“Photo-antibiotics” as promising chemotherapeutics
“Photo-antibiotics” as promising chemotherapeutics to target and inactivate (multi)resistant pathogenic bacteria with biomedical and environmental interest.
The photodynamic inactivation (PDI) of microorganisms, which combines a photosensitizer (PS), visible light and oxygen, is considered a valuable alternative to the use of conventional antibiotic approach. While antibiotics act on a specific cellular constituent, such as a key fitting into a lock, PDI, due to the reactive oxygen species formed during the lighting process, acts upon various critical molecular targets. The PS does not need to reach the intracellular compartment, since specific and proper adhesion to the external structures, cytoplasmic membrane and cell wall is adequate for its light-activated destruction even in the drug-resistant bacteria. As a consequence, the probability of resistance development in target microorganisms by blocking uptake, increasing metabolic detoxification or increasing the export of the drug is minimal. No doubt, one of the main advantages of PDI over the common antibiotics is the fact that being a multi-target therapeutic approach no photoresistance has yet been evidenced.
A detailed photophysical and photochemical studies of the interactions between the toxic species generated by the PS and surrounding key biomolecules, were discussed in this article in order to know of how the molecular targets are affected; an important issue to better understanding the photoinactivation process.
We believe that the new studies in this area will guide not only the establishment of improved photoinactivation protocols but also the design of enhanced molecules/materials. We are confident that PS will form the next generation of antibiotics, and PDI will be recognized as a powerful antibacterial protocol.
Article: Almeida A, João T, Amparo A (2015). Photodynamic inactivation of bacteria: finding the effective targets. Future Medicinal Chemistry, 7(10): 1221-1224.