Photodynamic action of some sensitizers by photooxidation of luminol

Naturwissenschaften. 2002 Oct;89(10):466-9. doi: 10.1007/s00114-002-0357-4. Epub 2002 Sep 6.


We report the development of a novel simple experimental method which allows the comparison of new photosensitizers based on their production of reactive oxygen species. A high-performance liquid chromatography (HPLC) assay permits the monitoring of several substances (sensitizer, reactant and oxidized end product) simultaneously on a single chromatogram. Photoreactions were monitored throughout their course by the HPLC assay surveying the sensitizers' efficiency of singlet oxygen production by the oxidative decomposition of luminol. Several photosensitizers were tested: Rose Bengal, Methylene Blue, Protoporphyrin IX, Photosan III, Photofrin, Hypericin and Pseudohypericin. Additionally, photoreactions were monitored by a standard pO(2) detection system. The measurements of the two detection methods were strongly correlated. Rose Bengal proved to be the most efficient photosensitizer, clearly decreasing the luminol concentration and causing a corresponding increase in aminophthalic acid. Our experiments show that when factors necessary for photochemical reactions are absent or are blocked (antioxidants), no reaction can be detected.

MeSH terms

  • Dihematoporphyrin Ether / chemistry
  • Drug Stability
  • Luminol / chemistry*
  • Methylene Blue / chemistry
  • Oxidation-Reduction
  • Photosensitizing Agents / chemistry*
  • Rose Bengal / chemistry
  • Solvents


  • Photosensitizing Agents
  • Solvents
  • Rose Bengal
  • Luminol
  • Dihematoporphyrin Ether
  • Methylene Blue