Combined effects of singlet oxygen and hydroxyl radical in photodynamic therapy with photostable bacteriochlorins: evidence from intracellular fluorescence and increased photodynamic efficacy in vitro

Free Radic Biol Med. 2012 Apr 1;52(7):1188-200. doi: 10.1016/j.freeradbiomed.2011.12.027. Epub 2012 Jan 14.


Sulfonamides of halogenated bacteriochlorins bearing Cl or F substituents in the ortho positions of the phenyl rings have adequate properties for photodynamic therapy, including strong absorption in the near-infrared (λ(max) ≈ 750 nm, ε ≈ 10(5) M(-1) cm(-1)), controlled photodecomposition, large cellular uptake, intracellular localization in the endoplasmic reticulum, low cytotoxicity, and high phototoxicity against A549 and S91 cells. The roles of type I and type II photochemical processes are assessed by singlet oxygen luminescence and intracellular hydroxyl radical detection. Phototoxicity of halogenated sulfonamide bacteriochlorins does not correlate with singlet oxygen quantum yields and must be mediated both by electron transfer (superoxide ion, hydroxyl radicals) and by energy transfer (singlet oxygen). The photodynamic efficacy is enhanced when cellular death is induced by both singlet oxygen and hydroxyl radicals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / therapy
  • Antioxidants / pharmacology
  • Ascorbic Acid / pharmacology
  • Cell Survival / drug effects
  • Energy Transfer
  • Fluorescence
  • Humans
  • Hydroxyl Radical / pharmacology*
  • In Vitro Techniques
  • Lung Neoplasms / therapy*
  • Melanoma / therapy*
  • Photochemotherapy*
  • Photosensitizing Agents / pharmacology*
  • Porphyrins / chemistry*
  • Reactive Oxygen Species / metabolism
  • Singlet Oxygen / pharmacology*
  • Tumor Cells, Cultured


  • Antioxidants
  • Photosensitizing Agents
  • Porphyrins
  • Reactive Oxygen Species
  • bacteriochlorin
  • Singlet Oxygen
  • Hydroxyl Radical
  • Ascorbic Acid