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

Abstract

Silymarin is a mixture of flavonolignans from the seeds of Silybum marianum (L.) Gaertner,containing silybinin, isosilybinin, silydianin, silychristin and the dihydroflavonol of taxifolin. Flavonolignancomponents are largely responsible for the medical benefits attributed to silymarin. The aim of this researchwas to study the variations in composition and content of flavonolignans of silymarin samples from seeds ofsome 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 theseeds. 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 separationbetween flavonoid components, especially diastereomers of silybinin A and B. The qualitative andquantitative 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 silymarinfrom cultivated ones, but they had higher amounts of other compounds such as silychristin, silydianin andisosilybinin.