IngredientsOvate buchu refers specifically to Agathosma crenulata (L.) Pillans, one of two species in the genus Agathosma (meaning "good fragrance") that were used in San-Khoi traditional medicine — the other being Agathosma betulina (round or short leaf buchu). The plant Agathosma crenulata (previously Barosma crenulata) is known as the oval leaf buchu, and has been used for the same purposes as its close relative.
Agathosma betulina (P.J. Bergius) Pillans and Agathosma crenulata (L.) Pillans are species known as Buchu in Khoi, boegoe or bergboegoe in Afrikaans, and ibuchu in isiXhosa. Common names include boegoe, boechoe, boekoe, boggoa, bookoo, bouchou, bugu, buccho, bucchuu, bucco, buchu, bucku and buku.
Linné first recorded the genus as Diosma in 1756, specifically D. crenulata and D. crenata, followed by Thunberg in his Prodromus and his botanical thesis dedicated to Diosma. Ecklon and Zeyher subsequently introduced the genus as Barosma and provided detailed botanical and geographical data. Until the authoritative revision by Pillans, multiple authorities named and renamed species.
The full synonymy for A. crenulata as established by that revision includes: Diosma crenulata L.; D. crenata L.; D. latifolia Andrews; D. serratifolia Curt.; Parapetalifera odorata Wendl.; Barapelutiflora serrata Wendl.; Barosma odorata Willd.; Baryosma odorata, B. serratifolia Roem. & Schultes; Bucco crenata Roem. & Schultes; Adenandra cordata, A. serratifolia Link; Barosma serratifolia Willd.; Diosma odorata DC.; Barosma crenata Sweet; Agathosma latifolia Loud.; Barosma crenulata Hook.; and B. eckloniana O. Berg.
Agathosma is a genus of 150 species of flowering plants in the family Rutaceae indigenous to South Africa. The two species in commerce are now known as A. betulina (P.J.Bergius) Pillans and A. crenulata (L.) Pillans.
Agathosma crenulata is an evergreen shrub growing to 1.5–2.5 m tall. The leaves are opposite, oval, 15–35 mm long and 7–18 mm broad. The flowers are white or pale pink, with five petals; the fruit is a five-parted capsule which splits open to release the seeds.
Younger plant stems are light green to dark red in colour, while older stems have a grey and woody, bark-like appearance. At approximately 30 mm, the leaves are more elongated than those of A. betulina and generally larger. They are green to dark green in colour, leathery and glossy, and situated opposite each other on the stems. The leaves are also serrated, but A. crenulata leaves have a softer and less curved appearance and are softer and more leathery to the touch. Round essential-oil glands are visible on the leaves.
The volatile oils in the glands dotting the leaves and fruit emit an easily recognizable buchu fragrance when touched or crushed. Flowers decorate the shrub for 6–8 weeks between June and November.
The Cape region of South Africa has veldt-types with arguably the richest composition of indigenous aromatic plant species in the whole of South Africa. It is in this epicentre of essential oil-bearing plants that the genus Agathosma and its close taxonomic allies (e.g., Diosma, Coleonema, Acmadenia) reside. These Rutaceous shrubs are typical of the fynbos — vegetation found in the western Cape Province — and are particularly abundant in the mountainous areas in the Cape.
Agathosma crenulata occurs on damp lower slopes of the mountains of southwestern Cape from Tulbagh to Riversdale. In nature it prefers the middle slopes, particularly on siltier valley or shaly soils and often near water.
Currently, the two species are differentiated on the basis of their leaf shape: A. betulina has round leaves while A. crenulata has long oval leaves. The two are also chemically distinct; for example, A. betulina contains quercetin-dimethyl ether-glucoside, while A. crenulata does not. The most pharmacologically important chemical distinction is their pulegone content, which is addressed in detail under constituents below.
Agathosma species are commercially marketed as fresh or dried leaves, tinctures, herbal water, and essential oils. There is a wide variety of buchu products on the market such as teas, capsules and herbal water where the therapeutic effect is claimed to be due to the non-volatile components. Traditional buchu tinctures can be prepared by placing leaves and stalks into brandy. "Buchu vinegar," prepared by steeping the leaves and stalks in vinegar, is also a traditional remedy used, for example, in compresses and also taken internally. Currently, the aromatic oils of these herbs are also used in food preparation as flavoring and in the manufacture of perfumes.
The Khoi-San used the word "Buchu" for any fragrant plant that could be dried and powdered, so in a historic sense this name does not designate a single species. Nowadays it is generally accepted that "Buchu" refers to Agathosma betulina and Agathosma crenulata.
Before the records of early settlers, colonists, and explorers, 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 every-day, 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.
Buchu was a traditional medicine used by the San (Bushmen) and Khoikhoi (Hottentot) people, who used it to treat wounds, stomach complaints, arthritis, and bladder and bowel ailments. Traditionally, buchu has served as an antipyretic, antispasmodic, diuretic, treatment for constipation, and urinary tract infections.
Traditionally, the plant is also used to treat cholera, indigestion, constipation, prostatitis, rheumatism, fever, respiratory and urinary tract infections, as well as for disinfecting wounds and relieving menstrual cramps.
The Khoikhoi introduced the herb to early Dutch settlers, who subsequently introduced it into Europe, where it was used to treat wounds, stomach ailments, arthritis, and diseases of the bladder.
Buchu was introduced in Great Britain around 1800 and was officially listed as a medicine in the British Pharmacopoeia by 1821. British physicians used it to treat inflammations of the urinary system including cystitis, urethritis, and nephritis.
Initially noted by the early settlers, knowledge and use of buchu spread to Europe and later to the United States. Its traditional use in urinary tract infections and related ailments made it a popular remedy, specifically in the US, in the 19th century, but with the advent of antibiotics it became largely obsolete.
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 was first exported to Britain in 1790.
Dutch Afrikaners adopted it for the treatment of kidney stones, arthritis, cholera, and muscle aches, as well as urinary tract infections.
The Khoisan and other indigenous peoples used buchu in dance rituals, for anointment, beautification, and perfume. Traditional knowledge pertaining to these uses is owned by the Khoisan and should be attributed and respected as such.
A distinctive traditional beverage arose from this heritage. The Khoikhoi developed an alcoholic beverage known as buchu brandy, which is still manufactured and distributed. This brandy was used medicinally by physicians for generations.
More than 120 compounds have been identified in buchu, including volatile oils, diosphenol, menthone, isomenthone, limonene, and pulegone, which is a suspected hepatotoxin. The phytochemical profile divides into two major categories: the volatile essential oil fraction and the non-volatile flavonoid fraction.
The essential oil is the best-studied fraction. 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 are the predominant volatile constituents identified across both buchu species.
The most chemically significant distinction between the two commercial species involves pulegone content. Agathosma betulina oil is identified by a pulegone content of 2.4% to 4.5%, while A. crenulata oil is characterised by 31.6% to 73.2%. Specifically, the A. crenulata oil contains very high quantities of pulegone (54%) besides considerable quantities of trans-8-acetylthio-p-menthan-3-one (7%).
A. crenulata oil has a sharper, minty note resulting from the very high percentages of pulegone and isopulegone isomers that characterise the oil. Pulegone was found to be the key component for identification of the oils.
In their study of the chemical composition of A. betulina, A. crenulata and their hybrid, Posthumus et al. (1996) identified several rare bi- and tri-functionalized monoterpenes besides the commonly known monoterpenes. These included hydroxylated diosphenols, several hydroxymenthones and some acetates thereof.
The sulfur-containing compounds present in minor proportions are responsible for the characteristic blackcurrant aroma. A. betulina oil has a higher content of 8-mercapto-p-menthan-3-one than 8-acetylthio-p-menthan-3-one, while the reverse is true for A. crenulata oil.
The volatile oil constituents of A. betulina and A. crenulata have been studied extensively, while relatively few studies have been done on the non-volatile components even though A. betulina is highly commercialised.
Flavonoids such as diosmin, rutin, kaempferol, quercetin, and hesperidin were identified in the methanol extract of buchu. Agathosma crenulata contains a higher concentration of rutin and a lower concentration of quercetin-dimethyl ether-glucoside compared to A. betulina.
The marker compounds in the non-volatile fraction were identified as diosmin, hesperidin, and rutin, based on both HPTLC and UPLC–MS analysis. An 80% methanol extract contained hyperoside, rutin, and a novel compound designated agathosin, which was shown to be a quercetin glucoside esterified with oleuropeic acid.
Additional flavonoids include diosmetin, quercetin, diosmin, quercetin-3,7-diglucoside, and rutin. Other constituents include mucilage, resin, thiamine, and sulfur compounds.
The following key quantitative differences between the two species are documented in the peer-reviewed literature:
The medicinal properties are attributed to the leaves of the plant, which are thought to have diuretic effects that may increase urine flow. Diosmin and related flavonoids have been specifically implicated; however, it must be noted that most mechanistic work has been performed in preclinical settings.
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. The 5-lipoxygenase enzyme is a key catalyst in the biosynthesis of leukotrienes, pro-inflammatory mediators. Inhibition of this pathway provides a plausible biochemical basis for the traditional anti-inflammatory reputation of buchu, though this evidence remains at the in vitro level.
The mode of action of essential oils from both buchu species from the Cape region of South Africa was studied on smooth muscle in vitro using guinea-pig ileum. 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, while that due to A. crenulata was also increased but not to a significant level. These results suggested a mode of action for the oils involving cyclic adenosine monophosphate.
These flavonoids have antioxidant properties and guard the cells against the harmful, unstable oxygen molecules. The main antioxidative compound in the aqueous extract was rutin. The only extract that suppressed the oxidation of linoleic acid was the acetone extract containing the four lipophilic flavonoids 3 and 3,3′-dimethyl ethers of quercetin and the 3 and 3,4′ dimethyl ethers of kaempferol.
Recent in vitro studies with a commercial aqueous extract of buchu revealed increased uptake of glucose added to 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.
Evidence level: In vitro, weak-to-moderate; no human clinical trials.
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, however, 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. Neither essential oil demonstrated antimicrobial action against Enterococcus hirae and Pseudomonas aeruginosa, but very low activity was observed against Escherichia coli, Saccharomyces cerevisiae, and Staphylococcus aureus, suggesting little potential for these oils.
Whereas the phytochemical differences between the two Agathosma species have been well illustrated, recent pharmacological studies could not alleviate the justified doubts regarding the traditional use of buchu for the treatment of urinary tract infection. The overall modest number of assays addressing the antimicrobial activity revealed only low to moderate effects against micro-organisms responsible for urinary tract infection for a methanol-dichloromethane extract that was not used in the traditional context.
The efficacy of buchu has not been proven in prospective clinical trials for any of these conditions.
Evidence level: In vitro enzyme inhibition and preclinical animal data only; no human trials.
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. Inhibition of the 5-LO pathway is relevant to inflammation; however, these assays do not constitute evidence of clinical efficacy in conditions such as arthritis or gout.
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. These uses all reflect historical tradition rather than demonstrated clinical efficacy.
Evidence level: In vitro; no controlled human trials specifically for buchu.
An aqueous extract of A. betulina showed a Trolox equivalent antioxidant capacity (TEAC) of 11.8 µM Trolox. Despite the presence of quercetin, kaempferol, and rutin, all of which have known radical scavenging properties, only a poor correlation could be found between these constituents and observed antioxidant activity in some assays.
Evidence level: In vitro cell line and preclinical rodent models; no human clinical trials.
Recent in vitro studies with a commercial aqueous extract of buchu revealed increased uptake of glucose added to a 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. In diabetic rats, ingestion of aqueous buchu extract completely normalized the glucose level, 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.
Ingredients responsible for the observed effects could not be identified, since the buchu water intake corresponded to a mean of 30 ml per day and the concentrations of the included flavonoids were very low at 0.0005 mg/L diosmin, 0.007 mg/L quercetin, 0.001 mg/L hesperidin, and 0.0035 mg/L rutin. When HFD rats ingested buchu water, the initial rise in blood pressure declined to control values at week 14 and infarct development induced in the isolated perfused hearts by regional ischemia was significantly smaller compared to the HFD group with no buchu ingestion.
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.
There is a lack of substantial scientific evidence supporting these claims, as most studies have been conducted in vitro or on animals. In case of verified positive effects in vitro, the results obtained should be further tested for efficacy in urinary tract infections in randomized, double-blind, and placebo-controlled clinical trials. Results obtained should be verified in randomized, double-blind, and placebo-controlled clinical trials. But until these studies are available, the answer to the question "rightfully forgotten or underutilized" remains open.
Based on peer-reviewed ethnobotanical and pharmacological literature, the following body systems are associated with ovate buchu's traditional and investigated uses:
There is no recent clinical evidence to guide dosage of buchu. Classical doses were from 1 to 2 g of the leaves daily.
Dosage typically involves 1 to 2 grams of dried leaves taken three times a day, although safety concerns arise due to the presence of the liver toxin pulegone.
Currently, the aromatic oils of these herbs are used in food preparation as flavoring and in the manufacture of perfumes. Dried buchu leaves have been used for medicinal purposes in tonics and as tablets or powders. As of 2012, bottled infusions continue to be prepared from Agathosma leaves.
For the animal studies on metabolic syndrome referenced above, the buchu water intake corresponded to a mean of 30 ml per day. No equivalent human dosage is established from these preclinical data.
The most significant and specifically documented safety concern for ovate buchu relates to its substantially elevated pulegone content relative to round-leaf buchu.
Buchu contains many compounds including 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. Large oral doses have been found to deplete glutathione, which may be the mechanism of its toxic effects.
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.
This depletion along with excess pulegone leads to centrilobar hepatocellular necrosis.
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.
The comparative safety implication is significant: in general, A. betulina should be preferred over A. crenulata because of the lower amounts of the hepatotoxic pulegone, inherent to both species. Agathosma betulina essential oil is recommended for use because of its low concentration of pulegone (<5%).
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. This case, documented in the NIH LiverTox database, represents one of the rare instances linking buchu use to clinical liver injury, though the combination with rooibos complicates causal attribution to buchu alone.
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.
The toxicity of methanol-dichloromethane (1:1) extracts of Agathosma species was evaluated using the MTT cellular viability assay. In this assay, several dilutions displayed different degrees of cellular inhibition, but 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.
Contraindications have not yet been formally identified. No drug interactions are well documented. However, given the hepatotoxic potential of pulegone via glutathione depletion, concomitant use with other hepatotoxic agents or drugs that are substrates for hepatic detoxification pathways is a theoretical concern that has not been studied in humans.
Agathosma crenulata is assessed as declining according to the Red List of South African Plants. It has been heavily impacted by harvesting for essential oils throughout its range, and while a reduction in the number of wild plants in some populations has been reported, its estimated decline is not more than 20%, so it is not regarded as threatened. Legislation has also been put in place to manage the trade, with the result that wild populations are no longer being harvested.
Agathosma crenulata is a historically wild-collected plant that has been cultivated on a large scale in selected areas of the Western Cape Province of South Africa. Buchu is an endemic, aromatic shrub around which a lucrative industry spanning diverse and distant markets has developed. Alongside its medicinal properties, buchu is primarily valued for its essential oil, which is exported for use in international flavour and fragrance industries.
Health conditions that Ovate buchu may help support.
Ovate Buchu (Agathosma crenulata) is one of the two officially recognized commercial buchu species, traditionally used by South African indigenous peoples and European herbal medicine for urinary tract infections, cystitis, and diuresis. Like other buchu species, clinical scientific evidence for UTI efficacy is lacking, though in vitro antimicrobial activity has been demonstrated.
Body systems that Ovate buchu may help support.
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