ABSTRACT
Information on toxicity of new sensitizers is seldom available. But the complexity of hematoporphyrin derivative (HPD), which has been troublesome in some respects, serves to simplify certain aspects of drug development, since no component of this mixture poses a toxic hazard to patients. In the field of photodynamic therapy, drug development has been hampered by the lack of sufficient clinical experience with new sensitizers. Therefore, a search among the components of HPD for more active agents with fewer adverse reactions appears justified. HPD contains hematoporphyrin (HP) and HP dehydration products, along with porphyrins joined by ether and ester linkages. To facilitate an unambiguous examination of ether-linked HPD components, we prepared di- and triporphyrins joined by ether linkages and bearing different peripheral substituents. Spectral properties of porphyrin monomers along with di- and tri-porphyrin ethers were assessed in protic and aprotic solvents. To facilitate studies in a variety of solvents, both methyl esters and free acids were employed.
