Presentation Information
[4FMBS-14]Interaction of Natural Saponins with Model Phospholipid Membranes
○Adam Grzywaczyk1, Monika Rojewska1, Wojciech Smułek1, Daniel McNaughton3, Krystyna Prochaska1, Philip Alan Gale2, Ewa Kaczorek1 (1. Institute of Chemical Technology and Engineering, Poznan University of Technology (Poland), 2. Zernike Institute for Advanced Materials, University of Groningen (Netherlands), 3. Monash Institute of Pharmaceutical Sciences (Australia))
Keywords:
saponins,biomembrane,liposome,antibiotic,Langmuir monolayer
Natural surfactants of plant origin are recognised as promising membrane-active compounds with potential applications in biotechnology, antimicrobial therapy, and drug delivery. Their amphiphilic structure enables interactions with lipid assemblies; however, the mechanisms by which they affect membrane organization and physicochemical properties still require clarification. This study investigated the interactions of saponin-rich extracts, mainly derived from Glycyrrhiza glabra L., with model phospholipid membranes using two complementary systems: Langmuir monolayers and liposomal vesicles.
In the monolayer experiments, phospholipid films mimicking biological membranes were used to evaluate the effect of saponins on lipid packing and elasticity. Surface pressure–area isotherms and relaxation studies demonstrated that saponins incorporated into the monolayers and expanded the lipid film, leading to a decrease in the compressibility modulus. These changes indicate membrane loosening and fluidization caused by saponin insertion. In the case of bacterial membrane models based on DOPG, the reduction in compressibility modulus reached approximately 25–50%, depending on saponin concentration, confirming a substantial impact on the mechanical properties of the membrane model. In earlier studies on DPPE monolayers, similar expansion effects were observed, accompanied by altered monolayer stability and morphology, indicating that extract composition and purity influence the extent of membrane perturbation.
Liposome-based studies provided insight into the behavior of saponins in three-dimensional bilayer systems. The addition of saponins changed the zeta potential of phospholipid vesicles, demonstrating modification of membrane surface properties and interfacial organization. Importantly, under the tested conditions, these effects occurred without complete vesicle disruption, suggesting that saponins modulate membrane properties while preserving overall bilayer integrity. When combined with tobramycin, licorice saponins further altered liposome surface charge, which points to membrane-level co-interactions that may facilitate antibiotic action.
The results confirm that plant-derived saponins interact efficiently with model phospholipid membranes, altering lipid packing, elasticity, and surface electrostatics in both two-dimensional and three-dimensional systems. These findings support the concept of saponins as membrane-modifying agents and potential adjuvants for antimicrobial compounds, as well as functional components in lipid-based delivery systems. The combined use of Langmuir monolayers and liposomes provides a valuable framework for understanding how natural surfactants influence membrane organization and for designing future biotechnological and pharmaceutical applications.
This work was supported by the National Science Centre Poland, grant number 2020/39/B/NZ9/03196.
In the monolayer experiments, phospholipid films mimicking biological membranes were used to evaluate the effect of saponins on lipid packing and elasticity. Surface pressure–area isotherms and relaxation studies demonstrated that saponins incorporated into the monolayers and expanded the lipid film, leading to a decrease in the compressibility modulus. These changes indicate membrane loosening and fluidization caused by saponin insertion. In the case of bacterial membrane models based on DOPG, the reduction in compressibility modulus reached approximately 25–50%, depending on saponin concentration, confirming a substantial impact on the mechanical properties of the membrane model. In earlier studies on DPPE monolayers, similar expansion effects were observed, accompanied by altered monolayer stability and morphology, indicating that extract composition and purity influence the extent of membrane perturbation.
Liposome-based studies provided insight into the behavior of saponins in three-dimensional bilayer systems. The addition of saponins changed the zeta potential of phospholipid vesicles, demonstrating modification of membrane surface properties and interfacial organization. Importantly, under the tested conditions, these effects occurred without complete vesicle disruption, suggesting that saponins modulate membrane properties while preserving overall bilayer integrity. When combined with tobramycin, licorice saponins further altered liposome surface charge, which points to membrane-level co-interactions that may facilitate antibiotic action.
The results confirm that plant-derived saponins interact efficiently with model phospholipid membranes, altering lipid packing, elasticity, and surface electrostatics in both two-dimensional and three-dimensional systems. These findings support the concept of saponins as membrane-modifying agents and potential adjuvants for antimicrobial compounds, as well as functional components in lipid-based delivery systems. The combined use of Langmuir monolayers and liposomes provides a valuable framework for understanding how natural surfactants influence membrane organization and for designing future biotechnological and pharmaceutical applications.
This work was supported by the National Science Centre Poland, grant number 2020/39/B/NZ9/03196.
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