Ahrysophanol and physcion are effective anthraquinones in rhubarb,but it is difficult to separate than other anthraquinones because of resemble structure and close characters.

• 大黄酚和大黄素甲醚是大黄中有功效的蒽醌类成份,由于两者结构相似,酸性与极性相近,往往难以分离。