Benzodiazepine-like compounds and GABA in flower heads of Matricaria chamomilla
The presence of benzodiazepine-like substances in dried flower heads of Matricaria chamomilla was investigated. After extraction and HPLC purification we tested several fractions for their ability to displace in vitro [3H]Flunitrazepam bound to its receptors in rat cerebellar membranes, [3H]Muscimol linked to GABA receptors in rat cortical membrane preparations and [3H]RO 5-4864 specifically bound to the so-called 'peripheral' benzodiazepine binding sites present in membrane preparations from rat adrenal glands. Few of these fractions displaced both central and peripheral benzodiazepine binding sites and GABA receptors, too. As regards this last activity, by further HPLC analysis we identified GABA as the main agent responsible for the displacing effect. Some of the extracted fractions, not containing GABA, were intracerebronventricularly injected in rats and produced a statistically significant reduction of the locomotor activity. Ongoing experiment by mass spectrometric technique will help in the identification of the benzodiazepine-like compounds present in the extract of Matricaria chamomilla responsible for its sedative effect.