Bioactivity‑Guided Isolation of Cytotoxic and Antioxidant Phytochemicals from Four Cousinia Species from Stenocephala Bunge Section

Objective: In this study, chemical compositions of four Cousinia species (Cousinia davisiana [CD], Cousinia foliosa, Cousinia ramosissima, and Cousinia stenocephala [CS]) were evaluated according to their cytotoxic and antioxidant effects using bioactivity‑guided isolation. Materials and Methods: The cytotoxic effect was investigated with Sulphorhodamine B method against Colo205 (human colon carcinoma), A549 (human non-small cell lung cancer) cell lines, and antioxidant activity tested with 1,1‑diphenyl‑2‑picrylhydrazyl, 2,2’‑azino‑bis 3‑ethylbenzothiazoline‑6‑sulphonic acid scavenging tests, and β‑carotene/ linoleic acid co‑oxidation test. Purified compounds were elucidated by one‑dimensional and two‑dimensional nuclear magnetic resonance and mass spectroscopic techniques. The quantitative and qualitative determination of unpurified compounds within the extracts was carried out by liquid chromatography‑mass spectrometry/mass spectrometry. Results: CS methanol extract, dichloromethane subextract, and FR‑3 showed more cytotoxicity; isolated compound (ψ‑taraxasterol) showed no cytotoxic activity. CD methanol extract and n‑butanol subextract showed significant antioxidant activity. Conclusion: This is the first report that these phytochemical compounds were identified in Cousinia genus, and it is thought that these compounds could contribute to the chemotaxonomy of the genus.