Rheum rhaponticum and Rheum rhabarbarum: a review of phytochemistry, biological activities and therapeutic potential

The Rheum genus (Polygonaceae) covers about 60 species of rhubarbs, including specimens with a long ethnomedicinal history in Asia, Europe and other regions of the world. The work reviews available literature (until March, 2020) on phytochemical profile, ethnomedicinal recommendations, biological activities, pharmacological uses and future prospects for therapeutic applications of Rheum rhabarbarum L. (garden rhubarb) and Rheum rhaponticum L. (rhapontic rhubarb). Although the above species are well-known vegetables, scientific interest in these plants is a relatively new issue; most of evidence of their biological activities and therapeutic potential derives from the last 15 years. Rhubarbs contain numerous bioactive substances, belonging to diverse groups of phytochemicals, e.g. stilbenes, anthraquinones and flavonoids. The registered special extract of R. rhaponticum (ERr731®) is administered to alleviate the menopause-related complaints. Furthermore, both ethnomedicinal surveys and recent studies on bioactive substances from rhubarbs indicate that these plants may have significantly broader range of beneficial effects such as antioxidant, anti-inflammatory, antimicrobial and cardioprotective activities.