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Correlation between photodynamic efficacy of differing porphyrins and membrane partitioning behavior
Author(s) -
Okunaka Tetsuya,
Eckhauser Mark L.,
Kato Harubumi,
Bomaminio Anthony,
Yamamoto Hideki,
Aizawa Katsuo,
Sarasua Martha M.,
Koehler Karl A.
Publication year - 1992
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.1900120115
Subject(s) - liposome , hematoporphyrin , photosensitizer , chemistry , lysis , photodynamic therapy , biophysics , bilayer , protoporphyrin , lipid bilayer , membrane , absorbance , melittin , vesicle , chromatography , biochemistry , porphyrin , photochemistry , biology , organic chemistry
The ability of a photosensitizer to partition into membrane is determined by its structure and physical properties. Partitioning behavior can be quantitated as the partition coefficient (K p ) for a particular drug. This property may be an important determinant of cytocidal efficacy in photodynamic therapy. The K p of five photoactive drugs—13,17‐ditetraammonium protoporphyrin (PH1008), photofrin II (PII), hematoporphyrin (Hp), benzopor‐phyrin derivative monoacid (BPD‐MA), coproporphyrin (Cp), and uroporphyrin (Up)—was determined using a simple liposome system composed of sonicated egg phosphatidylcholine single bi‐layer vesicles. The cytocidal efficacy of each drug was compared by determining the concentration of drug resulting in 50% maximal lysis (C 50 ) obtained by measuring the hemoglobin absor‐bance at 414 nm released from lysed human red blood cells. The percentage lysis at 1 μM final drug concentration was also determined. An argon‐dye laser was used to administer light of 630‐nm wavelength for a total exposure of 5 J/cm 2 . Porphyrins with a greater tendency to partition into phosphocholine bilayer membranes demonstrated a greater lytic efficacy in the rbc system utilized. The comparison of physical properties with lytic ability may be useful in understanding the mechanism by which PDT exerts its effects and in predicting the clinical efficacy of different drugs.