Photodynamic Inactivation of Antibiotic-Resistant and Sensitive Aeromonas hydrophila with Peripheral Pd(II)- vs. Zn(II)-Phthalocyanines.

Vanya N Mantareva,Petya Orozova,Ivan Angelov,Lyudmila Dimitrova,Hristo Najdenski,Mahmut Durmus,Vesselin Kussovski,Irem Kulu

doi:10.3390/biomedicines10020384

Abstract

The antimicrobial multidrug resistance (AMR) of pathogenic bacteria towards currently used antibiotics has a remarkable impact on the quality and prolongation of human lives. An effective strategy to fight AMR is the method PhotoDynamic Therapy (PDT). PDT is based on a joint action of a photosensitizer, oxygen, and light within a specific spectrum. This results in the generation of singlet oxygen and other reactive oxygen species that can inactivate the pathogenic cells without further regrowth. This study presents the efficacy of a new Pd(II)- versus Zn(II)-phthalocyanine complexes with peripheral positions of methylpyridiloxy substitution groups (pPdPc and ZnPcMe) towards Gram-negative bacteria Aeromonas hydrophila (A. hydrophila). Zn(II)-phthalocyanine, ZnPcMe was used as a reference compound for in vitro studies, bacause it is well-known with a high photodynamic inactivation ability for different pathogenic microorganisms. The studied new isolates of A. hydrophila were antibiotic-resistant (R) and sensitive (S) strains. The photoinactivation results showed a full effect with 8 µM pPdPc for S strain and with 5 µM ZnPcMe for both R and S strains. Comparison between both new isolates of A. hydrophila (S and R) suggests that the uptakes and more likely photoinactivation efficacy of the applied phthalocyanines are independent of the drug sensitivity of the studied strains.

Highlights

IntroductionZn(II)-phthalocyanine, zinc phthalocyanine complex (ZnPcMe) was used as a reference compound for in vitro studies, bacause it is well-known with a high photodynamic inactivation ability for different pathogenic microorganisms
Palladium and zinc phthalocyanine complexes with peripheral methylpyridiloxy substitution groups were synthesized according the Refs [22,23]
This study suggests that both phthalocyanines, which differ in the coordinated metal ions palladium and zinc (ZnPcMe), have comparable and slightly higher photoinactivation efficacy for zinc phthalocyanine complex (ZnPcMe)

Summary

Introduction

Zn(II)-phthalocyanine, ZnPcMe was used as a reference compound for in vitro studies, bacause it is well-known with a high photodynamic inactivation ability for different pathogenic microorganisms. The studied new isolates of A. hydrophila were antibiotic-resistant (R) and sensitive (S) strains. The photoinactivation results showed a full effect with 8 μM pPdPc for S strain and with 5 μM ZnPcMe for both R and S strains. Comparison between both new isolates of A. hydrophila (S and R) suggests that the uptakes and more likely photoinactivation efficacy of the applied phthalocyanines are independent of the drug sensitivity of the studied strains.

Methods

Results

Discussion

Conclusion