Dihydroagarofuranoid sesquiterpenes, a lignan derivative, a benzenoid, and antitubercular constituents from the stem of Microtropis japonica

Four new compounds, including two new dihydroagarofuranoid sesquiterpenes, 8-benzoyloxymutangin (1) and 15-acetoxyorbiculin G (2), a new lignan derivative, 9,9'-O-di-(Z)-feruloyl-(-)-secoisolariciresinol (3), and a new benzenoid, 5'-methoxyevofolin B (4), have been isolated from the stem of Microtropis japonica, together with 20 known compounds (5-24). 3-Ethoxy-4-hydroxybenzaldehyde (5) was identified from a natural source for the first time. The structures of these new compounds were determined through analyses of physical data. 15-Acetoxyorbiculin G (2), celahin C (6), and salasol A (7) exhibit antituberculosis activities (MICs <= 39.6 mu M) against Mycobacterium tuberculosis H(37)Rv in vitro.