Photosensitized oxidation and inactivation of pyocyanin, a virulence factor of Pseudomonas aeruginosa

Krzysztof J. Reszka, Gerene M. Denning, Bradley E. Britigan

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Pyocyanin (PyO-) (1-hydroxy-5-methylphenazine) is a cytotoxic compound secreted by Pseudomonas aeruginosa, an omnipresent bacterium and a human pathogen. We report that visible light illumination in the presence of rose bengal, or riboflavin, in aerated solutions (pH 7.0-7.2) induces irreversible loss of the pigment's characteristic absorption band at 690 nm, indicating its oxidation. This photobleaching was paralleled by generation of a multiline Electron Paramagnetic Resonance (EPR) spectrum attributed to a PyO--derived radical. The reaction was dependent on the presence of air, sensitizers and light, was inhibited by sodium azide and was unaffected by ethanol. This suggests that PyO- was oxidized largely via singlet oxygen and that hydroxyl radicals were not involved. The photochemically modified pigment was less efficient in oxidizing NAD(P)H and generated less superoxide (by ∼50%) than the intact PyO-, indicating its partial inactivation. 1-Methoxy-5-methylphenazine, a PyO- analog in which the -O- moiety was replaced by the methoxy group (-OMe), was resistant to oxidation, suggesting that oxidation of PyO- involves its phenolate moiety. These results also suggest that photosensitization could be a potentially useful method for inactivation of PyO- and, possibly, detoxification of superficial wounds (skin, eye) infected with P. aeruginosa.

Original languageEnglish (US)
Pages (from-to)466-473
Number of pages8
JournalPhotochemistry and Photobiology
Volume82
Issue number2
DOIs
StatePublished - Mar 1 2006

Fingerprint

Pyocyanine
virulence
pseudomonas
Virulence Factors
deactivation
Pseudomonas aeruginosa
pigments
Photobleaching
Photosensitivity Disorders
Rose Bengal
Light
Pigments
Oxidation
Sodium Azide
Singlet Oxygen
oxidation
Riboflavin
Electron Spin Resonance Spectroscopy
Lighting
Superoxides

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

Cite this

Photosensitized oxidation and inactivation of pyocyanin, a virulence factor of Pseudomonas aeruginosa. / Reszka, Krzysztof J.; Denning, Gerene M.; Britigan, Bradley E.

In: Photochemistry and Photobiology, Vol. 82, No. 2, 01.03.2006, p. 466-473.

Research output: Contribution to journalArticle

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