Identification of porphyrin modified photosensitizer porfimer sodium and its precursors by high performance liquid chromatography and mass spectrometry.

Photodit (porfimer sodium) is a complex mixture of porphyrin-modified oligomers that has demonstrated high photoactivity during photodynamic therapy of malignant tumors. Hematoporphyrin derivative monomer precursors of Photodit and its oligomers were analyzed using liquid chromatography and mass spectrometry to determine their chemical composition and structures. Hematoporphyrin (M-3), O,O'-diacetylhematoporphyrin (M-6), and isomers of 8(-3)-hydroxyethyl-3(-8)-vinyldeuteroporphyrin (M-2), 8(-3)-(1-acetoxyethyl)-3(-8)-vinyldeuteroporphyrin (M-4), and O-acetylhematoporphyrin (M-5), in ratio 0.59:0.94:0.21:0.34:1.00, were identified as hematoporphyrin derivative monomer precursors. The main compounds of Photodit as a porfimer sodium salt were dimers: D-1 [di-[8(-3)-hydroxyethyl-3(-8)-vinyldeuteroporphyrin] ether], D-2 [[Hematoporphyrin-8(-3)-hydroxyethyl-3(-8)-vinyldeutroporphyrin] ether], and D-3 [Dihematoporphyrin ether] in ratio 0.51:1.00:0.50, and trimers: T-1 [(M-2)-(D-2) ether], T-2 [(D-2)-(M-3) ether], and T-3 [(D-3)-(M-3) ether] in ratio 0.98:1.00:0.44, respectively. An average oligomer length of 2.23 porphyrin units was determined.