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-kappa B 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-kappa B.