Fig. 1

Schematic diagram of the chemical components in rhubarb and their role in Chinese herbal medicine-based concepts. Different chemical compounds in rhubarb correspond to various therapeutic properties. The terms in italics under the chemical structure indicate the structural characteristics of the chemical components. “Glc” in the chemical structure indicates a glycoside. “G” in the names of chemical constituents indicate glycosides. Conjugated anthraquinone represents anthraquinone glycosides with O-glycosides, where the aglycone moiety is an 8-dihydroxyanthraquinone derivative. Additional structures of conjugated anthraquinones not shown here are published elsewhere [24]