Three new iridoid glycosides isolated from the traditional herb Siphonostegia chinensis with NF-κB inhibitory activity

Abstract Siphonoids A–C ( 1 – 3 ), among which siphonoids A-B ( 1–2 ) are rare (E)-p-coumaroyl iridoids, were isolated from Siphonostegia chinensis along with ten known iridoids ( 4 – 13 ) and four lignans ( 14–17 ). The structures of the compounds were established by 1D- and 2D-NMR spectroscopy and mass spectrometry. Most of the iridoids isolated from S. chinensis were found to possess (E)-p-coumaroyl iridoid subtype skeletons. Hence, this type of iridoid could be regarded as a chemotaxonomic marker of S. chinensis . The inhibition activities for the NF-κB pathway of iridoids ( 1 – 6 ) were detected. The present results showed that compounds 1 – 2 and 4–6 processed moderate activity towards the inhibition of NF-κB.