Rheum palmatum and Rheum rhabarbarum
Rheum palmatum is commonly known as Chinese rhubarb, and Rheum rhabarbarum (also known as R. rhaponticum) is commonly referred to as wild rhubarb in the U.S. Both plants belong to the family Polygonaceae. Rhubarb has very broad leaves and elongated, often reddish, petioles (leaf stalks).
The petioles of rhubarb are edible, though the leaf blades are very toxic. The roots and rhizomes of R. palmatum and the roots of R. rhabarbarum are used in medicinal treatments. R. palmatum is considered a stronger medicinal than R. rhabarbarum. The most common medicinal use of these plants is as a laxative in humans.
- Chinese rhubarb
- Da huang
- Rhabarber -- Germany
- Garden rhubarb
- Papaz ravendi
- Rapontik -- Germany
- Rhapontic -- France
- Wild rhubarb
The roots of Rheum spp. contain anthranoid derivatives (approx. 3-4%). The predominant type of anthranoid derivatives are rhein, emodin, aloe-emedin, chrysophanol and physcion. R. rhabarbarum, unlike R. palmatum, contains rhaponticin, which has estrogen-like actions. The detection of rhaponticin is used to determine if R. palmatum has been mixed with R. rhabarbarum in supposedly pure medicinal mixtures.
Following is a list of compounds in R. palmatum and R. rhabarbarum. The compounds are divided by plant and the parts of the plant. Potential activities of some of the compounds are listed as well as the quantities of the compounds in parts per million. Rhubarb roots contain several minerals, though only a few are listed below. For further information regarding the compounds in the plant refer to USDA Phytochemical and Ethnobotanical Databases.
Rheum palmatum Root
- Aloe-emodin -- antiherpetic, antileukemic, antiseptic, antitubercular, antitumor, antiviral, bactericide, cathartic, cytotoxic, genotoxic, pesticide, purgative, termitifuge, and viricide
- Chrysophanol -- 690-3,190, antiseptic, bactericide, candidicide, cathartic, hemostat, pesticide, and purgative
- Cinnamic acid -- anesthetic, antiinflammatory, bactericide, cancer-preventive, choleretic, fungicide, herbicide, laxative, pesticide, and vermifuge
- Emodin -- antiaggregant, antifeedant, antiinflammatory, antimutagenic, antiseptic, antitumor (breast), antiulcer, antiviral, cathartic, cytotoxic, gonadotropic, immunosuppressive, pesticide, purgative, spasmolytic, styptic, vasoelaxant, viricide
- Gallic acid -- anticarcinomic, antifibrinolytic, antioxidant, antiseptic, antiviral, astringent, bacteristatic, cancer-preventive, carcinogenic, hemostat, nephrotoxic, pesticide, styptic, and xanthine-oxidase-inhibitor
- Hyperin -- antiinflammatory, antioxidant, antitussive, antiviral, capillarifortificant, capillarigenic, diuretic, hepatoprotective, hypotensive, pesticide, and viricide
- Physcion -- antiseptic, cathartic, pesticide, and purgative
- Quercitrin -- aldose-reductase-inhibitor, antiarrhythmnic, anticataract, antifeedant, antiflu,antihemorrhagic, antiinflammatory, antiviral, CNS depressant, cancer preventive, cardiotonic, choleretic, detoxicant, diuretic, dye, hepatotonic, hypotensive, paralytic, pesticide, spasmolytic, vasopressor, and viricide
- Rhein -- anticarcinomic, antiseptic, antitumor, antiviral, bactericide, candidicide, cathartic, cytotoxic, pesticide, proteinase-inhibitor, purgative, and viricide
- Rheinosides -- 12,900
- Sennoside-a -- 2,000-8,740, purgative
- Sennoside-b -- purgative
- Tannins -- 50,000-100,000, antidiarrheic, antidysenteric, antimutagenic, antinephritic, antioxidant, antiradicular, antiviral, bactericide, cancer-preventive, hepatoprotective, pesticide, psychotropic, and viricide
- Iron -- 100-180
- Magnesium -- 1,980-2,560
- Potassium -- 6,330-21,600
Rheum rhabarbarum Root
- (+)-Catechin and (+)-Catechin-5-o-glucoside
- (-)-Epicatechin and (-)-Epicatechin-3-o-gallate
- 1,2,6-tri-o-Galloyl-glucose and 1,6-di-o-Galloyl-glucose
- Emodin -- for activity refer to R. palmatum root
- Emodin methyl ether
- Chrysarone methyl ether
- Chrysophanic acid
- Chrysophanol -- for activity refer to R. palmatum root
- Chrysophanol-1-o-glucoside and chrysophanol-8-o-glucoside
- Chrysopontin, chrysorhapontin, and desoxyrhaponticin
- Ferulic acid
- Fallic acid -- for activity refer to R. palmatum root
- Gallic acid-3-o-(6'-o-galloyl)-glucoside and gallic acid-4-o-(6'-o-galloyl)-glucoside
- Lindleyin -- analgesic, antiarthritic, and antiinflammatory
- Methyl chrysophanic acid
- Physcion -- for activity refer to R. palmatum root
- Rhapontic acid
- Rhaponticin -- estrogenic, 14,200
- Rhein -- for activity refer to R. palmatum root
- Rheinosides -- 12,900
- Sennoside-a and sennoside-b -- for activity refer to R. palmatum root
- Sinapic acid -- cancer preventive
- alpha-Tocopherol -- 2-48
- Arsenic -- 0.01
- Caffeic acid
- Calcium -- 600-18,462
- Fumaric acid
- Gallic acid -- 53
- Oxalic acid -- 4,400-13,360
- Sinapic acid
- Vanillic acid
- alpha-Tocopherol -- 1,197-1,238
- Anthrones -- 10,000-15,000
- Calcium oxalate
- Dihydroxyglutamic acid
- Oxalic acid -- 3,000-11,000
- Rutin -- 6,000
The leaf blades of R. rhabarbarum are very toxic. They contain high levels of oxalic acid which can interact with blood calcium. Precipitation of calcium oxalate in the renal tubules can lead to renal failure. Symptoms of oxalate poisoning in humans include: nausea, vomiting, abdominal pain, anuria, and hemorrhages. In ruminants, oxalic acid can be degraded by rumen bacteria. The tolerance of ruminants to oxalate can be increased by gradually increasing the amount of oxalate in the diet. In general, however, oxalate is considered toxic to ruminants.
The active compounds (those that provide the laxative effect) in these plants also can cause side effects. Chronic consumption of anthranoid derivatives can turn urine a yellow or red color. Chronic use may also cause liver damage. During normal (non-chronic) use, anthranoid derivative laxatives cause increased losses of body water and electrolytes. Potassium loss may be responsible for symptoms such as a decrease in muscle activity and cardiac arrhythmia.
Many anthranoid derivatives have been shown in in vitro tests to be mutagenic. Positive results of mutagenicity have been obtained with chrysophanol, aloe-emodin, emodin, and chrysarobin in Salmonella/microsome assays. Tests with rhein were negative. There is some indication that chronic use of anthranoid derivative laxatives could be carcinogenic.
While Rheum spp. have definite laxative properties when used to treat human ailments, no scientific studies could be found proving its effectiveness in the treatment of livestock. In livestock, it is used as a treatment for diarrhea, chronic constipation, gastritis, anemia, nervousness, and lack of appetite. According to one source, the dose for livestock should be very small (1-2 roots, finely sliced). Also, some medicinal plant sources for humans and livestock recommend purchasing the powdered root versus trying to grow the plant and prepare the treatment at home.
Some Uses in Humans:
- Astringent -- China and U.S.
- Constipation -- China and U.S.
- Stomach (cancer) -- China and Japan
- Tonic -- China
- Laxative -- France and Turkey
- Astringent -- Turkey
- Depurative -- Turkey
- Stomachic -- Turkey
- Tonic -- Turkey
- de Bairacli Levy, Juliette. 1988. The Complete Herbal Handbook for Farm and Stable. Faber and Faber: Boston.
- Beckstrom-Sternberg, Stephen M., James A. Duke, and K.K. Wain. "The Ethnobotany Database." http://probe.nalusda.gov:8300/cgi-bin/browse/ethnobotdb. (ACEDB version 4.3 -data version July 1994).
- Beckstrom-Sternberg, Stephen M., and James A. Duke. "The Phytochemical Database." http://probe.nalusda.gov:8300/cgi-bin/browse/phytochemdb. (ACEDB version 4.3 - data version July 1994).
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