Centaury

Centaury (Centaurium erythraea Rafn): A Comprehensive Reference

1. Identity and Botanical Description

Scientific and Common Names

Centaurium erythraea Rafn (synonyms: C. umbellatum Gilibert, C. minus Moench, Erythraea centaurium Pers.) is a member of the family Gentianaceae, commonly known as common centaury. Additional common names include bitter herb, Centaurri herba, centaury gentian, Christ's ladder, European centaury, feverfoullie, feverwort, filwort, lesser centaury, minor centaury, and red centaury.

The genus name Centaurium comes from the Greek "kentaureion," meaning "belonging to the centaurs," the forest and mountain dwellers reputed to have healing powers. The species epithet erythraea derives from the Latin erythraeus (reddish) and refers to the color of the plant's pink flowers.

Botanical Description

Centaurium erythraea is defined as a variable biennial or annual plant found throughout Europe, typically in calcareous soils and dry grassy areas, characterized by smooth, erect stems, oval greyish-green leaves, and small tubular pink flowers that bloom in summer. Its stiff, square stem ranges from approximately 2 to 50 cm in height. The root is fibrous and woody. The plant has pale green, oval leaves, a capsule fruit, and light pink to red flowers. It grows from a small basal rosette and bolts a leafy, upright stem which may branch. The triangular leaves are arranged oppositely on the stem and the upright inflorescences emerge from the stem. Each inflorescence may contain many flowers. The petite flower is pinkish-lavender and about a centimeter across, flat-faced with yellow anthers. The fruit is a cylindrical capsule. It flowers from June until September.

Geographic Distribution

Centaurium erythraea is widespread in most of Europe, as far as Afghanistan, and limited to the south by North Africa. This glabrous plant from oceanic Europe and the Mediterranean is also naturalized in America. Common centaury is one of the most important pharmacological species from the Gentianaceae family.

Drug Material and Preparations

The botanical definition of the herbal drug is the whole or cut, dried flowering aerial parts of Centaurium erythraea Rafn s.l. The whole herb (Centaurii herba) is used medicinally. The dried preparation is easily identified by red particles (dried flower) among the pale green leaf matter.

Centaury preparations are obtained by drying and comminuting (reducing into tiny pieces) or powdering the aerial parts. They are also obtained by using a technique to extract compounds from plant material by dissolving them in a solvent (such as ethanol or water) to form a liquid extract or tincture (an alcoholic extract). The plant is also used as a flavoring in bitter herbal liqueurs and is an ingredient of vermouth. Centaury can be used to make tea to aid in digestion.

The EMA Assessment Report confirmed that sufficient information was found for the cut herbal substance, powdered herbal substance, liquid extract, tincture, and soft extract to justify at least 30 years of medicinal use, including at least 15 years in the European Union.

2. Traditional and Historical Use

Ancient and Classical Traditions

This medicinal plant was described by Dioscorides as early as the first century A.D. Hippocrates describes centaurium under the Greek "Kentareion," and according to legend, Chiron (founder of medicine) used centaury to heal a wound inflicted by a poisoned arrow. Centaury has been used traditionally since the 10th century, possibly even by Saxon herbalists, for treating fever; hence the common name "feverwort." It was described as early as the first century AD by Dioscorides.

European Folk Medicine

Centaury has a long history in European folk medicine, especially for its "bitter" qualities. It was used primarily to stimulate appetite, enhance digestion, treat gastrointestinal issues. Traditionally, centaury has been used as a remedy for snakebite, anorexia, and GI complaints such as bloating, dyspepsia, and flatulence. Historically, centaury has been used as an herbal medicine to kill worms, to treat dropsy, as a sedative, to treat snakebite and other wounds, and topically for freckles and spots.

Mediterranean and North African Traditions

It is used as a medicinal herb in numerous Mediterranean countries to treat digestive disorders, febrile conditions, hepatitis, and diabetes. Other therapeutic properties include the use of leaf decoctions and ingestions against constipation, obesity, arthritis, and dysmenorrhea, while leaf infusions in oil or honey have been reported against stomach ache, ulcers, enteritis, and waist pain.

Balkan and Eastern European Traditions

Studies provide evidence on traditional knowledge about the medicinal purposes of common centaury in the Pirot District (Southeastern Serbia). Based on surveys among the rural population, the above-ground parts of C. erythraea were usually used internally for stomach, appetite, improving the immune system, diabetes, stomach troubles and diseases, burns, wounds, high temperature, for sedation, as aphrodisiac, cough, and for digestion; and externally against burns, wounds, and rheumatic pain. Common centaury was also recorded, though less frequently, against gastric bacteria, blood purification, bronchitis, liver diseases, jaundice, urinary tract inflammation, and externally against hemorrhoids.

Traditional Internal and External Uses Summarized

Centaurium erythraea is used in internal traditional therapy as an anthelmintic, hypotensive, antipyretic, and antidiabetic. It is used externally for the treatment of wounds. It is used in folk medicine to treat various illnesses, and is also used as an antiapoplectic, anticoagulant, anticholagogue, antipneumonic, hematocathartic, and as a hypotensive agent.

3. Key Constituents and Active Compounds

Secoiridoid Glucosides (Primary Bitter Principles)

The main class of secondary metabolites of all Centaurium species is bitter secoiridoid glucosides. The iridoids (bitters) are considered to be the main active constituents of centaury, and include gentiopicroside (about 2%), with centapicrin, gentioflavoside, sweroside, and swertiamarin. Due to the occurrence of the very bitter secoiridoid esters centapicrin and desacetylcentapicrin, fruits are more bitter than the flowers, leaves, and stems. Swertiamarin is the major component.

Xanthones

Xanthones identified in C. erythraea include six methoxylated xanthones, including eustomin (1-hydroxy-3,5,6,7,8-pentamethoxyxanthone) and 8-demethyl-eustomin, among others. Phytochemical investigation of C. erythraea herb resulted in the isolation of 25 xanthones and three secoiridoids, with 1,3,8-trihydroxy-5,6-dimethoxyxanthone isolated from C. erythraea identified as a novel xanthone.

Alkaloids

Secoiridoid alkaloids found in C. erythraea include gentianine and gentianidin.

Phenolic Acids and Other Compounds

Organic and phenolic acids identified include p-coumaric, O-hydroxyphenylacetic, ferulic, protocatechuic, sinapic, vanillic, syringic, hydroxyterephthalic and 2,5-dihydroxy-terephthalic acids, as well as oleanolic acid (0.1%). Phytosterols identified include β-sitosterol, stigmasterol, and campesterol. Flavone components and anthocyanins have also been identified.

Ursolic acid, maslinic acid, secologanin, secologanin dimethyl acetal, centauroside A, erythraeaxanthone I, erythraeaxanthone II, and demethyleustomin have also been isolated from aerial parts of Centaurium erythraea and identified using spectroscopic methods including NMR and mass spectrometry.

The antioxidant properties of C. erythraea extract can be ascribed to polyphenols such as apigenin, luteolin, quercetin, astragalin, isoquercitrin, naringenin, caffeic, sinapic, ferulic, and p-coumaric acids, and xanthones.

Bitter Value

The bitter value of the drug is (per Ph.Eur.) at least 2000, while the bitter value of the flowers is 12,000. Centaury is nearly odorless and has a strong bitter taste. Some of its bitter principles are identical to those in gentian (gentiopicroside), and some are very closely related chemically (sweroside, centapicrin, swertiamarin).

4. Mechanisms of Action

Bitter Reflex and Digestive Stimulation

Bitter components support the traditional use of centaury as an appetite stimulant, although it is said to be less active than comparable bitter herbs such as gentian. The bitter secoiridoids interact with taste receptors on the tongue and upper gastrointestinal tract, triggering a cephalic-phase reflex that stimulates the secretion of saliva, gastric acid, and bile. Centaury's bitter tonic effects are detectable at a 1:3,500 dilution; it acts as a stomachic, sialagogue, cholagogue, and choleretic, and increases gastric motility.

Gastroprotective Mechanisms

Compounds in centaury exhibit gastroprotective properties through multiple mechanisms, such as enhancing the gastric mucosal barrier, inhibiting acid secretion, displaying antioxidant and anti-inflammatory effects, promoting ulcer healing, and combating Helicobacter pylori infection.

Antioxidant Activity

Antioxidant properties are evidenced by C. erythraea plants, acting as a superoxide radical scavenger or as inhibitor of xanthine oxidase. Secoiridoid swertiamarin, the prevalent component of C. erythraea extract, stimulated the activity of antioxidant enzymes in the serum, liver, and kidneys and restored antioxidant mechanisms in experimental models.

Gentiopicroside — Multiple Biological Activities

Several biological activities have been attributed to gentiopicroside, including inhibition of the spontaneous contraction of ileum smooth muscle, as well as analgesic, anti-inflammatory, and anti-acetylcholinesterase activities. This iridoid glycoside offers hepatoprotection against compounds that produce liver failure and can protect DNA from damage. Gentiopicroside was able to increase gastrointestinal motility by modifying the expression of several hormones related to intestinal propelling, as well as reducing total cholesterol in laboratory animals.

Xanthones — Enzyme Inhibition and Antitumor Activity

Xanthones present in C. erythraea have shown antitumor and anti-inflammatory activities. Xanthone derivatives can inhibit acetylcholinesterase (AChE) and block the acetylcholinesterase-induced β-amyloid aggregation. These compounds are also known for their antiproliferative effect and their ability to inhibit several molecular targets in tumor cells, including kinases, cyclooxygenases, and DNA polymerases.

Swertiamarin — Lipid and Glucose Metabolism

In silico docking studies report that swertiamarin acts at the level of several enzymes and transcription factors involved in the metabolism of glucose and lipids, including inhibition of HMG-CoA reductase (HMGR). Molecular docking studies have shown good docking energy with acceptable binding interactions of swertiamarin with the cyclooxygenase-2 (COX-2) protein.

5. Scientific Evidence by Area of Use

5.1 Digestive Health and Dyspepsia

The HMPC monograph for centaury establishes traditional use for mild dyspeptic and gastrointestinal complaints and intermittent loss of appetite. The ESCOP monograph recommends it for dyspeptic complaints and loss of appetite. The German Commission E monograph likewise approves it for loss of appetite and dyspeptic complaints. In empirical medicine it is used for chronic dyspeptic conditions, achylia, and as a digestive tonic.

The use of Centaurium erythraea herba has a long tradition in Europe, mainly in mild dyspeptic/gastrointestinal disorders and temporary loss of appetite. As adequate clinical studies are lacking, well-established use for this herb is not justified. The use of Centaurii herba-containing preparations in these indications is considered plausible on the basis of bibliographic and pharmacological data.

Evidence assessment: There is a lack of contemporary research or published evidence from human clinical trials regarding centaury, although the bitter constituents support the traditional use as an appetite stimulant. Clinical studies could not be found. Therefore, only the use as a traditional herbal medicinal product is recommended; well-established use is not justified.

5.2 Gastroprotection (Animal Studies)

A study determined the antiulcer and antioxidant activities of Centaurium erythraea L. in an aspirin-induced acute gastric ulcer model. The gastroprotective effect of the 50% aqueous-ethanolic small centaury extract was investigated in Sprague-Dawley albino rats divided into three groups of seven rats each. The percentage of lesion area to total gastric surface area (ulcer index) was significantly reduced (77%) in the aspirin plus centaury group as compared with the acute aspirin-treated group. Oral administration of aspirin decreased catalase (CAT) and reduced glutathione (GSH), and increased lipid peroxidation (LPO) levels, effects that were counteracted by the extract.

Evidence assessment: This is preclinical animal data only. No human gastric ulcer trials have been identified.

5.3 Antidiabetic Activity

There are many in vivo and in vitro studies on the medical effects of C. erythraea. Anti-inflammatory, antipyretic, antidiabetic, diuretic, and hepatoprotective effects have been reported in in vivo studies, as have gastroprotective, antidiabetic, antioxidant, antibacterial, cytotoxic, antimutagenic, and insecticidal effects in in vitro studies.

In one in vitro study of C. erythraea essential oil (CEEO), CEEO displayed significantly lower IC50 values — 168.62 μg/mL for α-amylase and 87.18 μg/mL for α-glucosidase — indicating a marked inhibition of these diabetes-relevant enzymes compared to the individual major chemotype compounds (menthol, carvacrol, and tricosane), which exhibited only moderate inhibition.

Centaurium erythraea has been used in traditional medicine for the treatment of diabetes. The antidiabetic interest focuses on inhibition of carbohydrate-hydrolyzing enzymes (α-amylase and α-glucosidase) and on the modulatory effects of swertiamarin on glucose-metabolizing enzymes in animal models.

Evidence assessment: All antidiabetic evidence is from in vitro assays and animal (rodent) models. No human clinical trials of centaury as an antidiabetic agent have been published.

5.4 Hepatoprotective Activity

In animal experiments, an oral dose of 300 mg/kg/day for 6 days or a single dose of 900 mg/kg for 1 day exhibited a significant protective effect, lowering serum glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT), and lactate dehydrogenase (LDH). Gentiopicroside offers hepatoprotection against compounds that produce liver failure.

Evidence assessment: Hepatoprotective findings are based on animal models and isolated compound studies only. No human clinical hepatoprotection trials have been identified.

5.5 Antimicrobial Activity

Two secoiridoid glycosides, swertiamarin and sweroside, were isolated from the aerial parts of Centaurium erythraea. Antibacterial, free radical scavenging activities, and general toxicity of these glycosides were assessed. Both compounds inhibited the growth of Bacillus cereus, Bacillus subtilis, Citrobacter freundii, and Escherichia coli. While swertiamarin was also active against Proteus mirabilis and Serratia marcescens, sweroside inhibited the growth of Staphylococcus epidermidis.

Evidence assessment: These are in vitro microbiological studies. Minimum inhibitory concentrations were not always compared to clinically used antibiotics. No human antimicrobial trials for standalone centaury are available.

5.6 Analgesic and Anti-inflammatory Activity

The analgesic activity of the ethanolic extract (EE) from the flowering aerial parts was examined in Wistar albino rats in pain models. The EE, characterised by the iridoid swertiamarin, was administered in pain models. Peripheral analgesic activity was evaluated using the acetic acid-induced writhing test, and a hot plate test was performed for central antinociceptive activity evaluation. Treatment with EE significantly decreased rats' writhing induced by acetic acid, suggesting peripheral analgesic activity. Elevation of mean basal reaction time in the hot plate method indicated central analgesic activity.

Evidence assessment: Analgesic data are from rodent models only. No human pain studies have been identified for centaury alone.

5.7 Antioxidant Activity

The antioxidant activity of an aqueous extract of centaury dried flowering tops has been demonstrated in vitro, via effectively scavenging reactive oxygen species. Significant antioxidant activities were observed following three assays: free radical DPPH reduction, lipoperoxidation, and NO radical scavenging capacity.

Evidence assessment: Antioxidant data are from in vitro chemical assays. Their translation to clinically meaningful outcomes in humans has not been demonstrated.

5.8 Cytotoxic / Anticancer Activity

The cytotoxic potency of compounds from Centaurium erythraea was evaluated by the XTT assay against human breast cancer MCF-7, MDA-MB-453, and mouse fibroblast 3T3-L1 cell lines. Erythraeaxanthone II was found to have the most potent cytotoxic activity. Xanthone compounds are known for their antiproliferative effect and their ability to inhibit several molecular targets in tumor cells, including kinases, cyclooxygenases, and DNA polymerases.

Evidence assessment: All cytotoxicity findings are from cell-line (in vitro) assays only. No animal tumor model studies or human cancer trials involving centaury have been identified.

5.9 Urinary Tract Health — Combination Product (Canephron® N)

The most extensive human clinical evidence involving centaury comes from studies of the multi-herb fixed combination product Canephron® N, which contains centaury as one of three ingredients alongside lovage (Levisticum officinale) and rosemary (Rosmarinus officinalis).

A systematic review evaluated 17 clinical studies from 18 selected publications concerning the safety, tolerability, and additional effects of Canephron® N as standard therapy in various clinical settings. Its role in the prophylaxis and treatment of urinary tract infections in adults and children, therapy and prophylaxis in adult patients with renal stones, treatment and prevention of urinary tract infections and other gestational diseases in pregnancy, and also its safety and tolerability were examined. Overall, Canephron® N was shown to be effective in the treatment and prophylaxis of UTI compared with standard therapy, both in adults and children, with a reduced number of relapses.

In a randomized, double-blind Phase III trial, treatment with Canephron N demonstrated non-inferiority to treatment with the antibiotic fosfomycin-trometamol in female patients with acute UTI, allowing them to avoid further antibiotic use.

The most active ingredients in the combination are phenolic glycosides and phenolcarboxylic acids (rosemary, lovage, and centaury), phthalides (centaury), secoiridoids (centaury), essential oils (lovage, rosemary), and flavonoids (centaury, rosemary).

Evidence assessment: The clinical evidence for Canephron® N is multi-study and includes a Phase III randomized controlled trial, but the contribution of centaury specifically, versus the other two herbs, cannot be isolated from these combination-product trials.

6. Body Systems and Health Areas of Association

• Gastrointestinal system: Appetite stimulation, dyspepsia, flatulence, bloating, gastroprotection, gastrointestinal motility, cholagogue and choleretic activity.
• Hepatobiliary system: Traditional use for liver complaints and jaundice; animal evidence for hepatoprotection.
• Endocrine/metabolic system: Traditional antidiabetic use; in vitro and animal evidence for enzyme inhibition relevant to glucose metabolism and lipid-lowering.
• Urinary tract: Traditional diuretic use; clinical evidence as part of the Canephron® N combination for UTI and urolithiasis.
• Immune/anti-infective: In vitro antibacterial activity against multiple pathogens.
• Musculoskeletal and pain: Traditional use in fever and rheumatic pain; animal evidence for analgesic activity.
• Integumentary (skin): Traditional topical use for wounds, freckles, and skin spots; emerging research on topical formulations.
• Neurological: AChE inhibition by xanthone constituents; preliminary neuroprotective interest in the context of Alzheimer's-related research (in vitro only).

C. erythraea is used in traditional medicine to treat various diseases such as diabetes, fever, rhinitis, stomach ailments, urinary tract infections, dyspeptic complaints, loss of appetite, and hemorrhoids, and as a diuretic. The essential oils and extracts of C. erythraea have exhibited biological properties including antibacterial, antioxidant, antifungal, antileishmanial, anticancer, antidiabetic, anti-inflammatory, insecticidal, diuretic, gastroprotective, hepatoprotective, dermatoprotective, neuroprotective activities, and inhibitory effects on larval development.

7. Dosage Forms and Reported Dosages

The daily dose per the German-language herbal drug literature is 6 g of the drug. For tea preparation, 2 to 3 g of finely chopped centaury is poured over 150 ml of boiling water and strained after 10 to 15 minutes. The infusion should be consumed half an hour before meals to stimulate appetite and after meals for digestive complaints.

A preparation protocol from another source specifies a fresh plant tincture at a ratio of 1:2, taken in 10 to 20 drops, or a cold infusion of 1 to 2 fluid ounces, both taken ten minutes before meals.

For the combination product Canephron® N, the specific centaury content per dosage form has been published: one coated tablet contains Herba centaurii 18 mg, Radix levistici 18 mg, and Folia rosmarini 18 mg. The 100 g drops contain 29 g of an alcoholic aqueous extract from Herba centaurii 0.6 g, Radix levistici 0.6 g, and Folia rosmarini 0.6 g (extract tincture, ethanol 59 vol%). A single dose of Canephron Uno is to be taken 3 times a day (morning, noon, evening).

There is no published clinical evidence to guide dosing of centaury as a standalone product. Animal studies have used doses that cannot be directly converted to human equivalent doses without additional pharmacokinetic data.

8. Safety Considerations and Interactions

Regulatory Safety Classification

Due to the lack of research from clinical trials, the Committee on Herbal Medicinal Products (HMPC) approves herbal medicine products containing centaury based on its traditional and long-standing use. The approval is based on previous evidence from pharmacopoeias, plausible effectiveness, and evidence of safe use for over 30 years.

Centaury is listed on the FDA's Generally Recognized As Safe (GRAS) list as a flavoring.

Adverse Effects

Centaury can cause nausea in higher doses, depending on the person's sensitivity to its bitter taste. This is why some sources advise sipping the infusion before meals to engage the taste reflex to stimulate digestion.

Contraindications

Centaury is contraindicated with ulcers of the stomach or intestines due to increased secretion of gastric acids. General contraindications for all bitter herbs include kidney stones, gallbladder diseases, dysmenorrhea, gastroesophageal reflux disease, hiatus hernia, gastritis, and peptic ulcers.

Additional contraindications cited in the literature include allergy to any of the ingredients, use in children and adolescents under 18 years, and use during pregnancy and lactation.

Canephron, the combination product containing centaury, is also contraindicated in cases of peptic ulcer, oedema due to impaired heart or kidney function, or where a reduced fluid intake has been recommended.

Drug Interactions

Specific data on pharmacokinetics and interactions are not available for centaury. A speculative interaction has been noted with H2-receptor antagonists and other antacids, as centaury acts as a stomach-acid secreting stimulant and may therefore act antagonistically to these medications.

Toxicological Data

Neither the chemical composition nor the long-standing widespread use in the European Community suggests that there is a potential risk associated with the use of centaury extract. Yet, due to the lack of data on acute and chronic toxicity, repeated dose toxicity, genotoxicity, mutagenicity, carcinogenicity, and reproductive and developmental toxicity, a list entry for Centaurii herba cannot be recommended for unrestricted use.

Pregnancy and Lactation

No fertility data are available. In accordance with general medical practice, the product should not be used during pregnancy and lactation.

Stability of Constituents

After six months of storage, decomposition of gentiopicroside and sweroside was observed. The swertiamarin content was nearly unchanged when stored at room temperature or in the refrigerator. This has practical implications for the quality and shelf-life of prepared herbal products.

9. Regulatory and Pharmacopoeial Status

Centaury has been classified by the HMPC as a traditional herbal medicinal product (Article 16a of Directive 2001/83/EC). Based upon long-standing use, centaury can be used for mild dyspeptic and gastrointestinal complaints and temporary loss of appetite.

Quality of Centaurii herba is defined in the European Pharmacopoeia (Ph. Eur.). The herb also appears in the British Herbal Pharmacopoeia, the ESCOP monographs, and the German Commission E monographs, all of which endorse its use for dyspeptic complaints and loss of appetite. The ESCOP monograph includes studies with its main characteristic constituents, the secoiridoid glucosides. The therapeutic indications are dyspeptic complaints and lack of appetite.

Canephron®, which contains centaury herbs, is approved in 31 countries for the short- and long-term treatment of various urological diseases.

References

• European Medicines Agency (EMA/HMPC/277491/2015): Assessment Report on Centaurium erythraea Rafn. s.l., herba (2015)
• European Medicines Agency: European Union Herbal Monograph on Centaurium erythraea Rafn. s.l., herba (EMA/HMPC/277493/2015)
• European Medicines Agency: Centaurii herba — Herbal Medicinal Product Overview
• ESCOP Monograph: Centaurii herba — Centaury (2015)
• El Menyiy N et al. Phytochemical properties, biological activities and medicinal use of Centaurium erythraea Rafn. Journal of Ethnopharmacology, 2021.
• ScienceDirect Topics: Centaurium — Overview (Gentianaceae pharmacology)
• ScienceDirect Topics: Centaurium erythraea — Overview
• Naber KG. Efficacy and safety of the phytotherapeutic drug Canephron® N in prevention and treatment of urogenital and gestational disease. Research and Reports in Urology, 2013. PMC3826901.
• Guedes et al. Bioactivities of Centaurium erythraea (Gentianaceae) Decoctions: Antioxidant Activity, Enzyme Inhibition and Docking Studies. Molecules, 2019. PMC6832739.
• Kumarasamy Y et al. Bioactivity of secoiridoid glycosides from Centaurium erythraea. Phytomedicine, 2003. PubMed 12809366.
• Kumarasamy Y et al. Bioactivity of gentiopicroside from the aerial parts of Centaurium erythraea. PubMed 12628413.
• Tuluce Y et al. Gastroprotective effect of small centaury (Centaurium erythraea L) on aspirin-induced gastric damage in rats. Toxicology and Industrial Health, 2011. PubMed 21415093.
• Algerian analgesic study: Analgesic effect of Centaurium erythraea and molecular docking investigation of the major component swertiamarin. Natural Product Research, 2023. PubMed 37948163.
• Aberham A et al. Analysis of iridoids, secoiridoids and xanthones in Centaurium erythraea, Frasera caroliniensis and Gentiana lutea. Journal of Pharmaceutical and Biomedical Analysis, 2011. PubMed 21050691.
• Treatment of Urinary Tract Infections with Canephron® in Germany: A Retrospective Database Analysis. PMC8226679.
• In Vitro and in Vivo Efficacy of Different Ointment Formulations Containing Centaurium erythraea Rafn. Aerial Extract. PMC12655704.
• Biological activities of Centaurium erythraea and its main chemotypes: menthol, carvacrol, and tricosane. AMB Express, 2025. PMC12540964.
• Altmeyer's Encyclopedia — Centauri herba (Phytotherapy)
• Arzneipflanzenlexikon: Centaury — Medicinal Use, Dosage, Side Effects
• Herbal Reality: Centaury (Centaurium erythraea) — Benefits, Safety, Uses
• Drugs.com Natural Products Database: Centaury Uses, Benefits & Dosage
• Traditional use of common centaury (Centaurium erythraea) in the Pirot District (Southeastern Serbia). ResearchGate, 2024.
• ND Health Facts: Centaurium erythraea (Bastyr Monograph–referenced)
• Biological activities of Centaurium erythraea and its main chemotypes. AMB Express, Springer Nature, 2025.