ANTIBACTERIAL PHOTODYNAMIC THERAPY OF CHITOSAN AND METALATED PORPHYRIN COMPLEXES ON MULTIDRUG-RESISTANT BACTERIA
Abstract
ABSTRACT
The search for novel antimicrobial agents has increased due to the continuous invasion of traditional antibiotic treatments by multidrug-resistant (MDR) pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter baumanii, Klebsiella pneumoniae and Enterococcus sp. One innovative approach is antibacterial photodynamic therapy (aPDT), which harnesses light-activated compounds to produce cytotoxic reactive oxygen species capable of inactivating bacteria without fostering tolerance. This study aimed to investigate the effectiveness of aPDT approach using chitosan-modified porphyrin complexes (such as tetraphenylporphyrin(TPP), meso-tetra(4-sulfonatophenyl) porphyrin(TPPS), meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP), meso-tetra(4-hydroxyphenyl)porphyrin (THPP), meso-tetrakis(N-methyl-4pyridyl)porphyrin (TMPyP), and meso-tetrakis(4-methoxyphenyl)porphyrin (TMePP) and their derivatives (silver (Ag); Zinc (Zn) and Tin (Sn) against MDR organisms. In this study, the antimicrobial activity of previously synthesized chitosan metalated porphyrins and was assessed against multidrug-resistant bacteria (S. aureus, A. baumanii, K. pneumoniae, P. aeruginosa and Enterococcus sp.) using the agar well diffusion method. The seeded plates were incubated at 37 ℃ for 24 hours, and afterwards the zone of inhibition was measured (in mm). For this experiment, C-AgTPP inhibited S. aureus (15mm), C-ZnTPPS inhibited S. aureus (19mm) and A. baumanii (16mm). K. Pneumoniae was inhibited by C-AgTHPP (13mm), C-ZnTHPP (18mm) and C-SnTHPP (16.5mm). C-AgTMePP inhibited P. aeruginosa1 (35.5mm), P. aeruginosa2 (30mm), A. baumanii (29.5mm), K. pneumoniae (26.5mm), Enterococcus sp. (29.5mm) and S. aureus (20.5mm). C-AgTMPyP inhibited P. aeruginosa1 (22.5mm), P. aeruginosa2 (22.5mm), A. baumanii (24mm), K pneumoniae (25.5mm), Enterococcus sp. (26.5mm) and S. aureus (17.5mm). The findings demonstrate that chitosan metalated porphyrin complexes are potential photosensitizers against the selected MDR bacteria, combining biocompatibility with strong phototoxic activity. Their mechanism offers an alternative therapeutic route that bypasses the conventional antibiotic resistance pathway. In conclusion, the aPDT approach using chitosan metalated porphyrin complex is a viable and effective treatment modality for combating infections caused by multidrug-resistant bacteria.
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