IngredientsPseudowintera colorata, or mountain horopito, is an evergreen shrub or small tree (1–2.5 m) commonly called pepperwood because its leaves have a hot taste. It is also known as the New Zealand pepper tree, winter's bark, or red horopito. The accepted botanical name is Pseudowintera colorata, in the family Winteraceae, order Canellales, genus Pseudowintera. Older synonyms include Drimys colorata Raoul, Drimys axillaris var. colorata (Raoul) Kirk, and Wintera colorata Tiegh.
It is so named because early taxonomists recognized the similarity between horopito and the South American Drimys winteri that provided the herbal remedy "winter's bark." They are both members of the family Winteraceae, which are mainly found on the landmasses that once made up the great southern continent of Gondwana — South America, Australia, New Zealand, and New Guinea.
The genus name "Pseudowintera" is derived from the resemblance of the plant to the genus Winteraceae, named after the Wintera plant family. The species name "colorata" derives from Latin, meaning "colored" or "painted," which references the plant's vibrant leaves.
The four species of Pseudowintera are found only in New Zealand, in a wide array of habitats. The most commonly known species (by virtue of its colorful, mottled leaves) is the mountain horopito, P. colorata. The lowland horopito, P. axillaris, is the next most common species, whilst the two remaining horopito species, P. traversii and P. insperata, are restricted to relatively limited areas within the wild. The Māori gave the name "horopito" to all three species of Pseudowintera they found in New Zealand, and this sometimes causes confusion. However, it is only the very hot-tasting Pseudowintera colorata that possesses the extraordinary antifungal properties described in the scientific literature.
Pseudowintera colorata, commonly known as Mountain Horopito or Pepperwood, is an evergreen shrub or small tree native to the cool temperate rainforests and subalpine areas of New Zealand. It typically grows to a height of 6–9 feet. The species is characterized by its yellowish-green leaves that are blotched with red, with new leaves in the spring being bright red.
It grows on coastal, lowland, or montane forest margins and shrubland. It is distributed within lowland forests up to higher montane forests from 36° 30′ South as far southward as Stewart Island/Rakiura.
The reproductive parts of the family Winteraceae are primitive, reflecting their origin among the first flowering plants. In New Zealand, horopito appears in the fossil record for more than 65 million years.
Leaves with wider red margins contained higher concentrations of polygodial and anthocyanins, and incurred less natural herbivory. Research published in New Phytologist demonstrated that the red leaf margins reduce leaf herbivory by signaling to herbivorous insects the presence of increased chemical defenses. Leaves were collected from a natural population of Pseudowintera colorata, and margin size, herbivory damage, anthocyanin content, and concentrations of polygodial — a sesquiterpene dialdehyde with antifeedant properties — were quantified.
Mountain horopito is available in a range of preparations. It has a wide variety of uses, from health and wellness through to culinary. It is applied as a hero ingredient in body care products such as creams and balms and health products. Horopito is also used in culinary for spices, salts, and unique beverages and herbal teas. In supplemental form, standardized extracts are available as soft-gel capsules; one commercially studied formulation contains 11.43 mg of mountain horopito (Pseudowintera colorata, leaf) extract (25:1 concentration, equivalent to 285.75 mg dried leaf), standardized to contain 2.5 mg polygodial, in a base of olive oil, gelatin, glycerin, and purified water.
Rongoā Māori is the traditional holistic healing system of the indigenous people of New Zealand. It involves the use of native plant remedies (rongoā rākau), physical therapies like massage (mirimiri), and spiritual healing through prayer (karakia). It focuses on the treatment of the whole person and maintaining a deep connection to the natural environment.
Horopito has long been used by the indigenous Māori population of New Zealand both internally and externally for many purposes. As far back as 1848, horopito is documented in the treatment of skin diseases such as ringworm, or venereal diseases. An 1848 source describes the preparation method: "The leaves and tender branches of this shrub are bruised and steeped in water, and the lotion used for ringworm; or the bruised leaves are used as a poultice for chaffing of the skin, or to heal wounds, bruises or cuts."
Traditionally, fresh leaves of horopito were chewed or boiled for toothache and stomachache. Early settlers used horopito as a substitute for quinine to treat diarrhea and gastric infections. It was also utilized for coughs, colds, and asthma. Māori used to chew horopito leaf to treat toothache, to heal fungal skin problems, and to support stomach complaints by creating a drink that was consumed like a herbal tea.
Topically, horopito was used for skin diseases, wounds, cuts, and burns as well as for painful bruising and sore joints. Horopito has a rich history of medicinal use by New Zealand's indigenous Māori. It was used for a wide range of ailments including fungal skin diseases, venereal diseases, toothache, and stomach complaints. Due to its painkilling properties, horopito is honoured with the name "Māori painkiller."
The indigenous Māori population and early European settlers to New Zealand used horopito internally and topically as an analgesic, antiseptic, and quinine substitute for chronic diarrhea and stomach pain. Traditional uses also included chest infections, colds and asthma, and topical applications for a range of skin conditions. When the early Europeans colonized New Zealand, many of them began using the herb as a source of vitamin C to prevent or treat scurvy.
The Māori people of New Zealand accumulated a vast storehouse of knowledge about indigenous flora. This is evident in the myriad of spiritual and practical uses that intertwine with the medicinal use of the 200 or so plants used by the Māori for ritual or herbal purposes. Māori believe plants and man have a common origin, both being offspring of Tane, in his capacity as controller of the forests and of fertilization. This article provides some insight into the traditional medicinal uses of one such New Zealand plant, horopito, and how such use is now corroborated by decades of scientific research.
The main active constituent present in horopito is a bicyclic sesquiterpene dialdehyde, polygodial, found primarily in P. colorata, and also responsible for the horopito hot peppery flavor. Polygodial is the most well-researched active constituent, considered to be responsible for the potent anti-fungal and anti-microbial activity of P. colorata leaves. Polygodial was first isolated from the leaves of horopito in 1982 by a team of researchers at New Zealand's University of Canterbury.
Polygodial is a "hot" peppery-tasting sesquiterpenoid that was first described for its anti-feedant activity against African armyworms. Apart from the anti-feedant activity against a number of pests, polygodial has been reported to possess biological activities such as antifungal, antibacterial, anti-tumor, larvicidal, antihelminthic, antifouling, anti-inflammatory, analgesic, antitrypanosomal, and antileishmanial activities.
Horopito leaves contain at least 21 terpenes (of which the sesquiterpene polygodial is dominant) and at least four flavonoids. Other active constituents present are tannins and essential oil components, such as eugenol, pinenes, limonene, humulene, and the flavonoids quercetin, luteolin, and proanthocyanidins. When chemists studied the constituents of horopito's essential oil, they discovered that it contained not one but 29 components — one of which was eugenol, a dental pain killer.
The red color of the leaves is enriched with anthocyanins, flavonols, and dihydroflavonols, all of which are known to have potent antioxidant activity. The leaves of the plant are naturally rich in two potent antioxidant flavonoids namely quercetin and taxifolin. Horopito also harbors a range of other beneficial constituents including volatile oils, flavonoids, anthocyanins, and tannins.
Leaves with wider red margins contained higher concentrations of polygodial and anthocyanins, and incurred less natural herbivory. This finding, published in peer-reviewed research, confirms that the characteristic red blotching of horopito leaves is a reliable visual indicator of the plant's primary defensive and medicinally relevant compound.
The primary antifungal action of polygodial comes in part from its ability to function as a nonionic surfactant, disrupting the lipid–protein interface of integral proteins and denaturing their conformation. As a result, the antifungal mechanism of this sesquiterpene dialdehyde is associated with the membrane functions or derangement of the membrane. For example, the glucose-induced medium acidification process of Saccharomyces cerevisiae was inhibited by polygodial, presumably caused by inhibition of the plasma membrane H⁺-ATPase. However, the potent antifungal activity of polygodial results from its multiple functions.
Further mechanistic research confirmed that polygodial triggers a dose-dependent vacuolar alkalinization and that it increases Ca²⁺ influx and inhibits glucose-induced Ca²⁺ signaling. Additionally, low concentrations of polygodial are not only active against the planktonic forms of C. albicans, but the compound is also active against its biofilm forms (biofilm inhibiting concentration: BIC₅₀ = 10.8 ± 5 μg/mL), which are a major menace to public health due to their increased resistance to currently available antifungals.
TRPA1 is activated by polygodial, a drimane sesquiterpene synthesized by plants and animals. TRPA1-deficient mice show greatly reduced nocifensive behavior in response to isovelleral, indicating that TRPA1 is the major receptor for deterrent sesquiterpenes in vivo. Polygodial is a TRPA1 channel activator (EC₅₀ = 400 nM) that is selective against TRPV1, TRPV2, TRPV3, TRPV4, and TRPM8 channels. It acts as an analgesic via desensitization of sensory neurons. It also exhibits antifungal activity via inhibition of mitochondrial ATPase.
Polygodial inhibits glutamate uptake by rat brain slices, suggesting a potential increase in extracellular glutamate. It is theorized that the modulation of endogenous prostaglandins and nitric oxide are responsible for its gastroprotective activity. Horopito has been traditionally used to treat painful abdominal conditions and, based on current in vitro evidence, it is theorized that polygodial allows relaxation of smooth muscle and thus alleviates abdominal discomfort by producing a concentration-dependent antagonism of gut contraction induced by inflammatory mediators such as bradykinin and tachykinins.
Polygodial was found to possess moderate antibacterial activity against gram-positive bacteria including Bacillus subtilis, Staphylococcus aureus and gram-negative bacteria including Escherichia coli and Salmonella choleraesuis with minimum bactericidal concentrations (MBC) of 100 and 100 μg/mL and 100 and 50 μg/mL, respectively. The time kill curve study showed that polygodial was bactericidal against B. subtilis and S. choleraesuis. However, there was a difference in its bactericidal action against endospore-forming B. subtilis and food-borne S. choleraesuis.
The main biologically active chemical component isolated from the leaves of P. colorata is polygodial. Polygodial, extracted from horopito, has been observed to strongly inhibit Candida albicans grown in vitro, with an activity comparable, and sometimes more powerful, than that of antifungal drugs such as amphotericin B. Available research reports its antifungal activity against different types of Candida: Candida albicans, Candida krusei, Candida utilis.
Polygodial has also demonstrated antifungal activity towards Candida utilis, Candida krusei, Saccharomyces cerevisiae, Cryptococcus neoformans, and also other filamentous fungi like Trichophyton rubrum, Trichophyton mentagrophytes, and Penicillium marneffei. The various susceptibility-testing conditions like incubation temperature, medium type, inoculum size, and medium pH had little effect on the antifungal activity of polygodial, while its activity is significantly enhanced under acidic conditions.
Early landmark research found that the activity of polygodial from the extract was compared with that of Amphotericin B (a proprietary pharmaceutical product used to treat systemic mycoses) and found to be stronger and faster acting. The polygodial extract from horopito gave larger zones of inhibition against C. albicans and was effective from day one, whereas the inhibitory effect of Amphotericin B against C. albicans required three to four days' incubation to become effective.
A synergistic effect has also been documented: a combination of milled horopito leaf with milled anise seed (containing anethole) showed a synergistic effect against budding yeast, Saccharomyces cerevisiae, and the human opportunistic pathogenic yeast, Candida albicans, and significantly improved chronic intestinal candidiasis in patients.
Evidence strength: In vitro evidence for antifungal activity against multiple Candida species is substantial and consistently replicated across multiple independent studies, representing a strong preclinical foundation.
Two published clinical trials provide the primary human evidence for horopito's antifungal effects. Two clinical studies evaluated the efficacy of an oral dose of horopito extract for the treatment of recurrent vulvovaginal candidiasis (RVVC). The first study involved 82 patients and the second 122. The first study lasted one year while the second lasted two years. In both studies, patients were divided into two groups: the first group was administered itraconazole, the second horopito. In both studies, symptom remission at the trial endpoint was comparable between the two groups.
The 12-month study (Kumari et al., 2011, PMID 22217987) involved 82 women. A clinical trial in 82 women with RVVC randomised subjects to oral treatment with the anti-fungal pharmaceutical Itraconazole, or horopito extract standardised to polygodial (10 mg extract twice daily for 4 weeks, then 10 mg extract twice daily for the first two weeks of each month).
The 24-month study (Chopra et al., 2013, PMID 24152852) used the following design: the aim was to assess the clinical efficacy of a one week/month treatment with a phytocompound with antimycotic properties (K-712, with 100 mg composition: 10 mg of oleoresin from Pseudowintera colorata at 30% concentration in polygodial, together with trace amounts of Olea europaea) in RVVC, as compared to once-a-week treatment with an azole drug for 24 months. This prospective randomized study involved 122 women (19 to 63 years old) with a history of proven episodes of RVVC in the prior 12 months. Patients were allocated to two treatment groups of 61 patients each: Itraconazole 200 mg orally once a week, or 1 tablet twice a day of K-712 for one week/month. Each treatment schedule was well tolerated, with 19 patients in the azole group complaining of transient mild symptoms, while only 3 patients on K-712 reported slight dyspepsia.
The benefits of horopito were more evident in the medium-to-long term, in the observation period and at the end of the study, highlighting a significantly lower percentage of relapses in the group that had been administered horopito.
Both studies are cited in the Cochrane Library's reference database on recurrent vulvovaginal candidiasis treatments. Evidence strength: These two randomized controlled trials provide moderate-quality human clinical evidence. Both compared horopito extract against an active comparator (itraconazole) rather than a placebo, which strengthens the findings for equivalence but limits conclusions about absolute efficacy. The trials were not placebo-controlled, and both were conducted by overlapping research groups. Independent replication and larger blinded trials are warranted.
In addition to its antifungal activities, polygodial has moderate antibacterial activity against both gram-positive bacteria (including Bacillus subtilis and Staphylococcus aureus) and gram-negative bacteria (including Escherichia coli and Salmonella choleraesuis) with minimum bactericidal concentrations ranging from 100–400 μg/mL.
Evidence strength: Antibacterial activity is currently established only at the preclinical (in vitro) level. No controlled human clinical trials specifically examining the antibacterial applications of horopito or polygodial have been identified in the literature. The minimum bactericidal concentrations reported are substantially higher than those demonstrated for antifungal activity, suggesting this is a secondary effect.
Research involving horopito and polygodial in recent years suggests anti-inflammatory, antifungal, antibacterial, and antinociceptive (analgesic) properties are contained within the leaves. The molecular basis of the analgesic effect involves initial activation and subsequent desensitization of the TRPA1 receptor: deterrent sesquiterpenes are potent activators of mammalian peripheral chemosensory neurons, causing pain and neurogenic inflammation. Despite their widespread synthesis and medicinal use as desensitizing analgesics, their molecular targets were previously unknown.
The topical application of polygodial in rat models led researchers to predict that the mechanism for the sensory changes in primary afferent nerve fibers responsible for pain transmission is TRPV1 agonist activity.
Evidence strength: Analgesic mechanisms have been characterized in preclinical (animal and in vitro) models, with TRPA1 receptor interaction confirmed experimentally. No human clinical trials specifically designed to evaluate the analgesic effects of horopito or polygodial were identified. Evidence remains at the preclinical stage for this indication.
Polygodial administration has been reported to reduce macrophage activity (as indicated by NAG) and mast cell density around sponge implants, without affecting neutrophil activity (MPO). This study also reported a reduction in the levels of the pro-inflammatory chemokines CXCL1 and CCL2 in the treated groups.
Evidence strength: Anti-inflammatory effects have been demonstrated in animal (in vivo) models and associated in vitro assays. No dedicated human clinical trials evaluating the anti-inflammatory effects of horopito as a primary endpoint were identified. This area remains preclinical.
Horopito's gastroprotective effects have been studied in animal models: polygodial displays potent gastroprotective effects in rat models as well as a reduction in colon permeability in malnourished mice. It is theorized that the modulation of endogenous prostaglandins and nitric oxide are responsible for this activity.
Evidence strength: Gastrointestinal evidence for horopito is derived from traditional use records, animal models, and the extrapolated findings of the RVVC clinical trials (which tracked digestive tolerability as secondary outcomes). No dedicated human clinical trials on digestive indications alone have been identified.
There is promising evidence using horopito topically in relapsing bacterial vaginosis, genital candidiasis, and fungal skin complaints. This is consistent with historical Māori use of bruised leaves applied directly to affected skin areas. Topical evidence is currently supported by in vitro susceptibility data, traditional use records, and limited clinical observations rather than large, blinded, controlled trials.
Evidence strength: Weak to preliminary for topical indications. Traditional use is well-documented, in vitro data is robust, but controlled human clinical trials of topical applications specifically are lacking.
The following doses are derived directly from published studies and should not be interpreted as prescriptive recommendations:
It is important to note that polygodial content in wild-harvested horopito leaf varies considerably across geographic populations. Standardized extracts attempt to normalize this variability.
Horopito leaf and its constituents are generally considered safe for both oral and topical administration when appropriately prescribed. There is no documented traditional evidence of toxicity to humans by either oral ingestion or topical application.
Contrary to compounds of a similar structure with potent antimicrobial action, polygodial exhibits the least cytotoxicity and is non-mutagenic, confirmed by Ames and V79/HGPRT assay.
No toxic effects were observed in rats following acute exposure up to 2 grams per kg bodyweight. In contrast to compounds of a similar structure with strong biological activity, polygodial has been shown to be non-mutagenic (Ames and V79/HGPRT assay) and to exhibit the least cytotoxicity.
A case report of contact vulvitis and persistent vulvar itch following vaginal application of a horopito-containing cream in a 16-year-old girl diagnosed with contact dermatitis to P. colorata has been published. In clinical studies, a sensation of heat has been reported in a minority of individuals. Mild transient digestive side effects have been reported in some clinical trials.
Horopito works rapidly against C. albicans in the digestive tract. So in the first few days of therapy by those with candida overgrowth, a Herxheimer reaction to dead candida cells is sometimes experienced, which is characterized by nauseous feeling and headache, both of which are usually mild and transient.
Safety in pregnancy and lactation has not been established, therefore use is not recommended. Polygodial exhibits the least cytotoxicity and is non-mutagenic confirmed by Ames and V79/HGPRT assay. Even though there is no evidence of teratogenicity, as a precaution, horopito has not been suggested during pregnancy or lactation.
Large doses should be avoided in acute gastritis and peptic ulcers. This caution is consistent with the known irritant properties of polygodial, which is the compound responsible for the plant's intense peppery heat.
There have been very few reports of side effects from using horopito — however, some reports of allergic reactions have been reported. Horopito should be avoided by epileptics due to a possible increase in extracellular glutamate. This is derived from the observation that polygodial inhibits glutamate uptake by rat brain slices, suggesting a potential increase in extracellular glutamate concentrations.
Due to the antimicrobial action of the herb, when prescribing a probiotic alongside horopito formulations, the two products should be recommended to be taken at separate times of the day. Beyond this practical consideration, cases of horopito interacting with other medications have not been reported in the literature. No pharmacokinetic drug interaction studies have been identified.
Safety studies on the use of horopito by children are not available and safety therefore cannot be guaranteed. Use by children under the age of 12 is not recommended by the primary manufacturer of standardized horopito extract.
Health conditions that Mountain horopito may help support.
Body systems that Mountain horopito may help support.
Go back