Artanomadimers A-F: six new dimeric guaianolides from Artemisia anomala

A novel dimeric guaianolide with an unprecedented skeleton, named artanomadimer A (1), and five new analogues, artanomadimers B-F (2-6), were isolated from the aerial parts of Artemisia anomala. Their structures and stereochemistry were elucidated by extensive spectroscopic methods, and the absolute stereochemistry of compound 4 was confirmed by X-ray crystallographic analysis. Artanomadimer A (1) is probably formed through a Diels-Alder reaction with the new carbon carbon bond formation of C-11/C-2' and C-13/C-5' based on its structure. A cytotoxic evaluation showed that compounds 1 and 6 exhibited significant inhibitory effects against the cell growth of BGC-823 tumor cell lines with IC50 values of 2.71 and 6.25 mu M, respectively. (C) 2012 Elsevier Ltd. All rights reserved.