Modulation of the catalytic activity of porphyrins by lipid-and surfactant-containing nanostructures

Abstract

Fatores estruturais que modulam a atividade das porfirinas englobam os ligantes equatoriais, o metal central e o número e estrutura dos seus ligantes axiais. A esses fatores se associam o microambiente fornecido por apoproteínas, solventes e membranas. Porfirinas são bastante utilizadas para a construção de estruturas supramoleculares com diferentes aplicações. A modulação da atividade das porfirinas tem sido freqüentemente obtida pela imitação da natureza, ou seja, fornecimento de diferentes microambientes. A associação das porfirinas a nanoestruturas lipídicas pode mudar a atividade destes compostos de tal forma a mimetizar diferentes enzimas como a SOD, citocromo P450, peroxidases e outros. As formas reativas das porfirinas são estados de alta valência: metal-oxo-p cátion e metal-oxo produzidos pela reação com peróxidos e perácidos. A modulação da atividade de porfirinas por nanoestruturas lipídicas também tem sido obtida para hemeproteínas uma vez que nanoestruturas lipídicas afetam a conformação das proteínas. The structural factors modulating porphyrin activity encompass pyrrole and equatorial ligands, as well as the central metal and the number and structure of their axial ligands. Of equal importance is the microenvironment provided by apoproteins, solvents and membranes. Porphyrins are often used to construct supramolecular structures with different applications. The modulation of activity of the porphyrins has been frequently achieved by mimicking nature, i.e., by the provision of different microenvironments for these molecules. The association of porphyrins to surfactant-and lipid-containing nanostructures has changed the activity of these compounds to mimic different enzymes such as SOD, cytochrome P450, peroxidases and others. In determined conditions, the reactive forms of the porphyrins are high-valence states of oxo-metal-p cations and oxo-metal produced by the reaction with peroxides and peracids. The modulation of porphyrin activity by surfactant-and lipid-containing nanostructures has also been achieved for hemeproteins, as the lipid nanostructures affect the conformation of proteins.

Photophysical properties of porphyrin derivatives: Influence of the alkyl chains in homogeneous and micro-heterogeneous systems

“…Porphyrins and their derivatives, due to their interesting photophysical, photochemical and electrochemical properties [3,4], as well as their ability to be accumulated in tissues of rapid growth as the tumor tissue [5,6], in recent years have aroused great interest as drugs in PDT [7][8][9][10][11][12]. A typical example is the Photophrin ® , a commercial PS consisting basically of porphyrin derivatives, whose use is approved by the FDA, the regulatory authority in the United States [13,14].…”

“…However, a drawback concerning the applications of porphyrins in biological environment is the formation of aggregates in aqueous media, due to p-p* interactions and the hydrophobicity of these compounds [7,15]. This feature affects the ability of porphyrins to be used as photoactive principle in PS biologically friendly [16].…”

“…To minimize this problem, many groups have studied the association of porphyrins with models of micellar systems, polymeric nanoparticles, dendrimers and liposomes [7,17,18], in order to investigate the interactions between photosensitizers and potential carriers of drugs, since the aforementioned micro-heterogeneous systems can mimic biological systems, e.g. plasma membranes and biological tissues [19,20].…”

“…plasma membranes and biological tissues [19,20]. The transport of porphyrins in biological medium through micro-heterogeneous systems has been considered an interesting alternative to enabling the delivery of the PS [7,18]. Thus, it is necessary to evaluate prototypes of the associations of porphyrinmicro-heterogeneous systems before developing efficient tests in vivo, so that the most suitable candidates to a set of tests on animals can be known beforehand.…”

Interaction and Reaction of the Antioxidant Mn^III [Meso-Tetrakis(4-NMethyI Pyridinium) Porphyrin] with the Apoptosis Reporter Lipid Phosphatidylserine

“…These studies are particularly important because the micro-environmental conditions of cells can shift more or less favorably the desirable antioxidant properties of porphyrins. Due to the close relation of the mitochondria with cell life and death events, several studies have been concerned with the interaction of metallo meso-tetrakis cationic porphyrins with mitochondria and membrane models of the organelle [39][40][41]. Recently, the glutathione peroxidase (GPx), superoxide dismutase (SOD) and cytochrome c-like antioxidant activities of para Mn III TMPyP in isolated rat liver mitochondria (RLM) and mitoplasts have been reported [42].…”