Effect of ginseng total saponin on bovine adrenal tyrosine hydroxylase.

Ginseng total saponin (GTS) can modulate dopaminergic activity at both presynaptic and postsynaptic dopamine receptors (Kim et al., 1998). The present study investigated the effect of GTS on the bovine adrenal tyrosine hydroxylase (TH), which catalyze L/tyrosine to DOP. GTS inhibited the bovine adrenal TH by 42.4, 51.5 and 55.3% at concentrations of 40, 80 and 100 micrograms/ml, respectively. The IC50 value of GTS was 77.5 micrograms/ml. GTS exhibited noncompetitive inhibition with a substrate L-tyrosine. The Ki value was 155 micrograms/ml.