Plant-derived biosurfactants of the group of saponins offer an attractive alternative to synthetic surfactants because of their unique foaming and emulsifying properties combined with generally low toxicity and high biocompatibility. Many saponins are known to interact with biological bilayers and the direct motivation for the present project was a peculiar penetration of lipid layers by saponins and its consequences for potential applications in cosmetics. In contrast to small-molecular weight synthetic surfactants, which simply remove the lipids by detergent action, saponins intercalate between the lipid molecules. We plan to gather molecular-level information on the differences in mode of action on skin-mimicking lipid membranes between 5 saponin-rich plant extracts from soapwort, cowcockle, quinoa, oat and quillaja and a synthetic surfactant - sodium lauryl sulphate (SLS).