The genus includes six species found in Europe. The Flora of Turkey gives two Ruta species, not including Ruta graveolens.
Ruta graveolens L. is a native of southeastern Europe but is widely naturalized in southern Europe and cultivated worldwide. It is a shrubby perennial with a distinctive smell. Smooth erect stems (14-45 cm) bear alternate, stalked bluish-grey-green pinnate leaves with deeply lobed obovate leaflets. Shiny yellow flowers with four spoon-shaped petals occur in terminal umbel-like groups in June-August. A smooth green capsule containing many seeds develops in each flower while other flowers around are still coming into flower.
Other species used
Ruta angustifolia Pers. and Ruta chalepensis L. are found in southern Europe and are similar but with fringed cilia on the petal edge.
All Ruta species are associated with phytophotodermatitis (see below) and plants should not be touched with bare hands, especially on sunny days.
Rue is included among the plants discussed in this book not because we ourselves use it, but because of its reputation as a great healing medicine in the Western herbal tradition and the suspicion that it is a neglected remedy. Its application extends even to culinary purposes – rue belongs to the citrus family – but it is said no longer to suit the modern palate. From this it may be thought that rue is a relatively innocuous herb, but current concerns about the risks involved in its administration coupled with a lack of a modern evidence base for its therapeutic benefits has led to calls for rue to be withdrawn from over-the-counter sale for safety reasons. If it is to remain in the repertoire of registered herbal practitioners, then they require a better understanding of its recorded actions and uses in order to weigh this against potential toxicity and safety concerns so that a judicious decision on the reasons for employment and method of administration may be properly reached.
In a section headed ‘Causes of contention’ and subtitled ‘False alarms?’, Mills & Bone (2000) record rue appearing on a list of herbs circulated in 1992 by the European Commission Committee for Proprietary Medicinal Products which, in the committee’s opinion, should be withdrawn from sale. It is, say Mills & Bone, one of a number of herbs on the list that are widely used and popular among practitioners. They bemoan the fact that there is too little representation of herbal expertise on such controlling bodies, making the herbal profession vulnerable to legislative decisions restricting the availability of medicinal herbs. This can happen because ‘it maybe easier to publish reports in medical journals on the risks of herbal remedies than it is to prepare a publishable account of their efficacy. In the first case, anecdotal evidence is the norm, in the latter case it would be dismissed out of hand’. Writing more than a decade after the shock announcement, the authors (2005) note that the list has had little impact on availability, but they do not speculate on the negative impact the call for withdrawal may have had on practitioner use. Bartram, however, is quick to suggest, writing in 1995, that the herb should be left to practitioner use only, that ‘internal use today [is] discouraged in modern practice’ and that excessive handling of the fresh plant may cause contact dermatitis.
The Commission E monograph for rue (dated 2 March 1989) (Blumenthal 1998) is one source from which the European Commission Committee for Proprietary Medicinal Products will have drawn. Here the dried leaf or dried aerial parts are linked with emmenogogic, antispasmodic, diuretic and antiinflammatory actions for use in menstrual disorders and discomforts; for loss of appetite and dyspepsia, circulatory disorders and arteriosclerosis, heart palpitations, nervousness and hysteria, fever, pleurisy and respiratory complaints, headache, neuralgic afflictions, toothache and weakness of the eyes. Both internally and externally, it is employed in arthritic complaints, dislocations, sprains, bone injuries and skin diseases. This represents quite a range of possible therapeutic actions but, according to the monograph, none of these applications has a verified effectiveness. Instead there is an unfavourable ratio of benefit to risk. The risks include contact dermatitis from the volatile oil component and phytophotodermatitis from the furocoumarins, while severe liver and kidney damage have been documented, and the deaths of pregnant women who used rue as an abortifacient reported. Therapeutic dosages can cause side-effects of melancholic moods, sleep disorders, tiredness, dizziness and spasms. The juice of the plant, particularly a fresh plant preparation, has been associated with painful irritations of the stomach and intestines, fainting, sleepiness, low pulse, abortion, swelling of the tongue and clammy skin.
Understandably, no dosage for rue is stated in the monograph but high doses are to be avoided, as the following case shows. A woman of 78 in Taiwan took a decoction prepared with 50 g of fresh aerial parts decocted in 1000 mL of water boiled down to 250 mL. The plant material was positively identified as rue on further investigation. She took two doses a day and over the next 3 days developed increasing dyspnoea, dizziness, nausea, weakness and decreased urination. On admission she had a pulse of 41, blood pressure of 78/50, atrial fibrillation and an abnormal electrocardiogram, an international normalized ratio of over 12, hyperkalaemia and acute kidney failure, which was treated with haemodialysis. She was in hospital for 5 days and was well at a checkup 3 months later. She was taking medications for a 5-year history of hypertrophic cardiomyopathy and on further investigation had some mitral regurgitation but her normal pulse had been 78. The authors give a medical history and review the case in detail, including the possibility of a drug-herb interaction, and conclude that high dosage was the most likely cause.
Rue is a known abortifacient and is one of the plants traditionally used an as antifertility agent. It is also recommended to ‘promote delayed menstruation’ in self-help books such as Parvati (1979). Wood suggests that it is ‘probably the single most important remedy in Latin American folk medicine’ and Riddle (1991) cites ethnobotanical evidence of traditional abortifacient use among Hispanic people in New Mexico. The following report brings into focus the dangers of rue in this regard: a retrospective review of cases where herbal infusions had been taken to procure abortion found 86 cases (ages 14-47) from 1986 to 1999 which were reported to the Poison Centre in Montevideo, Uruguay. Twenty-six women took rue (Ruta graveolens or Ruta chalepensis), which was the most common herb used. Seventeen had abdominal pain and vomiting, 13 had jaundice, 11 had genital haemorrhage, 9 had abortion and 4 women died. One woman who died had also suffered a self-inflicted instrumental attempt at abortion carried out a study on mice to determine whether rue affects preimplantation or embryo development, using aqueous extracts of the herb on the basis of a report from Chile that 500 mg twice a day is used by women there to prevent pregnancy.
Both this last study and another by de Freitas (2005) provide evidence that rue affects embryo development, producing abnormalities which lead to death of the embryo, while Al Mahmoud et al (2003), in a review of other studies where a range of preparations were used, found that implantation occurred but there was a higher rate of deaths of embryos. If embryo death leads to a sufficiently early spontaneous miscarriage, does this provide a modern explanation for the historical use of rue as an antifertility agent? Riddle, in reviewing this historical usage (1991), discusses both abortifacient and antifertility actions and explains how the extremely hot and particularly drying qualities of rue provide the Hippocratic rationale for the herb’s power to dry up the male sperm or female seed, and both curb sexual desire and block conception if intercourse nevertheless takes place. This effect is enshrined in the Greek name for rue: peganon, from pegas meaning a congealed thing. Since the quality of moisture is required for fertility in Hippocratic and Galenic medical theory, a drying out and congealing of seed renders it unable to perform its role in conception. Riddle points out that rue is still used to control fertility today, but its employment in Western medicine came to an end by the 19th century.
Use of rue as an abortifacient or antifertility agent requires knowledge of the correct dosage. Gutierrez-Pajares et al (2003) found a significant and dose dependent increase in abnormal embryos in their study. Riddle (1991) cites Gargilius Martialis, a 3rd century AD retired soldier and land-owner, on concerns for the employment of rue by women, deeming foolish those who declare its power to inhibit and debilitate the generative seed and to kill embryos in the womb without consideration of the strength and dosage of the preparation, nor the circumstances in which it is taken. Rue must be taken in moderation ‘so that it may not become a poison, rather than a remedy’. These studies support the recommendation that Rue should not be used in pregnancy or in women who intend to become pregnant.
A moderate dosage for rue will be required when treating other indications. In order to utilize its rutin content, which he says will be superior to rutin in isolated form, Weiss proposes a tea made with 1-2 tablespoons of dried rue to a cup of boiling water infused for 10-15 minutes. This is surely a large dose? If rutin in a complex is required for the treatment of circulatory disorders such as arteriosclerosis and capillary fragility, then the other herb he discusses in this regard, buckwheat Fagopyrum esculentum, must be preferable, and can be enjoyed as an item of the diet rather than as a medicine. Elsewhere in his text, Weiss proposes equal parts of dried rue leaf, hedge hyssop Gratiola officinalis and senna Senna alexandrina along with its corrective fennel seed Foeniculum vulgare as an effective emmenogogue. The inclusion of a laxative herb is very important, he says. The dose is 1 tablespoon (15 g) of herb to 500 mL of boiling water infused for 20 minutes. It is taken once daily, in the mornings within 1 hour of rising, on an empty stomach. Those among our modern authors who discuss rue repeat the emmenogogue and spasmolytic actions listed in the British Herbal Pharmacopoeia – both due to the quinoline alkaloid arborinine according to Tyler (1993) – its indication in amenorrhoea, prohibition in pregnancy and the British Herbal Pharmacopoeia dose of 500 mg-1 g of dried herb three times a day. Hoffmann proposes a larger dose of 1-4 mL tincture 1:5 40% and 1-2 teaspoons dried herb to a cup of boiling water as an infusion. Wood takes a different approach. He provides the same contraindication and warning about contact but generally provides a homoeopathic description of the uses of rue and gives a dosage of 1-3 drops of the tincture. It is hard to agree with him that the vulnerary power of rue was unknown before Hahnemann’s proving of the remedy to include strains, sprains, bruises and blows, when so many external applications are stated in the texts of the herbal tradition.
Since rue is according to Galenic pharmacology very heating and drying, it is appropriate as an internal remedy for cold and phlegmatic presentations. These imbalances are much more likely in older people, whereas rue may be too stimulating and heating for younger people.
Rue should be considered for internal administration in:
• Secondary amenorrhoea not linked to underlying disease. Weiss’ formula above should be considered for use.
• Rue may have a role in premenstrual syndrome.
• To sharpen vision.
• For external use (with the need to protect the area treated from exposure to sunlight):
• Skin diseases where a stimulation of the affected skin is required to improve healing, or an anti-microbial effect is needed.
• As a rub for chest conditions such as bronchitis
Dosage: the British Herbal Pharmacopoeia recommends 500 mg-1 g three times a day of dried herb. Equivalent dosage in liquid extract or tincture forms may be considered. Infusions of the fresh herb and specific tinctures should be used more cautiously in lower doses at first. A suitable fixed oil of rue and a derived ointment could be prepared for external use.
Quinoline: graveoline, furoquinoline: kokusagenine; quinoline (fresh leaves, cultivated, USA).
Quinoline: graveoline and eight analogues; furoquinoline: kokusagenine, skimmianine (cultivated, Bulgaria).
Acridones, unique to Rutacea, mainly in roots and slightly in leaf base.
Total 0.74% (38 compounds), linear ketones: 2-undecanone 47%, 2-nonanone 19%; monoterpenes 11%: alpha-pinene, limonene; oxygenated monoterpenes: 1,8-cineole, methyl salicylate 4% (aerial parts, Italy).
(37 compounds), linear ketones: 2-nonanone 45.3%, 2-undecanone 31.1%; oxygenated monoterpenes (leaves, cultivated, Columbia).
Undecanone is responsible for the characteristic smell and insect repellant action and is used in sprays to repel dogs and cats.
Total 0.4% (mean): psoralen 0.14%, bergapten (5-methoxypsoralen) 0.16%, xanthotoxin (8-methoxypsoralen) 0.1 %, isoopimpinellin (5,8-methoxypsoralen) (leaves, cultivated, 19 plants, France). Total concentration was highest in fruits and leaves and similar in all 19 accessions.
Total 0.5% (mean): psoralen, xanthotoxin, bergapten. Total concentration was highest in leaves higher during fruiting, and did not vary between sites (cultivation, France).
Rutamarin, bergapten, xanthotoxin, chalepin, rutaretin.
Chalepin, chalepensis, bergapten, psoralen, xanthotoxin, isopimpinellin (leaves, cultivated, Colombia).
Recommendations On Safety
1. Do not use in children.
Given the safety concerns discussed above, rue should not be used in children under any circumstances.
2. Use caution in dosage.
The dosage of this plant is discussed above.
3. Do not use where the patient may be pregnant or could become pregnant.
The authors and other sources discussed above indicate that rue can be an abortifacient. 4. Do not apply to the skin without first conducting a small patch test. Avoid exposing the treated part to the sun. Use gloves when gathering the plant as contact can cause an unpleasant, phototoxic skin reaction. Phytophotodermatitis is a light-sensitive contact dermatitis where skin which is exposed to sunlight comes into contact with an irritant substance and a red, oedematous rash, sometimes with blisters, develops, usually 1-2 days after exposure. The furocoumarins are linear coumarins, containing a lactone group and the main ones are psoralen, bergapten and xanthotoxin. A group of four adults and seven children applied fresh rue as an insect repellant and spent the afternoon outdoors. After 24 hours they developed reddish-purple rashes with blistering, which continued to erupt up to 12 days after the initial exposure. The rashes tended to be linear where the plant had been rubbed on the skin and people who had spent less time in the sun were less affected. A 2-year-old child suffered acute blistering on the hands and was poorly after touching the plant. A woman developed a painful rash after applying a decoction of dried rue the day before visiting a suntan parlour and again the rash was present where the rue extract had been applied.