New anti-HBV sesquiterpene glycosides and amino acid–sesquiterpene conjugates from the roots of Saussurea lappa

Sesquiterpenes are modified triterpenes widely distributed in many plants and show potential biological activities. As part of an ongoing effort to search for comprehensive anti-HBV sesquiterpenes from herbs, herein we reported six new sesquiterpenes, saussunosids A-E (1, 3−6) and saussureamine F (2), as well as three known sesquiterpenoids (7−9) and one known acetylenic glucosides (10), from the roots of S. lappa collected in Lijiang county, Yunnan province, China. Saussunosids A-E (1, 3−6) were new sesquiterpene glycosides and saussureamine F (2) was a new amino acid–sesquiterpene conjugate. Their structures were determined by extensive analyses of NMR, HR-ESI-MS and acid hydrolysis. The absolute configuration of the new compounds (1−6) was established by coupling constants and ROESY correlations, as well as comparisons of the calculated ECD with the experimental ECD spectrum. Anti-hepatitis B virus (anti-HBV) activity evaluation suggested that compounds 2 and 7 showed inhibition of HBsAg with the value of 66.50% and 72.97%, respectively, while having no effects on HBeAg at 30 μM. Moreover, compounds 2 and 7 showed significant cytotoxicity with CC50 values of 14.85 ± 4.95 and 11.70 ± 2.04 μM against human hepatic cancer (HepG2), respectively.