Eckl, Daniel B. and Dengler, Linda and Nemmert, Marina and Eichner, Anja and Baeumler, Wolfgang and Huber, Harald (2018) A Closer Look at Dark Toxicity of the Photosensitizer TMPyP in Bacteria. PHOTOCHEMISTRY AND PHOTOBIOLOGY, 94 (1). pp. 165-172. ISSN 0031-8655, 1751-1097
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Photodynamic inactivation of bacteria (PIB) is based on photosensitizers which absorb light and generate reactive oxygen species (ROS), killing cells via oxidation. PIB is evaluated by comparing viability with and without irradiation, where reduction of viability in the presence of the photosensitizer without irradiation is considered as dark toxicity. This effect is controversially discussed for photosensitizers like TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluensulfonate). TMPyP shows a high absorption coefficient for blue light and a high yield of ROS production, especially singlet oxygen. Escherichia coli and Bacillus atrophaeus were incubated with TMPyP and irradiated with different light sources at low radiant exposures (W per cm(2)), reflecting laboratory conditions of dark toxicity evaluation. Inactivation of E. coli occurs for blue light, while no effect was detectable for wavelengths >450 nm. Being more susceptible toward PIB, growth of B. atrophaeus is even reduced for light with emission >450 nm. Decreasing the light intensities to nW per cm(2) for B. atrophaeus, application of TMPyP still caused bacterial killing. Toxic effects of TMPyP disappeared after addition of histidine, quenching residual ROS. Our experiments demonstrate that the evaluation of dark toxicity of a powerful photosensitizer like TMPyP requires low light intensities and if necessary additional application of substances quenching any residual ROS.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ANTIMICROBIAL PHOTODYNAMIC THERAPY; SINGLET OXYGEN; ESCHERICHIA-COLI; G-QUADRUPLEX; ACINETOBACTER-BAUMANNII; METHYLENE-BLUE; IN-VITRO; INACTIVATION; PORPHYRIN; PHOTOINACTIVATION; |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie > Lehrstuhl für Mikrobiologie > Prof. Dr. Dina Grohmann |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 20 Mar 2020 07:49 |
| Last Modified: | 20 Mar 2020 07:49 |
| URI: | https://pred.uni-regensburg.de/id/eprint/15285 |
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