Valerian

A perennial flowering plant whose root has been used as a sedative and anxiolytic since ancient Greece and Rome. Valerian remains one of the most clinically studied herbal sedatives, with substantial evidence supporting its use for insomnia and anxiety.

Herbaceous perennial growing 50–100 cm in the first year, up to 150 cm when flowering. Pinnately divided leaves with 6–10 pairs of lanceolate leaflets. Small white to pale pink flowers in dense cymose inflorescences with a sweet, honey-like fragrance. Roots are short, thick, and yellowish-grey with a distinctive strong, musky odour when dried.

Described by Hippocrates and Galen for insomnia, anxiety, and digestive disorders. In medieval Europe, used as a remedy for epilepsy, nervous unrest, and as a general calmative. Native American tribes used related species (V. wallichii) for wound healing and digestive issues. Traditional use for menstrual cramps, headache, and palpitations. One of the most widely used sedative herbs in Western herbalism and European phytotherapy.

The primary bioactive constituents are valepotriates (0.5–2.0% of root), including valtrate, isovaltrate, and dihydrovaltrate. The iridoid valepotriates are unstable and hydrolyse during drying. Also present is valerenic acid and its derivatives (0.05–0.9%), which are used as marker compounds for standardisation. Essential oil (0.5–2.0%) contains bornyl acetate, valeranone, and camphene. Water-soluble compounds include γ-aminobutyric acid (GABA), glutamine, and arginine.

Valerian's sedative and anxiolytic effects are mediated through multiple GABAergic mechanisms: (1) Valerenic acid acts as a positive allosteric modulator of GABA-A receptors, enhancing GABAergic neurotransmission; (2) Inhibits GABA transaminase (GABA-T), reducing GABA catabolism; (3) May inhibit GABA reuptake at synapses. Valepotriates demonstrate partial agonist activity at central benzodiazepine receptors. Affinity for adenosine A1 receptors may contribute to sedative effects. 5-HT receptor interactions may contribute to anxiolytic and antidepressant activity.

Dried root: 2–3 g infused as tea, taken 30–60 minutes before bedtime. Standardised aqueous extract (0.8% valerenic acids): 400–900 mg, 30–60 minutes before bedtime. Tincture (1:5): 3–5 mL before bedtime. For anxiety: 120–200 mg of standardised extract three times daily. Maximum duration: 2–4 weeks of continuous use without medical supervision.

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