Mentha pulegium | |
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Scientific classification ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Lamiales |
Family: | Lamiaceae |
Genus: | Mentha |
Species: | M. pulegium |
Binomial name | |
Mentha pulegium | |
Mentha pulegium, commonly (European) pennyroyal, or pennyrile, also called mosquito plant [1] and pudding grass, [2] is a species of flowering plant in the mint family, Lamiaceae, native to Europe, North Africa, and the Middle East. [3] Crushed pennyroyal leaves emit a very strong fragrance similar to spearmint. Pennyroyal is a traditional folk remedy, emmenagogue, abortifacient, and culinary herb, but is toxic to the liver and has caused some deaths. [4] European pennyroyal is related to an American species, Hedeoma pulegioides . Though they differ in genera, they share similar chemical properties. [5]
An annual to perennial plant with creeping or erect branched stems to about 40 cm in height. The stems are square in cross-section and can vary from hairless on some plants to densely hairy on others, with a green to sometimes red or purplish colour. The leaves, which grow in opposite pairs, are narrowly oval, 2–3 cm long x 1 cm wide, downy, sparsely toothed towards the tip, and taper into a short stalk. All parts of the plant are strongly scented when crushed but it does not have noticeable glands on its surface. The small (6 mm) flowers are densely packed in whorls at the nodes, widely separated, above pairs of leaf-like bracts. The calyx is a ribbed tube about 3 mm long, with five triangular teeth, the lower two being narrower and slightly longer than the upper three; it is hairy both on the inside and the outside. The corolla has four mauve lobes or "petals" and is hairy only on the outside. The flowers are bisexual and have four long stamens, two (or all four) of which project well beyond the corolla lobes. There is one long style which is forked to produce two stigmas, which also project from the flower. The fruits consist of a cluster of four brown, 1-seeded nutlets, each about 0.7 mm long. [6]
The flowering period starts in June and continues into mid-summer, [7] although in northern countries it flowers rather later, sometimes as late as September, when it can fail to set seed. [8]
Its chromosome number is 2n = 20. [9]
The native range of pennyroyal is thought to be around the eastern Mediterranean, where it grows in damp meadows, around pools and in stream margins. [7] It is, however, very widely established around the world, including North and South America, throughout Africa, Asia, Australia and New Zealand. In many places it is considered a troublesome weed of agriculture. [10] [11] Towards the northern edge of its range, as in Britain, it is considered to be rare and declining, [12] except where introduced.[ citation needed ]
The habitat of pennyroyal is seasonally damp pasture, where standing water over the winter leaves bare ground in the summer, and where livestock preferentially graze other plants. An analogue of this habitat is found on roadsides, where trampling or disturbance of the ground produces similarly bare soil, particularly where there is waterlogging in winter. It is also found along watercourses, in wet woodland and in abandoned fields. [10]
In California, where it is considered an invasive species, it occupies a similar niche, in seeps, streamsides, vernal pools and swales, marshes, and ditches. There is some speculation that it may displace native species in these areas. [13]
Few animals eat pennyroyal. In Britain, the only insect known to feed on it is the bug Heterogaster artemisiae Schilling, which is a seed bug that normally feeds on wild thyme. [14]
It is considered an axiophyte in many British counties, because low-intensity pasture is a rare habitat, although it has been spreading in recent decades. [15] Its Ellenberg values in Britain are L = 8, F = 7, R = 5, N = 7, and S = 0. [16]
Documented use of pennyroyal dates back to ancient Greek, Roman, and Medieval cultures. Its name – although of uncertain etymology – is associated with Latin pulex (flea), alluding to the manner it was used to drive away fleas when smeared on the body. [17] Pennyroyal was commonly incorporated as a cooking herb by the Greeks and Romans. A large number of the recipes in the Roman cookbook of Apicius called for the use of pennyroyal, often along with such herbs as lovage, oregano and coriander. Although it was commonly used for cooking also in the Middle Ages, it gradually fell out of use as a culinary herb and is seldom used as such today. [18]
Records from Greek and Roman physicians and scholars contain information pertaining to pennyroyal's medicinal properties, as well as recipes used to prepare it. Pliny the Elder, in his encyclopedia Naturalis Historia (Natural History), described the plant as an emmenagogue, and that it also expelled a dead fetus. [19] Galen only listed pennyroyal as an emmenagogue, as did Oribasius. Roman and Greek writers Quintus Serenus Sammonicus and Aspasia the Physician however both agreed that pennyroyal, when served in tepid water, was an effective abortive method. [19] A medical text on gynecology attributed to Cleopatra (though it was actually written by a female Greek physician Metrodora) recommends the use of pennyroyal with wine to induce abortions. [19]
In regard to its contraceptive properties, it was referred to in a joking manner in Aristophanes' play Peace (421 BCE). The god Hermes provides the male character Trygaios a female companion; when Trygaios asks if there would be a problem if she became pregnant, Hermes responds, "Not if you add a dose of pennyroyal." [17] In a similar manner, in Aristophanes' comedy Lysistrata , after a pregnant female character on stage is told to withhold her body sexually from her husband, a slender female character, in comparison to the pregnant woman, is described as "a very lovely land Well croppy, and trimmed and spruced with pennyroyal." [17]
Early settlers in colonial Virginia used dried pennyroyal to eradicate pests. Pennyroyal was such a popular herb that the Royal Society published an article on its use against rattlesnakes in the first volume of its Philosophical Transactions in 1665. [20] 17th-century apothecary and physician Nicholas Culpeper mentions pennyroyal in his medical text The English Physitian , published in 1652. [21] In addition to its abortive properties, Culpeper recommends its use for gastrointestinal ailments, such as constipation and hemorrhoids, as well as itching and blemishes to the skin, and even toothaches. [21]
Pennyroyal is an essential ingredient in the North african dish, which is still eaten to this day, called Batata fliou .
Pennyroyal continued to be used up through the 20th and 21st centuries. Its oil is still commercially available today, though little is known about the appropriate dosages for humans. Scientists therefore likely consider it unsafe for use, as it is potentially toxic. [22]
Pennyroyal is frequently used as an insecticide and pest repellent. [23] As a pest repellent, it is used to keep fleas away from household animals as well as on humans to ward off gnats and mosquitos. Some flea collars for pets have pennyroyal oil or the herb can be crushed in the lining. Humans have also put crushed pennyroyal stems in their pockets or on their clothing to ward off unwanted insects. [24] However, when using the pennyroyal plant as a pest repellent, the use of the concentrated pennyroyal oil should be avoided. Pennyroyal oil can be extremely toxic to both humans and animals, even in small quantities. With the use of pennyroyal around animals and humans comes the risk of it being absorbed through the skin and causing negative health effects. The less concentrated leaves of the plant should be used instead as an insect repellent.
Pennyroyal has historically also been used as a mint flavoring in herbal teas and foods. Pennyroyal tea has been used for cold relief, fevers, coughs, indigestion, liver and kidney problems and headaches. [25] The fresh or dried leaves of pennyroyal have also been used when treating influenza, abdominal cramps, to induce sweating, as well as in the treatment of diseases such as smallpox and tuberculosis. [26] To make the tea, the leaves of the plant are boiled in hot water. The lower concentrations of toxic chemicals in these teas are less harmful than pennyroyal oil. It is recommended that people only drink pennyroyal tea periodically, as it is taxing on the body and should not be drunk on a regular basis. Consumption of pennyroyal tea can be fatal to infants and children. [27]
In Italy the fresh leaves of this plant, which in Rome and the surrounding area is called menta romana, are used in the capital's cuisine to flavour lamb and tripe. [28] In culinary use it should not be confused with lesser calamint (Clinopodium nepeta), which in Rome is used to prepare artichokes.
The pennyroyal plant has also been used as an emmenagogue and an abortifacient. [29] Chemicals in the pennyroyal plant cause the uterine lining to contract, causing a woman's uterine lining to shed. Women who struggle with regulating their menstrual cycle or suffer from a cystic ovary syndrome may choose to drink pennyroyal tea. Pennyroyal tea is subtle enough to induce menstrual flow with minimal risk of negative health effects. More concentrated versions of the plant, such as the oil, are much more toxic and will likely force a miscarriage if ingested by a pregnant woman. [30] Since the U.S. Congress passed the Dietary Supplement Health and Education Act in October 1994 all manufactured forms of pennyroyal in the United States have carried a warning label against its use by pregnant women, but pennyroyal is not regulated by the U.S. Food and Drug Administration. [31]
Rennie's 1833 supplement to the pharmacopeias admitted its use as an "expectorant, diuretic, and emmenagogue" in doses of 10 grains to 1 scruple (0.6–1.3g) of the powdered dried herb, but dismissed the use of the Pennyroyal Water (Aqua Pulegii) as "popularly but erroneously supposed" to be an abortifacient [no mention is made of toxicity]. [32]
At least one study has shown pennyroyal oil to have potent acaricidal activity against house dust mites. [33]
Pennyroyal is toxic to humans and has differing effects dependent on the volume and concentration ingested. The most concentrated and toxic form of the pennyroyal plant is pennyroyal oil. The oil contains 80% to 92% of cyclohexanone pulegone. Pulegone, the molecule in highest concentration in the pennyroyal plant, causes a variety of ailments in those who ingest it and is what causes the plant to have its peppermint flavor. [34]
Symptoms that may persist after ingesting a small dose (<10 mL) of pennyroyal oil are nausea, vomiting, abdominal pain and dizziness. Larger volumes may result in multiorgan failure that could lead to death. There are no current toxicokinetics studies performed on humans for the effects of pulegone, but there are some studies performed on other mammals. When pulegone is ingested, it is broken down by the liver and reacts to form multiple toxic metabolites that can wreak havoc in the body. Some identified metabolites are menthofuran, piperitenone, piperitone, and menthone. [35]
The active chemical in pennyroyal is pulegone. Pulegone is a ketone and on the cellular level, ketones can act as enzyme inhibitors. The carbonyl center of the pulegone structure acts as a strong electrophile, causing active sites on enzymes to bind with pulegone instead of the target protein.
The exocyclic double bond found in pulegone is vital to the activation and binding mechanism of the molecule and causes it to be an effective hepatotoxin. When ingested, pulegone targets the liver and kidney, among other organs. Studies have been conducted on rats show that one of the main effects is the inhibition of contractile activity in the myometrium and death by kidney failure. Also found in the study, long term exposure to pennyroyal increased incidences of urinary bladder tumors. [35]
The exact mechanism of action by which pennyroyal induces menses and abortions in humans is still unknown. Studies using animal models speculate the source of liver toxicity is due to one of the many constituents the plant contains: pulegone, a monoterpene. Pulegone is metabolized by cytochrome P450 (CYP 1A2 and 2E1) and converted to several toxins. [36] Both in vitro and in vivo studies have found the pulegone metabolite menthofuran to be an inhibitor of CYP2A6, accounting for a significant degree of pennyroyal's hepatotoxicity. [37] [38] [39]
The exact pathway pulegone undergoes to be converted to menthofuran is unknown, but one study strongly suggested it included allylic oxidation of a methyl group (from CYP450), intramolecular cyclization to form a hemiketal, and subsequent dehydration to form the furan. [38] Additionally, pulegone and menthofuran may deplete glutathione levels, leaving hepatocytes vulnerable to free radical damage. [38]
There is no known antidote for pennyroyal toxicity. [29] Case studies involving pennyroyal poisonings have reported the use of gastric lavages and administration of emetics or vomiting inducing agents, or absorbents like activated charcoal. [5] As glutathione depletion has been shown to regulate liver toxification, administration of N-acetylcysteine in similar doses as given for acetaminophen toxicity have been given to patients. [40]
A study testing pulegone toxicity found inhibitors of cytochrome P450, such as cobaltous chloride or piperonyl butoxide, blocked toxicity. [38] Such testing has not been expanded to humans, however, as the pennyroyal mechanism of toxicity is still not entirely understood.
Mentha is a genus of flowering plants in the family Lamiaceae. It is estimated that 13 to 24 species exist, but the exact distinction between species is unclear. Hybridization occurs naturally where some species' ranges overlap. Many hybrids and cultivars are known.
Peppermint is a hybrid species of mint, a cross between watermint and spearmint. Indigenous to Europe and the Middle East, the plant is now widely spread and cultivated in many regions of the world. It is occasionally found in the wild with its parent species.
Spearmint, scientific name Mentha spicata, also known as garden mint, common mint, lamb mint and mackerel mint, is native to Europe and southern temperate Asia, extending from Ireland in the west to southern China in the east. It is naturalized in many other temperate parts of the world, including northern and southern Africa, North America, and South America. It is used as a flavouring in food and herbal teas. The aromatic oil, called oil of spearmint, is also used as a flavoring and sometimes as a scent.
Herbal teas, also known as herbal infusions and less commonly called tisanes, are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water; they do not usually contain any true tea. Often herb tea, or the plain term tea, is used as a reference to all sorts of herbal teas. Many herbs used in teas/tisanes are also used in herbal medicine and in folk medicine. Some herbal blends contain true tea.
An essential oil is a concentrated hydrophobic liquid containing volatile chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is essential in the sense that it contains the essence of the plant's fragrance—the characteristic fragrance of the plant from which it is derived. The term "essential" used here does not mean indispensable or usable by the human body, as with the terms essential amino acid or essential fatty acid, which are so called because they are nutritionally required by a living organism.
An abortifacient is a substance that induces abortion. This is a nonspecific term which may refer to any number of substances or medications, ranging from herbs to prescription medications.
Nicholas Culpeper was an English botanist, herbalist, physician and astrologer. His book The English Physitian is a source of pharmaceutical and herbal lore of the time, and Astrological Judgement of Diseases from the Decumbiture of the Sick (1655) one of the most detailed works on medical astrology in Early Modern Europe. Culpeper catalogued hundreds of outdoor medicinal herbs. He scolded contemporaries for some of the methods they used in herbal medicine: "This not being pleasing, and less profitable to me, I consulted with my two brothers, Dr. Reason and Dr. Experience, and took a voyage to visit my mother Nature, by whose advice, together with the help of Dr. Diligence, I at last obtained my desire; and, being warned by Mr. Honesty, a stranger in our days, to publish it to the world, I have done it."
Glechoma hederacea is an aromatic, perennial, evergreen creeper of the mint family Lamiaceae. It is commonly known as ground-ivy, gill-over-the-ground, creeping charlie, alehoof, tunhoof, catsfoot, field balm, and run-away-robin. It is also sometimes known as creeping jenny, but that name more commonly refers to Lysimachia nummularia. It is used as a salad green in many countries. European settlers carried it around the world, and it has become a well-established introduced and naturalized plant in a wide variety of localities. It is also considered an aggressive invasive weed of woodlands and lawns in some parts of North America. In the absence of any biological control, research conducted by the USDA herbicides are relied upon particularly for woodland ecosystems. The plant's extensive root system makes it difficult to eradicate by hand-pulling.
Tansy is a perennial, herbaceous flowering plant in the genus Tanacetum in the aster family, native to temperate Europe and Asia. It has been introduced to other parts of the world, including North America, and in some areas has become invasive. It is also known as common tansy, bitter buttons, cow bitter, or golden buttons. The Latin word vulgare means "common".
Emmenagogues are herbs which stimulate blood flow in the pelvic area and uterus; some stimulate menstruation. Women use emmenagogues to stimulate menstrual flow, when menstruation is absent for reasons other than pregnancy, such as hormonal disorders or conditions like oligomenorrhea.
An insect repellent is a substance applied to the skin, clothing, or other surfaces to discourage insects from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne diseases such as malaria, Lyme disease, dengue fever, bubonic plague, river blindness, and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as flea, fly, and mosquito; and ticks (arachnids).
Ruta graveolens, commonly known as rue, common rue or herb-of-grace, is a species of the genus Ruta grown as an ornamental plant and herb. It is native to the Balkan Peninsula. It is grown throughout the world in gardens, especially for its bluish leaves, and sometimes for its tolerance of hot and dry soil conditions. It is also cultivated as a culinary herb, and to a lesser extent as an insect repellent and incense.
Pulegone is a naturally occurring organic compound obtained from the essential oils of a variety of plants such as Nepeta cataria (catnip), Mentha piperita, and pennyroyal. It is classified as a monoterpene.
Hedeoma pulegioides, also known as American pennyroyal or American false pennyroyal, is a species of Hedeoma native to eastern North America, from Nova Scotia and southern Ontario west to Minnesota and South Dakota, and south to northern Georgia and Arkansas.
Mentha cervina, commonly known as hart's pennyroyal, is a perennial herbaceous plant of the Mentha (mint) genus. It is native to the western Mediterranean Sea region, growing naturally from southwestern France to the Iberian Peninsula, and south to Azores, Morocco and Algeria. Its common name reflects a traditional association with the separate species Mentha pulegium or pennyroyal. The plants were associated due to their shared high pulegone content, which gives them both a distinctive, strong aroma.
Senecionine is a toxic pyrrolizidine alkaloid isolated from various botanical sources. It takes its name from the Senecio genus and is produced by many different plants in that genus, including Jacobaea vulgaris. It has also been isolated from several other plants, including Brachyglottis repanda, Emilia, Erechtites hieraciifolius, Petasites, Syneilesis, Crotalaria, Caltha leptosepala, and Castilleja.
Menthofuran is an organic compound found in a variety of essential oils including that of pennyroyal. It is highly toxic and believed to be the primary toxin in pennyroyal responsible for its potentially fatal effects. After ingestion of menthofuran, it is metabolically activated to chemically reactive intermediates that are hepatotoxic.
Mentha japonica is a species of plant in the family Lamiaceae, endemic to the islands of Hokkaido and Honshu, Japan. Initially described as Micromeria japonica by Friedrich Anton Wilhelm Miquel, it was first identified under its present name by Japanese botanist Tomitaro Makino in 1906. A relatively rare plant, it is classified by the Japanese Ministry of Environment as a Near Threatened species.
Mentha grandiflora is a plant species in the genus Mentha, endemic to eastern Australia. The species was described in 1848 by botanist George Bentham. Its epithet, grandiflora, means "with large flowers".
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: CS1 maint: location missing publisher (link)Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica (11th ed.). Cambridge University Press.