Abstract

Crude extract of milk thistle (Silbum marianum) seeds have been used for centuries as an herbal treatment for liver diseases. The seeds of milk thistle are usually pretreated with organic solvent to defat the seed prior to flavonolignan extraction. The current work aims to obtain maximum yield of phenolics-rich silymarin extract. The tested parameters were seed defatting, temperature, extraction time, solvent type and solvent concentration. The used solvents were water, ethanol, methanol, acetone, acetonitrile and ethylacetate. Comparison of all experiments under the chosen conditions showed that extraction for 3 h of defatted seeds with ethanol (95%) at 50°C proved to have the highest yield of phenolics-rich silymarin extract. With all solvents except water, deffatting leads to higher phenolics-yield. In addition, when using the whole seeds the maximum phenolics yield was obtained at the solvent boiling point.

Key words: Polyphenol, solvent concentration, herbal medicine, ethanol, methanol.