Chamaejasmins, cytotoxic guaiane sesquiterpenes from the root of Stellera chamaejasme L.

Four new guaiane-type sesquiterpenes, chamaejasmins A-D (1-4), were isolated from the root of Stellera camaejasme L. collected in Nepal, together with two known terpenes, stelleraguaianone B (5) and 1α,7α,10αH-guaia-4,11-dien-3-one (6). The structures of 1-4 including their absolute configurations were determined by extensive 2D NMR analyses, mass spectroscopy, and TDDFT calculations of their 13C chemical shifts and ECD spectra. Chamaejasmin A (1) showed cytotoxicity against HeLa cells with an IC50 value of 6.3 μM.