PROPOSED STRUCTURE OF THE TUMOR‐LOCALIZING FRACTION OF HPD (HEMATOPORPHYRIN DERIVATIVE)

Abstract

Abstract— Synthesis of the tumor‐localizing preparation HPD (hematoporphyrin derivative) results in the formation of dimers and oligomers of hematoporphyrin joined by labile linkages. Studies with HPD and an HPD analog containing the chlorin analog of mesoporphyrin suggest the presence of two different linkages, either of which yields a tumor‐localizing product. One such linkage is apparently derived from a hematoporphyrin‐based oligomer present in commercial preparations of hematoporphyrin as an impurity. The other linkage is formed during the chemical steps leading to the conversion of hematoporphyrin to “HPD”.