Synthesis of Phthalocyanines-ALA Conjugates: Water-Soluble Compounds with Low Aggregation

Syntheses of two water-soluble phthalocyanines (Pc) containing 5-aminolevulinic acid (ALA) linked to the core structure are described. These compounds were prepared by using original functionalizations, and they present remarkable structural and photophysical features, indicating that they could be applied to photodynamic therapy (PDT).

The importance of protoporphyrin IX efflux for ALA-PDT dosimetry

One of the major advances in PDT is the use of 5-aminolevulinic acid (ALA) to induce the production of an enclogenous photosensitizer inside the cells using intracellular enzymatic pathways. ALA is the first intermediate in heme biosynthesis and a precursor of the protoporphyrin IX (PpIX). When activated by light, this efficient photosensitizer accumulated in the target cells can produce cytotoxicity. The aim of this study was to find the best conditions for cell killing using ALA to temporarily increase the concentration of PpIX in two cell lines. It was shown that a considerable efflux of synthesized PpIX occurs. Since this efflux is time-dependent, it is essential to know the optimum time for irradiation after ALA administration. So, the efflux of PpIX from the cells is an important parameter to be considered for ALA-PDT dosimetry.