A new norlignan from Taxodium ascendens.

A new norlignan, (2R,3R,4S,5S)-2,4-bis(4-hydroxyphenyl)-3,5-dihydroxy-tetrahydropyran (1), together with 9 known compounds were isolated from the branches and leaves of Taxodium ascendens. Their structures were mainly determined on the basis of MS, IR, 1D and 2D NMR spectral evidences. Methanol extract showed inhibitory activity on carbonic anhydrase II with an IC(50) value of 4.27 microg/ml, acetone extract and methanol extract inhibited activity of cathepsin B with IC(50) values of 2.12 and 3.71 microg/ml, respectively.