Inhibition of DNA Topoisomerases I and II and Cytotoxicity by Lignans from Saururus Chinensis.

Thirteen lignans, erythro -austrobailignan-6 ( 1 ), meso -dihydroguaiaretic acid ( 2 ), sauchinone ( 3 ), 1′- epi -sauchinone ( 4 ), saucerneol D ( 5 ), manassantin B ( 6 ), manassantin A ( 7 ), nectandrin B ( 8 ), machilin D ( 9 ), saucerneol F ( 10 ), saucerneol G ( 11 ), saucerneol H ( 12 ) and saucerneol I ( 13 ), were isolated from the ethyl acetate extract of the roots of Saururus chinensis . Among these compounds, 5 showed potent inhibitory activities against DNA topoisomerase I and II, and 5, 6, 7 and 10 showed mild cytotoxicities against HT-29 (IC 50 values; 13, 12, 11, and 10 µM, respectively) and HepG2 cell lines (IC 50 values; 16, 11, 12, and 11 µM, respectively).