Photodynamic activity of chloro(5,10,15,20-tetraphenylporphyrinato)indium(III)

Abstract

A atividade fotodinâmica do cloro (5,10,15,20-tetrafenilporfirinato) de índio(III) (InTPP) in vitro foi investigado para possível uso em terapia fotodinâmica (PDT). O rendimento quântico de oxigênio singlete do InTPP (Φ ∆ = 0,72) em DMSO foi maior que da 5,10,15,20-tetrafenilporfirina (TPP) (Φ ∆ = 0,52). Os sítios de ligação entre os fotossensibilizadores e albumina bovina (BSA) são independentes e com células vermelhas de sangue humano (RBC) são cooperativos, com um e quatro sítios de ligação por molécula, respectivamente. As constantes de associação com BSA são (1,15 ± 0,07) × 10 5 e (2,6 ± 0,1) × 10 4 L mol -1 e com RBC são (2,40 ± 0,05) × 10 7 L mol -1 e (7,2 ± 0,2) × 10 4 L mol ) of photosensitizers were used. InTPP was 1.37-1.5 times more effective in the photooxidation of RBC than Photofrin®. Our results indicate that InTPP should be used in future studies of PDT.

Type II photooxidation mechanism of biomolecules using chloro (5,10,15,20-Tetraphenylporphyrinato) indium (III) as a photosensitizer

“…7, 2008 Therefore, InTPP has a high affinity for the erythrocyte membrane due to its lipophilicity. 23 It is thus expected that the InTPP molecules enter into the hydrophobic region of the lipid bilayer together with oxygen molecules where the singlet oxygen will be generated. However, the presence of D 2 O in the photooxidation medium decreased the InTPP affinity for the erythrocytes membrane.…”

“…5 Singlet oxygen quantum yields ( = 0.72) were obtained by laser flash photolysis experiments using pheophorbide-a as a reference. 23 An oxygraph apparatus was used to determine the concentration of oxygen ([O 2 ] = 723.7 0.6 µmol L -1 ) as described earlier.…”

“…Photohemolysis was carried out as described by Silva et al 23 Typically, human blood of a single donor was collected 48 hours before the hemolysis assays in a tube containing EDTA, which was used as an anticoagulant. The tube was kept in a freezer until the moment of use.…”

“…22 Recent studies carried out in our laboratory have shown that the singlet oxygen quantum yield of chloro(5,10,15,20-tetraphenylporphyrinato)indium(III) (InTPP) (Figure 1) in dimethylsulfoxide (DMSO) ( = 0.72) was higher than that of 5,10,15,20-tetraphenylporphyrin (TPP) ( = 0.52) and that InTPP was an excellent photosensitizer in the photooxidation of tryptophan, bovine albumin and erythrocytes. 23 Even with this high value of for InTPP, type I photosensitization pathways cannot be ruled out. 14 This work evaluates the main mechanism (type I or II) that acts in the photooxidation of tryptophan, bovine albumin and erythrocytes using InTPP or if both mechanisms proceed simultaneously in the photooxidation of the biomolecules and the cells.…”

“…5 Singlet oxygen quantum yields ( = 0.72) were obtained by laser flash photolysis experiments using pheophorbide-a as a reference. 23 An oxygraph apparatus was used to determine the concentration of oxygen ([O 2 ] = 723.7 0.6 µmol L -1 ) as described earlier.The remaining constants in Table 1 were obtained from the literature. 24,37 Comparing results with the kinetic model Therefore, a linear relation between k p and [P o ] must be maintained if photooxidations occur by the mechanism suggested in Table 1.…”