Inhibition of [3H] flunitrazepam binding to rat brain membranes in vitro by puerarin and daidzein.

Compounds acting on the central nervous system (CNS) have been isolated and identified from plants used for medicinal purposes. Radix Puerariae is used in Chinese traditional medicine for the treatment of drunkenness and alcoholic addiction. Benzodiazepine tranquilizers exert their pharmacological effects by modulating the efficacy of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) at the GABA/benzodiazepine-chloride channel complex in the brain. Since some of the pharmacological effects of ethanol are thought to be mediated via the GABA/benzodiazepine-chloride channel complex, we investigated if extracts from Radix Puerariae contain active substances at the benzodiazepine receptor which could explain its reported usefulness for medical purposes. Therefore, a bioassay-guided purification of active substances from Radix Puerariae was initiated.