Bacterial and Yeast Cells as Models for Studying Hematoporphyrin Photosensitization

Abstract

The photodynamic action of porphyrins has been mainly studied with eucaryotic cells or cells in a multicellular organism^1–3. These cells represent a complex experimental model owing to the variety of potential binding sites for the sensitizing dyes; in the case of porphyrins, the precise subcellular location is still largely unknown, although it appears to depend on the porphyrin dose and the incubation time⁴. As a consequence, the main cellular targets involved in the photoprocess have not been identified as yet. For these reasons we are studying the photodynamic action of hematoporphyrin (HP) using bacteria and yeast cells⁵. Procaryotic cells were chosen for their simple structural organization and absence of endomembrane systems; moreover, they represent easily reproducible experimental models. Our investigations have been carried out on several strains for each species of microorganism (see table 1) in order to detect whether the effect of the photoprocess is typical of the strain or the species.