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Quenching of singlet oxygen by pyocyanin and related phenazines

Krzysztof J Reszka1, Piotr J Bilski, Bradley E Britigan

  • 1Research Service and Medical Service, VA Medical Center, Cincinnati, OH, USA. reszkakj@ucmail.uc.edu

Photochemistry and Photobiology
|April 23, 2010
PubMed

Insights

Pyocyanin, a virulence factor from Pseudomonas aeruginosa, is oxidized by singlet oxygen. This interaction, studied using time-resolved techniques, suggests potential for photochemically targeting bacterial infections.

Area of Science:

  • Photochemistry
  • Microbiology
  • Biochemistry

Background:

  • Pseudomonas aeruginosa is a significant human pathogen causing opportunistic infections.
  • Pyocyanin, a cytotoxic pigment produced by P. aeruginosa, contributes to its virulence.
  • Previous studies indicated photosensitized oxidation of pyocyanin, with singlet oxygen as a likely oxidant.

Purpose of the Study:

  • To investigate the direct interaction of pyocyanin and related phenazines with singlet oxygen ((1)O(2)).
  • To quantify the rate constants for singlet oxygen quenching by these compounds.
  • To assess the potential of phenazines to photogenerate singlet oxygen.

Main Methods:

  • Utilized time-resolved spectroscopy to study the interaction of phenazines with singlet oxygen.
  • Determined rate constants for singlet oxygen quenching by pyocyanin and 1-hydroxyphenazine in D(2)O buffer.
  • Measured the singlet oxygen quantum yield for phenazine methosulfate in acetonitrile.

Main Results:

  • Pyocyanin and 1-hydroxyphenazine are efficient singlet oxygen quenchers, with rate constants of 4.8 x 10(8) M(-1)s(-1) and 6.8 x 10(8) M(-1)s(-1), respectively.
  • 1-methoxy-5-methylphenazine and phenazine methosulfate showed markedly lower singlet oxygen quenching efficiency.
  • Phenazine methosulfate was found to photogenerate singlet oxygen with a quantum yield of 0.56.

Conclusions:

  • The interaction of singlet oxygen with bacterial phenazines, particularly pyocyanin, is significant.
  • These findings support the potential utility of photochemical approaches for eradicating P. aeruginosa.
  • Further research into photodynamic therapies targeting P. aeruginosa infections is warranted.

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