Two new bioactive lignans from leaves and twigs of Cleistanthus concinnus Croizat

Two new lignans (1–2), along with five known compounds (3-7) with different structures were isolated from leaves and twigs of Cleistanthus concinnus Croizat. The new lignans were elucidated as (7′R,8′S)-3,3′,5′-trimethoxy-4,4′-dihydroxy-7-en-7′,9- epoxy-8,8′-lignan (1) and (7′R,8′S)-3,3′-dimethoxy-4,4′-dihydroxy-7-en-7′,9-epoxy-8, 8′-lignan (2) by comprehensive spectroscopic analysis including 1D and 2D NMR as well as HREIMS and comparing their NMR data with known compounds in the literature. Among these isolated compounds, compound 1, 2, 3, and 6 were tested for anti- inflammatory effects by inhibiting NO production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Compound 1, 2, and 6 exhibit NO inhibitory activity.