Cytotoxicity of Porphyrin-Based Photosensitizers on Staphylococcus Aureus Cells

Makeda Tekelmichael

Abstract

Bacterial infections remain a significant global health concern with the increase in antimicrobial resistance. In this study, the efficacy of photodynamic therapy (PDT) using porphyrin-based photosensitizers as an alternative approach to target bacterial cells was investigated. The synthesis of a porphyrin-based photosensitizer was attempted through an ester coupling reaction followed by a click reaction. Following the unsuccessful synthesis of this first compound, Tetrakis(4-aminophenyl) porphyrin (TAPP) was obtained for its potential to target the peptidoglycan layer of Gram-positive cells. Staphylococcus cells were selected as the model organism for assessing cell viability. Results revealed a reduction in cell growth when exposed to TAPP under red light conditions, indicative of its cytotoxic effects. S. aureus cells incubated in the dark exhibited sustained cell growth with CFU values in range 9,000 CFU/ml to 121,000 CFU/ml, highlighting the importance of light activation for TAPP's cytotoxic action. This study analyzes the potential of porphyrin-based photosensitizers in photodynamic therapy as a promising avenue for combating bacterial infections, particularly considering the growing challenge of antibiotic resistance. Future work can investigate the efficacy of porphyrin-based photosensitizers, such as TAPP, on multidrug-resistant strains of Staphylococcus aureus and Gram-negative bacteria like Escherichia coli, which could provide valuable insights into their potential as a versatile therapeutic.