Intracellular and in vivo Composition of Hematoporphyrin Derivative by Various Fluorescent Components

Due to a coincidence of tumor-localizing, fluorescent and photosensitizing properties, hematoporphyrin derivative (Hpd) and a purified version Photofrin II (containing mainly dihematoporphyrin ether or ester, DHE, with a large amount of aggregated compounds) are used for detection and photodynamic therapy of cancer /1/. Tumor localization and photo-sensitization, however, are attributed to different components of the porphyrin mixtures Hpd or Photofrin II. Dimeric and aggregated species were reported to be the main tumor localizers /1,2/, whereas the monomeric and dimeric components have the best photosensitizing properties /3/. Fluorescence is most pronounced for the monomeric species hematoporphyrin, hydroxyethyl-vinyldeutero-porphyrin and protoporphyrin /4/, less efficient by one order of magnitude for DHE, and very low for aggregated compounds.