A new lignan (4,4',5'-trihydroxy-5,3'-dimethoxy-3-O-9',2-(7'R)-lignan, 1) and eight C(6)-oxygenated flavonoids (2-9), including a newly identified flavonoid (7,3',4'-trihydroxy-3,5,6-trimethoxyflavone, 2), were isolated from the inflorescence of Ambrosia artemisiifolia L. The structures of these isolates were determined using extensive spectroscopic analyses and comparison with data previously reported in the literature. The absolute configuration of compound 1 was established using electronic circular dichroism (ECD) spectrum. All the flavonoids (2-9) showed inhibitory effects on LPS-induced NO production in RAW264.7 cells, with the inhibition rate ranging from 24.51 % to 69.82 % at 50 μM. The in vitro cytotoxicity study showed that compounds 3-8 have a 60 % inhibition rate against SMMC-7721 at a concentration of 40 μM, while compounds 5 and 8 also exhibited inhibitory activity against HL-60 at 40 μM with the inhibition rate of 83.36 % and 52.01 %, respectively.
Keywords: Ambrosia artemisiifolia; C(6)-oxygenated flavonoid; NO production; cytotoxicity; lignan.
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