A new sesquiterpene lactone isolated from Ainsliaea smithii and cytotoxic activity against the A549 cancer cell line

A new sesquiterpene lactone ainslialide (1) and eighteen known compounds were isolated from aq. methanolic extract of Ainsliaea smithii Mattf (Compositae). All the isolates were structurally elucidated by the analysis of spectroscopic data 1D, 2D-NMR, HR-ESI-MS and previously reported literature for the known compounds. Aq. methanolic extract and compounds (2-13) were evaluated for the cytotoxic activity against the A549 cancer cell line. Compounds 4 (epi-friedelanol), 5 (ursolic acid) and aq. methanolic extract showed activity against A549 with an IC₅₀ 0.44, 51.25 μM, and 31.86 μg/ml respectively.