Isolation, modification and cytotoxic evaluation of stilbenoids from Acanthopanax leucorrhizus

Twenty natural stilbenoids (1-20), including seven new stilbenoids (2, 4-7, 19, 20) and thirteen known stilbenoids (1, 3, 8-18), were isolated from the stem barks of Acanthopanax leucorrhizus, and six modified stilbenoid derivatives (1a, 2a, 4a, 4b, 7a and 17a) were obtained via methylation, demethylation and isopentenylation of the corresponding isolates (1, 2, 4, 7 and 17). These stilbenoids were structurally characterized by comprehensive analysis of their spectroscopic data and comparison with literature information, and evaluated for their cytotoxic activities against three human tumor cell lines (leukemia HL-60, hepatoma SMMC-7721 and breast carcinoma MCF-7) in vitro by MTT assay. The results showed that compounds 1a, 4a and 4b showed potent selective cytotoxicity against SMMC-7721 (IC₅₀=10.16±1.95μM and 9.76±1.32μM) and MCF-7 (IC₅₀=10.72±2.78μM) cell lines. The cytotoxic evaluation of these structurally modified stilbenoid derivatives have led to the establishment of a structure-activity relationship.