title: Mechanistic investigation of interactions between steroidal saponin digitonin and cell membrane models.
abstract: Digitonin is an amphiphilic steroidal saponin, a class of natural products that can bind to cholesterol and lyse cells. Despite the known cell membrane lysis activity, it remains unclear how it interacts with cell membranes. In the present work, the interaction mechanism between digitonin and cell membrane models has quantitatively been investigated using a combination of physical techniques. It has been demonstrated that digitonin molecules bind specifically to cholesterol in the membrane, resulting in the formation of cholesterol-digitonin complexes on the membrane surface by removing cholesterol from the membrane core. Changes in the mass density and the film mechanics caused by the digitonin were determined by using quartz crystal microbalance with dissipation (QCM-D), and the combination of X-ray reflectivity (XRR) and dual polarization interferometry (DPI) yielded the hydration level of the cholesterol-digitonin complexes. From differential scanning calorimetry (DSC) analysis, supporting evidence was obtained that cholesterol was removed from the membrane core.
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry and §Institute of Pharmacy and Molecular Biotechnology, Heidelberg University , D69120 Heidelberg, Germany.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Frenkel
authors.forename: Ali
authors.initials: A
authors.lastname: Makky
authors.forename: Ikhwan Resmala
authors.initials: IR
authors.lastname: Sudji
authors.forename: Michael
authors.initials: M
authors.lastname: Wink
authors.forename: Motomu
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D004072:Digitonin / Q000737:chemistry* / Q000378:metabolism; D007368:Interferometry / Q000379:methods; D008956:Models, Chemical; D058525:Quartz Crystal Microbalance Techniques; D013816:Thermodynamics
chemical_list: D002784:Cholesterol; D004072:Digitonin