Modulation of Radioligand Binding to the GABA_A-benzodiazepine Receptor Complex by a New Component from Cyperus Rotundus

抄録

Four sesquiterpenes, β-selinene, isocurcumenol, nootkatone and aristolone and one triterpene, oleanolic acid were isolated from the ethylacetate fraction of the rhizomes of Cyperus rotundus and tested for their ability to modulate γ-aminobutyric acid (GABA_A)-benzodiazepine receptor function by radioligand binding assays using rat cerebrocortical membranes. Among these compounds, only isocurcumenol, one of the newly identified constituents of this plant, was found to inhibit [³H]Ro15-1788 binding and enhance [³H]flunitrazepam binding in the presence of GABA. These results suggest that isocurcumenol may serve as a benzodiazepine receptor agonist and allosterically modulate GABAergic neurotransmission via enhancement of endogenous receptor ligand binding.