Two new chlorinated sesquiterpenes from Sigesbeckia orientalis

Two new chlorinated guaianane-type sesquiterpenes (named chlosigesolides A and B) together with eight known compounds were isolated from the leaves and twigs of Sigesbeckia orientalis. Their structures were determined by analysis of HR-ESI-MS, 1D- and 2D-NMR spectral data as well as comparison with the literature. Absolute configurations of new compounds were elucidated by NOESY and ECD methods. Chlosigesolide A inhibited NO production in LPS-stimulated RAW264.7 macrophages with IC50 value of 10.9 +/- 0.8 mu M. Other compounds exhibited inhibitory activity at IC50 in range of 26.5 to 49.7 mu M.

Automated summary

In this study, two new chlorinated guaianane-type sesquiterpenes were isolated from the leaves and twigs of Sigesbeckia orientalis, along with eight known compounds. The structures and configurations of these compounds were determined by various analytical techniques. One of the new compounds, chlosigesolide A, exhibited significant inhibitory activity against NO production in LPS-stimulated macrophages.