Review of Rhubarbs: Chemistry and Pharmacology

Rhubarb is a perennial herb belonging to the genus Rheum L. (Polygonaceae). Rhei Radix et Rhizoma (rhubarb roots and rhizomes) is one of the most popular Chinese materia medica and has been widely used for strong laxative function. About 200 compounds with six different types of skeletons (anthraquinone, anthrone, stilbene, flavonoids, acylglucoside, and pyrone) have so far been isolated from eighteen species of the genus Rheum L. These constituents showed extensive pharmacological activities including cathartic, diuretic, anticancer, hepatoprotective, anti-inflammatory, and analgesic effects, as well as toxicological effects. Chemical fingerprint, LC-MS, and other analytical techniques have been used for the quality control of rhubarb. This comprehensive review summarizes the researches into the isolation, pharmacological activities, and phytochemical analysis reported since investigations began in the late 1940s. In addition, pharmacokinetic studies and clinical application of rhubarb are also discussed in present paper.