(±)-Acortatarinowins A-F, Norlignan, Neolignan, and Lignan Enantiomers from Acorus tatarinowii

Three pairs of new 8-O-4'-type dinorneolignan enantiomers, (±)-acortatarinowins A-C (1a/1b-3a/3b), a pair of new 8-O-4'-type (4a/4b) and a pair of rare C7-C8'-type (5a/5b) neolignan enantiomers, (±)-acortatarinowins D and E, and a pair of new furofuran-type lignan enantiomers, (±)-acortatarinowin F (6a/6b), along with two pairs of known lignan enantiomers (7a/7b and 8a/8b), were obtained from the rhizomes of Acorus tatarinowii. The separation of 1-8 by chiral HPLC using a Daicel IC column led to the isolation of eight pairs of enantiomers, 1a/1b-8a/8b, which had variable enantiomeric excess (ee) values of approximately 66, 71, 63, 60, 0, 38, 48, and 75%, respectively. The structures were elucidated by extensive spectroscopic and chemical methods, and their absolute configurations were determined by a combined analysis of single-crystal X-ray diffraction and a modified Mosher's method, assisted by experimental and calculated electronic circular dichroism data. Among them, compounds 1a, 3a, 6b, 8a, and 8b showed weak inhibitory activities against NO production in activated macrophages with IC50 values ranging from 23.3 to 38.0 μM, respectively.