Photophysical and photobiological activities of a porphyrin peptide fraction derived from haemoglobin.
In a previous study, we described the preparation of a porphyrin peptide hydrolysate from haemoglobin, its isolation and its analysis by high performance liquid chromatography (HPLC) and fast atom bombardment (FAB) mass spectrometry. The purpose of the present paper is to test the photosensitizing activity of this fraction. We determined the singlet oxygen quantum yield (phi delta) in order to quantify the efficiency of the porphyrin peptide fraction. The quantum yield is about phi(1O2)=0.06. An analysis of the phototoxic effect on tumour cells in culture was performed and compared with haematoporphyrin derivative (HpD), the only photosensitizer in clinical use at present. The phototoxicity of the porphyrin peptide fraction is weaker than that of HpD. However, for a porphyrin dose of 50 micrograms ml-1, the difference in phototoxicity is low, and in the absence of irradiation porphyrin peptides are less toxic than HpD. These results suggest that porphyrin peptides could be potent photosensitizers; moreover, they are of great interest since they allow the solubilization of hydrophobic porphyrins and could be applied in the future as insoluble photosensitizer carriers.
Cempel
N
N
Laboratoire de Technologie des Substances Naturelles, IUT A de Lille I, Cité Scientifique, Villeneuve d'Ascq, France.
Piot
J M
JM
Aubry
J M
JM
Patrice
T
T
Foultier
M T
MT
Guillochon
D
D
D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D003110:Colonic Neoplasms; D004307:Dose-Response Relationship, Radiation; D017324:Hematoporphyrin Derivative / Q000494:pharmacology*; D006454:Hemoglobins; D006801:Humans; D007700:Kinetics; D007834:Lasers; D008433:Mathematics; D008962:Models, Theoretical; D010100:Oxygen / Q000032:analysis / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011789:Quantum Theory; D026082:Singlet Oxygen; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014407:Tumor Cells, Cultured
D006454:Hemoglobins; D010446:Peptide Fragments; D017319:Photosensitizing Agents; D026082:Singlet Oxygen; D017324:Hematoporphyrin Derivative; D010100:Oxygen