Preparatory separation of the silymarin flavonolignans by Sephadex LH-20 gel

• Silymarin polyphenols are separable with Sephadex LH-20 gel filtration.
• Separation of isobaric polyphenols with high recovery rate (96%) was achieved.
• Flavonolignans silychristin, silydianin and silybin were isolated.
• Silychristin was obtained as diastereomeric mixture.
• Here, we exemplified exclusion chromatography potential in polyphenol separation.

Silymarin, a crude extract of the seeds of Silybum marianum L. Gaertn., is widely used as an ingredient of nutraceuticals and functional food and also as therapeutics against mild liver afflictions. Most of the beneficial effects of silymarin have traditionally been ascribed to its major component — silybin. The influence of several minor constituents of the crude extract was often neglected, mostly due to their difficult isolation. In this work, we report on the development of a novel separation method using Sephadex LH-20 chromatography employing methanol as a mobile phase. Using this procedure, we were even able to separate polyphenols of identical molecular weight (isobaric), yielding ca 200 to 500 mg of the particular rare flavonolignans such as silydianin and silychristin out of a 4 g silymarin mixture within one day.