The Chuanxiong plant and the chemical structures of its major extract constituents. (a) Schematic diagram of crude Rhizoma Chuanxiong herb (drawn by Wang Lisheng). (b) The chemical structures of the major Rhizoma Chuanxiong constituents, tetramethylpyrazine and ferulic acid. (c) The chemical structure of tetramethylpyrazine hydrochloride. (d) The cover of the first academic monograph on tetramethylpyrazine published in China: chemistry, pharmacology, and clinical application of tetramethylpyrazine, edited by Chen Keji.