Molecular characteristics of the photosensitizer TONS504: Comparison of its singlet oxygen quantum yields and photodynamic antimicrobial effect with those of methylene blue.

Abstract

TONS504 (C51H58O5I2) is a chlorin derivative that exhibits a photodynamic antimicrobial effect (PAE) on various infectious keratitis pathogens. However, the molecular characteristics of TONS504 are not well understood. This study aimed to investigate the molecular characteristics of TONS504 by comparing its singlet oxygen (1O2) quantum yields and PAE with those of methylene blue (MB). To measure the 1O2 quantum yields, TONS504 and MB were dissolved in phosphate-buffered saline and phosphate-buffered saline containing 1% Triton X-100. The solutions were then activated by a Nd:YAG laser with an average output power of 8 mW. Near-infrared 1O2 luminescence was detected as an indicator of the 1O2 quantum yields. To evaluate the PAE, TONS504 and MB were activated by a light-emitting diode with a total light energy of 30 J/cm2. We compared the minimum molar concentration of each photosensitizer to show apparent PAEs on Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. TONS504 exhibited higher 1O2 quantum yields than MB in PBS/Triton X-100 but not in PBS. S. aureus and C. albicans were reduced by TONS504 at lower concentrations than by MB, but this was not the case for P. aeruginosa. Our results provide insight on the molecular characteristics of TONS504 and suggest that TONS504 has excellent 1O2 quantum yields and PAE. Compared with MB, TONS504 in PBS has stronger efficacy toward some infectious keratitis pathogens but not others.

• Authors: Koichiro Shinji, Taiichiro Chikama, Shigetoshi Okazaki, Yoshihiro Uto, Kentaro Sueoka, Yunialthy Dwia Pertiwi, Ji-Ae Ko, Yoshiaki Kiuchi, Takemasa Sakaguchi
• Journal: Journal of photochemistry and photobiology. B, Biology (J Photochem Photobiol B) Vol. 221 Pg. 112239 (Aug 2021) ISSN: 1873-2682 [Electronic] Switzerland
• PMID: 34116319 (Publication Type: Journal Article)
• Copyright: Copyright © 2021 Elsevier B.V. All rights reserved.

Chemical References

• Photosensitizing Agents
• Porphyrins
• TONS504
• Singlet Oxygen
• Methylene Blue

Topics

• Candida albicans (drug effects)
• Light
• Methylene Blue (chemistry, pharmacology)
• Microbial Sensitivity Tests
• Photosensitizing Agents (chemistry, pharmacology)
• Porphyrins (chemistry, pharmacology)
• Pseudomonas aeruginosa (drug effects)
• Singlet Oxygen (chemistry, metabolism)
• Staphylococcus aureus (drug effects)