Introducing 2-Thioxocoumarins as a New Class of Photosensitizers for Antimicrobial Photodynamic Therapy
- 1Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Carrer dels Til·lers , ,
- 2Universitat Autònoma de Barcelona (UAB) , , Bellaterra (Cerdanyola del Vallès), ,
Abstract
Antimicrobial photodynamic therapy (aPDT) has gained increasing attention as an alternative approach to combat bacterial resistance, although the development of efficient visible-light photosensitizers (PSs) remains a major challenge. Despite the extensive investigation of coumarin derivatives for photodynamic applications, 2-thioxocoumarins have not previously been explored for aPDT. Herein, we introduce 2-thioxocoumarins as a new class of photosensitizers for aPDT through the rational design and synthesis of four derivatives (TCM-1–TCM-4). Thionation, combined with strategic bromination, modulated the photophysical and photochemical properties of the coumarin scaffold, promoting visible-light absorption and efficient generation of reactive oxygen species (ROS) via both Type I and Type II photochemical pathways. Biological evaluation identified the monobrominated derivative TCM-2 as the lead photosensitizer, exhibiting potent light-induced antibacterial activity against methicillin-sensitive and methicillin-resistant Staphylococcus aureus with minimum inhibitory concentrations of 4–8 μM and no detectable dark toxicity. Although the tribrominated derivatives (TCM-3–TCM-4) exhibited enhanced Type I ROS generation, this was not accompanied by a proportional increase in photodynamic antibacterial activity, highlighting that efficient photodynamic inactivation depends not only on ROS generation but also on molecular properties governing bacterial interactions. These findings establish 2-thioxocoumarins as promising antimicrobial PSs for surface disinfection in healthcare settings and as a valuable molecular scaffold for the development of next-generation antimicrobial photosensitizers.
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BibTeX
@article{ordonezhernandez2026introducing,
title = {{Introducing 2-Thioxocoumarins as a New Class of Photosensitizers for Antimicrobial Photodynamic Therapy}},
author = {Javier Ordóñez-Hernández and Abel Jaume-Masferrer and Jordi Hernando and Marc Martínez-Miguel and Claire Brazzi and Elies Molins and Rosario Núñez},
journal = {ACS Omega},
year = {2026},
month = oct,
doi = {10.1021/acsomega.6c07980},
url = {https://pubs.acs.org/acsodf/article/11/41/63755/5444114/Introducing-2-Thioxocoumarins-as-a-New-Class-of},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Introducing 2-Thioxocoumarins as a New Class of Photosensitizers for Antimicrobial Photodynamic Therapy
AU - Javier Ordóñez-Hernández
AU - Abel Jaume-Masferrer
AU - Jordi Hernando
AU - Marc Martínez-Miguel
AU - Claire Brazzi
AU - Elies Molins
AU - Rosario Núñez
PY - 2026
DA - 2026/10/02
JO - ACS Omega
DO - 10.1021/acsomega.6c07980
UR - https://pubs.acs.org/acsodf/article/11/41/63755/5444114/Introducing-2-Thioxocoumarins-as-a-New-Class-of
AB - Antimicrobial photodynamic therapy (aPDT) has gained increasing attention as an alternative approach to combat bacterial resistance, although the development of efficient visible-light photosensitizers (PSs) remains a major challenge. Despite the extensive investigation of coumarin derivatives for photodynamic applications, 2-thioxocoumarins have not previously been explored for aPDT. Herein, we introduce 2-thioxocoumarins as a new class of photosensitizers for aPDT through the rational design and synthesis of four derivatives (TCM-1–TCM-4). Thionation, combined with strategic bromination, modulated the photophysical and photochemical properties of the coumarin scaffold, promoting visible-light absorption and efficient generation of reactive oxygen species (ROS) via both Type I and Type II photochemical pathways. Biological evaluation identified the monobrominated derivative TCM-2 as the lead photosensitizer, exhibiting potent light-induced antibacterial activity against methicillin-sensitive and methicillin-resistant Staphylococcus aureus with minimum inhibitory concentrations of 4–8 μM and no detectable dark toxicity. Although the tribrominated derivatives (TCM-3–TCM-4) exhibited enhanced Type I ROS generation, this was not accompanied by a proportional increase in photodynamic antibacterial activity, highlighting that efficient photodynamic inactivation depends not only on ROS generation but also on molecular properties governing bacterial interactions. These findings establish 2-thioxocoumarins as promising antimicrobial PSs for surface disinfection in healthcare settings and as a valuable molecular scaffold for the development of next-generation antimicrobial photosensitizers.
SN - 2470-1343
ER -