Preparative method for isosilybin isolation based on enzymatic kinetic resolution of silymarin mixture

The flavonolignan isosilybin (1) is one of the silybin congeners contained in the silymarin complex, which is isolated from the seeds of the milk thistle (Silybum marianum). A number of recent studies have demonstrated that isosilybin is probably the most potent anticancer agent found in silymarin. It occurs as a mixture of two diastereoisomers, A and B. Lipase Novozym 435 was found to allow the preparative production of both optically pure isosilybin A and B in a diastereoisomeric purity of over 95%. A preparatory method based on the enzymatic resolution and other purification methods has been developed, enabling multigram amounts of both optically pure isosilybins A (1a) and B (1b) to be obtained.

► Isosilybin is probably the most potent anticancer compound in silymarin. ► Preparatory method for isolation of optically pure isosilybin A and B was developed. ► A core of the method is diastereomeric discrimination with lipase Novozym 435. ► Other pure silymarin components, such as taxifolin and silydianin can be obtained.