Location and dynamics of α-tocopherol in model phospholipid membranes with different charges

Fukuzawa, Kenji; Ikebata, Wataru; Shibata, Akira; Kumadaki, Itsumaro; Sakanaka, Tatsumi; Urano, Shiro

doi:10.1016/0009-3084(92)90024-j

Cited by 49 publications

(48 citation statements)

References 26 publications

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“…3A,B). Therefore, these protective effects putatively result from the interaction of tocopherols with the erythrocyte membrane core (Shinitzky and Barenholz, 1978), in agreement with the hydrophobicity, the high membrane partition and ordering effects of these compounds in lipid bilayer (Micol et al, 1990;Fukuzawa et al, 1992;Cruz-Silva et al, 2000), indicating that OHTAM-induced hemolysis is related with membrane interaction. Moreover, the fact that a-TAc (with an inactivated functional hydroxyl and deprived of antioxidant activity) inhibits also the hemolytic process suggests that the free hydroxyl group of a-T is not critical for protection against OHTAMinduced damage and that the hemolysis will be not caused by oxidative disruption of erythrocyte.…”

Section: Ohtam-induced Hemolysismentioning

confidence: 55%

“…The inhibitory effects of a-T and a-TAc towards OHTAM-induced hemolysis (Fig. 3) reflect a decrease of the permeability or the exclusion of OHTAM from the membrane; that is, withdrawing the drug from the interaction with membrane components involved in the control of permeability due to the membrane stabilization induced by both tocopherols (Micol et al, 1990;Fukuzawa et al, 1992;Cruz-Silva et al, 2000).…”

Section: Discussionmentioning

confidence: 98%

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Hydroxytamoxifen interaction with human erythrocyte membrane and induction of permeabilization and subsequent hemolysis

Silva

Madeira

Almeida

et al. 2001

Toxicology in Vitro

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4-Hydroxytamoxifen (OHTAM) is the most active metabolite of the widely prescribed anticancer drug tamoxifen (TAM) used in breast cancer therapy. This work describes the effects of OHTAM on isolated human erythrocytes, using standardized test conditions, to check for a putative contribution to the TAM-induced hemolysis and to study basic mechanisms involved in the interaction of OHTAM with cell membranes. Incubation of isolated human erythrocytes with relatively high concentrations of OHTAM results in a concentration-dependent hemolysis, its hemolytic effect being about one-third of that induced by TAM. OHTAMinduced hemolysis is prevented by either a-tocopherol (a-T) or a-tocopherol acetate (a-TAc) and it occurs in the absence of oxygen consumption and hemoglobin oxidation, ruling out the oxidative damage of erythrocytes. However, OHTAM remarkably increases the osmotic fragility of erythrocytes, increasing the susceptibility of erythrocytes to hypotonic lysis. Additionally, the hemoglobin release induced by OHTAM is preceded by a rapid efflux of intracellular K + . Therefore, our data suggest that OHTAM-induced hemolysis does not contribute to TAM-induced hemolytic anemia and it is a much weaker toxic drug as compared with TAM. Moreover, at variance with the membrane disrupting effects of TAM, OHTAM promotes perturbation of the membrane's backbone region due to its strong binding to proteins with consequent formation of membrane paths of permeability to small solutes and retention of large solutes like hemoglobin, followed by osmotic swelling and cell lysis. The prevention of OHTAM-induced hemolysis by a-T and a-TAc is probably committed to the permeability sealing resulting from structural stabilization of membrane. #

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Section: Ohtam-induced Hemolysismentioning

confidence: 55%

Section: Discussionmentioning

confidence: 98%

Hydroxytamoxifen interaction with human erythrocyte membrane and induction of permeabilization and subsequent hemolysis

Silva

Madeira

Almeida

et al. 2001

Toxicology in Vitro

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“…6) On the other hand, the radical trapping site of α-tocopherol is limited to a phenolic group, although α-tocopherol diffusing freely in the lipid bilayer would effectively react with hydroxyl radicals generated on the outer layer surface of liposomes because of the location of α-tocopherol is not fixed in the lipid membranes. 20) In this experimental condition, luminol molecules would localize at the membrane interface due to its hydrophobicity. Therefore, Asx might competitively scavenge hydroxyl radicals with luminol at the interface of lipid membranes.…”

Section: )mentioning

confidence: 98%

Scavenging of Hydroxyl Radicals in Aqueous Solution by Astaxanthin Encapsulated in Liposomes

Hama

Uenishi

Yamada

et al. 2012

Biological & Pharmaceutical Bulletin

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Astaxanthin (Asx) is known to be a potent quencher of singlet oxygen and an efficient scavenger of superoxide anion. Therefore, Asx would be expected to be a useful antioxidant for the prevention of oxidative stress, a causative factor in severe diseases such as ischemic reperfusion injury. However, it is still unclear whether Asx has scavenging capability against the most potent reactive oxygen species (ROS), hydroxyl radical, because the hydrophobicity of Asx prevents analysis of hydroxyl radical scavenging ability in aqueous solution. In this study, to solve this problem, liposomes containing Asx (Asx-lipo), which could be dispersed in water, were prepared, and the scavenging ability of Asx-lipo for the hydroxyl radical was examined. The liposomal formulation enabled encapsulation of a high concentration of Asx. Asx-lipo gave a dose-dependent reduction of chemiluminescence intensity induced by hydroxyl radical in aqueous solution. Hydroxyl radical scavenging of Asx was more potent than α-tocopherol. The absorbance of Asx in the liposome decreased after reduction of hydroxyl radicals, indicating the direct hydroxyl radical scavenging by Asx. Moreover, Asx-lipo prevented hydroxyl radical-induced cytotoxicity in cultured NIH-3T3 cells. In conclusion, Asx has potent scavenging capability against hydroxyl radicals in aqueous solution, and this paper is the first report regarding hydroxyl radial scavenging by Asx.

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“…It is an amphiphilic molecule consisting of two functional domains, a chromanol nucleus with an OH-group and a hydrophobic phytyl side chain [34]. There is evidence that the polar OH-group terminates the chain of peroxidation reactions by trapping peroxyl radicals, whereas the hydrophobic phytyl side chain associates with fatty acids and retains alphatocopherol in the membrane bilayer to stabilize the membrane and enhance the effectiveness of their antioxidant action [35]. Our study demonstrated that alpha-tocopherol significantly reduced the formation of retinal edema during I/R injury.…”

Section: Discussionmentioning

confidence: 99%

Protective Effects of Vitamin E Forms (Alpha-tocopherol, Gamma-tocopherol and d-alpha-tocopherol Polyethylene Glycol 1000 Succinate) on Retinal Edema During Ischemia–reperfusion Injury in the Guinea Pig Retina

et al. 2004

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Location and dynamics of α-tocopherol in model phospholipid membranes with different charges

Cited by 49 publications

References 26 publications

Hydroxytamoxifen interaction with human erythrocyte membrane and induction of permeabilization and subsequent hemolysis

Hydroxytamoxifen interaction with human erythrocyte membrane and induction of permeabilization and subsequent hemolysis

Scavenging of Hydroxyl Radicals in Aqueous Solution by Astaxanthin Encapsulated in Liposomes

Protective Effects of Vitamin E Forms (Alpha-tocopherol, Gamma-tocopherol and d-alpha-tocopherol Polyethylene Glycol 1000 Succinate) on Retinal Edema During Ischemia–reperfusion Injury in the Guinea Pig Retina

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