Pharmaceutical Applications

R. palmatum belongs to family Polygonaceae and is a native plant of China, Tibet, and Mongolia. Also called as rhubarb or Da Huang, it is one of the few herbs which are still being used for its immense therapeutic benefits. The root of the plant is frequently used in traditional Chinese medicine for gastrointestinal and renal disorders as well as hyperlipidemia. It is also a very good astringent and laxative and has antibacterial, antiviral, and antifungal properties. The most active components in Da Huang roots are anthraquinones, emodin, aloe-emodin, and rhein (Wang et al. 2008). It also contains flavonoids, phenolic acids, and tannins. Emodin, aloe-emodin, and rhein, the major active compounds of the herb, have been described to have antitumor properties. They have caused cell cycle arrest and apoptosis in many human cancer cell lines, including human tongue cancer SCC-4 cells. Aloe-emodin, the root and rhizome anthraquinone of R. palmatum, has been shown to inhibit human oral cancer KB cells by causing cell cycle arrest at G2/M phase in a dosedependent manner (Xiao et al. 2007). Chen and his co-workers have demonstrated that these bioactive compounds inhibit migration and invasion of SCC-4 cells via preventing gene expression of matrix metalloproteinase-9 (MMP-9), an important enzyme for tumor migration (Chen et al. 2010a). The molecules have also been shown to induce DNA damage and inhibition of DNA repair gene expression in SCC-4 human tongue cancer cells (Chen et al. 2010b).