DETERMINATION OF THE ACTIVATION SPECTRUM OF ALUMINUM PHTHALOCYANINE CHLORIDE AGAINST CULTURED MENINGIOMA CELLS USING A TUNABLE LASER

The activation spectrum of the photosensitising agent aluminium phthal ocyanine chloride (ClAlPc) was determined using cultured meningioma ce lls as the biological target, Cells were irradiated with tunable laser s over the wavelength range 605-1000 nm and photocytotoxicity was meas ured 24 h later by a tetrazolium assay The photoactivation spectrum wa s found to be relatively narrow with a sharply defined maximum at 675- 680 nm, a readily accessible wavelength for commercially available dio de lasers, The absorption spectrum of ClAlPc in aqueous solution was b road and featureless, contrasting markedly with the activation spectru m, However, as the content of an organic solvent (dimethylsulphoxide) was increased, the absorption spectrum progressively resembled the act ivation spectrum, It is concluded that the absorption spectrum of ClAl Pc in aqueous solution is determined by drug aggregation, which can be prevented by an organic environment. This implies that the active for m of ClAlPc in cells is the monomeric species probably located in cell ular membranes. (C) Pearson Professional 1996