Bioactive sesquiterpenoids from the roots of Artabotrys hexapetalus

Abstract

Seven pairs of sesquiterpenes (1a/1b–7a/7b), a new peroxy-bridge sesquiterpene (8), and a new peroxy-bridge norsesquiterpene (9), together with five known compounds, were isolated from the roots of Artabotrys hexapetalus. Their structures with absolute configurations were elucidated based on extensive spectroscopic analysis, especially the modified Mosher's method, and electronic circular dichroism (ECD) analyses. Notably, the resolutions of seven pairs of stereoisomers (1a/1b–7a/7b) were achieved by chiral HPLC. All the compounds were evaluated for their antiviral and cytotoxic activities. Compounds 1a, 1b, 12a–12d, and 14 showed moderate antiviral activity against Coxsackie virus B3 with IC50 values of 6.41–33.33 μM and SI values > 2.1, whereas compounds 5b, 8, and 12a exhibited weak activity against influenza virus A H3N2 with IC50 values ranging from 19.24 to 33.33 μM and SI values > 3.0. Compound 12c exhibited selective cytotoxicity against A2780 cell line with an IC50 value of 8.30 μM, while compound 12d showed potent cytotoxicity against HCT-116, HepG2, and A2780 cell lines with IC50 values of 3.24, 3.23, and 3.14 μM, respectively.