Comparative effect of ALA derivatives on protoporphyrin IX production in human and rat skin organ cultures

CASAS, A.; DEL C BATLLE, A.M.; BUTLER, A.R.; ROBERTSON, D.; BROWN, E.H.; MACROBERT, A.; RILEY, P.A.

BRITISH JOURNAL OF CANCER

NATURE PUBLISHING GROUP

Año: 1999 vol. 80 p. 1525 - 1532

0007-0920

Samples of human and rat skin in short-term organ culture exposed to ALA or a range of hydrophobic derivatives were examined for their effect on the accumulation of protoporphyrin IX (PpIX) measured using fluorescence spectroscopy. With the exception of carbobenzoyloxy-D-phenylalanyl-5-ALA-ethyl ester the data presented indicate that, in normal tissues, ALA derivatives generate protoporphyrin IX more slowly than ALA, suggesting that they are less rapidly taken up and/or converted to free ALA. However, the resultant depot effect may lead to the enhanced accumulation of porphyrin over long exposure periods, particularly in the case of ALA-methyl ester or ALA-hexyl ester, depending on the applied concentration and the exposed tissue. Addition of the iron chelator, CP94, greatly increased PpIX accumulation in human skin exposed to ALA, ALA-methyl ester and ALA-hexyl ester. The effect in rat skin was less marked.