English horsemint

Other Names

Bibel-Minzebrook mintbrookmintdowny mintErva-de-São-Lourençofillymintgrey minthorse minthorsemintKahle Rossminzelong-leafed mintMenta-selvagemMentastrumMentha alaicaMentha asiaticaMentha candicansMentha darvasicaMentha kopetdaghensisMentha lavandulaceaMentha longifoliaMentha pamiroalaicaMentha spicata subsp. longifoliaMentha spicata var. longifoliaMentha sylvestrisMenthe à longues feuillesNagaba hakkaOu bo hePoejo-realRossminzeSt. John's horsemintwild mintМята длиннолистнаяМята лесная

Synopsis

English Horsemint (Mentha longifolia (L.) Huds.): A Comprehensive Reference

1. Identity and Botanical Description

Scientific Name and Taxonomy

Mentha longifolia L., commonly called horsemint, wild mint, or biblical mint, is a perennial herb belonging to the Mentha genus in the Nepetoideae subfamily of Lamiaceae. The accepted binomial authority is Mentha longifolia (L.) Huds., with Hudson first publishing the name in Flora Anglica (1762). The taxon carries the common names horsemint and English horsemint, and is formally listed in herbarium records under the family Labiatae (= Lamiaceae), with related synonyms including Mentha silvestris, Mentha salicina, and Mentha capensis.

Synonyms in widespread use include M. spicata var. longifolia L., M. sylvestris L., M. tomentosa D'Urv., and M. incana Willd. The species is native to Europe (excluding Britain and Ireland), western and central Asia (east to Nepal and the far west of China), and northern and southern — but not tropical — Africa. According to the monograph of the genus by Tucker and Naczi (2007), its natural distribution area is the largest among wild-growing Mentha species, covering temperate and Mediterranean regions of Eurasia and Africa.

Common Names

Common names in different languages and regions include: Cape mint, wild mint, African mint, horsemint, wild spearmint (English); inixina, inzinziniba (Xhosa); ufuthana lomhlanga (Zulu); and kruisement, balderjan (Afrikaans). In Iran the plant is known as "Fudanaj," "Pooneh," or "Pune." In Iran it is commonly consumed as a green vegetable and spice or additive with various foods.

Morphology

Wild mint is a fast-growing, perennial herb that creeps along an underground rootstock. It can reach up to 1.5 m high in favourable conditions, but is usually between 0.5–1 m high and even shorter in dry conditions. The plant is strongly aromatic, with leaves formed in pairs opposite each other along a square-shaped stem. The soft, lanceolate leaves are between 45–100 mm long and 7–20 mm wide, usually coarsely hairy and with sparsely toothed edges. Leaf colour varies from light and dark green to grey. The small flowers are crowded into spikes at the tip of the stems, varying in colour from white to mauve, flowering throughout the summer months.

The species name longifolia means "long leaves," appropriately highlighting one of the plant's most distinguishing features. Like almost all mints, Mentha longifolia can be invasive; care needs to be taken when planting it in non-controlled areas.

Infraspecific Variation and Chemotypes

The diversity of the chemical composition of the essential oil of the species in different regions indicates different chemotypes. M. longifolia has been grouped into at least one chemotype rich in pulegone and a second rich in menthone. Multiple varieties and subspecies are recognized across its range, including var. asiatica, subsp. typhoides, and subsp. wissii, among others.

Common Dosage Forms and Preparations

Mint is used as a herbal tea, in food additives, and as a traditional medicine all around the world, and is considered a popular functional food and natural remedy. Preparations documented in research include: aqueous infusion (herbal tea), ethanolic and hydroethanolic extracts, essential oil obtained by hydrodistillation or steam distillation, oral syrup, and dried aerial parts. Ancient peoples used the plant as a tea and as a salad ingredient. Some communities dried the whole plant for later use.

2. Traditional and Historical Use

Ancient Egypt

The Ebers Papyrus, dating to 1550 BCE, is one of the earliest surviving Egyptian medical papyri. The history of local Egyptian mint dates back to at least 1,000 BC, when the ancient Egyptians used it as part of their herbal medicine as found in the Ebers Papyrus.

Classical Antiquity: Greece and Rome

Some scholars, including Parry (1925), suggest that New Testament references to the tithing of herbs refer to Mentha longifolia, the long-leafed mint native to North Africa. Robert Gunther's 1934 translation of Dioscorides describes the wild mint, which the Romans called Mentastrum, as being "round in the leaves and altogether greater than Sisymbrium."

17th-Century English Herbal Tradition

Nicholas Culpeper's Complete Herbal (1653) states that horsemint "is good for wind and colic in the stomach," that "the juice, laid on warm, helps the King's evil or kernels in the throat," and that "the decoction or distilled water helps a stinking breath, proceeding from corruption of the teeth, and snuffed up the nose, purges the head."

Iranian and Islamic Traditional Medicine

Based on Iranian traditional medicine (ITM) texts, particularly the Canon of Medicine (Avicenna) and Al-Havi (Rhazes, 865–925 AD), Mentha longifolia is one of the medicinal herbs that can influence menstrual periods. Mint in traditional Galenic medicine in the Islamic period can be traced to the writings of Dioscorides and other Greek authors. Persian traditional medicine also used a concoction called sekanjabin, honey and vinegar flavoured with mint extract.

Iraq and the Middle East

In Iraqi folk medicine, the leaves are used for relief of minor sore throat and minor mouth or throat irritation. The plant is also used in treatments for minor aches and sprains and in nasal decongestants, in addition to its antipruritic, carminative, antiseptic, and stimulant properties.

Central and South Asia (Pakistan, Iran, Turkey)

Across Iraq, Iran, Pakistan, Turkey, and Arab countries, the plant is commonly used as a natural remedy for digestive diseases such as gas, indigestion, intestinal colic, intestinal ulcer, diarrhoea, intestinal spasm, and stomach problems, as well as for respiratory disorders including asthma, colds, bronchitis, tuberculosis, sinusitis, and cough; it is additionally used as an anti-hemolytic, anti-inflammatory agent and for treatment of headache caused by lung infection and nausea. In the Gojal region of upper Hunza (Pakistan), the plant (known locally as "whadaan") is used for the treatment of jaundice, intestinal infection, fever, and cough.

Southern Africa

Found in most parts of southern Africa and easy to harvest, wild mint is a popular traditional medicine, mainly used for respiratory ailments, though many other uses have also been recorded. Mentha longifolia is among the plants most frequently cited in southern African ethnobotanical studies and historical records as traditionally used to alleviate fever, with five or more independent ethnobotanical records supporting this use.

3. Phytochemistry: Key Constituents and Active Compounds

Essential Oil Fraction

Pulegone is considered the main compound of the plant responsible for most of its pharmacological effects, followed by menthone, isomenthone, menthol, 1,8-cineole, borneol, and piperitenone. However, the precise composition varies markedly by geographic origin, variety, and extraction method.

Representative GC/MS profiles from the published literature illustrate this range:

One Tunisian study identified pulegone (54.41%) as the major component, followed by isomenthone (12.02%), 1,8-cineole (7.41%), borneol (6.85%), and piperitenone oxide (3.19%).
A study using Iranian plant material reported main compounds of pulegone (26.07%), piperitone oxide (19.72%), piperitone (11.88%), 1,8-cineole (8.21%), cis-piperitone oxide (6.35%), and borneol (5.96%).
Another Iranian extraction by hydrodistillation identified dominant compounds of piperitenone (37.77%), piperitenone oxide (15.94%), pulegone (10.47%), 1,8-cineole (5.35%), 8,9-dehydrothymol (3.35%), and 4,6-diethyl-2-methoxypyrimidine (3.27%).
For the M. longifolia var. asiatica from Iran, the major leaf oil constituent was piperitone (67.6%), isomenthone (6.6%), and cis-piperitol (4.2%), while the flower oil contained piperitone (55.7%), carvone (16.2%), and pulegone (4.1%).

The essential oil belongs to the oxygenated monoterpene group, which includes pulegone, piperitenone oxide, and 1,8-cineole as primary representatives, alongside carvone, limonene, sabinene, α-pinene, isomenthone, borneol, menthol, menthone, piperitenone, and others.

Non-Volatile (Phenolic and Flavonoid) Fraction

Flavonoids isolated from the methanol extract of M. longifolia aerial parts include apigenin-7-O-glucoside, apigenin-7-O-rutinoside, apigenin-7-O-glucuronide, iso-orientin, hypolaetin, 5,3′,4′-trihydroxy-6,7,8-trimethoxyflavone, 5,7-dihydroxychromone 7-rutinoside, eriodictyol-7-rutinoside, and longitin.

HPLC analysis of M. longifolia infusion and ethanol extract has identified sixteen phenolic compounds — ten phenolic acids and six flavonoids — in which sinapic acid (7132 µg/g extract) and rosmarinic acid (6260 µg/g extract) were the most abundant compounds.

The plant is a precious trove of native active metabolites, particularly due to its high concentrations of phenolic compounds, terpenoids, and flavonoids, including rutin, kaempferol, quercetin, and gallic, caffeic, and rosmarinic acids.

A wide variety of natural components such as flavonoids, phenolic acids, cinnamates, ceramides, sesquiterpenes, terpenes, and terpenoids have been suggested to be responsible for the pharmacological action of M. longifolia. Notably, M. longifolia contains cinnamates and ceramides in its chemical profile, which distinguishes it from some closely related species.

Mechanisms of Action (Preclinical Evidence)

Anti-spasmodic activity of M. longifolia extract on ileum and jejunum has been demonstrated through blocking calcium mobilization and potassium channels.

Plant extracts have been shown to suppress lipid peroxidation, protein, and DNA damage, and to enhance antioxidant defense systems including glutathione and superoxide dismutase enzymes; rosmarinic acid and eriodictyol-glycopyranosyl-rhamnopyranoside are considered the active components responsible for this action.

Pretreatment with M. longifolia extracts significantly inhibits hepatic antioxidant status in CCl₄-induced liver damage in mice, mediated by enhancement of antioxidant power through elevating glutathione content and superoxide dismutase activity. The crude extract (100–1000 mg/kg) showed anti-diarrheal action in animal models.

In cell-based studies, co-treatment of Clostridioides difficile toxin-stimulated Caco-2 cells with hydroethanolic extract of M. longifolia showed significant anti-inflammatory and anti-apoptotic activities by downregulating gene expression of IL-8, IL-1β, TNF-α, iNOS, TGF-β, NF-κB, Bax, and caspase-3, while upregulating Bcl-2.

4. Scientific Evidence by Area of Use

4.1 Antimicrobial Activity

Evidence type: In vitro / preclinical (laboratory studies only; no human clinical trials on infection treatment)

An antimicrobial compound isolated from the essential oil of Iraqi M. longifolia leaves was identified as (–)-menthol. This compound was active against all tested bacteria (including Staphylococcus aureus, Streptococcus mutans, Streptococcus faecalis, Streptococcus pyogenes, and Lactobacillus acidophilus) except Pseudomonas aeruginosa; the highest inhibitory effect was observed against S. mutans (zone of inhibition: 25.3 mm). MIC values ranged from 15.6–125.0 µg/ml, with the most promising results against S. aureus and S. mutans (MIC 15.6 µg/ml).

Menthol also achieved considerable antifungal activity against the yeast Candida albicans (zone of inhibition range: 7.1–18.5 mm; MIC: 125.0 µg/ml).

A 2023 study investigated the antibacterial effects of M. longifolia essential oil and pulegone in edible coatings made of chitosan and alginate on the growth of Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli in cheese. The results showed that adding M. longifolia essential oils and pulegone to edible coatings significantly reduced bacterial growth during storage.

In a cell-based study, rosmarinic acid was identified as the main phytochemical component of the hydroethanolic extract, which showed significant antimicrobial activity against Clostridioides difficile RT001 by agar dilution and broth microdilution methods.

Strength of evidence: All antimicrobial evidence to date is from in vitro and preclinical studies. No controlled human clinical trials of M. longifolia for the treatment of infectious disease have been identified in the peer-reviewed literature. The isolation of an antimicrobial compound from M. longifolia leaves validates traditional use of the plant in treatment of minor sore throat and minor mouth or throat irritation, but does not constitute clinical proof of therapeutic efficacy.

4.2 Gynaecological Use: Secondary Amenorrhea and Oligomenorrhea

Evidence type: One double-blind, placebo-controlled, randomized clinical trial (strongest level of human evidence available for this plant)

This was the first double-blind, placebo-controlled, randomized study to assess Mentha longifolia syrup in this condition. The multicenter study (6 centers in Tehran and Qom, Iran) was carried out among 120 women with secondary amenorrhea or oligomenorrhea (cessation of bleeding for at least 60 days without pregnancy); patients were between 18 and 35 years old with premenopausal FSH levels (<20 IU/l).

Treatment consisted of sequential oral syrup, 45 ml (15 ml three times a day) for 2 weeks.

The number of women with bleeding during the first treatment cycle was significantly higher in the drug group than in the placebo group (68.3% vs. 13.6%; p < 0.001). Regularity of bleeding throughout the study was markedly better in the drug group compared with placebo (33.3% vs. 3.3%; p < 0.001). No notable complication or side effect was reported in relation to Mentha longifolia L. syrup.

Limitations: This is a single trial from a single country. The proprietary syrup formulation is not standardized for a specific constituent. The study does not clarify the underlying mechanism (hormonal, uterotonic, or other). Replication in independent populations is needed before firm conclusions can be drawn.

4.3 Gastrointestinal Effects: Diarrhoea, Spasm, and Dyspepsia

Evidence type: Animal (preclinical) studies; one referenced clinical report

Antidiarrheal activity of M. longifolia essential oil (at doses of 20–80 mg/kg) was investigated against castor oil-induced diarrhoea in a rat model, using loperamide as the standard reference drug.

The crude extract (100–1000 mg/kg) showed anti-diarrheal action with a protection rate of 31–80% in animal experiments, comparable to the standard drug in those models.

One clinical source reports the efficacy of M. longifolia in relieving postprandial distress syndrome (PDS) symptoms and improving the quality of life of patients with PDS.

Strength of evidence: Evidence for gastrointestinal effects is primarily animal-based and mechanistic (anti-spasmodic via calcium channel and potassium channel blockade). The single clinical reference to dyspepsia relief requires fuller published data for assessment. This area warrants properly designed human clinical trials.

4.4 Antioxidant Activity

Evidence type: In vitro studies

Sixteen phenolic compounds (ten phenolic acids, six flavonoids) were identified by HPLC in M. longifolia extracts; strong antioxidant effects were observed in DPPH radical, ABTS, cupric ion reducing activity, ferric reducing antioxidant power, phosphomolybdenum, and metal chelating assays.

The essential oil of one M. longifolia variety stood out for antioxidant activity with IC₅₀ of 0.86 ± 0.01 mg/mL by the DPPH method and 0.64 ± 0.02 mg/mL by the β-carotene/linoleic acid system method. Antioxidant activity in Mentha species is related to a higher content of piperitenone oxide, especially in M. longifolia oil.

Antioxidant effects of Mentha longifolia are attributed to the presence of phytosterols, unsaturated fatty acids, phenolic compounds, and specific volatile constituents.

Strength of evidence: Antioxidant activity is well demonstrated in vitro. No clinical trials in humans have tested whether oral consumption of M. longifolia reduces oxidative stress biomarkers in vivo.

4.5 Anti-inflammatory Activity

Evidence type: In vitro and animal studies

Cell-based studies have documented that M. longifolia extract significantly downregulated the expression of pro-inflammatory genes including IL-8, IL-1β, TNF-α, iNOS, TGF-β, and NF-κB in stimulated intestinal cells, while upregulating the anti-apoptotic protein Bcl-2.

In the modern era, various pharmacological activities have been confirmed for M. longifolia, including antinociceptive and anti-inflammatory effects, among others, in preclinical models.

Strength of evidence: Preliminary; all evidence is from cell and animal models. No controlled human trials on anti-inflammatory endpoints have been published.

4.6 Hepatoprotective Activity

Evidence type: Animal studies

A study investigated the effects of essential oil of M. longifolia on oxidative stress and inflammatory responses in the liver and kidneys in the context of drug-induced liver injury caused by the anti-tuberculosis drugs rifampicin, isoniazid, and pyrazinamide (INH-RIF-PZA) in Wistar rats. Both tested doses of M. longifolia essential oil therapy effectively regulated all biochemical indicators of hepatic impairment and reduced the damage caused by the drug mixture, suggesting potential as a natural remedy for treating anti-TB-induced liver and kidney injuries.

Strength of evidence: Animal data only. These findings are preliminary and cannot be extrapolated to humans without clinical testing.

4.7 Antidiabetic and Enzyme-Inhibitory Activity

Evidence type: In vitro studies

The chemical composition of essential oil of wild mint (Mentha longifolia var. calliantha) was determined together with its antioxidant and enzyme inhibitory potential linked to Alzheimer's disease, diabetes mellitus, and skin disorders. Total bioactive contents, radical scavenging, reducing power, metal chelating, and enzyme inhibitory activities relevant to Alzheimer's disease, diabetes mellitus, and skin disorders were also evaluated using phenolic profiling.

Compounds found in M. longifolia have been reported to exhibit pharmacological benefits including anticancer, antidiabetic, antibacterial, and antifungal activity in laboratory settings.

Strength of evidence: Exclusively in vitro; no human studies on glycaemic control or diabetes management with M. longifolia have been published.

4.8 Anticancer / Anti-proliferative Activity

Evidence type: In vitro studies only

The aqueous and methanolic extracts of M. longifolia showed anti-tumor and anti-mutagenic effects in laboratory studies, indicating the presence of bioactive constituents which might be useful in the development of novel anticancer agents.

Recent studies have stated that M. longifolia reduces tumor cell viability and exhibits anti-quorum-sensing activities in cell culture models.

Strength of evidence: Entirely preclinical. No human data. These findings do not establish clinical efficacy or safety for any cancer indication.

4.9 Insect Repellent and Antiparasitic Activity

Anti-parasitic and anti-insect properties have been confirmed for M. longifolia in preclinical pharmacological studies. In vitro and in vivo experimental analyses have demonstrated antiparasitic effects, though all evidence remains preclinical.

5. Body Systems and Health Areas Associated with English Horsemint

Gastrointestinal system: Carminative, digestive, anti-spasmodic, anti-diarrheal, and anti-ulcer uses are documented across multiple traditional medicine systems.
Respiratory system: The plant is mainly used for respiratory ailments in South African traditional medicine, and cross-culturally for asthma, colds, bronchitis, sinusitis, and cough.
Reproductive/gynaecological system: Iranian traditional medicine texts recognize M. longifolia as influencing menstrual periods, supported by the single randomized clinical trial described above.
Immune and infectious disease: In vitro evidence supports antibacterial and antifungal properties; no human trial data are available.
Hepatic system: Preclinical data suggest hepatoprotective activity.
Skin: Traditional use for wounds, and in vitro evidence for enzyme inhibitory activity relevant to skin conditions.
Neurological: In vitro enzyme-inhibitory studies relevant to Alzheimer's disease have been conducted; no human data are available.

6. Dosage Forms and Dosages Reported in Studies

The following dosages are stated directly in published sources and are presented for reference only:

Oral syrup for secondary amenorrhea: 45 ml per day (15 ml three times a day) for 2 weeks, in a randomized clinical trial setting.
Essential oil for antidiarrheal activity: 20–80 mg/kg, investigated in a rat model against castor oil-induced diarrhoea.
Essential oil for hepatoprotection in rats: administered orally at doses of 50 mg and 100 mg/kg body weight, in a 30-day animal study.
Hydroethanolic extract in cell culture: concentrations of <25 µg/ml had no significant effect on cell viability compared to untreated cells; at 10 or 25 µg/ml, significantly increased cell viability in C. difficile toxin-challenged Caco-2 and Vero cells.
Based on variation in essential oil yields (1.39%–4.05% v/w) and pulegone content across samples, it has been proposed that any final pharmaceutical product containing M. longifolia must be standardized based on a safe extent of pulegone, meaning a maximum of 25 mg/kg in foodstuffs and 100 mg/kg in beverages.

No standardized therapeutic dose has been established for any clinical indication. Dosages used in animal models cannot be directly extrapolated to human use.

7. Safety Considerations and Interactions

Pulegone: Established Hepatotoxicity Risk

The most important and best-documented safety concern relates to pulegone, a major constituent in many chemotypes of M. longifolia.

Pulegone is a hepatotoxic compound and is one of the major components of the essential oil. Given the wide range of essential oil yields among different samples (1.39%–4.05% v/w) and various percentages of pulegone content, any pharmaceutical product containing M. longifolia must be standardized based on a safe extent of pulegone: a maximum of 25 mg/kg in foodstuffs and 100 mg/kg in beverages.

In biochemical studies, extensive pulegone metabolism generates p-cresol (a glutathione depletory); however, the role of p-cresol in the hepatotoxicity of pulegone is considered minimal. Hepatic injury caused by pulegone is largely due to the covalent binding of its reactive metabolite γ-ketoenal to cellular proteins in the liver.

Pulegone is recognized as a hepatotoxin and should be restricted in food and herbal products.

Dose-Dependent Toxicity

The plant may dose-dependently exert toxic effects in different systems of the body, and further studies are required to determine the precise quality and safety of the plant to be used by clinicians.

Clinical Safety Profile (from Human Studies)

In clinical studies involving 120 women and 40 patients of both sexes, no complications or side effects were observed with oral syrup use at the studied doses. These represent the only formal human safety data available.

Pregnancy and Reproductive Concerns

In the randomized clinical trial, a positive pregnancy test was an explicit exclusion criterion, meaning the plant was not administered to pregnant women. Given its documented emmenagogue (menstruation-inducing) effect demonstrated in the clinical trial, use during pregnancy is not supported by available evidence and carries a theoretical risk.

Chemotype Variability and Standardization

The composition of essential oils in the plant varies depending on the parts used, extraction methods, and geographical conditions, which means that different commercial preparations may carry substantially different phytochemical and toxicological profiles. This variability makes safety generalization difficult and underscores the need for product standardization, particularly with respect to pulegone content.

Invasive Nature and Botanical Misidentification

The identification of mints can be quite difficult because they are extremely variable and easily hybridized, and the many common names can be confusing, as the same common name is often given to different plants, or the same plant may have different common names in different areas and languages. This creates a practical risk of substitution or adulteration in the supply chain.

8. Overall Evidence Assessment

Reviews of M. longifolia confirm a wide range of pharmacological activities that have been demonstrated for this herb in preclinical settings, including anti-parasitic, antimicrobial, anti-insect, antimutagenic, antinociceptive, anti-inflammatory, antioxidant, keratoprotective, hepatoprotective, anti-diarrheal, and spasmolytic effects. The plant has also shown therapeutic benefits in irritable bowel syndrome, amenorrhea, oligomenorrhea, and oxidative stress-associated diseases.

M. longifolia encompasses a wide range of therapeutic functions and various highly bioactive components; further preclinical and clinical investigations exploring therapeutic efficacy and safety of the plant and its phytoconstituents are recommended.

As of the available published literature, the only area of use supported by a formal randomized controlled trial in humans is the induction of menstrual bleeding in secondary amenorrhea and oligomenorrhea. All other claimed activities are supported by in vitro or animal data only and should not be interpreted as established human efficacy.

References

Health Conditions

Health conditions that English horsemint may help support.

No conditions available.

Body Systems

Body systems that English horsemint may help support.

No body systems available.