Chemical Constituents from the Roots and Rhizomes of Asarum heterotropoides var. mandshuricum and the In Vitro Anti-Inflammatory Activity

Anti-inflammatory compounds were investigated from the ethanol extract of the roots and rhizomes of Asarum heterotropoides var. mandshuricum, a traditional Chinese medicine called Xixin and used for pain and inflammatory. Nine new compounds were isolated, including six new lignans, neoasarinin A–C (1–3), neoasarininoside A and B (4 and 5), and asarinin B (7), and one new monoterpene, asarincin A (8), two new amides, asaramid II and III (10 and 11), and one new natural monoterpene, asaricin B (9), along with 37 known compounds (6, 12–47). Their structures and absolute configurations were elucidated on the basis of spectroscopic methods and chemical analyses. This is the first report of the absolute configuration of asarinin A (6). The 8-O-4′ neolignans (1–5) were reported in the genus Asarum for the first time. The 15 compounds 17, 19, 22–25, 28, 31, 36, 40, 42, 43, 45–47 were isolated from the genus Asarum, and compounds 16, 32, 33, 37 and 39 were isolated from A. heterotropoides var. mandshuricum for the first time. Thirty-seven of the isolates were evaluated for anti-inflammatory activity against the release of β-glucuronidase in polymorphonuclear leukocytes (PMNs) induced by the platelet-activating factor (PAF), and compounds 1, 4, 7, 8, 14, 17–19, 22, 24, 25, 29, 30, 32, 33, 40–43, 45, and 46 showed potent anti-inflammatory activities in vitro, with 27.9%–72.6% inhibitions at 10−5 mol/L. The results of anti-inflammatory assay suggested that lignans obtained from the CHCl3 extract might be the main active components of Xixin.