Separation procedures applicable to lignan analysis.

Lignans are a class of secondary plant metabolites produced by oxidative dimerization of two phenylpropanoid units. They have been found in many plants of Oriental medicine. In consequence of recent knowledge it is held that lignans are responsible for the key pharmacological activities of these plants. This review surveys the chromatographic, electromigration and hyphenated methods so far applied for the separation of lignans in Oriental plants used in phytotherapy as well as for the analyses of these lignans and their metabolites in biological matrices and food samples. In addition, the sample clean-up procedures--solvent extractions and supercritical fluid extractions--are also included.