title: Membrane Disintegration Caused by the Steroid Saponin Digitonin Is Related to the Presence of Cholesterol.
abstract: In the present investigation we studied the molecular mechanisms of the monodesmosidic saponin digitonin on natural and artificial membranes. We measured the hemolytic activity of digitonin on red blood cells (RBCs). Also different lipid membrane models (large unilamellar vesicles, LUVs, and giant unilamellar vesicles, GUVs) in the presence and absence of cholesterol were employed. The stability and permeability of the different vesicle systems were studied by using calcein release assay, GUVs membrane permeability assay using confocal microscopy (CM) and fluorescence correlation spectroscopy (FCS) and vesicle size measurement by dynamic light scattering (DLS). The results support the essential role of cholesterol in explaining how digitonin can disintegrate biological and artificial membranes. Digitonin induces membrane permeability or causes membrane rupturing only in the presence of cholesterol in an all-or-none mechanism. This effect depends on the concentrations of both digitonin and cholesterol. At low concentrations, digitonin induces membrane permeability while keeping the membrane intact. When digitonin is combined with other drugs, a synergistic potentiation can be observed because it facilitates their uptake.
authors.affiliation: Department of Biology, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, INF 364, 69120 Heidelberg, Germany. ir.sudji@gmail.com.
authors.forename: Ikhwan Resmala
authors.initials: IR
authors.lastname: Sudji
authors.affiliation: Interfaculty Institute for Biochemistry, University of Tübingen, 72076 Tübingen, Germany. yamunabio@gmail.com.|Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany. yamunabio@gmail.com.
authors.forename: Yamunadevi
authors.initials: Y
authors.lastname: Subburaj
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, 69120 Heidelberg, Germany. n.frenkel@stud.uni-heidelberg.de.|Institute for Toxicology and Genetics, Karlsruhe Institute for Technology, 76021 Karlsruhe, Germany. n.frenkel@stud.uni-heidelberg.de.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Frenkel
authors.affiliation: Interfaculty Institute for Biochemistry, University of Tübingen, 72076 Tübingen, Germany. ana.garcia@uni-tuebingen.de.
authors.forename: Ana J
authors.initials: AJ
authors.lastname: García-Sáez
authors.affiliation: Department of Biology, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, INF 364, 69120 Heidelberg, Germany. wink@uni-hd.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Wink
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000737:chemistry*; D002463:Cell Membrane Permeability / Q000187:drug effects; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D004072:Digitonin / Q000737:chemistry* / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects; D005452:Fluoresceins / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D008051:Lipid Bilayers / Q000737:chemistry; D012503:Saponins / Q000737:chemistry*; D012756:Sheep; D013256:Steroids / Q000737:chemistry*
chemical_list: D005452:Fluoresceins; D008051:Lipid Bilayers; D012503:Saponins; D013256:Steroids; D002784:Cholesterol; D004072:Digitonin; C007740:fluorexon
keywords: calcein release; cholesterol; digitonin; dynamic light scattering; giant unilamellar vesicles; membrane permeability