Fast atom bombardment mass spectral analyses of Photofrin II^® and its synthetic analogs

Fast atom bombardment (FAB) mass spectroscopy was used to characterize the components of Photofrin II^®. The data indicate that the oligomeric components of Photofrin II^® contain up to nine porphyrin units. In order to elucidate the nature of covalent linkages between porphyrin units, Photofrin II^® methyl ester and a porphyrin derivative‐2 (2A) were synthesized and characterized by FAB mass spectroscopy. Model studies were also performed by analyzing possible components of Photofrin II^®, namely, porphyrin dimers 3, 4, 5, 6 and trimer 7 with ether or ester linkages. The higher porphyrin oligomers joined by only ether linkages were also synthesized and characterized by FAB mass spectroscopy. The model studies indicate that the porphyrin units in Photofrin II^® are linked with ether or ether/ester linkages.