Silymarin is a poorly water-soluble flavonoid (total flavonoid) extracted from the milk thistle plant. It has been proved by experiments that silymarin has obvious protective effect on liver damage caused by various liver poisons. It is present in plasma, bile and urine in the form of bound silymarin, and have good curative effect on acute and chronic hepatitis, cirrhosis and metabolic toxic liver injury. Silymarin is a kind of flavonoid lignan compound extracted from the seed coat of the medicinal plant Milk Thistle.