Saponins do not affect the ecdysteroid receptor complex but cause membrane permeation in insect culture cell lines

► Triterpenoid and steroid saponins have strong cytotoxic effects on Drosophila S2 cells. ► These cytotoxic effects can be explained by rapid permeation of the insect cell membrane. ► We found no true agonistic or antagonistic activity on the EcR-receptor. ► Lower saponin concentrations induce apoptosis with DNA fragmentation. ► The saponin effects were counteracted by cholesterol.