Secondary Metabolites of Ainsliaea fragrans and Their Cytotoxic Activity

Phytochemical investigation of Ainsliaea fragrans led to the isolation of two new compounds, a coumarin derivative ainslfragrsin A (1) and a sesquiterpenoid ainslfragrsin B (2), along with seven known compounds (3-9). Their structures were elucidated by comprehensive spectroscopic analyses (MS, IR, UV, and NMR) and comparison with data reported in the literature. The absolute configurations of compounds 1-2 were assigned by comparing the experimental and calculated electronic circular dichroism (ECD) spectra. Structurally, compound 1 was a rare coumarin derivative, featuring a phenylethane unit connected to the coumarin scaffold via a C─C bridge at C-8. All the isolated compounds exhibited cytotoxic activities against the human lung cancer cell line A549 in the MTT assay, and compounds 1-2 and 4-6 exhibited moderate inhibitory activity with IC₅₀ values ranging from 38.7 to 65.1 µM.