Complexation of phospholipids and cholesterol by triterpenic saponins in bulk and in monolayers

Kamil Wojciechowski , Marta Orczyk , Thomas Gutberlet , Thomas Geue

Abstract

The interactions between three triterpene saponins: α-hederin, hederacoside C and ammonium glycyrrhizate with model lipids: cholesterol and dipalmitoylphosphatidylcholine (DPPC) are described. The oleanolic acid-type saponins (α-hederin and hederacoside C) were shown to form 1:1 complexes with lipids in bulk, characterized by stability constants in the range (4.0 ± 0.2)·103-(5.0 ± 0.4)·104 M- 1. The complexes with cholesterol are generally stronger than those with DPPC. On the contrary, ammonium glycyrrhizate does not form complexes with any of the lipids in solution. The saponin-lipid interactions were also studied in a confined environment of Langmuir monolayers of DPPC and DPPC/cholesterol with the saponins present in the subphase. A combined monolayer relaxation, surface dilational rheology, fluorescence microscopy and neutron reflectivity (NR) study showed that all three saponins are able to penetrate pure DPPC and mixed DPPC/cholesterol monolayers. Overall, the effect of the saponins on the model lipid monolayers does not fully correlate with the lipid-saponin complex formation in the homogeneous solution. The best correlation was found for α-hederin, for which even the preference for cholesterol over DPPC observed in bulk is well reflected in the monolayer studies and the literature data on its membranolytic activity. Similarly, the lack of interaction of ammonium glycyrrhizate with both lipids is evident equally in bulk and monolayer experiments, as well as in its weak membranolytic activity. The combined bulk and monolayer results are discussed in view of the role of confinement in modulating the saponin-lipid interactions and possible mechanism of membranolytic activity of saponins.
Author Kamil Wojciechowski ZMB
Kamil Wojciechowski,,
- Department Of Microbioanalytics
, Marta Orczyk ZMB
Marta Orczyk,,
- Department Of Microbioanalytics
, Thomas Gutberlet
Thomas Gutberlet,,
-
, Thomas Geue
Thomas Geue,,
-
Journal seriesBiochimica et Biophysica Acta-Biomembranes, ISSN 0005-2736
Issue year2016
Vol1858
No2
Pages363-373
Publication size in sheets0.5
Keywords in EnglishAmmonium glycyrrhizate; Biosurfactant; Dilatational surface rheology; Hederacoside C; Saponin; Surface pressure; α-Hederin
DOIDOI:10.1016/j.bbamem.2015.12.001
URL http://www.sciencedirect.com.doi.eczyt.bg.pw.edu.pl/science/article/pii/S0005273615003983
Languageen angielski
File
1-s2.0-S0005273615003983-main.pdf 1.65 MB
Score (nominal)35
ScoreMinisterial score = 35.0, 28-11-2017, ArticleFromJournal
Ministerial score (2013-2016) = 35.0, 28-11-2017, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 3.498 (2) - 2016=3.542 (5)
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