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St. John’s Wort

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.

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St. John’s Wort

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  1. St. John’s Wort Does it do anything?

  2. 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

  3. 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

  4. 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

  5. Chemical Constituents • Substances found and described using various chromatographic methods (esp. HPLC). • Flavonol derivatives • Biflavones • Proanthocyanidines • Xanthones • Phloroglucinols* • Naphthodianthrones* • *Most notable: hypericin and hyperforin

  6. 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).

  7. 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.

  8. 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

  9. 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…

  10. 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

  11. 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

  12. 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.

  13. 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.

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