Investigação do potencial de inativação fotodinâmica de compostos porfirínicos (3PtTPyP e 4PtTPyP) contra Aspergillus flavus

Abstract

Photoinactivation therapy or antimicrobial photodynamic therapy (aPDT) is na alternative technique to treatments against microorganisms and with great potential for expanding its applications. In aPDT, the combination of three important elements induces cell death: light, photosensitizer and oxygen. The photosensitizer absorbs light and is excited, interacting with oxygen molecules and producing reactive species of this molecule, such as singlet oxygen, a highly oxidizing and reactive species that can react with various targets in the microbial cell, such as nucleic acids, proteins and lipids. First, the incorporation experiment was carried out, preparing samples (Aspergillus flavus incubated with 100 μM of porphyrin in liquid culture medium) and blanks (A. flavus incubated without porphyrin in liquid culture medium) in triplicate for each porphyrin photosensitizer (3PtTPyP and 4PtTPyP); after incubation and washing, the reading was carried out in a spectrophotometer. With the readings, it was observed that 3PtTPyP porphyrin was more absorbed by the fungus compared to 4PtTPyP. After verifying the incorporation, the experiment of viability test of A. flavus incorporated with the photosensitizer and light incidence was carried out; after irradiation, the growth of the fungus mycelium was measured for 4 days. Subsequently, the mycelial growth velocity index (IVCM) and mycelial growth index (ICM) were calculated and statistical analyzes were performed. It was found that the porphyrin 4PtTPyP o did not present a significant photoinactivation capacity at any of the doses studied (10 J/cm2 and 50 J/cm2). On the other hand, 3PtTPyP porphyrin showed a higher and more significant photodynamic inactivation capacity (p<0.05) at a dose of 50 J/cm2 . Furthermore, light and the photosensitizer alone do not cause significant effects on the IVCM and ICM of the fungus