Rheum palmatum L. [Fam. Polygonaceae]
Aqueous extract of coarsely cut or powdered dried root
– Cellular Regeneration
The root of Turkish rhubarb, Rheum palmatum L. [Fam. Polygonaceae], has been used traditionally to improve both digestion and loss of appetite. The bitter tea is rich in tannins that increase the flow of saliva and gastric secretions and can be used as an astringent or stomachic at a low dosage to stop diarrhea (0.1-0.2g). Formerly, the root was an important drug in many army camps, said to stop the deadly scourge of dysentry in its tracks. At a higher dosage (1.0-2.0g) the anthraquinones that it contains function as a safe and effective laxative. This is an example of a plant that can be used for opposite purposes depending upon the dosage. The German Pharmacopoeia recommends the root against constipation and for all disorders in which defecation with a soft stool is desired, e.g. anal fissures, hemorrhoids and after rectal operations. It also recommends a small dose for stomach and bowel catarrh. Today the drug is mostly used as a laxative and is a component of many choleretic drugs (a choleretic increases the flow of bile into the intestines and is recommended in cases of liver and biliary disorders that often cause constipation). The active glycosides are hydrolyzed in the gut into their aglycones at least in part by the action of bacterial enzymes; by influencing the water and electrolyte transport in the colon, these aglycones are responsible for the laxative action. In China, Rheum officinale (considered interchangeable with R. palmatum by most authors) is also used against toothaches, and is said to improve bleeding ulcers up to 90% within a few days, based on a study with 312 people. Emodin at different concentrations has many therapeutic benefits including: anti-inflammatory at 15mg/kg; antiseptic; antispasmodic; antiulcer, cathartic; vasorelaxant and viricidal. Anthraquinones are also cytotoxic and stimulate cellular regeneration, detoxification and cleansing.
Turkish rhubarb root contains: 3-12% anthraquinones including 60-80% chrysophanol, emodin, aloe-emodin, rhein, physcionin, citreorosein, chrysophanol 1, emodin1, aloe-emodin 8-glucoside; 10-25% dianthraquinones: sennosides A, B, C, D, E & F; naphtalins, 1% stilbenes; 5-10% tannins; and 2-3% flavonoids including rutin and several polyphenols.
Unless otherwise prescribed: The finely chopped or powdered root, or powdered dry extract is used for making an infusion or decoction. Hot water (approximately 150ml) is poured over approximately one half to one flat teaspoonful of finely chopped Turkish rhubarb root and after 10-15 minutes passed through a strainer. For constipation, a cup of the freshly prepared infusion is drunk in the morning and/or at night before going to bed. For stomach and bowel catarrh, a tablespoonful of the infusion is taken several times. The average daily dosage as a laxative contains 30-120mg hydroxyanthracene derivatives corresponding to 1.2-4.8g of drug (powdered root). The average daily dosage as a bitter tea used as an astringent, stomachic and against ulcers contains 3-9mg of hydroxyanthracene derivatives corresponding to 0.12-0.36g of powdered root. For soothing a toothache, Chinese herbalists fry the root then steep it in alcohol to create a tincture and then apply this on the affected tooth with a cotton ball for five minutes. (Rhubarb root contains at least five different pain-relieving compounds, however, there are better remedies than this for toothache that should be used first if available).
In large dosages, the anthraquinones-type laxative compounds may increase the action of other laxatives and should not be taken at the same time. With chronic use/abuse, a potassium deficiency may develop that may potentiate the effects of cardiotonic glycosides.
Laxatives are contraindicated in the case of impacted bowel (serious bowel obstruction) or ileus of any origin (danger of intestinal rupture). Rhubarb root should also not be taken during pregnancy due to reflex stimulation of the uterus or during lactation because a proportion of the active aglycones reach the mother’s milk.
If used as prescribed, none known. Like all other anthracene-glycoside laxatives, rhubarb root should not be used continuously over a prolonged period as this disturbs the water and electrolyte balance of the body. An increased loss of water and salts, especially potassium salts, may occur and ultimately a dangerous electrolyte imbalance can develop that can be fatal if it persists. Large doses of Turkish rhubarb root tea may cause gastric disturbance, nausea and diarrhea due to anthraquinones-type laxative compounds.
Dreessen M, Eyssen H, and Lemli J. 1981. The metabolism of sennosides A and B by the intestinal microflora: in vitro and in vivo studies on rat and mouse. J Pharm Pharmacol 33: 678-681.
Driscoll JS, Hazard JrHB, Wood Jr, and Goldin A. 1974. Structure-antitumor activity relationships among quinone derivatives. Cancer Chem Rep, Part 2 4: 1-27.
Duke JA. 1985. Turkish rhubarb. In Handbook of Medicinal Herbs. CRC Press, Boca Raton, FL, p. 404; Emodin. p. 572.
Wichtl M (ed). 1994. Rhei radix – Turkish rhubarb root (English translation by Norman Grainger Bisset). In Herbal Drugs and Phytopharmaceuticals. CRC Press, Stuttgart, pp. 415-418.
Yagi T, Yamauchi K, and Kuwano S. 1997. The synergistic purgative action of aloe-emodin anthrone and rhein anthrone in mice: synergism in large intestinal propulsion and water secretion. J Pharm Pharmacol 49: 22-25.