Iso chicoric acid and extraction separation method thereof and usage in medicament

The invention discloses a new compound -iso chicoric acid, which comprises the following steps: water-extracting alcohol deposition for embrace stem gutweed vegetable; centrifuging; adding burnt lime into supernatant fluid; depositing with pH value at 9-12; centrifuging; depositing; adding into alcohol to float; adding into sulfuric acid to adjust pH value at 1-4; centrifuging; reclaiming alcohol; proceeding polyamide or macroreticular resinous column chromatography; washing; eluting with diverse density alcohol; collecting eluent of each section; condensing; disposing with acetone, acetic ester and methyl alcohol; recrystallizing repeatedly; getting the product. This invention also discloses usages of iso chicoric acid.