ANALYSIS OF SILYMARIN COMPONENTS IN THE SEED EXTRACTS OF SOME MILK THISTLE ECOTYPES FROM IRAN BY HPLC

Silymarin is a mixture of flavonolignans from the seeds of Silybum marianum (L.) Gaertner, containing silybinin, isosilybinin, silydianin, silychristin and the dihydroflavonol of taxifolin. Flavonolignan components are largely responsible for the medical benefits attributed to silymarin. The aim of this research was to study the variations in composition and content of flavonolignans of silymarin samples from seeds of some native milk thistle ecotypes of Iran, along with a foreign cultivar. Silymarin was extracted by a two-step (defatting and extraction) process using n-hexane, ethyl acetate and methanol in a Soxhlet extraction from the seeds. The content and composition of the main components in different silymarin samples were analyzed by the HPLC method against external standard of silybinin. The HPLC method allowed a good separation between flavonoid components, especially diastereomers of silybinin A and B. The qualitative and quantitative data obtained by HPLC clearly showed that silymarin samples were the same with respect to their flavonolignan composition and they were mainly different based on the content of their components. Silymarin samples from native ecotypes had lower quantities of silybinin as compared to that of silymarin from cultivated ones, but they had higher amounts of other compounds such as silychristin, silydianin and isosilybinin.