet Oxygen / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D008081:Liposomes; D017319:Photosensitizing Agents; D011166:Porphyrins; D014867:Water; D026082:Singlet Oxygen; D020003:1-Octanol