Studies on the constituents of Hibiscus syriacus (I)

Hibiscus syriacus L. (Malvaceae) is widely distributed over Korea, China, India and Siberia. The dried flower of H. syriacus is used as a folk medicine for curing of hematochezia, dysentery, obstruction due to wind- phlegm regurgitation, and vomiting of food, and the dried root bark is used as antipyretic, anthelmintic, and antifungal agents. From a chloroform extract of root bark of this plant, compounds I, II, and III were isolated and the structures were elucidated by various spectroscopic analyses. These compounds were identified as syringaresinol, E-N-feruloyltyramine, and Z-N- feruloyltyramine, respectively and were isolated from this plant for the first time. Compounds II and III exhibited lipid peroxidation inhibitory activities with IC⁵⁰ of 15.5 and 28.6 μg/ml, respectively.