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Hematoporphyrin ethers--III. Cellular uptake and photosensitizing properties
J Moan1, C Rimington, A Western
1Institute for Cancer Research, Norwegian Radium Hospital, Oslo.
The International Journal of Biochemistry
|January 1, 1988
Summary
New hematoporphyrin (Hp) diethers show improved cellular uptake and photoinactivation efficiency compared to Photofrin II. These Hp diethers offer enhanced photodynamic therapy potential due to better cell penetration and higher quantum yields.
Area of Science:
- Photodynamic Therapy
- Biochemistry
- Cell Biology
Background:
- Hematoporphyrin (Hp) derivatives are investigated for photodynamic therapy (PDT).
- Photofrin II is a clinically used porphyrin preparation for PDT.
- Understanding cellular uptake and photoinactivation efficiency is crucial for developing effective PDT agents.
Purpose of the Study:
- To evaluate the cellular uptake and photoinactivation efficiency of three novel hematoporphyrin (Hp) diethers: Hp diphenyl ether, Hp dicyclohexyl ether, and Hp dihexyl ether.
- To compare the performance of these Hp diethers with the clinically used porphyrin preparation, Photofrin II.
- To elucidate the relationship between porphyrin aggregation, cellular uptake, and photosensitizing efficacy.
Main Methods:
- Cellular uptake studies were performed for Hp diphenyl ether, Hp dicyclohexyl ether, and Hp dihexyl ether.
- Photoinactivation efficiency was quantified by measuring quantum yields for cell sensitization.
- Spectroscopic techniques (fluorescence and absorption) were employed to assess porphyrin aggregation within cells.
- Drug retention studies were conducted by incubating loaded cells in porphyrin-free medium with serum.
Main Results:
- Hp dicyclohexyl ether and Hp dihexyl ether exhibited 3-4 times greater cellular uptake than Photofrin II.
- All three Hp diethers demonstrated similar quantum yields for photoinactivation, which were twice as high as that of Photofrin II.
- Spectroscopic analysis indicated less aggregation of Hp diethers within cells compared to Photofrin II.
- Hp dicyclohexyl ether showed the highest drug removal (50%) in retention studies, followed by Hp dihexyl ether (20%) and Hp diphenyl ether (28%).
Conclusions:
- The novel Hp diethers, particularly Hp dicyclohexyl ether and Hp dihexyl ether, offer superior cellular uptake and photoinactivation efficiency compared to Photofrin II.
- Reduced aggregation of Hp diethers within cells likely contributes to their enhanced performance in photodynamic therapy.
- These findings suggest that Hp diethers hold significant promise as improved photosensitizers for clinical applications in photodynamic therapy.