“…The adjuvant activity of the QS‐21 fraction of saponins from Quillaja saponaria Molina (Fernández‐Tejada et al, ; Sanders et al, ), as well as recent results on synergistic biological activity of saponins from Saponaria and Gypsophila species with saporins (type I ribosome‐inactivating protein, RIP‐I) (Gevrenova et al, ; Gilabert‐Oriol et al, ; Holmes et al, ; Smith et al, ), confirm that saponins generally interact with biological membranes in a gentle and reversible way. Although most authors link biological activity of saponins with their affinity for cholesterol (Glauert et al, ; Lorent et al, ; Schulman and Rideal, ; Windaus, ), our recent results suggest that interaction with phospholipids present in the membrane might be equally important (Orczyk and Wojciechowski, ; Wojciechowski et al, , ).…”