The experiments with different triterpenoid saponins showed a significant difference
in the microphysiometric activity between acylated and non-acylated compounds. Only
acylated saponins in low concentrations were able to activate the metabolism of endothelial
cells after short-time incubation in a transient manner lasting approximately 2 hours.
The strongest effect was produced by virgaureasaponin b, an incubation with 4 microg/ml
over 6 min induced a stimulation of the metabolic activity of 190% maximum after 30
min. This treatment did not induce non-reversible toxic effects, and could be repeated
in the same way after a recovery period. The saponins without acylation in the glycosidic
part did not induce metabolic stimulation, even in concentrations higher than observed
for the acylated compounds. The current interpretation of the results is connected
with the suggestion that especially acylated saponins are able to integrate into the
cellular membrane transiently. This integration might induce pore-like structures
which change the membrane permeability associated with alterations in the ionic homeostasis
between intracellular and extracellular compartments.