Biosynthesis and Regulation of Antioxidant Flavonolignans in Milk Thistle

Mature fruits (achenes) of milk thistle (Silybum marianum (L.) Gaertner, Asteraceae) accumulate high amounts of silymarin, a complex mixture of bioactive antioxidant flavonolignans deriving from taxifolin. Their biological activities in relation with human health promotion and disease prevention have been well described. The conditions of their biosynthesis in planta, however, have long been elusive and thus tend to be a limiting factor for their future applications. Significant advances in understanding their biosynthesis and regulation have been made over the last decade and are outlined in the current chapter.