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REACTION OF SINGLET OXYGEN WITH CHOLESTEROL IN LIPOSOMAL MEMBRANES. EFFECT OF MEMBRANE FLUIDITY ON THE PHOTOOXIDATION OF CHOLESTEROL
Author(s) -
Suwa Kunihiko,
Kimura Tokuji,
Schaap A. Paul
Publication year - 1978
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1978.tb06951.x
Subject(s) - singlet oxygen , membrane , chemistry , autoxidation , hematoporphyrin , liposome , phospholipid , photochemistry , oxygen , phosphorylcholine , membrane fluidity , cholesterol , yield (engineering) , singlet state , organic chemistry , biochemistry , materials science , photodynamic therapy , excited state , metallurgy , physics , nuclear physics
Abstract— The photosensitized oxygenation of cholesterol in liposomal membranes results in the formation of the characteristic singlet oxygen product, 3β‐hydroxy‐5α‐cholest‐6‐ene‐5‐hydroperoxide. The yield of this product was found to be strongly temperature dependent with 6‐ to 7‐fold increase above the transition temperature of the membrane using 1,2‐dipalmitoyl‐ sn ‐glycero‐3‐phosphorylcholine or 1.2‐dimyristoyl‐ sn ‐glycero‐3‐phosphorylcholine. In contrast, the formation of the radical autoxidation products of cholesterol was not significantly enhanced in these systems by higher temperatures. We conclude from the results that the oxidation of cholesterol by singlet oxygen in the artificial membranes is affected by both membrane fluidity and amount of hematoporphyrin incorporated into the membrane. The ratio of cholesterol to phospholipid which affects the morphology of membranes is a crucial factor in determining the yield of the singlet oxygen product.