Biosynthesis of lignans and norlignans

Lignans and norlignans constitute abundant classes of phenylpropanoids. Biosynthesis of these compounds has received widespread interest, mainly because they have various clinically important biological activities. In addition, lignans and norlignans are often biosynthesized and deposited in significant amounts in the heartwood region of trees as a metabolic event of heartwood formation, probably preventing heart rot by heart-rot fungi. Furthermore, biosynthetic reactions of lignans and norlignans involve unique stereochemical properties that are of great interest in terms of bioorganic chemistry and are expected to provide a model for biomimetic chemistry and its application. We outline the recent advances in the study of lignan and norlignan biosynthesis.