Kadsindutalignans A-C: three new dibenzocyclooctadiene lignans from Kasura induta A.C.Sm. and their nitric oxide production inhibitory activities.

Phytochemical study on the methanol extract of the stems and leaves of Kadsura induta led to the isolation of six dibenzocyclooctadiene lignans, including three new compounds named kadsindutalignans A-C ( 1-3 ), and three known ones, heteroclitalignan B ( 4 ), kadsuphilin C ( 5 ) and kadsulignan E ( 6 ). Their structures were elucidated based on extensive spectroscopic analyses, including HRESIMS, 1D- ( 1 H NMR and 13 C NMR), 2D-NMR (HSQC, HMBC, 1 H- 1 H COSY and NOESY), and experimental circular dichroism (CD) spectra. All the isolates inhibited NO production in LPS-activated RAW264.7 cells with IC 50 values in the range from 5.67 ± 0.54 µM to 38.19 ± 2.03 µM, compared to that of the positive control of N G -monomethyl-L-arginine acetate (L-NMMA) with an IC 50 value of 8.90 ± 0.48 µM. Interestingly, the new compound 2 showed potential inhibition of NO production with an IC 50 value of 5.67 ± 0.54 µM, which was higher than that of the positive control.