categoryZShrubs Shrubs List 
categoryZBroadleaf Broadleaf List 
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RUE

Ruta graveolens

Rue Family [Rutaceae]

month8may month8jun month8june month8jul month8july month8aug

category
category8Shrubs
category
category8Broadleaf
category
category8Evergreen
status
statusZneophyte

flower
flower8yellow
 
inner
inner8green
 
morph
morph8actino
 
petals
petalsZ4
mostly
petals
petalsZ5
 
type
typeZpanicle
 
stem
stem8round
 
smell
smell8awful
awful
toxicity
toxicityZhigh
 
contact
contactZlowish
 
sex
sexZbisexual
 

27th May 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
An evergreen shrub growing to 1m high. This in a garden in Walkden, with other garden plants sneaking in at the edges of the photo.


27th May 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
The leaves are glaucous green, flowering stems bright green and round with shortish flowering branches. [Other garden plants at the sides]


27th May 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
The flower has either 4 or 5 petals which mirror the number of carpels in the dark-green fruit in the centre of the flower, and the number of petals (doubled). So flowers with 4 petals have 4 carpels in the fruit and 8 stamens; and flowers with 5 petals have 5 carpels and 10 anthers. As-yet unopened flowers surround the only open one.


27th May 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
As-yet unopened flower buds have 4 or 5 bulges corresponding to the number of petals contained within.


27th May 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
A 5-petalled flower, with 5 parts to the dark-green warty carpel in the centre with a central short green style just poking out from its centre. [The 10 anthers are partly hiding; 5 down the centre0line of the petals with 5 others rayed out between the petals.]




THREE WEEKS LATER

27th May 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
It has grown a bit more of its potential 1m in height. Of those which can be discerned, most flowers here seem to have 4 petals.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
Most, if not all(?), flowers here have 4 rather than 5 petals.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
The two objects at top left corner are as-yet unopened flower-buds amidst the others which have all opened.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
The dark-green ruckled surface and the sepal cup surrounding the lower half with a ring of 'port-holes' in the side.
The long central single style has a small discoidal stigma atop. The anthers are small and at the tips of long yellow stamens which slightly exceed the extent of the petals.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
A closer-view reveals that the ruckles on the surface are like craters with a central tiny pip. There may be 8 'port-holes' in the sepal cup for fruits with 4 carpels (or 10 'port-holes' for those specimens with 5 carpels). There are 4 (or 5) short, triangular, pale-green sepal teeth below the fruit.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
The sepal cups have fallen off these fruits, leaving just the paler-green set of sepals teeth below the fruits. Most have 4 compartments, but the nearest has 5.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
Fruit with their crater-pits and 4 (or 5) lobed compartments each containing numerous ovules within.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
A 5-lobed fruit.


22nd June 2020, a garden, Walkden, Greater Manchester. Photo: © RWD
The glaucous leaves are deeply 2 (to 3-) -pinnately lobed and have a strong distinctive (some say obnoxious) smell when crushed.


Not to be semantically confused with : Wall-rue (Asplenium ruta-muraria), Goat's-Rue (Galega officinalis), Rue-Leaved Saxifrage (Saxifraga tridactylites), Common Meadow-Rue (Thalictrum flavum), Dusty Meadow-rue (Thelypteris palustris), Lesser Meadow-Rue (Thalictrum minus), Chinese Meadow-rue (Thalictrum delavayi), French Meadow-Rue (Thalictrum aquilegiifolium) nor with Alpine Meadow-rue (Thalictrum alpinum) [plants with similar names belonging to differing families].

Uniquely identifiable characteristics

Distinguishing Feature : There is no other plant quite like this!

It is a neophyte which can become naturalised on rough ground, producing seedlings in waste places, shrubberies or cracks in walls.

Rue has quite a plethora of differing secondary metabolites, many being toxic to various degrees. It contains the Coumarins Scopoletin and Umbelliferone plus two first discovered in Rue: Rutamarin and Rutacultin.

The essential oil from Rue can cause contact dermatitis and it also contains photosensitive substances (Furocoumarins) which can not only cause skin blisters which lasts up to 2 years but also severe damage to the kidneys. Therapeutic doses can cause depression, fatigue, cramp, sleep disorders and dizziness. Fresh sap from the leaves may cause a week heart pulse, fainting, sleepiness, painful stomach cramps, abortion, a swollen tongue and make your skin feel cool. But despite these symptoms, Rue has traditionally been used in Indian and many other countries as a medicine. The herb has been used as an antispasmodic, irritant, abortifacient, and for the treatment if cough, colic and wind. The leaves have been used for amenorrhea, menorrhea, colic and externally for sciatica, headache, muscular chest pain, bronchitis and arthritis. The oil is an anti-spasmodic, anti-epileptic, a rubifacient and an emmenogogue. But your Author would not use Rue for any of these things! If he needed then he would go to the doctors for a prescription from a proper chemist where there is usually only one active compound in a highly-controlled dosage (rather than a whole plethora of differing potentially harmful compounds in unknown highly-variable quantities)...

Rue extracts are mutagenic and hepatotoxic. Large doses can cause violent gastric pain, vomiting, systemic complications, and death. Exposure to common rue, or herbal preparations derived from it, can cause severe phytophotodermatitis which results in burn-like blisters on the skin.

According to WebMed: " Rue is UNSAFE when used as a medicine. When taken by mouth, it can cause side effects such as stomach irritation, changes in mood, sleep problems, dizziness, spasms, serious kidney and liver damage, and death. When applied to the skin, it can cause rash and increased sensitivity to the sun "

LIMONOIDS


Two Limonoids found in Rue, one called Limonin, the other Nomilin. They are phytochemical TetraNorTriTerpenoid compounds found in Citrus fruits and in 3 other plant families, Cucerbaticaea, Rutacea and Meliaceae, the latter having no presence in the UK it being the Mahogany family. Limonoids contribute to the sweet (or sour) tastes of citrus fruits.

Nomilin is a new bitter compound found in Grapefruit juice, oranges, lemons and Rue. Nomilin is twice as bitter as Limonin.

At their core Limonoids contain a FuroLactone (the two rings on the right-most, one above the other). Nomilin has a 7-membered ring (bottom left). They both have an epoxy bridge (depicted here with two pointed arrows holding an oxygen atom almost in the centre of the diagram). Typically Limonoids have four 6-membered rings plus a furan ring but in Nomilin one of those four rings is 7-membered.


COUMARINS and FUROCOUMARINS


Rutacultin is a Coumarin with extra moieties attached. It is found in herbs and spices, and in Rue. Rue also contains the Coumarins Gravelliferone, isoRutarin, Rutaretin and Suberenone.

The other two compounds, Chalepensis and Rutamarin, are FuroCoumarins both found in Rue.

Other FuroCoumarins found in Rue are Dictamnine, Xanthotoxin, Psoralen, Bergapten and isoPimpinellin. FuroCoumarins are far more toxic than Coumarins because of the Furano moiety (the 5-membered ring with an oxygen atom in the ring).


QUINOLINES


Both Eduline and the more complex Graveolin (plus Graveolinine - not shown here) are all Quinoline alkaloid secondary metabolites to be found in Rue.

There are also a set of three variations on Graveolin where the moiety bottom right of two fused rings are replaced by a zig-zag linear hydrocarbon chain of 10, 11 or 12 of CH2 units like the linear strings on the two ketone hydrocarbons shown below this pane.




FURO-QUINOLINES


6-MethoxyDictamnine, Kokusaginine and Skimmianine are FuroQuinoline alkaloids found in Rue (as is Dictamnine itself - not shown here).


Kokusaginine, just like the other compounds with a heterocyclic nitrogen atom in a ring, is an oxacycle compound. It occurs in significant amounts in species of Rutaceae, including Rue. Both Kokusaginine and Skimmianine inhibit the proliferation of cancer cells and it is suggested by a researcher that both of these compounds are to be recommended as starting materials to design other chemical structures that are even more effective at killing cancer cells than either of these two chemicals.

Skimmianine is also found in Japanese Skimmia (Skimmia Japonica) (which is also in the same Rutaceae family as Rue). Skimmianine is ultimately derived from Anthranilic Acid (which is found in abundance in Rue) via an 11-step biosynthetic process.


KETONE HYDROCARBONS

2-Nonanone (how many N's in that) is present not only in Rue but also in a great many other plants such as Banana, Ginger, Cloves, Coconut, Passionflower, Sorghum Mosses, Asparagus, Tomato, Corn, Melon but also in Strawberry Jam, Wine, Beer and Cheese (probably amongst many others). It is a clear but slightly yellow liquid used a a flavouring and as a fragrance.



2-Undecanone, aka MethylNonylKetone is a colourless oil is also found in various plants such as Banana, cloves, ginger, guava, tomato and strawberry as well as in the plant Chameleon (Houttuynia cordata) and in Rue. It has a strong odour and is used primarily as an insect repellent but is also used for flavouring and in perfume. It tastes waxy or of fat, creamy or a bit cheesy but comes up smelling of Roses (or of Citrus fruit, such as Pineapple).


ACRIDONES

Acridones always have two benzene rings straddling a moiety with an exocyclic =O moiety directly opposite a nitrogen atom in the ring. They also have a ketone moiety (the exocyclic =O just above the nitrogen atom, hence the 'one' [pronounced 'own'] ending in 'Acridone').



Arborinine (aka Arborin) is found in Rue and in the leaves of the plant Glycosmis parva and exhibits strong anti-cancer activity and inhibits tumour spheroid growth more effectively than do the chemotherapy drugs Cisplatin, Gemcitabine or Bleomycin. Also, unlike cisplatin, it activates caspase-dependent cancer-cell apoptosis without inducing a DNA damage response. It also stops cancer cell migration.It also stops cancer cell migration. It thus shows potential for use in treating cervical cancer. It also exhibited moderate levels of anti-hepatitis C (HCV) activity.



The biosynthesis of Melicopicine within Rue, with two extra epoxy groups on the lower side (left), makes it possible for the more complex Furo-Acridones and Acridone to also be constructed within Rue as shown below.




A DIOXOLO-ACRIDONE


Evoxanthine is the odd one out in this section: it is the only compound shown here with a Dioxolane moiety (the 5 membered ring on the left with two oxygen atoms in the ring).
It occurs widely in the Rutaceae family of plants and in several other un-related species. In crystaline form it occurs as yellow cubes with a strong blue-violet fluorescence.





FURO-ACRIDONES

The chemicals shown below that have a 5-membered 2,5-dihydrofuran ring (with only one oxygen atom in the ring).



Rutacridone is a Furo-acridine on account of its 5-membered ring with one oxygen atom within.



Rutacridone Epoxide is similar to Rutacridone, except that it has swapped one moiety for a much more potent epoxide moiety (the triangular moiety with an oxygen atom at one apex).
Like all the other chemicals shown on the Rue page it occurs in Rue. This one exhibits anti-microbial properties (as probably do the many other compounds shown on this page), slowing the growth of microorganisms including fungi, bacteria, viruses and protozoans, but your Author wonders if that includes covid-19, which is rampant around the world in the year 2020 (and probably many other years to come). But because the epoxy group usually makes compounds more toxic, this one in particular is probably more effective than most.



20-HydroxyRutacridone Epoxide has swapped a CH3 moiety for another -OH group (it already has one at the top).




PYRO-ACRIDONES



Compared to Rutacridone - Acronycine has the furano ring replaced by a pyrano moiety. This compound is a potent anti-tumor agent with a broad spectrum of modest activity including numerous solid tumours.




  Ruta graveolens  ⇐ Global Aspect ⇒ Rutaceae  

Distribution
 family8Rue family8Rutaceae
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genus8Ruta
Ruta
(Rue)

RUE

Ruta graveolens

Rue Family [Rutaceae]