Long buchu

Long Buchu (Agathosma serratifolia / Barosma serratifolia): A Comprehensive Reference

1. Identity and Botanical Description

1.1 Nomenclature and Taxonomy

Agathosma serratifolia, known as longleaf buchu or long buchu, is an erect, South African shrub belonging to the citrus family Rutaceae. The accepted current botanical name is Agathosma serratifolia (Curtis) Spreeth, previously classified under the genus Barosma as Barosma serratifolia (Curtis) Willdenow — the synonym most commonly encountered in historical pharmacopoeial and trade literature. The genus epithet Agathosma means "good smell," while serratifolia means "serrate-leaved."

Of the 150 Agathosma species indigenous to South Africa, Agathosma betulina (round-leaf buchu; "bergboegoe"; short buchu) and Agathosma crenulata (oval-leaf buchu; "anysboegoe"; long-leaf buchu) are probably the best known South African herbs used locally and internationally for medicinal purposes. Long buchu (A. serratifolia) forms a third, historically significant, commercial species alongside these two. The standard buchus of commerce were obtained from three species: Barosma betulina, known as "shorts"; B. crenulata, known as "ovals" and "shortbroads"; and B. serratifolia, known as "longs."

Linnaeus first recorded the genus as Diosma in 1756, and Ecklon and Zeyher later introduced the genus as Barosma and provided detailed botanical and geographical data (Ecklon and Zeyher, 1835). Until the authoritative revision by Pillans, multiple authorities named and renamed species. The name "Buchu" is from the Khoikhoi word for the plant meaning "dusting powder."

Common synonyms and alternate names for long buchu include:

• Barosma serratifolia (Curtis) Willd. (most prevalent pharmacopoeial synonym)
• Diosma serratifolia Curtis
• Parapetalifera serratifolia and Parapetalifera serrata (older synonyms)
• Common trade names: Longs (trade), Long-leaved buchu, Longleaf buchu, Bookoo, Bucco, Bucku, Diosma

These plants should not be confused with "Indian buchu" (Myrtus communis), which is native to the Mediterranean regions.

1.2 Botanical Characteristics

Agathosma serratifolia is an erect South African shrub and one of about 135 species mainly occurring in the south-western Cape Province, where it is found on mountain slopes, wooded ravines, and valleys. The leaves are simple, ovoid, slightly serrated, and 0.5–3.5 cm long. In April and May, the plant produces 5-petalled flowers.

Long buchu is obtained from Barosma serratifolia Willd. The leaves are 12–40 mm long and 4–10 mm broad, and linear lanceolate in shape; the apex is truncate and possesses a terminal oil gland; the margin is serrate. B. serratifolia has linear-lanceolate, sharply serrulate leaves. They are all, as found in commerce, of a pale yellow-green colour; they emit a peculiar aromatic odour, and have a slightly astringent bitter taste.

The three buchu species produce oval, serrated leaves with the leaf of B. serratifolia being the longest and most slender. Agathosma serratifolia is strongly aromatic and is gathered for medicinal use.

In a taxonomic appraisal of commercially important Agathosma species (previously named Barosma), Spreeth (1976) includes Agathosma betulina, Agathosma crenulata and Agathosma serratifolia in his treatment; the latter species is no longer of commercial importance and is not further considered in more recent reviews.

1.3 Common Preparations and Commercial Forms

Agathosma buchu species are commercially marketed as fresh or dried leaves, tinctures, herbal water, and essential oils. Historically, long buchu leaves were prepared and traded in several forms:

• Dried leaves (herbal tea / infusion): Buchu leaves are collected while the plant is flowering and fruiting, and are then dried and exported from Cape Town.
• Tincture: Traditional buchu tinctures can be prepared by placing leaves and stalks into brandy.
• Buchu vinegar: "Buchu vinegar," prepared by steeping the leaves and stalks in vinegar, is also a traditional remedy used in compresses and also taken internally.
• Essential oil: The essential oil is used in the manufacture of flavorings and perfume.
• Capsules and powders: Dried buchu leaves have been used for medicinal purposes in tonics and as tablets or powders.
• Bottled infusions: Bottled agathosma infusions were widely sold in English-speaking countries as "buchu tea" in the 1860s and 1870s, and as of 2012, bottled infusions continue to be prepared from agathosma leaves.

Because the constituent profile of buchu leaves oil is rich in pulegone, menthone, and isomenthone — common constituents of mint oils — this ingredient is evaluated alongside the Mentha natural flavor complexes under FEMA's GRAS assessment program. The FEMA Expert Panel affirmed the GRAS status of Buchu Leaves Oil (FEMA 2169) and determined FEMA GRAS status for Buchu Leaves Extract (FEMA 4923).

2. Historical and Traditional Use

2.1 Indigenous Khoisan Origins

Before moving on to discuss the records of traditional use of buchu made by early settlers, colonists, and explorers, it must be stressed that the knowledge of buchu and its medicinal properties by the Khoisan precedes written records, probably by centuries. The Digital Bleek and Lloyd, a digital archive of the ethnographical exploration of the Khoisan people, lists the use of buchu in multiple everyday, spiritual, and medicinal contexts. The Khoisan and other indigenous peoples considered multiple aromatic species as buchu and used them in dance rituals, for anointment, beautification, perfume, and also as medicine.

The first published record of "boggoa" leaves being used in tribal dance practices was made by an early settler in 1668 and later reiterated in other settlers' records. The Hottentots used an infusion of the dried leaves as a diuretic and cure for urinary tract disorders and pulverised the fragrant rue-like leaves to powder their bodies and act as an insect deterrent.

The indigenous people of the Cape used buchu as a tea for various internal ailments or used the leaves on cuts or burns. It was also powdered and mixed with animal fat to anoint their bodies and repel insects.

Within the realm of those recorded uses, traditional knowledge is owned by the Khoisan and should be attributed and respected as such.

2.2 Colonial-Era Adoption and Spread to Europe

Traditionally, buchu has been used by the Khoisan for spiritual and medicinal purposes. Initially noted by the early settlers, knowledge and use of buchu spread to Europe and later to the United States.

Buchu was first exported to Britain in 1790. In 1821, it was listed in the British Pharmacopoeia as a medicine for "cystitis, urethritis, nephritis and catarrh of the bladder." The drug had been included in the US National Formulary and was described as a diuretic and antiseptic.

The standard buchus of commerce were obtained from three species: Barosma betulina (shorts), B. crenulata (ovals and shortbroads), and B. serratifolia (longs). The leaves of the first-named were most valued and constitute the Folia Buchu of the British Pharmacopoeia.

Long buchu (B. serratifolia) was thus an established trade article alongside round-leaf buchu and was commercially relevant through the 19th century. In 1863, Bedford provided some insight into the wholesale value of buchu: long-leaved (B. serratifolia) and short-leaved (B. crenulata) were traded at 80 and 40 cents per pound, respectively.

2.3 Pharmacopoeial Recognition and the 19th–20th Century

Buchu was monographed in the first edition of the Dispensatory of the US of America (Wood and Bache, 1833) — referring to the Dublin Pharmacopoeia. Buchu entered the Primary List of Materia Medica in the second decennial revision of the USP (1842), listed as: "Diosma. Buchu. The leaves of Diosma crenata." A monograph for one preparation was included, Infusum Diosmae USP.

Elixir Buchu, Elixir Buchu Compositum, Elixir Buchu et Potassii Acetatis, and Extractum Buchu Fluidum Compositum appeared in the first edition of the National Formulary (NF) of the American Pharmaceutical Association (1888). Buchu and Fluidextractum Buchu were dismissed from the eleventh decennial revision (USP XI, 1930).

The British Pharmacopoeia contained an infusion and tincture of buchu. The former could be given in doses of an ounce and the latter in doses of a drachm.

Early patent medicines sold in the United States hailed the virtues of the plant and its volatile oil for the management of diseases ranging from diabetes to nervousness. Buchu remained a popular remedy well into the 20th century; interest only began to wane with the discovery of antibiotics and synthetic diuretics.

2.4 Traditional Therapeutic Uses Recorded

Traditionally, buchu has served as an antipyretic, antispasmodic, diuretic, treatment for constipation, and urinary tract infections. Dried buchu leaves have been used for medicinal purposes in tonics and as tablets or powders to treat musculoskeletal pain, chronic arthritis, dyspepsia, edema, fever, the common cold, ulcers, irritable bowel syndrome, gout, prostatitis, prostatic hypertrophy, and sexually transmitted diseases.

The oil also contains limonene, menthone, isomenthone, pulegone, and isopulegone; the leaves are used internally in the treatment of urinary tract infections (especially prostatitis and cystitis), digestive problems, gout, rheumatism, coughs, and colds.

3. Key Constituents and Phytochemistry

3.1 Volatile Fraction (Essential Oil)

Buchu leaves contain volatile oil, diosmin, mucilage, resin, and calcium oxalate. In addition to the principal components pulegone, menthone, isomenthone, and limonene, the oil — in which over 120 components have been identified — contains diosphenol or buchu camphor, to which the diuretic activity of the drug has been ascribed.

More than 120 compounds have been identified in buchu including volatile oils, diosphenol, menthone, isomenthone, limonene, and pulegone, which is a suspected hepatotoxin.

For the two principal commercial species, detailed chemical profiling has been published. Isomenthone, diosphenol, limonene, menthone, pulegone, pseudo-diosphenol, 8-mercapto-p-menthan-3-one, 8-acetylthio-p-menthan-3-one, 8-methylthio-p-menthan-3-one, 4-hydroxydiosphenol, and 1-hydroxydiosphenol were the predominant compounds in the essential oil of A. betulina, as determined by GC–MS analysis.

Agathosma betulina oil was characterized by 31% isomenthone, 41% (ψ)-diosphenol, and 3% of the olfactory cis- and trans-8-mercapto-p-menthan-3-ones. Buchu is the only genus that produces diosphenol, responsible for the distinctive blackcurrant flavor; hence its use in the food industry to enhance fruit flavors in sweets and beverages.

The presence of diosphenol as a distinctive constituent of A. betulina essential oil, in addition to pseudo-diosphenol, limonene, 1,8-cineole, menthone, isomenthone, and trans-8-mercapto-p-menthan-3-one, was confirmed in a recent quality control protocol published as part of a monograph by Viljoen and colleagues.

Regarding chemical differences between species relevant to long buchu: A. betulina contains quercetin-dimethyl ether-glucoside, while A. crenulata does not. The constituent most relevant to long buchu's safety distinction is pulegone: the concentration of pulegone is higher in leaves from Agathosma crenulata than in those of Agathosma betulina.

3.2 Non-Volatile (Phenolic) Fraction

The marker compounds in the non-volatile fraction were identified as diosmin, hesperidin, and rutin, based on both HPTLC and UPLC–MS analysis. Chemical profiling of a methanol extract of A. betulina also revealed the presence of hesperidin, rutin, and diosmin, all serving as non-volatile marker compounds.

Buchu contains bioactive compounds such as diosphenol, menthone, and pulegone, which have demonstrated antibacterial, anti-inflammatory, and antioxidant properties in preclinical studies.

3.3 Sulfur-Containing Compounds

The unique sulfur-containing compounds in the volatile fraction with desirable organoleptic properties have diverted attention from the medicinal uses to various applications in the fragrance and flavour industry. These include cis- and trans-8-mercapto-p-menthan-3-one (also known as buchu mercaptan), 8-acetylthio-p-menthan-3-one, and 8-methylthio-p-menthan-3-one, which collectively produce the plant's characteristic blackcurrant-like aroma.

4. Scientific Evidence by Area of Use

4.1 Urinary Tract Infections and Antiseptic Activity

Its traditional use in urinary tract infections and related ailments made buchu a popular remedy, specifically in the US, in the 19th century, but with the advent of antibiotics it became largely obsolete.

Preclinical evidence: Based on the traditional use of buchu in urinary tract infections, several assays have been utilized to study the antimicrobial activity of the hydro-distilled essential oils and methanol-dichloromethane (1:1) extracts of A. betulina and A. crenulata. It is noteworthy that these extracts do not correspond with traditional extraction methods as an infusion in water or a tincture in ethanol. Applying the micro-titre plate dilution method in the minimum inhibitory concentration (MIC) assay, the methanol-dichloromethane (1:1) extracts of both species revealed moderate antimicrobial activity with a MIC in the range of 2 mg/ml–4 mg/ml against the tested pathogens Bacillus cereus, Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans.

A review of the scarce pharmacological research revealed moderate antimicrobial activity for a leaf extract but not the essential oil of both species in the MIC assay. The oils showed less activity against the Gram-negative pathogen K. pneumoniae.

Clinical evidence: The efficacy of buchu has not been proven in prospective clinical trials for any of these conditions. Health claims for buchu products need to be substantiated by randomized, double-blind, and placebo-controlled studies. Only then can they be promoted for their true therapeutic potential.

Evidence strength: Antimicrobial activity is limited to preclinical, in-vitro studies; no human clinical trials have been conducted. The Commission E and pharmacopoeial assessments note that activity in these claimed uses has not been substantiated.

4.2 Anti-Inflammatory Activity

Preclinical evidence: In the 5-lipoxygenase (5-LO) assay, the essential oil of both species revealed IC50 values of 50.37 ± 1.87 μg/ml and 59.15 ± 7.44 μg/ml, respectively. In another study, 98% inhibitory activity was determined for 250 μg/ml of an ethanolic extract of A. betulina on cyclooxygenase (COX)-1 and a 25% inhibitory activity on COX-2.

Analgesic activity of an ethanolic extract of A. betulina was shown in mice. All the oils tested across 17 Agathosma species exhibited good in vitro anti-inflammatory activity in the 5-LO assay.

Recent in vitro studies with a commercial aqueous extract of buchu revealed increased uptake of glucose added to the 3T3-L1 cell line, significant inhibition of the respiratory burst of neutrophils and monocytes, reduction in the expression of adhesion molecules, and inhibition of the release of IL-6 and TNF-α.

Mechanism of action (in vitro/preclinical): The spasmolytic properties of buchu essential oils have been characterized in animal studies. At high concentration, the oils had an initial spasmogenic activity followed by spasmolysis. The spasmolytic action was post-synaptic, not atropine-like, and did not involve adrenoceptor or guanylyl cyclase activation. In the presence of the phosphodiesterase inhibitor rolipram, the spasmolytic action of A. betulina was significantly increased. These results suggested a mode of action for the oils involving cyclic adenosine monophosphate (cAMP).

Clinical evidence: No human clinical trials evaluating anti-inflammatory endpoints have been published for any buchu species, including long buchu specifically.

Evidence strength: Preliminary; in-vitro and animal data only. No clinical translation has been demonstrated.

4.3 Diuretic Activity

Diosphenol — also called buchu camphor — is the compound to which the diuretic activity of the drug has been ascribed. The Khoikhoi used buchu as a stimulant, a diuretic, and to relieve bloating.

Buchu is listed in the German Commission E Monographs to treat inflammation, kidney and urinary tract infections, and also is used as a diuretic, but the monograph explains that the plant's activity in these claimed uses has not been substantiated.

Clinical evidence: The efficacy of buchu has not been proven in prospective clinical trials for any of these conditions. It has been compendial since 1826 for its diuretic effects and use in the treatment of genito-urinary tract infections; however, it became obsolete in the 20th century due to the sparsity of scientific evidence for its efficacy and the advent of antibiotics.

Evidence strength: The diuretic claim has historical and traditional backing and a plausible mechanistic attribution to diosphenol, but has never been confirmed in controlled human trials.

4.4 Antioxidant Activity

Moderate antioxidant activity was determined for methanol:dichloromethane extracts of A. betulina and A. crenulata, and an aqueous extract of A. betulina showed a Trolox equivalent antioxidant capacity (TEAC) of 11.8 µM Trolox.

Evidence strength: In vitro only; clinical relevance not established.

4.5 Metabolic and Cardiometabolic Effects

In vitro studies with a commercial aqueous buchu extract revealed significant inhibition of the respiratory burst of neutrophils and monocytes, reduction in adhesion molecules, and inhibition of IL-6 and TNF-α release. In diabetic rats, ingestion of aqueous buchu extract completely normalized glucose levels, and in rats receiving a high-fat diet, consumption of aqueous buchu extract resulted in less weight gain and less intraperitoneal fat gain, as well as reduction of elevated blood pressure to normal, associated with cardioprotective effects.

Limitations in the hitherto conducted research lie in the undisclosed composition of the buchu extracts used and the difficulty in extrapolating data from animal studies to humans.

Evidence strength: Animal and in-vitro data only. No human clinical studies have been conducted to evaluate metabolic or cardiovascular outcomes.

4.6 Digestive and Gastrointestinal Uses

Buchu has been used to treat inflammation and kidney and urinary tract infections; as a diuretic; and as a stomach tonic. Other uses include carminative action and treatment of cystitis, urethritis, prostatitis, and gout. The spasmolytic properties demonstrated in guinea pig ileum preparations (see Section 4.2) provide a preliminary biological rationale for carminative or antispasmodic applications, but no clinical data support these uses.

5. Body Systems Associated with Buchu

• Urogenital system: Historically the primary focus — cystitis, urethritis, prostatitis, pyelonephritis, gout (urinary uric acid excretion), and sexually transmitted diseases. Buchu is used to disinfect the urinary tract during infections of the bladder (cystitis), urethra (urethritis), prostate (prostatitis), or kidney (pyelonephritis).
• Musculoskeletal system: Dried buchu leaves have been used in tonics and as tablets or powders to treat musculoskeletal pain and chronic arthritis.
• Gastrointestinal system: Carminative, antispasmodic, and treatment of dyspepsia, constipation, and irritable bowel syndrome in traditional use.
• Immune/inflammatory: In vitro inhibition of pro-inflammatory cytokines (IL-6, TNF-α) and eicosanoid biosynthetic enzymes (5-LO, COX-1).
• Metabolic: Preliminary animal studies suggest glucose-normalizing and antiobesogenic effects.
• Dermatological: External use — historically applied to cuts and burns, and as a body anointment.

6. Dosage Forms and Reported Dosages

There is no recent clinical evidence to guide dosage of buchu. Classical doses were from 1 to 2 g of the leaves daily.

Traditional recommendations for the herb include the use of 1–2 grams of the dried leaf taken three times daily in capsules or in a tea. Tinctures can be used at 2–4 ml three times per day.

The British Pharmacopoeia contained an infusion and tincture of buchu. The infusion could be given in doses of an ounce and the tincture in doses of a drachm.

These dosage figures are drawn exclusively from historical/traditional records and have not been validated by modern clinical trials. No evidence-based dosing guidelines currently exist for Agathosma serratifolia specifically or for long buchu as a distinct preparation.

7. Safety Considerations

7.1 Pulegone Hepatotoxicity

More than 120 compounds have been identified in buchu, including pulegone, which is a suspected hepatotoxin. Buchu contains pulegone, which causes liver injury in rodent models and induces cytotoxicity in cell culture systems. The concentration of pulegone is higher in leaves from Agathosma crenulata than in those of Agathosma betulina.

Essential oils at high doses were found to be hepatotoxic in rats, affecting liver and uterine functions. This was attributed to R-(+)-pulegone, which is known to be a hepatotoxic compound causing depletion of glutathione at high doses.

In in vivo studies, it was demonstrated that the direct conjugation of GSH with pulegone accounts for 9–13% of metabolites, derived from direct Michael addition of GSH to the α,β-unsaturated ketone of pulegone. It has been shown in vivo that the hepatotoxicity of pulegone depends to a large extent on the GSH contents of the liver, and its depletion caused higher hepatotoxicity as observed by histopathology.

Large oral doses of pulegone have shown to be hepatotoxic by depleting glutathione, which is needed in detoxification processes. This depletion, along with excess pulegone, leads to centrilobar hepatocellular necrosis.

Large oral doses have been found to deplete glutathione, which may be the mechanism of toxic effects. Hepatotoxicity from buchu must be quite rare if it occurs at all. In the presence of liver injury, stopping use of buchu promptly, even when used as an herbal tea, is warranted.

A clinical case has been documented: A 52-year-old man developed jaundice one month after starting buchu and rooibos herbal tea. He had no history of liver disease or alcohol abuse and no risk factors for viral hepatitis.

7.2 Uterine Stimulant and Reproductive Effects

Documented adverse effects include uterine stimulant effects. Buchu can cause stomach and kidney irritation, is hepatotoxic, and can be an abortifacient. It can also induce increased menstrual flow.

7.3 Essential Oil Toxicity

In the MTT cellular viability assay, extracts of A. betulina and A. crenulata were not toxic at concentrations up to 100 μg/ml. The essential oils of both species proved to exhibit higher toxicity at the concentration tested, both having IC50 values of <0.0001 μg/ml.

The essential oil should be considered as irritant to skin and eyes, and as a skin and respiratory sensitiser.

7.4 Gastrointestinal and Renal Irritation

Buchu can cause stomach and kidney irritation. The volatile oil content of the leaf is the component principally implicated in this effect, consistent with the known irritant properties of terpenoid-rich essential oils taken internally in high doses.

7.5 Drug and Supplement Interactions

Buchu is used in combination with other herbs such as cornsilk, juniper, and uva-ursi in commercial herbal diuretic preparations. No well-documented herb–drug pharmacokinetic or pharmacodynamic interactions have been identified in the peer-reviewed literature; however, the potential for additive effects with pharmaceutical diuretics or anticoagulants, and for pulegone to interact with hepatically metabolized drugs via CYP-related glutathione depletion, represents a theoretically plausible concern supported by the mechanistic toxicological data above.

7.6 Product Quality, Adulteration, and Identity Issues

Buchu used in commerce is mainly derived from Agathosma betulina, known as round-leaf or short buchu. However, leaves of Agathosma crenulata, which may contain high levels of pulegone in the essential oil, and other closely related species are often marketed as or used to adulterate buchu, thus making the product potentially unsafe for human consumption.

In a study assessing 43 samples of authentic and commercial buchu by microscopy and HPTLC, adulterations or contaminations with senna, grass, and various other extraneous materials were observed in some of the buchu products. HPTLC fingerprinting showed that the profiles of 11 samples were not comparable to those of authentic and botanically verified buchu samples.

Pharmacological experiments in the early 2000s were mostly carried out with hydro-distilled essential oils and/or methanol-dichloromethane (1:1) extracts of both Agathosma species. It is noteworthy that these extracts do not correspond with traditional extraction methods as an infusion in water or a tincture in ethanol. This methodological inconsistency in the research literature makes direct comparison of studies difficult and means that the pharmacological profile of traditionally prepared long buchu has not been systematically studied in its own right.

7.7 Current Regulatory Context

Buchu belongs to a handful of Southern African medicinal plants that reached international markets through colonial interests. It has been compendial since 1826 for its diuretic effects and use in the treatment of genito-urinary tract infections; however, it became obsolete in the 20th century due to the sparsity of scientific evidence for its efficacy and the advent of antibiotics. Nevertheless, buchu is still found in numerous herbal preparations, sold over-the-counter or on the internet, for promoting health and treatment of urinary tract disorders.

Buchu remains a popular ingredient in over-the-counter herbal diuretic preparations.

8. Summary of Evidence Quality

Long buchu (Agathosma serratifolia / Barosma serratifolia) shares the same traditional use profile and closely related phytochemical composition as the two principal commercial buchu species. In a taxonomic appraisal of commercially important Agathosma species, Spreeth (1976) includes Agathosma serratifolia in his treatment; the latter species is, however, no longer of commercial importance. As a result, essentially all recent pharmacological and clinical research on buchu has focused on A. betulina and A. crenulata; findings from these studies are the closest available proxy for understanding long buchu's properties.

Across all investigated areas of use, the overall evidence base remains limited to in vitro studies, animal models, and historical/traditional records. Further research should focus on cultivation practices, non-volatile constituents, in vitro, in vivo, and clinical research on the species' health benefits. No randomized controlled trials in humans have been published for any indication for any buchu species, including long buchu, as of the date of this article.

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