Regensburg 2025 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 14: Poster Session I

BP 14.15: Poster

Dienstag, 18. März 2025, 10:00–12:30, P3

Influence of the sapogenin gypsogenin on vesicles from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) — •Melanie Gettinger and Thomas Hellweg — Physical & Biophysical Chemistry, University Bielefeld, Bielefeld, Germany

Small unilamellar vesicles (SUVs) composed of phospholipids, such as 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), are commonly used as model membrane systems. DMPC bilayers undergo phase transitions from a gel to a fluid phase at around 24°C. While the effects of saponins on DMPC membranes are well-documented, the impact of their aglycones, sapogenins, remains less explored. Gypsogenin, a pentacyclic triterpenoid found in soapwort (Saponaria officinalis) and gypsum herb (Gypsophila oldhamiana), is of interest due to its anti-cancer potential. Gypsogenin shares structural features with cholesterol but has contrasting effects on membrane properties. While cholesterol increases membrane thickness and reduces fluidity, gypsogenin incorporation decreases the vesicle core radius and membrane thickness, as shown by small-angle X-ray scattering (SAXS) and cryo-TEM. UV-vis spectroscopy was used to monitor turbidity in solutions containing 0 to 25 mol% gypsogenin over a wide temperature range, showing a reversible increase upon cooling, indicating thermally reversible phase transitions. SAXS measurements revealed significant structural changes at 25 mol%. The core radius and membrane thickness decreased compared to pure DMPC vesicles. These findings suggest that gypsogenin alters DMPC membranes significantly at higher concentrations.

Keywords: phospholipids; DMPC; Small-Angle X-ray Scattering (SAXS); sapogenin; gypsogenin