St. John’s Wort Does it do anything?
Taxonomy • Kingdom Plantae • Subkingdom Tracheobionta • Superdivision Spermatophyta • Division Magnoliophyta • Class Magnoliopsida • Subclass Dilleniidae • Order Theales • Family Clusiaceae • Genus Hypericum L. • Species Hypericum perforatum L. • Common Names--St. John's wort, hypericum, Klamath weed, goat weed
Botanical Information • Considered a weed in many areas • Perennial • Rhizomous • Native to Europe • Found in Europe, North America, & Asia • Grows well in sandy, dry soil with few nutrients as long as it has ample sun
Distribution and Use • Leaves are used for antidepressant and other purposes • Flowers are used to promote wound healing • Alcoholic extracts commonly available in your local grocery store • Usually in pill form or tea-ointments or other dermal applications also used • Typical Dose: ~2g of herb or 500-1800 mg extract per day • Over $200 million in sales in the US. Over $500 million worldwide
Chemical Constituents • Substances found and described using various chromatographic methods (esp. HPLC). • Flavonol derivatives • Biflavones • Proanthocyanidines • Xanthones • Phloroglucinols* • Naphthodianthrones* • *Most notable: hypericin and hyperforin
Pharmacokinetics • Metabolized by cytochrome P450 in the liver (like many drugs) • Hypericin may not cross the blood-brain barrier, hyperforin more likely an active ingredient • Most of the purported active ingredients are heterocyclic and are metabolized quickly (half life < 6 hrs).
Pharmacodynamics • Weak Inhibitor of MAO • Weak Reuptake Inhibitor of NE, DA, & 5-HT • Weak direct agonist of GABAA, GABAB, adenosine, & glutamate receptors • Causes upregulation of 5-HT2 receptors and downregulation of β-adrenergic receptors • These effects exerted by a combination of hypericin, hyperforin and several flavonoids.
Animal Models • Extracts increased performance of rats in forced swim test. • Protected against effects of stress in learned helplessness experiments (also rats) • These effects observed using methanol extracts containing hypericin, hyperforin and several flavonoids. Pure hypericin was ineffective. • Reduced alcohol withdrawal in rats
Clinical Trials • Big 2001 study funded by NIMH and Pfizer found St. John’s Wort did not relieve major depression any more than a placebo • Herbalists slam big 2001 study funded by NIH • Older studies mixed; review finds “inconsistent an confusing results” • Dropout rates/side effects • Mixed results may be due to poorly characterized St. John’s Wort, as well as inconsistent measurements of depressive symptoms…
More Clinical Trials • Limited research on anxiety disorders • No better than a placebo at treating social phobia • Ineffective in treating neuropathic pain • “Subthreshold” depression • 9 current trials funded by NCCAM • Antiviral studies
Toxicology • Allergic Reactions (rare but serious) • Photosensitization • Hypericism in animals-causes severe skin irritation and loss of appetite • Alters pharmacokinetics of other drugs by inducing CYP3A4 and altering P-glycoprotein • Interaction with medication-including antidepressants • Rarely toxic in humans
References • Butterweck V, Wall A, Lieflaender-Wulf U, et al. 1997. Effects of the total extract and fractions of Hypericum perforatum in animal assays for antidepressant activity. Pharmacopsychiatry, 30 Suppl. 2, 117-24 • Butterweck, V. 2003. Mechanism of action of St John’s wort in depression: What is known?, CNS Drugs,17(8), 539-562 • Coskun, I., Uzbay, I., Ozturk, N., & Ozturk, Y. 2006. Attenuation of ethanol withdrawal syndrome by extract of Hypericum perforatum in Wistar rats. Fundamental and Clinical Pharmacology, 20(5), 481-488. • Gambrana C, Ghiglieri O, Tolu P, et al. 1999. Efficacy of an Hypericum perforatum (St John’s wort) extract in preventing and reverting a condition of escape deficit in rats. Neuropsychopharmacology,21(2), 247-54 • Hypericum Depression Trial Study Group. 2002. Effect of Hypericum perforatum (St. John's wort) in major depressive disorder: a randomized controlled trial. Journal of the American Medical Association. 287(14), 1807–1814.
More References • Linde K, Mulrow CD, Berner M, Egger M. 1998. St John's Wort for depression. Cochrane Database of Systematic Reviews • Schulz, V. 2006. Safety of St. John's Wort extract compared to synthetic antidepressants. Phytomedicine, 13(3), 199-205. • Sindrup, S., Madsen, C., Bach, F., Gram, L., & Jensen, T. 2001. St. John's wort has no effect on pain in polyneuropathy. Pain, 91(3), 61-65. • Wonnemann M, Singer A, Siebert B, et al. 2001. Evaluation of synaptosomal uptake inhibition of most relevant constituents of St John’s wort. Pharmacopsychiatry,41 Suppl. 1, S148-S51. • Wurglics, M. & Schubert-Zsilavecz, M. 2006. Hypericum perforatum: A modern herbal antidepressant: pharmacokinetics of active ingredients. Clinical Pharmacokinetics, 45(5), 449-469.