Rheum undulatum is a synonym of the accepted name R. rhabarbarum. Rhubarb is a tall and sturdy perennial plant cultivated in Asia for over 5,000 years for its medicinal benefits. Chinese herbalists consider it a mainstay of their dispensary in treating gastric ulcers, chronic renal failure, and pregnancy-induced hypertension. The anti-inflammatory action is understood to be due to the concentration of tannins, which in animal studies have been shown to inhibit the metabolism of arachidonic acid to prostaglandins E2 and F2. The tannins may also be responsible for the astringent action. Research has demonstrated rhein, an anthranoid, to be effective against Bacteroides fragilis in vitro by inhibiting the enzymes in the mitochondrial electron transport system.