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''Hypericum perforatum'', known as St. John's wort, is a
flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
in the family
Hypericaceae Hypericaceae is a plant family in the order Malpighiales, comprising six to nine genera and up to 700 species, and commonly known as the St. John's wort family. Members are found throughout the world apart from extremely cold or dry habitats. ' ...
and the
type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...
of the genus ''
Hypericum ''Hypericum'' is a genus of flowering plants in the family Hypericaceae (formerly considered a subfamily of Clusiaceae). The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. Many ''Hy ...
''. Possibly a hybrid between '' H. maculatum'' and '' H. attenuatum'', the species can be found across temperate areas of Eurasia and has been introduced as an
invasive weed An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
to much of North and South America, as well as South Africa and Australia. While the species is harmful to livestock and can interfere with
prescription drug A prescription drug (also prescription medication or prescription medicine) is a pharmaceutical drug that legally requires a medical prescription to be dispensed. In contrast, over-the-counter drugs can be obtained without a prescription. The re ...
s, it has been used in
folk medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...
over centuries, and remains commercially cultivated in the 21st century.
Hyperforin Hyperforin is a phytochemical produced by some of the members of the plant genus ''Hypericum'', notably ''Hypericum perforatum'' (St John's wort). Hyperforin may be involved in the pharmacological effects of St. John's wort, specifically in its ...
, a
phytochemical Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poisons ...
constituent of the species, is under basic research for possible therapeutic properties.


Description

''Hypericum perforatum'' is an
herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition o ...
perennial plant A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
with extensive, creeping
rhizomes In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ho ...
. Its reddish stems are erect and branched in the upper section, and can grow up to high. The stems are woody near their base and may appear jointed from
leaf scar A leaf scar is the mark left by a leaf after it falls off the twig. It marks the site where the petiole attached to the stem. A leaf scar is typically found below a branch as branches come from axillary buds located above leaf scars. Formation Le ...
s. The branches are typically clustered about a depressed base. It has opposite and stalkless leaves that are narrow and oblong in shape and long. Leaves borne on the branches subtend the shortened branchlets. The leaves are yellow-green in color, with scattered
translucent In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions a ...
dots of glandular tissue. The dots are conspicuous when held up to the light, giving the leaves a perforated appearance. The flowers measure up to across, have five petals and
sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined ...
s, and are colored bright yellow with conspicuous black dots. The flowers appear in broad helicoid cymes at the ends of the upper branches, between late spring and early to mid-summer. The cymes are leafy and bear many flowers. The pointed sepals have black glandular dots. The many
stamens The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...
are united at the base into three bundles. The pollen grains are
ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface;  that is, a surface that may be defined as the z ...
al. The black and
lustrous Lustre (British English) or luster (American English; see spelling differences) is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin ''lux'', meaning "light", and generally im ...
seeds are rough, netted with coarse grooves. When flower buds (not the flowers themselves) or seed pods are crushed, a reddish or purple liquid is produced.


Chemistry

The plant contains the following: *
Flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...
s (e.g.
epigallocatechin Gallocatechol or gallocatechin (GC) is a flavan-3-ol, a type of chemical compound including catechin, with the gallate residue being in an isomeric trans position. This compound possesses two epimers. The most common, (+)-gallocatechin (GC), CAS ...
,
rutin Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is the glycoside combining the flavonol quercetin and the disaccharide rutinose (α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranose). It is a flavonoid found in a wide variety of pla ...
,
hyperoside Hyperoside is a chemical compound. It is the 3-''O''- galactoside of quercetin. Natural occurrences Hyperoside has been isolated from ''Drosera rotundifolia'', from the Lamiaceae ''Stachys sp.'' and ''Prunella vulgaris'', from ''Rumex acetosell ...
,
isoquercetin Isoquercetin, isoquercitrin or isotrifoliin is a flavonoid, a type of chemical compound. It is the 3-''O''-glucoside of quercetin. Isoquercitrin can be isolated from various plant species including ''Mangifera indica'' (mango) and '' Rheum nobile'' ...
,
quercitrin Quercitrin is a glycoside formed from the flavonoid quercetin and the deoxy sugar rhamnose. Austrian chemist Heinrich Hlasiwetz (1825-1875) is remembered for his chemical analysis of quercitrin. Occurrence Quercitrin is a constituent of the d ...
,
quercetin Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor a ...
,
amentoflavone Amentoflavone is a biflavonoid (''bis''-apigenin coupled at 8 and 3' positions, or 3′,8′′-biapigenin) constituent of a number of plants including '' Ginkgo biloba'', ''Chamaecyparis obtusa'' (hinoki), ''Hypericum perforatum'' (St ...
, biapigenin,
astilbin Astilbin is a flavanonol, a type of flavonoid. Astilbin is the (2R-trans)-isomer; neoisoastilbin is the (2S-cis)-isomer and isoastilbin is the (2R-cis)-isomer. Natural occurrences Astilbin can be found in St John's wort (''Hypericum perforatum'' ...
,
myricetin Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is structu ...
,
miquelianin Miquelianin (quercetin 3-''O''-glucuronide) is a flavonol glucuronide, a type of phenolic compound present in wine, in species of St John's wort, like '' Hypericum hirsutum'', in ''Nelumbo nucifera'' (Indian lotus) or in green beans. It is also ...
,
kaempferol Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. Kaempferol is a yellow crystalline solid with a melting ...
,
luteolin Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance. Luteolin is the principal yellow dye compound that is obtained from the plant ''Reseda luteola'', which has been used as a source of the dye since at least the firs ...
) *
Phenolic acid Phenolic acids or phenolcarboxylic acids are types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important naturally occurring types of p ...
s (e.g.
chlorogenic acid Chlorogenic acid (CGA) is the ester of caffeic acid and (−)-quinic acid, functioning as an intermediate in lignin biosynthesis. The term "chlorogenic acids" refers to a related polyphenol family of esters, including hydroxycinnamic acids (caffe ...
,
caffeic acid Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is an intermediate in the biosynthesis of lignin, on ...
, p-coumaric acid,
ferulic acid Ferulic acid is a hydroxycinnamic acid, an organic compound with the formula (CH3O)HOC6H3CH=CHCO2H. The name is derived from the genus ''Ferula'', referring to the giant fennel (''Ferula communis''). Classified as a phenolic phytochemical, ferulic ...
,
p-hydroxybenzoic acid 4-Hydroxybenzoic acid, also known as ''p''-hydroxybenzoic acid (PHBA), is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar ...
,
vanillic acid Vanillic acid (4-hydroxy-3-methoxybenzoic acid) is a dihydroxybenzoic acid derivative used as a flavoring agent. It is an oxidized form of vanillin. It is also an intermediate in the production of vanillin from ferulic acid. Occurrence in nat ...
) *
Naphthodianthrone ''For the parent molecule 9,10-anthraquinone, see anthraquinone'' Anthraquinones (also known as anthraquinonoids) are a class of naturally occurring phenolic compounds based on the 9,10-anthraquinone skeleton. They are widely used industrially a ...
s (e.g.
hypericin Hypericin is a naphthodianthrone, an anthraquinone derivative which, together with hyperforin, is one of the principal active constituents of ''Hypericum'' (Saint John's wort). Hypericin is believed to act as an antibiotic, antiviral and non-spec ...
, pseudohypericin, protohypericin, protopseudohypericin) *
Phloroglucinol Phloroglucinol is an organic compound with the formula C6H3(OH)3. It is a colorless solid. It is used in the synthesis of pharmaceuticals and explosives. Phloroglucinol is one of three isomeric benzenetriols. The other two isomers are hydroxyqu ...
s (e.g.
hyperforin Hyperforin is a phytochemical produced by some of the members of the plant genus ''Hypericum'', notably ''Hypericum perforatum'' (St John's wort). Hyperforin may be involved in the pharmacological effects of St. John's wort, specifically in its ...
, adhyperforin) *
Tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...
s (unspecified, proanthocyanidins reported) *
Volatile oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...
s (e.g. 2-methyloctane,
nonane Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tracto ...
, 2-methyldecane,
undecane Undecane (also known as hendecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)9CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants.Hölldobler B, Wils ...
,
α-pinene α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also ...
, β-pinene, α-terpineol,
geraniol Geraniol is a monoterpenoid and an alcohol. It is the primary component of citronella oil and is a primary component of rose oil, palmarosa oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in water ...
,
myrcene Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from '' Myrcia'', from which it gets its name. It is an intermediate in the production of several fragrances. � ...
,
limonene Limonene is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the oil of citrus fruit peels. The -isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring a ...
,
caryophyllene Caryophyllene (), more formally (−)-β-caryophyllene, (BCP), is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of '' Syzygium aromaticum'' (cloves), the ess ...
,
humulene Humulene, also known as α-humulene or α-caryophyllene, is a naturally occurring monocyclic sesquiterpene (C15H24), containing an 11-membered ring and consisting of 3 isoprene units containing three nonconjugated C=C double bonds, two of them be ...
) *
Saturated fatty acid A saturated fat is a type of fat in which the fatty acid chains have all single bonds. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched c ...
s (e.g. isovaleric acid (3-methylbutanoic acid),
myristic acid Myristic acid (IUPAC name: tetradecanoic acid) is a common saturated fatty acid with the molecular formula CH3(CH2)12COOH. Its salts and esters are commonly referred to as myristates or tetradecanoates. It is named after the binomial name for nut ...
,
palmitic acid Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra. The L ...
,
stearic acid Stearic acid ( , ) is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a waxy solid and its chemical formula is C17H35CO2H. Its name comes from the Greek word στέαρ "''stéar''", which means tallow. ...
) *
Alkanol In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...
s (e.g. 1-tetracosanol, 1-hexacosanol) *
Vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrien ...
s & their analogues (e.g.
carotenoids Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, co ...
,
choline Choline is an essential nutrient for humans and many other animals. Choline occurs as a cation that forms various salts (X− in the depicted formula is an undefined counteranion). Humans are capable of some ''de novo synthesis'' of choline but ...
,
nicotinamide Niacinamide or Nicotinamide (NAM) is a form of vitamin B3 found in food and used as a dietary supplement and medication. As a supplement, it is used by mouth to prevent and treat pellagra (niacin deficiency). While nicotinic acid (niacin) may ...
,
nicotinic acid Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
) * Miscellaneous others (e.g.
pectin Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component o ...
,
β-sitosterol β-sitosterol (beta-sitosterol) is one of several phytosterols (plant sterols) with chemical structures similar to that of cholesterol. It is a white, waxy powder with a characteristic odor, and is one of the components of the food additive E49 ...
, hexadecane, triacontane, kielcorin, norathyriol) The naphthodianthrones hypericin and pseudohypericin along with the phloroglucinol derivative hyperforin are thought to be among the numerous active constituents. It also contains essential oils composed mainly of
sesquiterpene Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificatio ...
s. Hypericin2DACS.svg,
Hypericin Hypericin is a naphthodianthrone, an anthraquinone derivative which, together with hyperforin, is one of the principal active constituents of ''Hypericum'' (Saint John's wort). Hypericin is believed to act as an antibiotic, antiviral and non-spec ...
Pseudohypericin2DACS2.svg, Pseudohypericin Adhyperforin2DACS.svg, Adhyperforin Hyperforin2DACS.svg,
Hyperforin Hyperforin is a phytochemical produced by some of the members of the plant genus ''Hypericum'', notably ''Hypericum perforatum'' (St John's wort). Hyperforin may be involved in the pharmacological effects of St. John's wort, specifically in its ...
Amentoflavone2DACS.svg,
Amentoflavone Amentoflavone is a biflavonoid (''bis''-apigenin coupled at 8 and 3' positions, or 3′,8′′-biapigenin) constituent of a number of plants including '' Ginkgo biloba'', ''Chamaecyparis obtusa'' (hinoki), ''Hypericum perforatum'' (St ...
Hyperoside2DACS.svg,
Hyperoside Hyperoside is a chemical compound. It is the 3-''O''- galactoside of quercetin. Natural occurrences Hyperoside has been isolated from ''Drosera rotundifolia'', from the Lamiaceae ''Stachys sp.'' and ''Prunella vulgaris'', from ''Rumex acetosell ...
Rutin2DACS.svg,
Rutin Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is the glycoside combining the flavonol quercetin and the disaccharide rutinose (α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranose). It is a flavonoid found in a wide variety of pla ...
Kaempferol2DACS.svg,
Kaempferol Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. Kaempferol is a yellow crystalline solid with a melting ...
Myricetin2DACS.svg,
Myricetin Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is structu ...
Quercetin2DACS.svg,
Quercetin Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor a ...
Quercetrin2DACS.svg,
Quercitrin Quercitrin is a glycoside formed from the flavonoid quercetin and the deoxy sugar rhamnose. Austrian chemist Heinrich Hlasiwetz (1825-1875) is remembered for his chemical analysis of quercitrin. Occurrence Quercitrin is a constituent of the d ...
Isoquercitrin2DACS.svg,
Isoquercitrin Isoquercetin, isoquercitrin or isotrifoliin is a flavonoid, a type of chemical compound. It is the 3-''O''-glucoside of quercetin. Isoquercitrin can be isolated from various plant species including ''Mangifera indica'' (mango) and '' Rheum nobile'' ...
Luteolin2DACS.svg,
Luteolin Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance. Luteolin is the principal yellow dye compound that is obtained from the plant ''Reseda luteola'', which has been used as a source of the dye since at least the firs ...
Catechin2DACS.svg,
Catechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from '' catechu'', which is the tanni ...
Epicatechin2DACS.svg,
Epicatechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from '' catechu'', which is the tanni ...
Epigallocatechin2DACS.svg,
Epigallocatechin Gallocatechol or gallocatechin (GC) is a flavan-3-ol, a type of chemical compound including catechin, with the gallate residue being in an isomeric trans position. This compound possesses two epimers. The most common, (+)-gallocatechin (GC), CAS ...
Chlorogenic acid2DACS.svg,
Chlorogenic acid Chlorogenic acid (CGA) is the ester of caffeic acid and (−)-quinic acid, functioning as an intermediate in lignin biosynthesis. The term "chlorogenic acids" refers to a related polyphenol family of esters, including hydroxycinnamic acids (caffe ...
Caffeic acid2DACS.svg,
Caffeic acid Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is an intermediate in the biosynthesis of lignin, on ...
Kielcorin2DACS.svg, Kielcorin Norathyriol2DACS.svg, Norathyriol


Detection in bodily fluids

Hypericin Hypericin is a naphthodianthrone, an anthraquinone derivative which, together with hyperforin, is one of the principal active constituents of ''Hypericum'' (Saint John's wort). Hypericin is believed to act as an antibiotic, antiviral and non-spec ...
, pseudohypericin, and
hyperforin Hyperforin is a phytochemical produced by some of the members of the plant genus ''Hypericum'', notably ''Hypericum perforatum'' (St John's wort). Hyperforin may be involved in the pharmacological effects of St. John's wort, specifically in its ...
may be quantitated in plasma as confirmation of usage and to estimate the dosage. These three active substituents have plasma elimination half-lives within a range of 15–60 hours in humans. None of the three has been detected in urine specimens.


Taxonomy


Phylogeny

It is probable that ''H. perforatum'' originated as a hybrid between two closely related species with subsequent doubling of chromosomes. One species is certainly a
diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...
a
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of '' H. maculatum'', either subspecies ''maculatum'' or ''immaculatum''. Subspecies ''maculatum'' is similar in distribution and hybridizes easily with ''H. perforatum'', but subspecies ''immaculatum'' is more similar morphologically. The other parent is most likely '' H. attenuatum'' as it possesses the features of ''H. perforatum'' that ''H. maculatum'' lacks. Though ''H. maculatum'' is mostly western in its distribution across Eurasia and ''Hypericum attenuatum'' is mostly eastern, both species share distribution in
Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...
, where hybridization likely took place. However, the subspecies ''immaculatum'' now only occurs in south-east Europe.


Etymology

The
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''perforatum'' is
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, referring to the perforated appearance of the plant's leaves. The common name "St John's wort" may refer to any species of the genus ''
Hypericum ''Hypericum'' is a genus of flowering plants in the family Hypericaceae (formerly considered a subfamily of Clusiaceae). The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. Many ''Hy ...
''. Therefore, ''Hypericum perforatum'' is sometimes called "common St John's wort" or "perforate St John's wort" to differentiate it. St John's wort is named as such because it commonly flowers, blossoms and is harvested at the time of the summer solstice in late June, around St John's Feast Day on 24 June. The herb would be hung on house and stall doors on St John's Feast day to ward off evil spirits and to safeguard against harm and sickness to people and live-stock. Alternatively, there may be a connection with the
Knights Hospitaller The Order of Knights of the Hospital of Saint John of Jerusalem ( la, Ordo Fratrum Hospitalis Sancti Ioannis Hierosolymitani), commonly known as the Knights Hospitaller (), was a medieval and early modern Catholic military order. It was headqu ...
. The
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencla ...
name ''Hypericum'' is possibly derived from the
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
words ''hyper'' (above) and ''eikon'' (picture), in reference to the tradition of hanging plants over religious
icon An icon () is a religious work of art, most commonly a painting, in the cultures of the Eastern Orthodox, Oriental Orthodox, and Catholic churches. They are not simply artworks; "an icon is a sacred image used in religious devotion". The most c ...
s in the home during St John's Day.


Distribution and habitat

''H. perforatum'' is native to
temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
parts of Europe and Asia, but has spread to temperate regions worldwide as a
cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...
invasive
weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
. It was introduced to North America from Europe. The species 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 , rainfall less than , and daily mean temperatures greater than are considered limiting thresholds. The flower occurs in prairies, pastures, and disturbed fields. It prefers sandy soils.


Ecology

St John's wort reproduces both
vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or speci ...
and sexually. 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.Ramawat, Kishan Gopal. ''Bioactive Molecules and Medicinal Plants''. Springer Science & Business Media, 2008. p. 152. The seeds can persist for decades in the
soil seed bank The soil seed bank is the natural storage of seeds, often dormant, within the soil of most ecosystems. The study of soil seed banks started in 1859 when Charles Darwin observed the emergence of seedlings using soil samples from the bottom of a lak ...
, germinating following disturbance.


Diseases

''H. perforatum'' is affected by
phytoplasma Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-lik ...
diseases, and when infected with ''Candidatus'' phytoplasma fraxini it undergoes several
phytochemical Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poisons ...
changes and shows visible symptoms, including yellowing and witches' bloom symptoms.
Naphthodianthrone ''For the parent molecule 9,10-anthraquinone, see anthraquinone'' Anthraquinones (also known as anthraquinonoids) are a class of naturally occurring phenolic compounds based on the 9,10-anthraquinone skeleton. They are widely used industrially a ...
,
flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...
,
amentoflavone Amentoflavone is a biflavonoid (''bis''-apigenin coupled at 8 and 3' positions, or 3′,8′′-biapigenin) constituent of a number of plants including '' Ginkgo biloba'', ''Chamaecyparis obtusa'' (hinoki), ''Hypericum perforatum'' (St ...
, and pseudohypericin levels are reduced;
chlorogenic acid Chlorogenic acid (CGA) is the ester of caffeic acid and (−)-quinic acid, functioning as an intermediate in lignin biosynthesis. The term "chlorogenic acids" refers to a related polyphenol family of esters, including hydroxycinnamic acids (caffe ...
levels increased. Additionally, phytoplasma diseases greatly reduced the essential oil yield of the plant.


Invasiveness

Although ''H. perforatum'' is grown commercially in some regions of southeast Europe, it is listed as a
noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or liv ...
in more than twenty countries and has introduced populations in South and North America, India, New Zealand, Australia, and South Africa. In pastures, St John's wort acts as both a toxic and invasive weed. It replaces
native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entertai ...
plant communities A plant community is a collection or association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The components of each plant ...
and
forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...
vegetation to the extent of making productive land nonviable or becoming an invasive species in natural
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s and
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
s. Ingestion by livestock such as horses, sheep, and cattle can cause photosensitization, central nervous system depression, spontaneous abortion, or death.Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962 Effective herbicides for control of ''Hypericum perforatum'' include 2,4-D,
picloram Picloram is a systemic herbicide used for general woody plant control. It also controls a wide range of broad-leaved weeds, but most grasses are resistant.
, and
glyphosate Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshik ...
. In western North America the beetles '' Chrysolina quadrigemina'', '' C. hyperici'', and '' Agrilus hyperici'' have been introduced as
biocontrol Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...
agents.


Toxicity

In large doses, St John's wort is poisonous to grazing livestock. Behavioral signs of poisoning are general restlessness and skin irritation. Restlessness is often indicated by pawing of the ground,
headshaking Headshaking is a behaviour displayed by horses, where the horse continuously shakes its head vertically and/or horizontally. In the 1980s it was considered a bad behaviour, but instead it turned out to be a painful medical condition. Minor head to ...
, 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 grazers include the appearance of circular patches giving hillsides a "crop circle" appearance, it is presumed, from this phenomenon. Animals typically seek shade and have reduced appetites. 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 An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin ''exsūdāre'' 'to (ooze out) sweat' (''ex-'' 'out' and ''sūdāre'' 'to ...
, and scab formation. Lesions and inflammation that occur are said to resemble the conditions seen in
foot and mouth disease Foot-and-mouth disease (FMD) or hoof-and-mouth disease (HMD) is an infectious disease, infectious and sometimes fatal virus (biology), viral disease that affects cloven-hoofed animals, including domestic and wild Bovidae, bovids. The virus causes ...
. 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
udder An udder is an organ formed of two or four mammary glands on the females of dairy animals and ruminants such as cattle, goats, and sheep. An udder is equivalent to the breast in primates and elephantine pachyderms. The udder is a single mass h ...
s are often apparent. Horses may show signs of
anorexia Anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. ''Anorexia'' is a term of Gre ...
, depression (with a comatose state), dilated pupils, and injected
conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium and ...
.


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 are more affected than old animals. In severe cases death may occur, as a direct result of starvation, or because of secondary disease or
septicaemia Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
of lesions. Some affected animals may accidentally drown. Poor performance of suckling lambs (pigmented and non-pigmented) has been noted, suggesting a reduction in milk production, or the transmission of a toxin in the milk. It may result in an undesirable flavor.


Potential for adverse effects

St John's wort may cause
allergic reaction Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermati ...
s and can interact with some
prescription drug A prescription drug (also prescription medication or prescription medicine) is a pharmaceutical drug that legally requires a medical prescription to be dispensed. In contrast, over-the-counter drugs can be obtained without a prescription. The re ...
s. St John's wort is generally well-tolerated, but it may cause
gastrointestinal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
discomfort (such as nausea, abdominal pain, loss of appetite, and diarrhea), dizziness, confusion, fatigue, sedation, dry mouth, restlessness, headache and hypertension. The organ systems associated with
adverse drug reactions An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The meaning of this term ...
to St John's wort and
fluoxetine Fluoxetine, sold under the brand names Prozac and Sarafem, among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is used for the treatment of major depressive disorder, obsessive–compulsive disorde ...
have a similar incidence profile; most of these reactions involve the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
. St John's wort also decreases levels of
estrogens Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activ ...
, such as
estradiol Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development of ...
, by accelerating its metabolism, and women on contraceptive pills are not advised to take it. St. John's wort should not be taken by women during pregnancy or breast-feeding.


Uses


Traditional medicine

Common St John's wort has been used in
herbalism Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remedies ...
for centuries. It was thought to have medical properties in classical antiquity and was a standard component of
theriac Theriac or theriaca is a medical concoction originally labelled by the Greeks in the 1st century AD and widely adopted in the ancient world as far away as Persia, China and India via the trading links of the Silk Route. It was an alexipharmic, o ...
s, from the
Mithridate Mithridate, also known as mithridatium, mithridatum, or mithridaticum, is a semi-mythical remedy with as many as 65 ingredients, used as an antidote for poisoning, and said to have been created by Mithridates VI Eupator of Pontus in the 1st cent ...
of
Aulus Cornelius Celsus Aulus Cornelius Celsus ( 25 BC 50 AD) was a Roman encyclopaedist, known for his extant medical work, ''De Medicina'', which is believed to be the only surviving section of a much larger encyclopedia. The ''De Medicina'' is a primary source on d ...
' ''De Medicina'' ( CE) to the
Venice treacle Theriac or theriaca is a medical concoction originally labelled by the Ancient Greece, Greeks in the 1st century AD and widely adopted in the ancient world as far away as Parthian Empire, Persia, History of China#Ancient China, China and Middle k ...
of ''d'Amsterdammer Apotheek'' in 1686. Folk usages included oily extract (St John's oil) and ''Hypericum''
snaps Snaps ( ) is a Danish and Swedish word for a small shot of a strong alcoholic beverage taken during the course of a meal. A ritual that is associated with drinking snaps is a tradition in Scandinavia, especially in Denmark and Sweden, where i ...
. ''Hypericum perforatum'' is a common species and is grown commercially for use in herbalism and traditional medicine. The red, oily extract of ''H. perforatum'' has been used in the treatment of wounds, including by the
Knights Hospitaller The Order of Knights of the Hospital of Saint John of Jerusalem ( la, Ordo Fratrum Hospitalis Sancti Ioannis Hierosolymitani), commonly known as the Knights Hospitaller (), was a medieval and early modern Catholic military order. It was headqu ...
, the Order of St John. Both hypericin and hyperforin are under study for their potential
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
properties.


Medical research


Antidepressant

A 2015 meta-analysis review concluded that it has superior efficacy to placebo in treating depression, is as effective as standard
antidepressant Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness, heada ...
pharmaceuticals for treating depression, and has fewer
adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term complica ...
s than other antidepressants. The authors concluded that it is difficult to assign a place for St. John's wort in the treatment of depression owing to limitations in the available evidence base, including large variations in efficacy seen in trials performed in German-speaking countries relative to other countries. In Germany, St. John's wort may be prescribed for mild to moderate depression, especially in children and adolescents. A 2008
Cochrane review Cochrane (previously known as the Cochrane Collaboration) is a British international charitable organisation formed to organise medical research findings to facilitate evidence-based choices about health interventions involving health profess ...
of 29 clinical trials concluded that it was superior to
placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. In general, placebos can aff ...
in patients with
major depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introd ...
, as effective as standard antidepressants and had fewer side-effects. A 2016 review noted that use of St. John's wort for mild and moderate depression was better than
placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. In general, placebos can aff ...
for improving depression symptoms, and comparable to antidepressant medication. A 2017 meta-analysis found that St. John's wort had comparable efficacy and safety to SSRIs for mild-to-moderate depression and a lower discontinuation rate. While some studies and research reviews have supported the efficacy of St John's wort as a treatment for depression in humans, in the United States, it is not recommended as a replacement for more studied treatments, and it is advised that symptoms of depression warrant proper medical consultation. In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
, St John's wort is considered a
dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
by the
FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...
, and is not regulated by the same standards as a
prescription drug A prescription drug (also prescription medication or prescription medicine) is a pharmaceutical drug that legally requires a medical prescription to be dispensed. In contrast, over-the-counter drugs can be obtained without a prescription. The re ...
. According to the United States
National Center for Complementary and Integrative Health The National Center for Complementary and Integrative Health (NCCIH) is a United States government agency which explores complementary and alternative medicine (CAM). It was initially created in 1991 as the Office of Alternative Medicine (OAM), ...
, St. John's wort appears to be more effective than placebo and as effective as standard antidepressant medications for mild and moderate depression, and that it is uncertain whether this is true for severe depression or for longer than 12 weeks. Supplement strength varies by manufacturer and possibly by batch. With antidepressants, one "may have to try a few before finding what works best," notes the United States
National Library of Medicine The United States National Library of Medicine (NLM), operated by the United States federal government, is the world's largest medical library. Located in Bethesda, Maryland, the NLM is an institute within the National Institutes of Health. Its ...
. In China, St. John's wort combined with '' Eleutherococcus senticosus'' is sold as an antidepressant under the name ''Shugan Jieyu Jiaonang'' (), according to the ''
Pharmacopoeia of the People's Republic of China A pharmacopoeia, pharmacopeia, or pharmacopoea (from the obsolete typography ''pharmacopœia'', meaning "drug-making"), in its modern technical sense, is a book containing directions for the identification of compound medicines, and published by ...
''. The pharmacopoeia states in Chinese that it is used "for mild and moderate unipolar depression".


Phytochemicals and dietary supplement

St John's wort, similarly to other herbs, contains different phytochemical constituents. Although St. John's wort is sold as a
dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
, there are no
standardized Standardization or standardisation is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organizations and governments. Standardization ...
manufacturing procedures, and some marketed products may be contaminated with
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typica ...
s,
fillers In processed animal foods, a filler is an ingredient added to provide dietary fiber, bulk or some other non-nutritive purpose. Products like corncobs, feathers, soy, cottonseed hulls, peanut hulls, citrus pulp, screening, weeds, straw, and cere ...
or other impurities. Notes:


Interactions

Besides its allergenic effects, St John's wort can interfere (in potentially life-endangering ways) with the effects of many prescription drugs, including the anti-psychotics
risperidone Risperidone, sold under the brand name Risperdal among others, is an atypical antipsychotic used to treat schizophrenia and bipolar disorder. It is taken either by mouth or by injection (subcutaneous or intramuscular). The injectable versions ...
and 9-hydroxyrisperidone (i.e. paliperidone, Xeplion or Invega),
cyclosporine Ciclosporin, also spelled cyclosporine and cyclosporin, is a calcineurin inhibitor, used as an immunosuppressant medication. It is a natural product. It is taken orally or intravenously for rheumatoid arthritis, psoriasis, Crohn's disease, ...
,
digoxin Digoxin (better known as Digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. Digoxin is on ...
, HIV drugs, cancer medications including
irinotecan Irinotecan, sold under the brand name Camptosar among others, is a medication used to treat colon cancer, and small cell lung cancer. For colon cancer it is used either alone or with fluorouracil. For small cell lung cancer it is used with cisp ...
, and
warfarin Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent str ...
. Combining both St John's wort and antidepressants could lead to increased
serotonin Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vas ...
levels causing
serotonin syndrome Serotonin syndrome (SS) is a group of symptoms that may occur with the use of certain serotonergic medications or drugs. The degree of symptoms can range from mild to severe, including a potentiality of death. Symptoms in mild cases include high ...
. It should not be taken with the heart medication ranolazine. Combining estrogen-containing oral contraceptives with St John's wort can lead to decreased efficacy of the contraceptive and, potentially, unplanned pregnancies. Consumption of St John's wort is discouraged for those with
bipolar disorder Bipolar disorder, previously known as manic depression, is a mental disorder characterized by periods of depression and periods of abnormally elevated mood that last from days to weeks each. If the elevated mood is severe or associated with ...
,
schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...
or
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affec ...
, and for people using dietary supplements, headache medicine,
anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where the ...
s, and
birth control pill The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control that is designed to be taken orally by women. The pill contains two important hormones: progesti ...
s.


Pharmacodynamics

St John's wort has been shown to cause multiple drug interactions through induction of the
cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various comp ...
enzymes CYP3A4 and
CYP1A2 Cytochrome P450 1A2 (abbreviated CYP1A2), a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the human body. In humans, the CYP1A2 enzyme is encoded by the ''CYP1A2'' gene. Function ...
. This drug-metabolizing enzyme induction results in the increased metabolism of certain drugs, leading to decreased plasma concentration and potential clinical effect. The principal constituents thought to be responsible are
hyperforin Hyperforin is a phytochemical produced by some of the members of the plant genus ''Hypericum'', notably ''Hypericum perforatum'' (St John's wort). Hyperforin may be involved in the pharmacological effects of St. John's wort, specifically in its ...
and
amentoflavone Amentoflavone is a biflavonoid (''bis''-apigenin coupled at 8 and 3' positions, or 3′,8′′-biapigenin) constituent of a number of plants including '' Ginkgo biloba'', ''Chamaecyparis obtusa'' (hinoki), ''Hypericum perforatum'' (St ...
. There is strong evidence that the mechanism of action of these interactions is activation of the pregnane X receptor. St John's wort has also been shown to cause drug interactions through the induction of the P-glycoprotein efflux transporter. Increased P-glycoprotein expression results in decreased absorption and increased clearance of certain drugs, leading to lower plasma concentrations and impaired clinical efficacy.


See also

*
Dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
* EU Food supplements directive *
List of plants poisonous to equines Many plants are poisonous to equines; the species vary depending on location, climate, and grazing conditions. In many cases, entire genera are poisonous to equines and include many species spread over several continents. Plants can cause reactio ...
* St John's-bread


Notes


References

{{Authority control perforatum CYP2D6 inhibitors CYP3A4 inducers Flora of Europe Flora of Lebanon Garden plants of Europe Abortifacients Antidepressants Medicinal plants Serotonin–norepinephrine–dopamine reuptake inhibitors Plants described in 1753 Pregnane X receptor agonists Herbs Subshrubs Taxa named by Carl Linnaeus