St John's wort

From Wikipedia, the free encyclopedia

Jump to: navigation, search
St John's wort

Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Malpighiales
Family: Clusiaceae
Genus: Hypericum
Species: H. perforatum
Binomial name
Hypericum perforatum
L.

St John's wort (pronounced /seɪntˈdʒɒnzwərt/, or spelling pronunciations in /-wɔrt/)[1] is the plant species Hypericum perforatum, also known as Tipton's Weed or Klamath weed, but, with qualifiers, is used to refer to any species of the genus Hypericum. Therefore, H. perforatum is sometimes called Common St John's wort to differentiate it. The species of Hypericum have been placed by some in the family Hypericaceae, but more recently have been included in the Clusiaceae.[2] Approximately 370 species of the genus Hypericum exist worldwide with a native geographical distribution including temperate and subtropical regions of North America, Europe, Asia Minor, Russia, India, and China. St. John's wort is today most widely known as an herbal treatment for depression. According to the Cochrane Review, a key resource in evidence-based medicine, "the available evidence suggests that the hypericum extracts tested in the included trials are superior to placebo in patients with major depression; are similarly effective as standard antidepressants; and have fewer side effects than standard antidepressants."[3]

Contents

[edit] The plant

Hypericum perforatum is a yellow-flowering, stoloniferous or sarmentose, perennial herb indigenous to Europe, which has been introduced to many temperate areas of the world and grows wild in many meadows. The common name comes from its traditional flowering and harvesting on St John's day, 24 June. The genus name Hypericum is derived from the Greek words hyper (above) and eikon (picture), in reference to the traditional use of the plant to ward off evil, by hanging plants over a religious icon in the house during St John's day. The species name perforatum refers to the presence of small oil glands in the leaves that look like windows, which can be seen when they are held against the light.

Although Hypericum perforatum is grown commercially in some regions of south east Europe, it is listed as a noxious weed in more than twenty countries and has introduced populations in South America, India, New Zealand, Australia, and South Africa.[4] In pastures, St John’s wort acts as both a toxic and invasive weed.[5] It replaces useful vegetation to the extent of making productive land unviable or acts as an alien species in natural ecosystems. Ingestion by livestock can cause photosensitization, central nervous system depression, spontaneous abortion, and can lead to death. Effective herbicides for control of Hypericum include 2,4-D, picloram, and glyphosate. In western North America three beetles Chrysolina quadrigemina, Chrysolina hyperici and Agrilus hyperici have been introduced as biocontrol agents.

[edit] Identification

St John’s wort can be visually recognized by leaf and flower type. Yellow, five petaled flowers approximately 20 mm across occur between late Spring and early to mid Summer. Leaves exhibit obvious translucent dots when held up to the light, giving them a ‘perforated’ appearance, hence the plant's Latin name. When flowers or seed pods are crushed, a reddish/purple liquid is produced.

The translucent dots on the St John's wort leaves

[edit] Botanical description

St John's wort is a perennial plant with extensive, creeping rhizomes. Its stems are erect, branched in the upper section, and can grow to 1 m high. It has opposing, stalkless, narrow, oblong leaves which are 12 mm long or slightly larger. The leaves are yellow-green in color, with transparent dots throughout the tissue and occasionally with a few black dots on the lower surface. Its flowers measure up to 2.5 cm across, have five petals, and are colored bright yellow with conspicuous black dots. The flowers appear in broad cymes at the ends of the upper branches. The sepals are pointed, with glandular dots in the tissue. There are many stamens, which are united at the base into three bundles.

[edit] Ecology

St John’s wort has a complex life cycle that includes a mature plant cycle with vegetative and sexual reproduction. It thrives in areas with either a winter- or summer-dominant rainfall pattern; however, distribution is restricted by temperatures too low for seed germination or seedling survival. Altitudes greater than 1500 m, rainfall less than 500 mm, and a daily mean January temperature greater than 24 degrees are considered limiting thresholds. Depending on environmental and climatic conditions, and rosette age, St John’s wort will alter growth form and habit to promote survival. Summer rains are particularly effective in allowing the plant to grow vegetatively, following defoliation by insects or grazing.

The seeds can persist for decades in the soil seed bank, germinating following disturbance.[4]

[edit] Medicinal use

St John's wort is today most widely known as a herbal treatment for depression. In some countries, such as Germany, it is commonly prescribed for mild depression, especially in children, adolescents, and where cost is a concern.[6] Standardized extracts are generally available over the counter — however, in some countries (such as Ireland) a prescription is required. Extracts are usually in tablet or capsule form, and also in teabags and tinctures.

[edit] Earaches, ear infections, tinnitus

St. John's wort is also used in its extract form in ear oils/drops for ear infections, ear pain, or tinnitus. The dosage of this is likely lower than those used for depression but is still unknown.

[edit] Major depressive disorder

Seedlings of St John's wort

An analysis of 29 clinical trials with more than 5000 patients was conducted by Cochrane Collaboration. The review concluded that extracts of St. John's wort were superior to placebo in patients with major depression. St. John's wort had similar efficacy to standard antidepressants. The rate of side effects was twice lower than for newer SSRI antidepressants and five times lower than for older tricyclic antidepressants.[3]

National Center for Complementary and Alternative Medicine (NCCAM), a U.S Government Agency and other NIH-affiliated organizations hold that St John's wort has minimal or no effects beyond placebo in the treatment of major depression[7][8] This conclusion is based primarily on one trial with negative outcome conducted by NCCAM.[9] The authors of the study themselves, as well as several others pointed out the low assay sensitivity of this study, and how only limited conclusions can be drawn from its results.[10][11]

St. John's wort was not effective for patients suffering from dysthymia, a less severe and more chronic variety of depression.[12]

[edit] Other medical uses

A constituent chemical, hyperforin may be useful for treatment of alcoholism, although dosage, safety and efficacy have not been studied.[13] Hyperforin has also been found to have antibacterial properties against gram-negative bacteria, although dosage, safety and efficacy has not been studied.[14]

Hyperforin has been shown to inhibit the reuptake of the neurotransmitter norepinephrine, leading to speculation that it might alleviate the symptoms of attention-deficit hyperactivity disorder (ADHD). A randomized controlled trial of St. John's wort found no significant difference between it and placebo in the management of ADHD symptoms over eight weeks. However, the St. John's Wort extract used in the study, originally confirmed to contain 0.3% hypericin, was allowed to degrade to levels of 0.13% hypericin and 0.14% hyperforin. Given that the level of hyperforin was not ascertained at the beginning of the study, and levels of both hyperforin and hypericin were well below that used in other studies, little can be determined based on this study alone.[15]

[edit] Adverse effects and drug interactions

St John's wort is generally well tolerated, with an adverse effect profile similar to placebo.[16] The most common adverse effects reported are gastrointestinal symptoms, dizziness, confusion, tiredness and sedation.[17]

St John's wort may rarely cause photosensitivity. This can lead to visual sensitivity to light and to sunburns in situations that would not normally cause them.[16] Related to this, recent studies concluded that the extract reacts with light, both visible and ultraviolet, to produce free radicals, molecules that can damage the cells of the body. These can react with vital proteins in the eye which, if damaged, precipitate out causing cataracts.[18]

[edit] Pharmacokinetic interactions

St John's wort has been shown to cause multiple drug interactions mainly through induction of the cytochrome P450 enzyme CYP3A4, but also CYP2C9. This results in the increased metabolism of those drugs, resulting in decreased concentration and clinical effect. The principal constituent thought to be responsible is hyperforin.

Examples of drugs causing clinically-significant interactions with St John's wort
Class Drugs
antiretrovirals non-nucleoside reverse transcriptase inhibitors, protease inhibitors
benzodiazepines alprazolam, midazolam
hormonal contraception combined oral contraceptives
immunosuppressants calcineurin inhibitors, cyclosporin, tacrolimus
others digoxin, methadone, omeprazole, phenobarbitol, theophylline, warfarin, levodopa, suboxone, Irinotecan
Reference: Rossi, 2005

For a complete list, see CYP3A4 ligands and CYP2C9 ligands. For further updating on interactions and appropriate management, see Herbological.com - St John's Wort Interactions table.

[edit] Pharmacodynamic interactions

St John's wort may also contribute to serotonin syndrome in combination with other drugs which may elevate 5-HT (serotonin) levels in the central nervous system (CNS).[19]

Drugs which may contribute to serotonin syndrome with St John's wort
Class Drugs
Antidepressants MAOIs, TCAs, SSRIs, mirtazapine, venlafaxine
Opioids tramadol, pethidine
CNS stimulants phentermine, diethylpropion, amphetamines, sibutramine, cocaine
5-HT1 agonists triptans
Psychedelic drugs methylenedioxymethamphetamine (MDMA), lysergic acid diethylamide (LSD)
Others selegiline, tryptophan, buspirone, lithium, linezolid, dextromethorphan, 5-HTP
Reference: Rossi, 2005

[edit] Chemical composition

Hyperforin
Hypericin

Herb and flowers contain different flavonoids (rutin, hyperoside, isoquercetin, quercitrin, quercetin, I3,II8-biapigenin, amentoflavone, astilbin, miquelianin), phenolic acids (chlorogenic acid, 3-O-coumaroylquinic acid), different naphtodianthrones (hypericin, pseudohypericin, protohypericin, protopseudohypericin), phloroglucinols (hyperforin, adhyperforin), and also essential oils (composed mainly of sesquiterpenes). The naphthodianthrones hypericin and pseudohypericin along with the phloroglucinol derivative hyperforin are thought to be the active components.

[20][21][22].

[edit] Pharmacology

The exact mechanism by which St John's wort — and even conventional antidepressants — functions is unclear and subject to conjecture. The St John's wort mechanism is believed to involve inhibition of serotonin (5-HT) reuptake, much like the conventional selective serotonin reuptake inhibitor (SSRI) antidepressants.[23] The major active antidepressive constituents in St John's wort are thought to be hyperforin and hypericin, although other biologically active constituents present, for example, flavonoids and tannins, may also be involved.[24][25][26]

Some believe that hyperforin is the major constituent responsible for antidepressant activity, and it has been shown to inhibit the uptake of 5-HT, dopamine, noradrenaline, GABA and glutamate. [25] On the other hand, a hyperforin free extract of St John's wort (Ze 117 - Remotiv) has been shown to still have significant antidepressive effects.[27][28]

[edit] Hypericum poisoning (livestock)

[edit] Clinical signs

In large doses, St John's wort is poisonous to grazing livestock (cattle, sheep, goats, horses).[5]

St John's Wort, New England (Australia)

Behavioural signs of poisoning are general restlessness and skin irritation. Restlessness is often indicated by pawing of the ground, head shaking, head rubbing, and occasional hindlimb weakness with knuckling over, panting, confusion and depression. Mania and hyperactivity may also result including running in circles until exhausted. Observations of thick wort infestations by Australian graziers include the appearance of circular patches giving hillsides a ‘crop circle’ appearance, possibly from this phenomenon. Animals typically seek shade and have reduced appetite. Hypersensitivity to water has been noted, and convulsions may occur following a knock to the head. Although general aversion to water is noted, some may seek water for relief.

Severe skin irritation is physically apparent, with reddening of non-pigmented and unprotected areas. This subsequently leads to itch and rubbing, followed by further inflammation, exudation and scab formation. Lesions and inflammation that occur are said to resemble the conditions seen in foot and mouth disease. Sheep have been observed to have face swelling, dermatitis, and wool falling off due to rubbing. Lactating animals may cease or have reduced milk production, pregnant animals may abort. Lesions on udders are often apparent. Horses may show signs of anorexia, depression (with a comatose state), dilated pupils, and injected conjunctiva.

[edit] Early diagnosis

Increased respiration and heart rate is typically observed while one of the early signs of St John’s wort poisoning is an abnormal increase in body temperature. Affected animals will lose weight, or fail to gain weight; young animals more affected than old animals. In severe cases death may occur, as a direct result of starvation, or because of secondary disease or septicaemia of lesions. Some affected animals may accidentally drown. Poor performance of suckling lambs (pigmented and non-pigmented) has been noted, suggesting a reduction in the milk production, or the transmission of a toxin in the milk.

[edit] Photosensitisation

Most clinical signs are caused by photosensitisation.[29] Plants may induce either primary or secondary photosensitisation: primary photosensitisation directly from chemicals contained in ingested plants, or secondary photosensitisation from plant-associated damage to the liver. Araya and Ford (1981) explored changes in liver function and concluded there was no evidence of Hypericum-related effect on the excretory capacity of the liver, or any interference was minimal and temporary. However, at high and continuous dose rates changes in blood plasma indicative of some liver damage have been observed.

Photosensitisation causes skin inflammation by a mechanism involving a pigment or photodynamic compound, which when activated by a certain wavelength of light leads to oxidation reactions in vivo. This leads to lesions of tissue, particularly noticeable on and around parts of skin exposed to light. Lightly covered or poorly pigmented areas are most conspicuous. Removal of affected animals from sunlight results in reduced symptoms of poisoning.

[edit] History

The first recorded use of Hypericum for medicinal purposes dates back to ancient Greece, and it has been used ever since. Hypericum was also used by Native Americans internally as an abortifacient and externally as an anti-inflammatory, astringent, and antiseptic.

Its use as a herbal tea has long been enjoyed.

The flowers and stems of St John's wort have also been used to produce red and yellow dyes.

[edit] References

  1. ^ Random House
  2. ^ "#914: Hypericum frondosum - Floridata.com". http://www.floridata.com/ref/H/hype_fro.cfm. Retrieved on 2008-11-02. 
  3. ^ a b Linde K, Berner MM, Kriston L (2008). "St John's wort for major depression". Cochrane Database Syst Rev 8 (4): CD000448. doi:10.1002/14651858.CD000448.pub3. PMID 18843608. 
  4. ^ a b "SPECIES: Hypericum perforatum". Fire Effects Information System. http://www.invasive.org/weedcd/pdfs/feis/Hypericumperforatum.pdf. 
  5. ^ a b St John's wort
  6. ^ Fegert JM, Kölch M, Zito JM, Glaeske G, Janhsen K (2006). "Antidepressant use in children and adolescents in Germany". J Child Adolesc Psychopharmacol 16 (1-2): 197–206. doi:10.1089/cap.2006.16.197. PMID 16553540. 
  7. ^ St. John's Wort and Depression NCCAM on St John's wort and depression]
  8. ^ How is depression detected and treated? NIMH on depression, including a section on St John's wort
  9. ^ Hypericum Depression Trial Study Group (2002). "Effect of Hypericum perforatum (St John's wort) in major depressive disorder: a randomized controlled trial". JAMA 287 (14): 1807–14. doi:10.1001/jama.287.14.1807. PMID 11939866. 
  10. ^ Kupfer DJ, Frank E (2002). "Placebo in clinical trials for depression: complexity and necessity". JAMA 287 (23): 1853–4. doi:10.1001/jama.287.14.1853. PMID 11939872. 
  11. ^ Spielmans GI (2002). "St John's wort and depression". JAMA 288 (4): 448–9. PMID 12132963. 
  12. ^ Randløv C, Mehlsen J, Thomsen CF, Hedman C, von Fircks H, Winther K (2006). "The efficacy of St. John's Wort in patients with minor depressive symptoms or dysthymia--a double-blind placebo-controlled study". Phytomedicine 13 (4): 215–21. doi:10.1016/j.phymed.2005.11.006. PMID 16423519. 
  13. ^ Kumar V, Mdzinarishvili A, Kiewert C, et al. (September 2006). "NMDA receptor-antagonistic properties of hyperforin, a constituent of St. John's Wort" ([dead link]). J. Pharmacol. Sci. 102 (1): 47–54. doi:10.1254/jphs.FP0060378. PMID 16936454. http://joi.jlc.jst.go.jp/JST.JSTAGE/jphs/FP0060378?from=PubMed. 
  14. ^ Cecchini C, Cresci A, Coman MM, et al. (June 2007). "Antimicrobial activity of seven hypericum entities from central Italy". Planta Med. 73 (6): 564–6. doi:10.1055/s-2007-967198. PMID 17516331. 
  15. ^ Weber, Wendy; Ann Vander Stoep, Rachelle L. McCarty, Noel S. Weiss, Joseph Biederman, Jon McClellan (2008-06-11). "Hypericum perforatum (St John's Wort) for Attention-Deficit/Hyperactivity Disorder in Children and Adolescents". Journal of the American Medical Association 299 (22): 2633–2641. doi:10.1001/jama.299.22.2633. PMID 18544723. http://jama.ama-assn.org/cgi/content/full/299/22/2633. Retrieved on 2009-03-22. 
  16. ^ a b Ernst E, Rand JI, Barnes J, Stevinson C (1998). Adverse effects profile of the herbal antidepressant St. John's wort (Hypericum perforatum L.). Eur J Clin Pharmacol 54 (8), 589-94.
  17. ^ Barnes J, Anderson LA, Phillipson JD (2002). Herbal Medicines: A guide for healthcare professionals (2 ed.) London: Pharmaceutical Press. ISBN 0-85369-474-5. Parker, V; Wong, AH; Boon, HS; Seeman, MV (February). "Adverse reactions to St John's Wort.". Canadian Journal of Psychiatry 46 (1): 77–79. http://www.ncbi.nlm.nih.gov/pubmed/11221494. 
  18. ^ Schey KL, Patat S, Chignell CF, Datillo M, Wang RH, Roberts JE (August 2000). "Photooxidation of lens alpha-crystallin by hypericin (active ingredient in St. John's Wort)". Photochem. Photobiol. 72 (2): 200–3. doi:10.1562/0031-8655(2000)072<0200:POLCBH>2.0.CO;2. PMID 10946573. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0031-8655&date=2000&volume=72&issue=2&spage=200. 
  19. ^ Rossi S (Ed.) (2005). Australian Medicines Handbook 2005. Adelaide: Australian Medicines Handbook. ISBN 0-9578521-9-3.
  20. ^ Umek A, Kreft S, Kartnig T, Heydel B.Quantitative phytochemical analyses of six hypericum species growing in slovenia. Planta Med. 1999;65:388-90 [1]
  21. ^ Tatsis EC, Boeren S, Exarchou V, Troganis AN, Vervoort J, Gerothanassis IP.Identification of the major constituents of Hypericum perforatum by LC/SPE/NMR and/or LC/MS. Phytochemistry. 2007;68:383-93. [2]
  22. ^ Schwob I, Bessière JM, Viano J.Composition of the essential oils of Hypericum perforatum L. from southeastern France.C R Biol. 2002;325:781-5.
  23. ^ Leuner K, Kazanski V, Müller M, Essin K, Henke B, Gollasch M, Harteneck C, Müller WE (2007). "Hyperforin--a key constituent of St. John's wort specifically activates TRPC6 channels". FASEB J. 21 (14): 4101–11. doi:10.1096/fj.07-8110com. PMID 17666455. 
  24. ^ Nahrstedt A, Butterweck V (1997). "Biologically active and other chemical constituents of the herb of Hypericum perforatum L". Pharmacopsychiatry 30 Suppl 2: 129–34. doi:10.1055/s-2007-979533. PMID 9342774. 
  25. ^ a b Butterweck V (2003). "Mechanism of action of St John's wort in depression : what is known?". CNS Drugs 17 (8): 539–62. doi:10.2165/00023210-200317080-00001. PMID 12775192. 
  26. ^ Müller WE (2003). "Current St John's wort research from mode of action to clinical efficacy". Pharmacol. Res. 47 (2): 101–9. doi:10.1016/S1043-6618(02)00266-9. PMID 12543057. 
  27. ^ Woelk H (2000). "Comparison of St John's wort and imipramine for treating depression: randomised controlled trial". BMJ 321 (7260): 536–9. doi:10.1136/bmj.321.7260.536. PMID 10968813. 
  28. ^ Schrader E (2000). "Equivalence of St John's wort extract (Ze 117) and fluoxetine: a randomized, controlled study in mild-moderate depression". Int Clin Psychopharmacol 15 (2): 61–8. doi:10.1097/00004850-200015020-00001. PMID 10759336. 
  29. ^ St John's wort

[edit] Further reading

  • British Herbal Medicine Association Scientific Committee (1983). British Herbal Pharmacopoeia. West Yorkshire: British Herbal Medicine Association. ISBN 0-903032-07-4

[edit] See also

[edit] External links

Search Wikispecies Wikispecies has information related to: Hypericum
Search Wikimedia Commons Wikimedia Commons has media related to: Hypericum perforatum
Retrieved from "http://en.wikipedia.org/wiki/St_John%27s_wort"
Personal tools