Central nervous system effects of natural and synthetic flavonoids

Flavonoids are naturally occurring molecules present in the human diet. We demonstrate that some flavonoids possess central nervous system effects act ing through the central benzodiazepine receptors. The pharmacological chara cterization of chrysin (5,7-dihydroxyflavone) and apigenin (5,7,4'-trihydro xyflavone), isolated from Passiflora coerulea and Matricaria recutita, resp ectively showed their anxiolytic, but not myorelaxant or amnesic effects. C irsiliol (5,3',4'-trihydroxy-6,7-dimethoxyflavone), however isolated from S alvia guaranitica, had sedative-depressant properties. We were able to incr ease the biochemical and pharmacological potency of the natural flavonoids by means of the addition of halo and/or nitro groups to the flavone nucleus . Some flavonoids are partial agonists of the benzodiazepine receptors and may become new therapeutic drugs, devoid of the unwanted side effects of cl assical benzodiazepines.