Protopanaxadiol is a ginseng saponin that enhances axonal and dendritic formation activity. Shown to have characteristic effects on the proliferation of human leukemia cells in vitro. Protopanaxadiol is a ginseng saponin that enhances axonal and dendritic formation activity. Shown to have characteristic effects on the proliferation of human leukemia cells in vitro. Protopanaxadiol [20(R)-protopanaxadiol], a dammarane-type tetracyclic terpene sapogenin, may be used to study its binding to and modulation of endothelial cell function via glucocortoid (GR) and the oestrogen (ER) receptors. Protopanaxadiol may be used to study its catabolism by cytochrome-P450s. 20(R)-protopanaxadiol may be used in comparative studies versus 20(S)-protopanaxadiol.