Peppermint

Mentha piperita (L.) Hudson – Peppermint
Lamiaceae (Labiatae) – Mint family

It is a hybrid of three species, M. spicata L. [M.longifolia (L.) Huds. + M. rotundifolia (L.) Huds] and M. aquatica.

The raw material is the peppermint leaf and the leafy shoot tip, harvested from non-flowering plants, dried quickly in the shade, in max. 35° C.

Peppermint – appearance and origin:

A perennial from the mint family, not found in the wild, widespread in Europe, North and South Americas, Asia and Africa; in Poland it is grown on a big scale in some regions. It requires sandy-loamy, water-rich soil. Peppermint has a distinct, strong, pleasant smell. The stem grows up to 90 cm, it is straight, branching, bare or lightly pubescent. The leaves are oblong-ovate or ovate, irregularly sharpy serrated, with short hairs on the veins from the bottom. The flowers are pink or lilac, clustered into pseudowhorls at the tip which create dense, cylindrical or almost capitate panicles. It blooms between June and August. The peppermint fruit is a mericarp.

Peppermint – effects and use:

The main active substances in the peppermint leaf are essential oil (1-3%), tannins (6-12%), flavonoids (i.a. luteolin and luteolin 7-glucoside, rutin, hesperidin, eriocitrin, highly oxidised phenols and small amounts of triterpenes. The peppermint leaf has mainly relaxant activity on smooth muscles of the gastrointestinal tract, and also a choleretic and carminative effect. It is used for digestive disorders associated with pain, colic, nausea, flatulence, and for gastrointestinal catarrhs and inflammation, liver diseases, inflammation of the gallbladder and bile duct. According to the ESCOP monograph, adults and the elderly are to drink 3 infusions a day made from 1.5-3 g of peppermint in 150 ml of water or 2-3 ml of tincture (1:5, 45% ethanol). Children can take only the infusion made from the amount of the raw material that is equivalent to the daily dose, i.e. 3-5 g for children 4-10 years and 3-6 g for children from 16 years. The European Commission recommends to use 3-6 g of peppermint leaves or 5-15 g of tincture for spasmodic symptoms of the stomach and bowels, the gallbladder and the bile duct.

– The peppermint leaf is used in sedatives and products meant for the skin and mucosas.

– It mainly exhibits relaxant activity on smooth muscles of the gastrointestinal tract, and also a choleretic and carminative effect. Studies have shown its antibacterial properties at 0.1-0.2% (m/v) – Salmonella typhimurium, Staphylococcus aureus, Vibrio parahaemolyticus and antiviral activity at 4-8 mg/ml – Newcastle disease, herpes, vaccinia, Semliki Forest virus and West Nile virus. Studies performed on rats observed also an antiulcer effect, while in mice it showed analgesic, anti-inflammatory and sedative activity.

– Menthae pip. aetheroleum (peppermint oil) is obtained by way of steam distillation of the herb of Mentha piperita L. Hudson. It is composed of menthol, mainly (-)-menthol (35-55%), a small amount of stereoisomers, such as (+)-neomenthol (around 3%) and (+)-isomenthol (around 3%), and menthone (10-35%). It also contains many other monoterpenes and small amounts of sesquiterpenes, especially viridiflorol (approx. 5%).

– The peppermint oil has a similar effect to the leaf, but is a stronger sedative, spasmolytic and antiseptic. It relieves IRS symptoms. An ethanol solution with 10% of the oil was found to reduce tension headaches. A lot of the oil's properties are thanks to menthol, which affects the cold receptors in the body and mucosas, giving a cold sensation. When sprayed in the air, it facilitates breathing. Menthol increases bile secretion and inhibits the activity of HMG-CoA reductase of the liver. The oil has also been proven to be antibacterial. In in vitro studies, it inhibited the growth of Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Trichophyton equinum, T. rubrum (at a concentration of 0,4 µg/ml) and Aspergillus flavus, A. fumigatus, A. niger, although it did not affect Bacillus cereus, Penicillium cyclopium or Aspergillus aegyptiacus.

– Externally, the peppermint oil is used for inhalations to relieve coughing and common colds, rheumatic symptoms, tension headaches (a 10% solution for rubbing the forehead and temples), for itching, hives and painful skin irritation; for skin infections – a solution or semisolid with the equivalent of 0.1-1% m/m of menthol as an anesthetic or antipruritic, or containing an equivalent of 1.25-16% m/m of menthol as a mild anti-inflammatory and analgesic.

– Do not use peppermint oil products in case of hypersensitivity to menthol or peppermint oil. Do not apply directly to the nose or chest in infants and small children, as it can cause spasms of the larynx and bronchi.

Peppermint and peppermint oil are known not only to the pharmaceutical industry, where they have been traditionally used for digestive symptoms. They are also used in food products as a flavoring, e.g. in drinks, alcohols (peppermint liqueur), or chewing gum. They are added to cosmetics, such as shampoos, balms, perfumes. They are used for aromatherapy, baths, massages, inhalations and air aromatisation.