Análise comparativa da eficiência fotodinâmica de fotossensibilizadores em sua forma base livre e formando complexados com zinco
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2014-04-09
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Universidade Federal de Goiás
Resumo
Photodynamic therapy (PDT) is a technique that has been increasingly used in
cancer treatment. It consists in introduce a photosensitizer (PS) in cancerous tissue and
irradiate it with light in the visible range. Targeting a more effective treatment of PDT,
currently there are several studies on the efficacy of these PS. In this work, we studied
the photodynamic efficiency seven PS: meso-tetrametilpiridil, meso-tetrasulfonatofenil
and carboxiftalocianinas with their base free or metallated with zinc atom in its center
ring and protoporphyrin IX. Erythrocytes suspended in 2 to 10% hematocrit were
treated with or without 25 μM of PS were exposed to light from a halogen lamp, and
measured the time required to obtain 50 % hemolysis (T1/2). To examine whether the
photodynamic efficiency is related to the affinity of PS by membrane, we performed
measurements of the octanol/water partition coefficient (PO/W) of each PS. Our results
indicated that the PS studied were very hydrophilic and showed a trend for greater
photodynamic efficiency the PS with higher Log PO/W. To better understand the
mechanism of action of the studied PS the degree of lipid peroxidation in erythrocyte
membranes irradiated with PS was assessed by measuring the formation of
malondialdehyde (MDA) and a correlation between the rate of peroxidation and
hemolytic potential was found. The ability of PS to degrade proteins was assessed using
bovine serum albumin (BSA), monitoring the fluorescent signal of this protein into
solution and under irradiation in the presence of PS.
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ALONSO, Lais. Análise comparativa da eficiência fotodinâmica de fotossensibilizadores em sua forma base livre e formando complexados com zinco. 2014. 59 f. Dissertação (Mestrado em Física) - Universidade Federal de Goiás, Goiânia, 2014.