Antimicrobial mechanisms behind photodynamic effect in the presence of hydrogen peroxide

Author(s)

Garcez, Aguinaldo Silva ^[1] ; Nunez, Silvia Cristina ^[2] ; Baptista, Mauricio S. ^[3] ; Daghastanli, Nasser Ali ^[4] ; Itri, Rosangela ^[5] ; Hamblin, Michael R. ^{[6, 7, 8]} ; Ribeiro, Martha Simoes ^[9]

Affiliation

^[1] Ctr Pesquisa & Posgrad Sao Leopoldo Mandic, Campinas, SP - Brazil

^[2] Ctr Estudos Treinamento & Aperfeicoamento Odontol, Sao Paulo - Brazil

^[3] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-01498 Sao Paulo - Brazil

^[4] Univ Fed ABC, Santo Andre, SP - Brazil

^[5] Univ Sao Paulo, Inst Fis, Dept Fis Aplicada, BR-01498 Sao Paulo - Brazil

^[6] Massachusetts Gen Hosp, Wellman Ctr Photomed, Boston, MA 02114 - USA

^[7] Harvard Univ, Sch Med, Dept Dermatol, Boston, MA 02115 - USA

^[8] MIT, Harvard Mit Div Hlth Sci & Technol, Cambridge, MA 02139 - USA

^[9] IPEN CNEN SP, Ctr Laser & Aplicacoes, BR-05508000 Sao Paulo - Brazil

• Document type: Journal article
• Source: PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES; v. 10, n. 4, p. 483-490, 2011.
• Web of Science Citations: 19

Abstract

This study describes the use of methylene blue (MB) plus light (photodynamic inactivation, PDI) in the presence of hydrogen peroxide (H(2)O(2)) to kill Staphylococcus aureus, Escherichia coli, and Candida albicans. When H(2)O(2) was added to MB plus light there was an increased antimicrobial effect, which could be due to a change in the type of ROS generated or increased microbial uptake of MB. To clarify the mechanism, the production of ROS was investigated in the presence and absence of H(2)O(2). It was observed that ROS production was almost inhibited by the presence of H(2)O(2) when cells were not present. In addition, experiments using different sequence combinations of MB and H(2)O(2) were performed and MB optical properties inside the cell were analyzed. Spectroscopy experiments suggested that the amount of MB was higher inside the cells when H(2)O(2) was used before or simultaneously with PDI, and ROS formation inside C. albicans cells confirmed that ROS production is higher in the presence of H(2)O(2). Moreover enzymatic reduction of MB by E. coli during photosensitizer uptake to the photochemically inactive leucoMB could be reversed by the oxidative effects of hydrogen peroxide, increasing ROS formation inside the microorganism. Therefore, the combination of a photosensitizer such as MB and H(2)O(2) is an interesting approach to improve PDI efficiency. (AU)

• FAPESP's process: 05/51598-7 - Photodynamic therapy: physical, biochemical and clinical aspects
• Grantee: Mauricio da Silva Baptista
• Support Opportunities: Research Projects - Thematic Grants