The aqueous extracts of the seeds of oat (Avena sativa L.), horse chestnut (Aesculus hippocastanum L.), soybean (Glycine max L.), cowherb (Vaccaria hispanica [P. Mill.] Rauschert) and quinoa (Chenopodium quinoa Willd.), and the roots of soapwort (Saponaria officinalis L.) without any preservatives were characterized in terms of their surface tension, surface compression (dilational) rheology, foamability and foam stability. The saponin content in the extracts was determined using UPLC-MS and their interaction with model lipid monolayers consisting of dipalmitoylphosphatidylcholine (DPPC)/cholesterol and Ceramide AP/stearic acid/cholesterol were analyzed by surface pressure relaxation, surface compression elasticity and neutron reflectometry (NR). The lipid composition was chosen to mimic the cell membrane of keratinocytes - major constituents of the human deeper skin layers, and the intercellular lipids ("mortar") in the "bricks and mortar" model of the outermost layer of the epidermis (stratum corneum). Bilayers of DPPC/cholesterol were additionally characterized using dynamic light scattering (DLS) and NR. The oat and soybean extracts were shown to be much less abundant in saponins as compared to cowherb, horse chestnut, soapwort or quinoa, and showed limited foaming abilities. They did not affect significantly the model lipid mono- and bilayers mimicking the skin outer layers, either. The horse chestnut extract affected both model membranes to the highest extent, yet without solubilizing the lipids.