Valerian: Binding of Brain Receptor Sites Studied

Reference: Mennini T, Bernasconi P: In vitro study on the interaction of extracts and pure compounds from Valeriana officinalis roots with GABA, benzodiazepine and barbiturate receptors. Fitoterapia 64: 291-300, 1993

Summary: The interaction with GABA-benzodiazepine (BDZ) receptor complex in rat brain was investigated using a hydroalcoholic and aqueous extract from the roots of V. officinalis (Valerian). Both extracts, as well as the aqueous fraction derived from the hydroalcoholic extract showed affinity for the GABA-A receptor. The chemical nature of the compounds responsible for the activity was not correlated with sesquiterpenes or valepotriates (two major groups of constituients in valerian root). The lipophilic fraction of the hydroalcoholic extract as well as dihydrovaltrate showed affinity for the barbiturate receptor and, to a lesser extent, peripheral benzodiazepine receptors. The evidence indicates that the interaction of unknown constituents, present in whole-root extracts, with GABA-A receptors could represent the molecular base for the sedative and anti-anxiety effect observed in humans.

Comments/Opinions: Valerian is growing in stature as a potential non-addictive substitute for benzodiazepines. This in vitro study completed in Italy serves to deepen our understanding aborn the activity of valerian in the central nervous system (CNS).

Sedation in the CNS is mainly mediated by the inhibitory neurotransmitter GABA through the GABA-A receptors. Important modulatory sites have been shown for GABA-A chloride channel receptor complex, like central benzodiazepine receptors and barbiturate receptors (like those observed in this study).

The findings in this study support previous clinical findings that indicate the ability of an aqueous extract of valerian to reduce sleep latency (sedation) and as a useful tool in reducing the need for benzodiazepines like xanax and valium. The additional information on barbiturate-receptor binding may indicate a place for valerian in withdrawal from the barbiturate category of drugs also. The impact on these receptors is 50 to 100 times lower than that of the reference drug (somewhat analogous to the impact that plant estrogens have on estrogen receptors in the body).

It is also interesting to note that most of the major phytopharmceutical companies producing valerian root extracts in Europe have chosen to remove the valepotriates in the finished product. Long thought to be the primary active constituent group with'regard to sedation, valepotriates may have some carcinogenic potential according to limited in vitro studies. This study indicates that the valepotriate-free extracts now being used have the same potential for sedation and anti-anxiety activity.

Natural Product Research Consultants, Inc.

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By D. Brown

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