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Beta-lactam antibiotics under light: optical and photochemical characterization
Renata Salani1, Alessandro Melo Deana1, Silvia Cristina Ñunez2
1Postgraduate Program in Biophotonics-Medicine, Universidade Nove de Julho - UNINOVE, São Paulo, Brazil.
Summary
Beta-lactam antibiotics and light therapies can interact in complex ways. Some antibiotics, like cephalosporins, generate reactive oxygen species, while others, like meropenem, enhance photodynamic therapy, and penicillins may reduce its effectiveness.
Area of Science:
- Photochemistry
- Photobiology
- Pharmacology
Background:
- Antibiotics (ATBs) are crucial for bacterial infections, often used with light therapies like photobiomodulation (PBM) and photodynamic therapy (PDT).
- Potential photochemical interactions between beta-lactam ATBs and light therapies are not well understood, impacting combined treatment efficacy and safety.
Purpose of the Study:
- To characterize optical and photochemical properties of beta-lactam ATBs.
- To assess reactive oxygen species (ROS) generation of ATBs under light exposure.
- To understand interactions between ATBs and photodynamic therapy (PDT) conditions.
Main Methods:
- Diffuse transmittance and reflectance spectroscopy used to calculate Kubelka-Munk absorption and scattering coefficients.
- Reactive oxygen species (ROS) generation assessed under blue light (460 nm) and in PDT-like conditions with methylene blue (MB).
Main Results:
- Cephalosporins generated significant ROS under blue light; penicillins and meropenem did not.
- Meropenem enhanced MB-mediated ROS production and photobleaching, suggesting PDT potentiation.
- Penicillins suppressed MB-driven ROS generation, potentially limiting PDT efficacy; cephalosporins showed varied effects.
Conclusions:
- Beta-lactam ATBs exhibit distinct photobiological behaviors with clinical implications.
- Cephalosporins may act as photosensitizers, meropenem may potentiate PDT, and penicillins may attenuate phototherapy.
- Understanding these interactions is vital for optimizing combined ATB-phototherapy regimens and preventing adverse effects.
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