Active oxygen chemistry within the liposomal bilayer. Part IV: Locating 2',7'-dichlorofluorescein (DCF), 2',7'-dichlorodihydrofluorescein (DCFH) and 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) in the lipid bilayer.
2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) is commonly used to detect the generation of reactive oxygen intermediates and for assessing the overall oxidative stress in toxicological phenomenon. It has been suggested that DCFH-DA crosses the cell membrane, subsequently undergoing deacetylation by intracellular esterases. The resulting 2',7'-dichlorodihydrofluorescein (DCFH) is proposed to react with intracellular hydrogen peroxide or other oxidizing ROS to give the fluorescent 2',7'-dichlorofluorescein (DCF). Using an NMR chemical shift-polarity correlation, we have determined that DCFH-DA and DCFH are located well within the lipid bilayer and certainly not at the interface. These results, therefore, put into serious question the proposed ability of DCFH to come in contact with the aqueous phase and thereby interact with aqueous intracellular ROS and components. However, H2O2 and superoxide can cross or at least penetrate the lipid bilayer and react with certain lipophilic substrates. This may well describe the mode of reaction of these and other ROS with DCFH.
Afri
Michal
M
The Department of Chemistry, Bar Ilan University, Ramat Gan 52900, Israel. afrimi@mail.biu.ac.il
Frimer
Aryeh A
AA
Cohen
Yael
Y
D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005452:Fluoresceins / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry; D014867:Water / Q000737:chemistry
C110400:2',7'-dichlorodihydrofluorescein diacetate; D005452:Fluoresceins; D008051:Lipid Bilayers; D017382:Reactive Oxygen Species; D014867:Water; D013481:Superoxides; C029569:diacetyldichlorofluorescein; D006861:Hydrogen Peroxide; D010100:Oxygen