Rue

Rue (Ruta graveolens L.): A Comprehensive Reference

1. Identity and Botanical Description

1.1 Nomenclature and Taxonomy

Ruta graveolens L., popularly known as rue, is a multipurpose herb belonging to the family Rutaceae. It is commonly known as rue, common rue, ruda, arruda, or herb-of-grace. It is the source of rue or rue oil, called Sadab or Satab in Hindi. The word graveolens comes from Latin and means "strong smelling"; a strong unpleasant odor emanates from the plant's leaves. In Chinese traditional medicine, it is also called "Chou Cao," meaning a smelly herb. Its name derives from the ancient Greek ῥυτἠ, from the verb ῥυομαι meaning "to save, to protect," probably in reference to its capacity to preserve its leaves for a very long time and to protect health.

As currently described in literature, the genus Ruta has 14 accepted species, and among them R. graveolens L. and R. chalepensis L. are reported in Indian floras. There are two main species used in traditional medicine, of which R. graveolens is more widely studied.

1.2 Geographic Origin and Distribution

Ruta graveolens L. is a shrubby perennial plant of the Rutaceae family that originated in the Mediterranean region and was brought to Mexico and tropical America from Spain. R. graveolens is now cultivated worldwide, including in Europe and many African, Asian, and South American countries such as Ethiopia, China, and Japan. Its country or region of origin is southeastern Europe and the Balkans.

1.3 Botanical Morphology

Rue is a woody, perennial shrub. Its leaves are oblong, blue-green and arranged bipinnately with rounded leaflets; they release a strong aroma when bruised. The flowers are small with 4 to 5 dull yellow petals in cymes. It is grown throughout the world in gardens, especially for its bluish leaves, and sometimes for its tolerance of hot and dry soil conditions. It is also cultivated as a culinary herb, and to a lesser extent as an insect repellent and incense.

1.4 Common Preparations and Forms

Rue is encountered in several preparation forms across both traditional and contemporary contexts:

• Herbal infusion (tea): Dried leaves or aerial parts steeped in boiling water. Traditional use of infusions should not exceed 1 or 2 g/day of the plant according to IPCS documentation.
• Tincture: Proposed doses in herbal literature include 1–4 mL of a 1:5, 40% tincture.
• Essential oil: Obtained by hydrodistillation of the aerial parts. Volatile oil of light yellow color is extracted from the aerial parts of R. graveolens by hydrodistillation with a 1.29% yield (v/w).
• Crude extracts: Methanol or ethanol extracts are the most frequently reported in pharmacological research, followed by aqueous, ethyl acetate, and other organic solvent extracts.
• Homeopathic preparations: Homeopathic use is associated with dosages as low as 1–3 drops of a tincture.
• Culinary use: The flavor is very bitter, although it is used in ethnic cuisines such as a coffee flavoring in Ethiopia, a milk tea flavoring in Guangdong province in China, and to flavor grappa, an Italian type of brandy.

2. Traditional and Historical Use

2.1 Ancient Greece and Rome

The ancient Greeks and Romans held the plant in high esteem. Rue has been among the key plants of the European pharmacopoeia since ancient times. The so-called Corpus Hippocraticum — a collection of 62 treatises written between the 5th century BCE and the 2nd century BCE, arguably the most ancient systematic record of medical practice of the Mediterranean world — refers to medical applications of these plants. Hippocratic physicians considered Ruta plants as a remedy suitable for diseases in women and as an effective pharmakon (the Greek word for drug) in the cure of pulmonary affections.

Dioscorides wrote that mixing R. graveolens with certain foods provides protection "against the bitings of vipers and serpentes," and its juice protects "against the bitings and stingings of Scorpions, Bees, Waspes, Hornettes and madde [dogs]."

2.2 European Folk Tradition

Rue was one of the main medicinals in the European folk tradition, and it was also considered an important means of protection against supernatural evil in many parts of the world. The results of ethnobotanical study of Spain show a high correspondence of the main medicinal uses to the pharmaceutically demonstrated properties of the plant: emenagogue and abortifacient; digestive; improving circulation; treating rheumatism; treating infections and inflammation; relieving pain; and removing parasites, among others.

In southern Italy, rue is mainly used against the flu, colds, and coughs, for stomach ache treatments, and topically against toothaches. In the Italian ethnobotanical literature, rue is also widely cited as an anthelmintic.

In folk medicine across Europe, rue has been used to treat cough, diphtheria laryngitis, colic, headache, and as an antidote in case of mushroom poisoning, snake bites, and insect bites; in addition, it has been used for its stimulating, stomachic, and emmenagogue effects consumed as an infusion, and to treat headache, muscular and joint pain, as well as an anti-inflammatory using the oil or extract. In the Middle Ages, rue was used to ward off the plague: its smell is very strong and pungent.

2.3 Ayurveda, Unani, and Traditional Chinese Medicine

Rue is used in Ayurveda, Homoeopathy, and Unani medicine. Ruta graveolens L. is an important traditional Chinese medicine used to treat fever caused by cold, wind-fire toothache, headache, bruises and sprains, irregular menstruation, and infantile eczema.

In the Chinese tradition, it has the effect of clearing away heat and detoxifying the toxin, cooling the blood and dispersing blood stasis, and it can be used for treating colds and fevers, rheumatism and paralysis, pediatric fevers and convulsions, feverish sores and canker sores, insect and snake bites, amenorrhea and abortion, as well as eczema and other skin disorders.

2.4 Gynecological and Reproductive Use

Plants of the Ruta genus are used as abortifacients, contraceptives, anti-fertility agents, and to regulate menstrual flow and bleeding. Today, the common rue (Ruta graveolens L.) remains an important plant in traditional medicine in many countries, notably utilized in the treatment of female menstrual diseases. In herbal medicine, Ruta is an emmenagogue herb that is taken by women to induce and increase menstrual flows and to cleanse the body. It has been used as an abortifacient in Europe, Asia, Africa, and South America and is found to be endemic in the Mediterranean countries.

2.5 Cultural and Symbolic Significance

The bitter taste of its leaves led to rue being associated with the (etymologically unrelated) verb "rue" meaning "to regret." Rue is well known for its symbolic meaning of regret and it has sometimes been called "herb-of-grace" in literary works. Rue is mentioned in the New Testament, Luke 11:42: "But woe unto you, Pharisees! For ye tithe mint and rue and all manner of herbs." Sephardic Jewish tradition has long valued ruda for its diverse applications in health, religious practices, and spiritual well-being. It was in the Ottoman Balkans, rather than Medieval Spain, that Sephardic Jews encountered ruda and adopted its associated traditions and beliefs.

3. Key Chemical Constituents

3.1 Overview of Phytochemical Complexity

More than 200 compounds have been identified in R. graveolens. In one comprehensive review, 92 papers were reviewed and 231 chemical constituents were identified. Numerous volatile oil components have been reported in R. graveolens, which produce its strong and unique odor. The compounds in the non-volatile fraction are mainly phenylpropanoids, especially coumarins and alkaloids — predominantly acridone and quinoline alkaloids. Flavonoids are less present in the plant, and the least abundant non-volatile components are steroids and quinones.

3.2 Alkaloids

Rue contains acridone alkaloids, such as furacridone and gravacridone; quinoline alkaloids, such as graveoline and graveolinine; and the furanoquinoline dictamnine. The alkaloid skimmianine is also notable: skimmianine has been demonstrated to have anti-inflammatory activity. Among the alkaloids isolated from rue, skimmianine was active as a specific agonist of the bitter taste receptor T2R14.

3.3 Coumarins and Furanocoumarins

Rue contains coumarins such as gravelliferone, isorutarin, rutacultin, rutaretin, and suberenone, and the furanocoumarins 5-methoxypsoralen (bergapten) and 8-methoxypsoralen (xanthotoxine). Psoralenes, among the main constituents of rue, are known for their photosensitization effects, which can produce a very strong undesirable syndrome in the form of photodermatitis. They are also used for therapeutic purposes in photochemotherapy to treat cutaneous T-cell lymphoma and granuloma annulare.

R. graveolens is a valuable source of linear furanocoumarins (derivatives of psoralen) that have been used for treating skin diseases such as vitiligo and psoriasis in the so-called PUVA therapy (psoralens and UVA irradiation). The content of xanthotoxin and bergapten in plants cultivated in the field is approximately: xanthotoxin 100 mg/100 g DW and bergapten 160 mg/100 g DW.

3.4 Flavonoids: Rutin and Quercetin

The name "rutin" comes from the plant Ruta graveolens, which also contains rutin. Chemically it is a glycoside comprising flavonolic aglycone quercetin along with the disaccharide rutinose. It has demonstrated a number of pharmacological activities, including antioxidant, cytoprotective, vasoprotective, anticarcinogenic, neuroprotective, and cardioprotective activities.

Rutin (3,3′,4′,5,7-pentahydroxyflavone-3-rhamnoglucoside) is a flavonol category of flavonoid. Chemically, rutin is a glycoside combining the flavonol quercetin with the disaccharide rutinose (rhamnose and glucose). The term "rutin" is derived from the plant Ruta graveolens, which contains rutin as one of its main chemical constituents. Various beneficial biological properties of rutin include anticancer, antioxidant, antidiabetic, anti-inflammatory, antibacterial, antifungal, neuroprotective, cardioprotective, hepatoprotective, nephroprotective, antiarthritis, and anthelmintic activities.

3.5 Rutamarin

It has been reported that (+)-rutamarin is a dual inducer of both GLUT4 translocation and expression and therefore ameliorates glucose homeostasis in insulin-resistant mice. Rutamarin is also an agonist of TRPM5 and TRPV1 and a strong antagonist of TRPM8 ion channels.

3.6 Volatile Oil Components

α-Pinene, limonene, and 1,8-cineole were identified as the main monoterpene constituents for R. graveolens essential oil. The essential oil contains two main constituents, undecan-2-one (46.8%) and nonan-2-one (18.8%). In the essential oil, ketones are the predominant compounds (76%), including 2-nonanone (23.5%).

3.7 Receptor Interactions of Key Phytochemicals

From the leaves, stems, and fruits of rue, researchers have isolated rutin, rutamarin, three furanocoumarins, two quinolinic alkaloids, a dicoumarin, and two long-chain ketones. Bitter taste and chemesthetic properties have been evaluated by in vitro assays with twenty receptors of the TAS2R family and four TRP ion channels involved in gustation and nociception. The furanocoumarins activate TAS2R10, 14, and 49 with different degrees of selectivity, as well as the TRPA1 somatosensory ion channel. The antinociceptive activity of rue has been studied in mice, showing a mechanism mediated by opioidergic and alpha-adrenergic receptors, but not by serotonergic receptors.

4. Scientific Evidence by Area of Use

4.1 Anticancer and Antiproliferative Activity

In vitro assays performed with human cell lines have indicated the anticancer potential of furanoacridones and acridone alkaloids isolated from R. graveolens.

A key cell-line study (preclinical, in vitro) published in Anticancer Research examined crude methanolic extract against colon, breast, and prostate cancer cells: the extract dose-dependently decreased the viability and the clonogenicity of treated cells and induced G2/M arrest, aberrant mitoses, and caspase-3 activation. It also induced the p53 pathway and focal concentration of the DNA damage response proteins 53BP1 and γ-H2AX. Moreover, the levels of phospho-Akt and cyclin B1 were reduced by treatment, whereas only cyclin B1 was reduced in normal dermal fibroblasts.

Regarding its key flavonoid rutin specifically: Rutin has been reported to counteract numerous cancers via several mechanisms such as cell cycle arrest, inflammation, malignant cell growth inhibition, oxidative stress, apoptosis induction, and angiogenesis modulation, mediated through the regulation of cellular signaling pathways. Several in vitro studies have reported the significant anticancerous potential of rutin via its inhibition of the proliferation of several cancer types including glioma, breast, liver, pancreas, colon, lung, prostate, skin, ovarian, and cervical cancer.

Rutin is demonstrated to inhibit the proliferation of breast, colon, lung, and prostate cancers and other tumors. Furthermore, rutin alone or in combination with other therapeutic agents has been shown to regulate several signalling pathways involving the Ras/Raf and PI3K/Akt, MAPK, and other pathways.

Evidence strength assessment: This research summarizes that rutin can be a promising candidate in combination with drugs for cancer treatment in vitro. All anticancer evidence for R. graveolens itself remains at the in vitro (cell line) and animal-model level. No clinical trials in human cancer patients testing whole R. graveolens preparations have been identified. Evidence is preliminary and cannot be translated directly to clinical practice.

4.2 Antimicrobial Activity

R. graveolens presents diverse pharmacological activities, the most commonly reported of which are its antibacterial and anti-inflammatory effects. Anticancer, antiproliferative, antioxidant, fertility-regulating, antiviral, and anthelmintic properties are also well documented, as well as their effects on the nervous system. Methanol or ethanol extracts are the most frequently reported, followed by aqueous, ethyl acetate, and other organic solvent extracts.

In gram-positive bacteria: In an evaluation of antimicrobial activity of polyphenol extract of R. graveolens against five pathogenic strains, Staphylococcus aureus was the most sensitive bacteria with an inhibition zone of 14.37 mm and MIC value of 0.625 mg/mL, followed by Listeria monocytogenes (11.75 mm and MIC = 1.25 mg/mL) and Escherichia coli (10.25 mm and MIC = 1.25 mg/mL), though this study lacked a positive control.

Against MRSA specifically: An ethanolic active extract of R. graveolens was tested against 100 MRSA strains causing skin and soft-tissue infections. The extract showed strong antimicrobial activity against the MRSA strains with MIC 0.78 mg/mL. At subinhibitory concentration (1/2 MIC), the extract had high biofilm inhibitory effects with mean inhibition of 70%. Transcriptional analysis results showed that mean percentages of inhibition in expression of mecA, icaA, and icaD genes were 52.3%, 34.8%, and 33.7%, respectively, with all showing statistically significant differences (p ≤ 0.05).

Evidence strength assessment: These studies did not evaluate the compounds in vivo or investigate their mechanisms of action. Antimicrobial evidence is exclusively preclinical (in vitro). No human trials have been conducted. The data are of interest for drug discovery but cannot support clinical use.

4.3 Antifungal Activity

Research aimed to evaluate the antifungal activity of Colombian rue essential oil (REO) against clinical strains of Candida albicans, Candida parapsilopsis, Candida glabrata, and Candida tropicalis. Data showed that C. tropicalis and C. albicans were the most sensitive strains, showing minimum inhibitory concentrations (MIC) of 4.1 and 8.2 µg/mL of REO. Time–kill kinetics assay demonstrated that REO showed a fungicidal effect against C. tropicalis.

The essential oil has shown significant antifungal activity against F. oxysporum, A. alternaria, and A. flavus at concentrations <163 µg/mL, and the antifungal effect improves as the concentration of the essential oil increases. The suggested inhibition effect could be attributed to the high content of ketones and some monoterpenes and alcohols in the essential oil.

Preliminary studies demonstrated that the antifungal activity of the essential oil is due overall to the main components 2-nonanol and 2-undecanone, which exhibited the most potent antifungal effect.

Evidence strength assessment: All antifungal data are in vitro. No human clinical trials exist. Evidence is preliminary.

4.4 Anti-inflammatory Activity

The anti-inflammatory activity of the essential oils of R. chalepensis of Algerian origin was evaluated by the carrageenan-induced paw edema method using albino mice. It was found that this essential oil at a dose of 0.5 mL/mouse could significantly reduce carrageenan-induced edema, comparable to the positive control, diclofenac. It was assumed that the anti-inflammatory activity could be mediated through the inhibition of inflammation mediators like serotonin, prostaglandin, and histamine.

The alkaloid skimmianine has been demonstrated to have anti-inflammatory activity.

Evidence strength assessment: Anti-inflammatory evidence is limited to animal models and in vitro experiments. No human clinical trials have been conducted on this endpoint.

4.5 Antidiabetic / Antihyperglycemic Activity

A key preclinical study investigated R. graveolens infusion and rutin in a rat model of type 2 diabetes: this study was designed to evaluate and compare the efficacy of infusion of R. graveolens and its pharmacologically active constituent, rutin, on impaired glucose tolerance, lipid profile, and oxidative stress in nicotinamide-streptozotocin-induced (type 2) diabetic albino rats. R. graveolens infusion and rutin were orally administered to diabetic rats at doses of 125 and 50 mg/kg body weight/day, respectively, for 30 days. In vitro and in situ studies indicated that both significantly enhanced insulin release from isolated islets of Langerhans, insulin binding to its receptors in rat diaphragm, and peripheral glucose uptake by the rat diaphragm, whereas intestinal glucose and cholesterol absorption was significantly decreased. Both treatment agents decreased resistin expression in adipose tissue, while rutin only was found to be effective in increasing adipose tissue peroxisome proliferator-activated receptor (PPAR)γ expression.

At the molecular level, the coumarin constituent rutamarin has been the subject of a notable mechanistic study: (+)-Rutamarin (Rut) functions as an efficient dual inducer on both insulin-induced GLUT4 translocation and expression. Rut-treated 3T3-L1 adipocytes exhibit efficiently enhanced insulin-induced glucose uptake, while diet-induced obese (DIO) mice assays further confirm the Rut-induced improvement of glucose homeostasis and insulin sensitivity in vivo. Rut acts as a specific protein tyrosine phosphatase 1B (PTP1B) inhibitor, inducing basal GLUT4 translocation, and as an agonist of retinoid X receptor α (RXRα), it potently increases GLUT4 expression.

Evidence strength assessment: Evidence is confined to animal models and cell-based in vitro assays. No human clinical trials have been conducted. Rutamarin's mechanisms are of significant interest to drug discovery but have not been evaluated clinically.

4.6 Antioxidant Activity

Phenolic compounds (13 µg/mL) exerted major antioxidant activity in the ethanolic extract, showing a strong concentration-dependent antioxidant capacity. However, the study was limited to in vitro application. Using a 70% methanolic extract of R. graveolens, the inhibitory effect on acetaldehyde oxidase activity was 89–96% at a dose of 100 µg/mL. The IC50 values for inhibition of benzaldehyde, vanillin, and phenothiazine oxidation were 10.4, 10.1, and 43.2 µg/mL, respectively.

Rutin, a phytochemical compound isolated from rue, has already shown multiple pharmacological benefits including antioxidant, neuroprotective, cardioprotective, and anticarcinogenic effects.

Evidence strength assessment: Antioxidant data are in vitro only. No human clinical intervention studies for antioxidant endpoints have been identified for R. graveolens.

4.7 Effects on Reproductive and Fertility Function

Studies over the past twenty-one years on both female and male mammals have shown abortive effects, specifically implantation loss, premature infant losses, and paralyzing sperm activities. Extracts of Ruta graveolens demonstrated anti-implantation activity in albino rats, inhibiting pregnancy in 50% to 60% of rats. Among its chemical components, coumarins and xanthotoxins have been identified as compounds with fertility-disrupting properties.

To determine its effect on pregnancy, the lyophilized hydroalcoholic extract of aerial parts was administered orally at a dose of 1000 mg/kg per day to mice between different days of pregnancy. The extract did not cause pre-implantation embryonic loss or reabsorptions, but fetal death was found. Estrogenic activity was not exhibited by the extract.

Evidence strength assessment: Fertility and anti-implantation evidence is exclusively from animal studies. Reproductive toxicity in humans is documented via case reports and poisoning surveillance, not prospective trials. The well-documented traditional use as an abortifacient, combined with animal data showing anti-implantation effects, provides consistent signal of reproductive hazard.

4.8 Nervous System and Analgesic Effects

Skimmianine was found to have significant inhibitory effect on spontaneous motor activity, exploratory behavior, cataleptogenic activity, conditioned avoidance response, and long-term isolation-induced fighting of animals, with some anti-methamphetamine effect observed in animal studies.

The antinociceptive activity of rue has been studied in mice, showing a mechanism mediated by opioidergic and alpha-adrenergic receptors, but not by serotonergic receptors.

In homoeopathy, rue is used for pain management in different joint-related disorders.

Evidence strength assessment: All evidence for central nervous system and analgesic effects is from animal models and in vitro receptor assays. No controlled human trials exist.

4.9 Photochemotherapy (PUVA) — Therapeutic Use of Constituent Furanocoumarins

R. graveolens is a valuable source of linear furanocoumarins (derivatives of psoralen) that have been used for treating skin diseases such as vitiligo and psoriasis in the so-called PUVA therapy (psoralens and UVA irradiation). Psoralenes are used for therapeutic purposes in photochemotherapy to treat cutaneous T-cell lymphoma and granuloma annulare.

Evidence strength assessment: This is the most clinically established pharmacological use of rue-related compounds. However, isolated or synthesized psoralens, not whole rue preparations, are used in clinical PUVA therapy. The evidence base for psoralens in dermatology is robust, but is not equivalent to evidence for medicinal use of the whole plant.

5. Body Systems Associated with Rue

• Reproductive system: Emmenagogue, abortifacient, and anti-fertility effects documented in traditional use and animal studies.
• Gastrointestinal system: Plants of the Ruta genus are used to treat pain, fever, nausea, and inflammation, among other conditions. Traditional antispasmodic and digestive use is well-established ethnobotanically.
• Dermatological / Skin system: Psoralen-containing furanocoumarins are applied in photochemotherapy for vitiligo, psoriasis, and cutaneous T-cell lymphoma, albeit as isolated constituents.
• Immune and inflammatory system: Anti-inflammatory effects demonstrated in animal models via inhibition of prostaglandins, serotonin, and histamine pathways.
• Metabolic / Endocrine system: Antidiabetic and antihyperlipidemic effects suggested by animal studies via GLUT4, PTP1B, and PPARγ mechanisms.
• Central nervous system: Antinociceptive and sedative effects observed in animal experiments; alkaloid skimmianine interacts with motor and behavioral pathways.
• Cardiovascular system: At high concentrations, this plant is associated with high toxicity on the functionality of multiple organs, particularly at the cardiovascular and hepatic level, sometimes even causing mortality.
• Oncology (investigational): Significant in vitro antiproliferative activity across multiple cancer cell lines; no clinical evidence.

6. Dosage Forms and Dosages Reported in Studies

IPCS documentation notes that ingestion arising from the traditional use of the infusion should not exceed 1 or 2 g/day of the plant. Herbalist Hoffmann proposes a dose of 1–4 mL tincture (1:5, 40%) and 1–2 teaspoons of dried herb to a cup of boiling water as an infusion.

In the animal antidiabetic study: R. graveolens infusion and rutin were orally administered to diabetic rats at doses of 125 and 50 mg/kg body weight/day, respectively, for 30 days.

In the CYP450 enzyme study in mice: administration of 0.5 g/kg rue extract resulted in a concurrent exposure to 12 mg/kg rutin, 1.3 mg/kg psoralen, 0.05 mg/kg 8-MOP, 1.4 mg/kg 5-MOP, and 0.05 mg/kg chalepensin.

For essential oil antifungal activity: the most sensitive strains, C. tropicalis and C. albicans, showed minimum inhibitory concentrations (MIC) of 4.1 and 8.2 µg/mL of essential oil.

A safe dose for human consumption of Ruta graveolens has not been determined.

7. Safety, Toxicity, and Drug Interactions

7.1 Phototoxicity

When psoralens from rue come in contact with human skin that is subsequently exposed to ultraviolet A light, an impressive photoirritant reaction can occur. This distinguishes photoirritant reactions from photoallergic reactions. R. graveolens can be associated with an impressive photoirritant reaction and should not be used as an insect repellent.

Published case reports describe a family, including a 5-year-old and 6-year-old, who developed redness, blistering, and lasting dark patches on their skin simply from handling the fresh plant and then going into sunlight.

7.2 Systemic Toxicity and Organ Damage

The essential oil of rue can cause contact dermatitis and phototoxic reactions, as well as severe hepatic and renal toxicity. Therapeutic doses can lead to depression, sleep disorders, fatigue, dizziness, and cramps.

A case report describes multiorgan toxicity in a 78-year-old woman consuming R. graveolens for cardiovascular protection. After 3 days of use, the patient entered the emergency department with bradycardia, coagulopathy, and acute renal failure with hyperkalemia requiring hemodialysis.

Data from a South American poison center showed that people who consumed rue tea in high doses for self-managed abortions experienced liver damage, kidney problems, and blood abnormalities at elevated rates. In severe cases, large ingestions have caused multiorgan failure, dangerous drops in blood pressure, and electrolyte imbalances serious enough to require emergency dialysis.

7.3 Reproductive Toxicity

R. graveolens has an abortifacient effect and can cause uterine bleeding and inflammation; women should use R. graveolens with caution and avoid the drug if pregnant. Early pregnancy may be interrupted by the abortifacient effect of rue. In traditional medicine, its use in children is contraindicated.

7.4 Mutagenicity

Rue extracts are mutagenic, and furocoumarins have been associated with photosensitization.

7.5 Drug Interactions via CYP450 Enzyme Modulation

Aqueous extracts of R. graveolens can play a partial role in the induction of cytochrome P450 enzymes (CYP450), with rutin increasing CYP1A activity and furanocoumarin increasing CYP2B activity in the mouse liver.

The furanocoumarin chalepensin, a constituent of rue, has been studied in detail for CYP interactions: Chalepensin was found to inhibit human CYP1A1, CYP1A2, CYP2A13, CYP2C9, CYP2D6, CYP2E1, and CYP3A4 to different extents. CYP1A1 and CYP3A4 underwent pronounced mechanism-based inactivation by chalepensin. The threshold concentrations of chalepensin for potential drug interactions through inhibition of CYP2A6 and CYP3A4 were estimated to be consistently low. These results demonstrate that chalepensin inhibits multiple P450s and that epoxidation activity is crucial for the potential drug interaction through mechanism-based inhibition.

This means that R. graveolens preparations could potentially alter the metabolism of drugs that are substrates of CYP3A4, CYP2A6, CYP1A1, and CYP1A2, including many commonly used pharmaceuticals. This interaction has been characterized in in vitro and animal studies; clinical magnitude in humans remains to be formally evaluated.

7.6 Summary of Documented Adverse Effects

• Severe hepatic and renal toxicity from the essential oil.
• Depression, sleep disorders, fatigue, dizziness, and cramps at therapeutic doses.
• Phototoxic and photoirritant skin reactions from topical contact with the fresh plant combined with UV-A exposure.
• Abortifacient effects and uterine hemorrhage in pregnant women.
• Multiorgan failure, bradycardia, coagulopathy, and hyperkalemia in severe poisoning cases.
• Potential mechanism-based inhibition of multiple CYP450 enzymes, with implications for drug metabolism.
• No established safe human dose.

References

• Traditional Uses, Phytochemistry, Pharmacology and Toxicology of Ruta graveolens L.: A Critical Review and Future Perspectives — PMC / Drug Design, Development and Therapy (Dove Press)
• Identity and Pharmacognosy of Ruta graveolens Linn — Ancient Science of Life, PMC
• Phytochemistry and Pharmacological Properties of Ruta graveolens L. — ResearchGate
• Ruta Graveolens Extract Induces DNA Damage Pathways and Blocks Akt Activation to Inhibit Cancer Cell Proliferation and Survival — PMC
• Rutin: A Flavonoid as an Effective Sensitizer for Anticancer Therapy — PMC
• The Pharmacological Potential of Rutin — PMC
• Rutin (Bioflavonoid) as Cell Signaling Pathway Modulator: Prospects in Treatment and Chemoprevention — PMC
• Phytochemicals from Ruta graveolens Activate TAS2R Bitter Taste Receptors and TRP Channels Involved in Gustation and Nociception — PMC / Molecules (MDPI)
• (+)-Rutamarin as a Dual Inducer of Both GLUT4 Translocation and Expression Efficiently Ameliorates Glucose Homeostasis in Insulin-Resistant Mice — PMC / PLOS ONE
• Effects of Aqueous Extract of Ruta graveolens and Its Ingredients on Cytochrome P450, UDP-Glucuronosyltransferase, and NAD(P)H-Quinone Oxidoreductase in Mice — PMC
• Mechanism-based Inhibition of CYP1A1 and CYP3A4 by the Furanocoumarin Chalepensin — ScienceDirect / Drug Metabolism and Pharmacokinetics
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• Phytochemical Characterization, and Antioxidant and Antimicrobial Properties of Agitated Cultures of Three Rue Species — PMC
• Ruta angustifolia Pers. (Narrow-Leaved Fringed Rue): Pharmacological Properties and Phytochemical Profile — PMC
• Dynamized Ultra-Low Dilution of Ruta graveolens Disrupts Plasma Membrane Organization and Decreases Migration of Melanoma Cancer Cell — PMC
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• Ruta graveolens Overview — ScienceDirect Topics (Meyler's Side Effects of Drugs)
• Antihyperglycemic, Antihyperlipidemic and Antioxidant Effects of Ruta graveolens Infusion and Rutin in Diabetic Rats — ResearchGate
• Rue (Ruta L., Rutaceae) in Traditional Spain: Frequency and Distribution of Its Medicinal and Symbolic Applications — Economic Botany / Springer
• Ruta graveolens — Wikipedia (for botanical/cultural cross-reference, not as primary scientific source)