Brain-to-plasma distribution ratio of the biflavone amentoflavone in the mouse.

Amentoflavone crosses the blood-brain barrier in vitro but did not inhibit benzodiazepine binding in vivo suggesting poor brain permeability. This prompted us to examine its brain distribution in mice. After Hypericum perforatum and Gingko biloba extracts its brain concentrations were below the limit of quantification. Levels were consistently detected only after intraperitoneal amentoflavone (10 mg/kg), with mean brain-to-plasma ratio of about 0.02. These concentrations were possibly related to the compound's contribution from residual blood, but in any case are too low to support any interaction with central mechanisms so far tested.