Quinones and coumarins from Ajania salicifolia and their radical scavenging and cytotoxic activity.

1,4-Naphthoquinone (1) and a new coumarin (3) were isolated from Ajania salicifolia, together with two known compounds (2, 4). The structures and stereochemistry of new compounds were elucidated using spectroscopic methods. Two compounds exhibited potent ABTS cation radical scavenging activities with IC50 values ranging 7.97-8.44 μM. Two quinones (1, 2) exhibited moderate cytotoxic activity against the human cancer cell lines (Hela, HepG2, and K562) with IC50 values of 11.24-35.15 μM in vitro. This is the first report of naphthoquinone in the genus Ajania.