Sesquiterpenes from Artemisia argyi: Absolute Configurations and Biological Activities

Nine guaiane-type sesquiterpenes and one eudesmane-type one - namely argyinolides A-J (1-10) - as well as nine known analogues were isolated from the leaves of Artemisia argyi Levl. et Vant. Their structures were determined by interpretation of spectroscopic data (MS, 1D and 2D NMR). A combination of X-ray crystal diffraction, specific optical rotations, CD spectroscopy, ECD calculation, and Mosher ester methods was employed to resolve the absolute configurations of the isolated compounds. Biological investigations into their cytotoxicities and anti-inflammatory effects showed that 1, 13, 16, and 18 were remarkably cytotoxic against Bel-742 and/or A549 cells, with IC50 values of 3.3-6.0 M, whereas 7, 11-13, 16, and 18 exhibited sound inhibitory activity on LPS-stimulated NO production in BV-2 microglial cells, with IC50 values ranging from 3.2 to 8.6 M. In addition, a brief discussion on the applicability of Geissman's rule for the sesquiterpene lactones, the probable reason for the presence of chlorine-containing sesquiterpenes, and preliminary structure-activity relationships (SARs) are included.