Plasma membrane permeabilization by
saponin and anticancer avicins was studied using light dispersion measurements, since high correlation between light dispersion changes and
hemolysis has been demonstrated. Nevertheless, we observed that rat red blood cell swelling in moderately hypotonic media was accompanied by up to 20% decrease of light dispersion, when
hemolysis was not yet detectable.
Avicin G and
avicin D were significantly more efficient than
saponin in inducing cytotoxicity in PC3 human
prostate cancer cells. We found that the preincubation of avicins with the plasma membrane, but not with the cytosolic fraction of previously lysed red blood cells, completely protected fresh cells against permeabilization. The data suggest that the plasma membrane can tightly bind the avicins, but not the
saponin. Using the "osmotic protection" method with 100mOsm PEGs of increasing molecular weight in isotonic media, the size of the pores generated by
avicin G and
avicin D in the plasma membrane was estimated to be higher than the hydrodynamic radius of PEG-8000. The obtained results indicate that the anticancer activity of
avicin G and
avicin D could be related, at least partially, to their high ability to permeabilize
biological membranes. These data might represent interest for possible applications of these anticancer drugs in vivo.