Mechanism of action of 4-hydroxymethyl-1,6,8-trimethylfuro[2,3-h]quinolin-2(1H)-one, a very active angular furocoumarin-like sensitizer

Photochem Photobiol. 2005 Nov-Dec;81(6):1371-9. doi: 10.1562/2005-01-13-RA-413.

Abstract

The molecular structure of 1,4,6,8-tetramethylfuro[2,3-h]quinolin-2(1H)-one (FQ), a recent furocoumarin-like photosensitizer, has been modified with the aim of reducing its strong genotoxicity, by replacing the methyl group at 4 position with a hydroxymethyl one, and so obtaining 4-hydroxymethyl-1,6,8-trimethylfuro[2,3-h]quinolin-2(1H)-one (HOFQ). This modification gave rise to a strong reduction of lipophilicity and dark interaction with DNA. The formation of monoadducts (MA) was deeply affected, whereas the induction of bifunctional adducts between DNA and proteins (DPC(L>0)) was replaced by an efficient production of DNA-protein cross-links at zero length (DPC(L=0)), probably via guanine damage. Because of its angular molecular structure, HOFQ does not form interstrand cross-links (ISC): therefore, DPC(L=0) and MA represent the main lesions induced by HOFQ in DNA. In comparison with FQ (which induces MA and DPC(L>0)) and 8-methoxypsoralen (8-MOP) (MA, ISC, DPC(L>0)), HOFQ seems to be a more selective agent. In fact, contrary to FQ and 8-MOP, HOFQ, together with a noticeable antiproliferative activity, shows low levels of point mutations in bacteria and of clastogenic effects in mammalian cells. HOFQ is also an efficient apoptosis inducer, especially in comparison with 8-MOP, when tested at equitoxic experimental conditions; this property might be correlated with the complete HOFQ inability of inducing skin erythemas, a well-known side effect of classic furocoumarin photosensitization.

MeSH terms

  • Animals
  • Cell Line
  • Cell Proliferation
  • DNA / metabolism
  • DNA-Binding Proteins / metabolism
  • Furans / chemistry*
  • Furans / pharmacology
  • Furocoumarins / chemistry*
  • Furocoumarins / metabolism
  • Furocoumarins / pharmacology
  • Humans
  • Light
  • Molecular Structure
  • Photosensitizing Agents / chemistry*
  • Photosensitizing Agents / metabolism
  • Photosensitizing Agents / pharmacology
  • Quinolones / chemistry*
  • Quinolones / pharmacology
  • Reactive Oxygen Species / metabolism
  • Ultraviolet Rays*

Substances

  • 4-hydroxymethyl-1,6,8-trimethylfuro(2,3-h)quinolin-2(1H)-one
  • DNA-Binding Proteins
  • Furans
  • Furocoumarins
  • Photosensitizing Agents
  • Quinolones
  • Reactive Oxygen Species
  • DNA