![]() In this work, the temperatures investigated extend from DMPC’s L β′ to its L α phase in dependence of different amounts of the saponin (0–6 mol% for calorimetric and 0–1 mol% for structural analyses) and the steroid (1–10 mol%). At these aescin contents model membranes are conserved in the form of small unilamellar vesicles (SUVs) and major overall structural modifications are avoided. Additionally, interactions between aescin and cholesterol can be studied for both phase states of the lipid, the gel and the fluid state. In addition, it becomes clearly visible that the entire phase behaviour is dominated by phase separation which indeed also depends on the complexes formed between aescin and cholesterol.įrom calorimetric experiments by differential scanning calorimetry (DSC), it could be shown that both, the steroid and the saponin content, have a significant impact on the cooperative phase transition behaviour of the DMPC molecules. We show by various methods that the addition of cholesterol alters the impact of aescin on structural parameters ranging from the acyl chain correlation to vesicle-vesicle interactions. While the specific saponin-phospholipid interaction is reduced, addition of cholesterol leads to deformation of SUVs. The analyses of the structures formed were performed by wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS).Ī mixture of saponins can be isolated from the seeds of the horse chestnut tree Aesculus hippocastanum 1, 2. From this mixture, two crystalline products are saparable: aescin (haemolytic) and prosapogenin (non-haemolytic) 1, 3. Aescin is a mixture of triterpenoid saponins 4. It exists in two forms, the α- and the β-form from which the latter is haemolytically active and the compound of interest in this study 1. The aescin molecule is constituted of a large and well-defined head group made of one glucuronic acid and two glucose molecules linked to a lipophilic sapogenin 1, 5, 6. The aglycones of aescin are derivatives of proto-ascigenin, acylated by acetic acid at C-22 and by either angelic or tiglic acids at C-21 1. ![]() ![]() They can be distinguished by their melting point, the specific rotation, haemolytic index, and solubility in water 1. ![]() To the triterpenoid backbone, additional polar groups are attached giving this molecule a polar and an apolar side. Saponins, such as aescin, are consumed on a daily basis as they are found in common foods, such as peanuts, spinach, tomatoes and tea 7, 8.įigure 1(a) shows the molecular structure of β-aescin. Therefore, it is used to treat chronic venous insufficiency (CVI).Īescin possesses anti-inflammatory and anti-oedematous properties 9. The anti-oedematous effect is attributed to aescin, because in case of a hypoxia it i.a. ![]()
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