Secondary metabolites from Achillea biserrata M.Bieb. with cytotoxic activities and their chemotaxonomic significance

Achillea biserrata M. Bieb., distributed in northern and northeastern Türkiye, was investigated for its cytotoxic metabolites through bioassay-guided isolation. The aerial parts of the plant were extracted with ethanol, and solvent–solvent partitioning yielded dichloromethane, ethyl acetate, n-butanol, and H2O subextracts. The cytotoxic activities of the crude extract and subextracts were evaluated in vitro against Colo 205, Colo 320, HeLa, MDA-MB-231, and KCR cells using the MTT assay. Among them, the dichloromethane subextract showed moderate cytotoxicity towards all tested cancer cell lines (IC50 = 26.45 ± 1.61 - 61.81 ± 1.27 μg/mL), whereas the ethyl acetate subextract exhibited weak cytotoxicity only against MDA-MB-231 cells (IC50 = 93.49 ± 2.97 μg/mL). Chromatographic separation of the dichloromethane and ethyl acetate subextracts led to the isolation of eight compounds, including three coumarins (1–3), two flavonoids (4 and 5), and three quinic acid derivatives (6–8). Structural elucidation was achieved by spectroscopic analyses and comparison with literature data. Among the isolated metabolites, scoparone (1) showed weak cytotoxicity against MCF-7 (IC50 = 158.5 ± 13.5 μM) and MDA-MB-231 (IC50 = 187 ± 13 μM) cells, while scopoletin (2) exhibited weak activity against MCF-7 (IC50 = 130 ± 29.2 μM) and moderate cytotoxicity against MDA-MB-231 cells (IC50 = 74.2 ± 12.9 μM). The chemotaxonomic relevance of these compounds within the genus and broader context of Asteraceae was also addressed.