Valeriana officinalis has been used in traditional medicine for its sedative, hypnotic, and anticonvulsant effects. There are several reports in the literature supporting a GABAergic mechanism of action for valerian. Valerian (British Pharmaceutical Codex, 1963) consists of the dried rhizome or roots of Valeriana officinalis containing not less than 18% alcohol (60%)-soluble extractive. It has been used in the form of infusion, tinctures (1 in 8 prepared by maceration in alcohol [60%]; dose 4-8 mL, Tinct. Valerian Simp, British Pharmaceutical Codex, 1949) to calm. Some evidence has already been presented that indicates that the anxiolytic and sedative effects of valerian involve the GABAergic system. In vitro, the aqueous and hydroalcoholic extracts of Valeriana officinalis L. displace [3H]muscimol from GABAA receptor (36,37). Yuan et al. made the important observation that valerian extract (3 mg/mL) and valerenic acid (100 pM) inhibit the firing rate in most brainstem neurons with IC50 values of 240 mg/mL and 23 mM, respectively (37). Bicuculline antagonized the inhibitory effects of both the valerian extract and valerenic acid.
The rhizomes and roots of Valeriana wallichii DC. contain 6-methylapigenin, which is a competitive ligand for GABAA receptor (38). In the Asia-Pacific region, Nar-dostachys chinensis L., Nardostachys jatamansis DC., Patrinia scabiosaefolia Link, Valeriana officinalis L., Valeriana dageletiana Nak. ex Maekawa, and Valeriana hardwickii Wall. are used as alternative remedies.
Nardostachys chinensis L. is an herb that grows to a height of 50 cm. The stem is erect and develops from an aromatic rhizome. The leaves are linear and somewhat spathulate. The flowers are small, tubular, and packed in a terminal cyme (Fig. 47). In China, the rhizome is used to treat swollen ankles, assuage toothache, and is given for congested chest and stomach. The plant is interesting because it elaborates a sesquiter-pene known as nardosinone, which is an enhancer of the neuritogenic action of dibu-tyryl cyclic (dbc)AMP and staurosporine, hence the potential as a pharmacological tool for studying the mechanism of action of neuritogenic substances. Nardosinone enhances staurosporine- or dbcAMP-induced neurite growth from PC12D cells in a
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