Sedative and hypnotic properties of Salvia guaranitica St Hil, and of its active principle, Cirsiliol

Salvia guaranitica St. Hil. is a traditional medicinal plant used in Latin America as sedative. We have recently demonstrated the presence of cirsiliol in its extracts and found that this flavonoid is a competitive low affinity benzodiazepine receptor ligand (Marder et al., 1996). This report describes the pharmacological properties of Salvia guaranitica extracts and of its active principle, cirsiliol. A partially purified fraction of this plant, administered intraperitoneally in mice (in a dose equivalent to 3 g of the fresh plant), exhibited sedative and hypnotic effects as measured in the hole board and in the pentobarbital-induced sleep tests, respectively. On the other hand, this fraction had no anxiolytic or myorelaxant effects. In the pentobarbital-induced sleep test, cirsiliol (2-10 mg/kg, i.p.) exhibited a dose-dependent hypnotic action. In contrast, it did not produce myorelaxant (up to 30 mg/kg) or anticonvulsant (up to 10 mg/kg) effects. Cirsiliol was found to be more potent in displacing H-3 zolpidem binding (K-i = 20 mu M) than H-3 flunitrazepam binding (K-i = 200 mu M) to benzodiazepine receptors from rat cerebral cortex. It is concluded that Salvia guaranitica extracts and its active principle cirsiliol, possess sedative and hypnotic properties; cirsiliol produces these effects probably acting on the so-called type I benzodiazepine receptor.