Rhubarb

 

RHEUM PALMATUM

COMMON NAME : Rhubarb

FAMILY  :        Polygonaceae   (Dock family)


HABIT / GROWING  :   Native to northeast Asia


PARTS USED :  rhizome of plants 6 – 10 years old. Harvested in autumn. The leaves should not be used as they are potentially toxic.


TRADITIONAL & MODERN USE:

Rhubarb has been used in medicine for more than 2000 years, reaching Europe during the Renaissance, overland via Asia Minor, hence the common name, Turkey rhubarb. It was a favourite remedy with early Persian and Arabian physicians. The rhubarb grown for cooking and eating is usually Rheum rabarbarum.


The plant is used to stimulate the appetite and improve digestion. It stimulates the intestinal muscles and increases the absorption of water and electrolytes. It is used to treat liver and gallbladder problems and to soothe inflammation and oral infections. It is laxative, astringent, and antibacterial. It is believed to move stagnant blood and also cleanse the blood by reducing excessive amounts of urea and other nitrogenous waste products. It is also believed to inhibit the chain of reactions in the body that leads to the constriction of blood vessels.


A strong decoction is effective for chronic constipation or period cramps with delayed menstruation. It can also be used externally on boils and suppurating skin diseases.


Rhubarb is best avoided in arthritic conditions and gout due to its oxalate content.


CONSTITUENTS:

·        Anthracine derivatives responsible for laxative action, mainly consisting in the dried rhizome of

         anthraquinone glycosides.

·        Flavonoids and tannins are also present. Tannins are thought to be responsible for the constipation

         sometimes induced by low doses of rhubarb. The astringency of rhubarb is due to a peculiar tannic acid

         rheo-tannic.

·        Calcium oxalate, resins including phaoretin, which is purgative.

·        Minerals.


Purgative constituents exist in the form of an unstable crystalline substance rheopurgarin. This splits into 4 glucosides : two of these yield chrysophanic acid and rheochrysidin. The other two glucosides have not yet been isolated but they appear to yield emodin and rhein.