β-aescin is a versatile biosurfactant extracted from the seeds of the horse chestnut
tree Aesculus hippocastanum with anti-cancer potential and is commonly used in the food and
pharmaceutical and cosmetic industries. In this article, wide-angle X-ray scattering (WAXS) is
used in order to study the modifications of the structural parameters at the molecular scale of lipid
bilayers in the form of bicelles composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)
and the triterpenoid saponin β-aescin. In particular, the impact on the cooperative phase transition
and the structural parameters of the DMPC bilayers at different compositions and temperatures is
of special interest. Moreover, we show how cholesterol and the non-steroidal anti-inflammatory
drug (NSAID) ibuprofen modulate the structural parameters of the β-aescin-DMPC assemblies on
a molecular scale. Ibuprofen and cholesterol interact with different parts of the bilayer, namely the
head-region in the former and the tail-region in the latter case allowing for specific molecular packing
and phase formation in the binary and ternary mixtures
