title: Effects of ginsenosides on bovine adrenal tyrosine hydroxylase.
abstract: The present study was undertaken to investigate the effects of ginsenosides on bovine adrenal tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis. Ginsenoside-Rb1, Rc, Re and Rg, inhibited the TH activity by 51.5, 25.4, 31.3, 44.3 and 43.3%, respectively, at a concentration of 80 microg/ml. Ginsenoside-Rb1, Rc, Re and Rg1 exhibited noncompetitive inhibition of TH activity with a substrate L-tyrosine. From these results, it is presumed that the effects of ginsenosides on TH activity observed in vitro might be also produced in vivo, and thereby the inhibitory effects of ginsenosides on TH activity may be partially responsible for the antidopaminergic action of ginsenosides by reducing the availability of dopamine at the presynaptic dopamine receptor in vivo.
authors.affiliation: Department of Pharmacology, College of Pharmacy, Chungbuk National University, Cheongju, South Korea. hskim@trut.chungbuk.ac.kr
authors.forename: H S
authors.initials: HS
authors.lastname: Kim
authors.forename: Y H
authors.initials: YH
authors.lastname: Zhang
authors.forename: L H
authors.initials: LH
authors.lastname: Fang
authors.forename: M K
authors.initials: MK
authors.lastname: Lee
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects* / Q000201:enzymology; D000818:Animals; D002417:Cattle; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D036145:Ginsenosides; D007700:Kinetics; D012503:Saponins / Q000494:pharmacology*; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D036145:Ginsenosides; D012503:Saponins; D014446:Tyrosine 3-Monooxygenase