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Effects on Gram-Negative and Gram-Positive Bacteria Mediated by 5-Aminolevulinic Acid and 5-Aminolevulinic Acid Derivatives

  • Fotinos, Nicolas Department of Pharmaceutics and Biopharmaceutics, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, 30 Quai Ernest Ansermet, Geneva 1211, Switzerland
  • Convert, Maruska Institute of Microbiology, Via Mirasole 22A, Bellinzona 6500, Switzerland
  • Piffaretti, Jean-Claude Institute of Microbiology, Via Mirasole 22A, Bellinzona 6500, Switzerland
  • Gurny, Robert Department of Pharmaceutics and Biopharmaceutics, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, 30 Quai Ernest Ansermet, Geneva 1211, Switzerland
  • Lange, Norbert Department of Pharmaceutics and Biopharmaceutics, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, 30 Quai Ernest Ansermet, Geneva 1211, Switzerland
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  • Antimicrobial Agents and Chemotherapy. - American Society for Microbiology. - 2008, vol. 52, no. 4, p. 1366-1373
Pharmacology (medical)
Pharmacology
Infectious Diseases
English ABSTRACT
Due mainly to the extensive use of antibiotics, the spread of multiresistant bacterial strains is one of the most worrying threats to public health. One strategy that can be used to overcome potential shortcomings might be the inactivation of these microorganisms by 5-aminolevulinic acid (5-ALA) or 5-ALA derivative-mediated photodynamic therapy (PDT). 5-ALA has no photoactive properties, but when it is given exogenously, it acts as a precursor of photosensitive porphyrins predominantly in tissues or organisms that are characterized by a high metabolic turnover, such as tumors, macrophages, and bacteria. However, the weak ability of 5-ALA to cross biological barriers has led to the introduction of more lipophilic derivatives, such as methyl aminolevulinate or hexyl aminolevulinate, which display improved capacities to reach the cytoplasm. Starting from the hypothesis that more lipophilic compounds carrying only a permanent positive charge under physiological conditions may more easily cross the bacterial multilayer barrier, we have tested the efficacies of some 5-ALA n-alkyl esters for the inactivation of bacteria. For this purpose, different bacterial strains were incubated with 5-ALA or its corresponding esters of different lipophilicities. Then, the bacteria were irradiated with light and the numbers of CFU post-PDT were counted and compared to those for the controls, which were kept in the dark. Furthermore, the total amount of accumulated porphyrins was quantified by high-pressure liquid chromatography analysis. In our studies, analysis of the bacterial extracts revealed the presence of all the porphyrins involved in heme biosynthesis, from uroporphyrin to protoporphyin IX. The efficacy of bacterial inactivation was a function of the total amount of porphyrins produced, independently of their nature. The 5-ALA methyl and butyl esters were the most effective compounds with respect to the photodynamic inactivation of bacteria. We observed significant differences in terms of the optimal drug concentration, bactericidal activities, and porphyrin production.
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  • English
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bronze
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https://sonar.ch/global/documents/23466
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