Kadsindutalignans A-C: three new dibenzocyclooctadiene lignans from Kasura induta ACSm. 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- (H-1 NMR and C-13 NMR), 2D-NMR (HSQC, HMBC, H-1-H-1 COSY and NOESY), and experimental circular dichroism (CD) spectra. All the isolates inhibited NO production in LPS-activated RAW264.7 cells with IC50 values in the range from 5.67 +/- 0.54 mu M to 38.19 +/- 2.03 mu M, compared to that of the positive control of N-G-monomethyl-L-arginine acetate (L-NMMA) with an IC50 value of 8.90 +/- 0.48 mu M. Interestingly, the new compound 2 showed potential inhibition of NO production with an IC50 value of 5.67 +/- 0.54 mu M, which was higher than that of the positive control.