Mentha pulegium L.

Last updated: 5 June 2017

Scientific Name

Mentha pulegium L.

Synonyms

Calamintha fenzlii Vis., Melissa pulegium (L.) Griseb. Mentha albarracinensis Pau, Mentha aromatica Salisb., Mentha aucheri Pérard, Mentha aucheri Pérard, Mentha daghestanica Boriss., Mentha erinoides Heldr., Mentha exigua L., Mentha gibraltarica Willd., Mentha hirtiflora Opiz ex Heinr.Braun, Mentha montana Lowe ex Benth., Mentha pulegioides Dumort. [1]

Vernacular Name

English Pudding grass, true pennyroyal, fleabane, pennyroyal [2][3]

Geographical Distributions

Mentha pulegium originated in Europe and Asia and is thought to be naturalized in the United States via European colonists. It is often found growing near water, such as streams, pools and lakes. M. pulegium flourishes in nutrient-rich, sandy, moist soil and sunny conditions. [2][3]

Botanical Description

M. pulegium is a member of Lamiaceae family. [1]

The common name of ‘Pennyroyal’ actually refers to two different plants: Hedeoma pulegioides, known as American pennyroyal; and M. pulegium, known as European pennyroyal. European pennyroyal is a perennial herb found in Europ and Asia, whereas American pennyroyal is an annual. Both plants produce a light purple or blue flower. The information on the two plants is basically interchangeable. [2]

Pennyroyal has a long history of use in foods as flavouring as it has a taste and odour that is slightly similar to spearmint. The essential oil of Pennyroyal is used in scenting soaps and as insect repellants. The traditional uses that are not verified by science include its use as a remedy for spasms, flatulence, gall stones, gout, coughs and colds. [3]

While the use as an abortifacient is not conclusive, the misuse of Pennyroyal for this purpose has caused coma and death. [4]

M. pulegium is a perennial from the mint genus. Growing to a height of 25 cm, the stems of the plant are prostrate, and are square upon a cross-section, a common trait of the mint family. The heavily branched stems are covered in a downy pubescence, so too, is the majority of the rest of the plant. The leaves of M. pulegium are elliptical, pubscent, and have a scent similar to spearmint. Very similar in many respects to H. pulegioides, M. pulegium can be identified by its smaller leaves, which are often, though not always, toothed. The hermaphroditic flowers are small, and grow into whorl-like patterns to form their calyxes. Blooming from August to October, each 1cm long flower is two-lipped, often bluish-lilac or lavender in colour. In contrast to H. pelugioides, the flower has four stamens, as opposed to two. [2][3]

Cultivation

No documentation

Chemical Constituent

M. pulegium has been reported to contain pugelone, α-pinene, β pinene, limonene, 3-octanone, p-cymene, 3-octylactate, 3-octanol, 1-octen-3-ol, 3-methylcyclohexanone, menthone, isomenthone, isopulegone, piperitone, lauric acid, myristic acid, palmitic acid among others. [3]

Plant Part Used

Leaves [5]

Traditional Use

Pennyroyal has shown insecticidal activity in several studies. On the common house fly (Musca domestica L.) the essential oil of pennyroyal showed fumigant activity and was stronger than 13 other essential oils. [5] Another study found that M. pulegium oil was also toxic against Spodoptera littoralis (Egyptian Armyworm). [6]

The essential oils from different species of the mint family, including their primary chemical constituents were tested against Drosophila melanogaster, more commonly known as the fruit fly. Pulegone, a constituent of this herb, exhibited the strongest insecticidal activity of all chemicals measured. [7]

Sixteen different essential oils from Argentina that have been used to treat common head lice were studied for their efficacy. It was found that M. pulegium essential oil demonstrated the highest repellency of the sixteen plants used. The authors stated that this could possibly be useful for future products to treat lice. [8]

The acaricidal outcome was measure using 6 essential oils including pennyroyal against Dermatophgoides farinae and D. pteronyssinus (common house mites). The results showed that pennyroyal exhibited the highest acaricidal activity killing 98% of the house mites in 5 minutes. The chemical component thought to contribute to this action was pulegone. [9]

M. pulegium has been ingested as an infusion for gastrointestinal complaints by several Native American tribes including the Delaware, Ojibwa and Oklahoma while the Mohegan tribe thought that it warmed the digestive tract. Other reported uses include its use as an analgesic poultice by the Cherokees and as an infusion for pain by Shinnecock and Iroquois. [10]

One of the most popular traditional uses is for promoting menstruation. Because of this effect, this plant, an abortifacient, is used to unblock menses. M. pulegium has been used to induce labour and strengthen menstrual flow. [10][11]

Preclinical Data

Pharmacology

Insect repellent and insecticidal activity

The use of M. pulegium as an antibacterial agent and insect repellent is supported by laboratory studies. [12] The essential oils, including pulegone, are the components that are responsible for the antimicrobial and insecticidal activity. [13]

Abortfacient activity

The most reported and yet controversial use of M. pulegium is as an abortifacient. The constituents of M. pulegium (mainly pulegone) are reported to have emmenagogic properties, stimulating uterine contraction and promoting menstrual flow. [14] Although the essential oil has been used for centuries to induce abortion, there is no scientific proof to support this use. Therefore, the use of M. pulegium as an abortifacient cannot be substantiated by clinical evidence at this time. [15]

Antibacterial activity

The use of M. pulegium as an antibacterial agent and insect repellent is supported by laboratory studies. [16] The essential oils, including pulegone, are the components that are responsible for the antimicrobial and insecticidal activity. [12]

Clinical Data

Clinical findings

No documentation

Side effects

M. pulegium may cause allergic reactions such as contact dermatitis. Do not use if allergic to M. pulegium or the essential oils of M. pulegium. [17]

M. pulegium oil ingestion has been associated with severe hepatotoxicity and death. The primary constituent, R-(+)-pulegone, is metabolized via hepatic cytochrome P450 to toxic intermediates. Do not use in individuals with liver or kidney problems. [18]

Pregnancy/Breast Feeding

Based on historical use, M. pulegium should not be used in pregnancy due to the potential for abortifacient effects. [19]

Adverse reaction

Death has been reported after consumption of half an ounce (15 mL) of the oil. If ingestion of M. pulegium is suspected there will be a characteristic strong, minty smell on the patient’s breath. The healthcare personnel can determine if M. pulegium ingestion is the cause of toxicity by using gas chromatography to test for the active metabolite menthofuran in urine, blood, or other tissues. The overdose management includes lavage, and/or administration of activated charcoal. The symptoms of M. pulegium toxicity may mimic that of acetaminophen. [20]

Interaction & Depletion

No documentation

Contraindications

Animal studies have shown that ingestion of pennyroyal tea can lead to hepatotoxicity so extreme caution should be taken with this oil and it should never be ingested. [21]

Dosage

Tincture: 2-10 drops daily.  Tea: 1 teaspoon in one cup boiling water. [11]

Poisonous Management

No documentation

Line drawing

No documentation

References

  1. The Plant List. Ver1.1. Mentha pulegium L. [homepage on the Internet]. c2013 [updated 2012 Mar 23; cited 2017 June 5]. Available from: http://www.theplantlist.org/tpl1.1/record/kew-125243
  2. Simon JE, Chadwick A, Craker L. Herbs: An indexed bibliography 1971-1980. The scientific literature on selected herbs, and aromatic and medicinal plants of the temperate zone. Hamden CT: Archon Books; 1984.
  3. Duke JA. Handbook of medicinal herbs. Florida: CRC Press; 1985.
  4. McGuffin M, et al. Botanical Safety Handbook. Boca Raton: CRC Press; 1997.
  5. Pavela R. Insecticidal properties of several essential oils on the house fly (Musca domestica L.). Phytother Res. 2008;22(2):274-278.
  6. Pavela R. Insecticidal activity of some essential oils against larvae of Spodoptera littoralis. Fitoterapia. 2005;76(7-8):691-696.
  7. Franzios G. Insecticidal and genotoxic activities of mint essential oils. J Food Agric Chem. 1997;45(7): 2690-2694.
  8. Toloza AC. Fumigant and repellent properties of essential oils and component compounds against permethrin-resistant Pediculus humanus capitis (Anoplura: Pediculidae) from Argentina. J Med Entomol. 2006;43(5):889-895.
  9. Rim IS.Korean Acaricidal effects of herb essential oils against Dermatophagoides farinae and D. pteronyssinus (Acari: Pyroglyphidae) and qualitative analysis of a herb Mentha pulegium (pennyroyal). J Parasitol. 2006;44(2):133-138.
  10. Moerman DE.  Native American ethnobotany. Portland OR: Timber Press, 2009; p. 353.
  11. Hutchens AR. Indian herbalogy of North America. Boston MA: Shambhala Publications, 1991; p. 215
  12. Mahboubi M, Haghi G. Antimicrobial activity and chemical composition of Mentha pulegium L. essential oil. J Ethnopharmacol. 2008;119(2):325-327.
  13. Martins HM, Martins ML, Dias MI, et al. Evaluation of microbiological quality of medicinal plants used in natural infusions. Int J Food Microbiol. 2001;68(1-2):149-153.
  14. Black DR. Pregnancy unaffected by pennyroyal usage. J Am Osteopath Assoc. 1985;85(5):282.
  15. Soares PM, Assreuy AM, Souza EP, et al. Inhibitory effects of the essential oil of Mentha pulegium on the isolated rat myometrium. Planta Med. 2005;71(3):214-218.
  16. Martins HM, Martins ML, Dias MI, et al. Evaluation of microbiological quality of medicinal plants used in natural infusions. Int J Food Microbiol. 2001;68(1-2):149-153.
  17. Pérez-Calderón R, Gonzalo-Garijo A, Bartolomé-Zavala B, et al. Occupational contact urticaria due to pennyroyal (Mentha pulegium). Contact Dermatitis. 2007;57(4):285-286.
  18. Carmichael PG. Pennyroyal metabolites in human poisoning. Ann Intern Med. 1997;126(3):250-251.
  19. Anderson IB, Sidney DN, Paul DB. Pennyroyal metabolites in human poisoning. Annals of Internal Medicine. 1997;126(3):250–251.
  20. Bakerink JA, Gospe SM Jr, Dimand RJ, Eldridge MW. Multiple organ failure after ingestion of pennyroyal oil from herbal tea in two infants. Pediatrics.1996;98(5):944-947.
  21. Sztajnkrycer MD. Mitigation of pennyroyal oil hepatotoxicity in the mouse. Acad Emerg Med. 2003;10(10):1024-1028.