Carlina acaulis is highly valued in the traditional medicine of many European countries for its diuretic, cholagogue, anthelmintic, laxative, and emetic properties. Moreover, practitioners of natural medicine indicate that it has anti-cancer potential. However, its phytochemistry is still little known. In the present study, the polyphenolic composition of the plant was investigated using ultra-high-performance liquid chromatography coupled with a high-resolution/quadrupole time-of-flight mass spectrometer (UHPLC-HR/QTOF/MS-PDA). The fractionation of the extract was carried out using liquid-liquid extraction and preparative chromatography techniques. Cytotoxicity was assessed based on neutral red and MTT assays. The obtained data showed that the species is rich in chlorogenic acids and C-glycosides of luteolin and apigenin. The total amount of chlorogenic acids was 12.6 mg/g. Among flavonoids, kaempferol dihexosidipentose and schaftoside were the most abundant, reaching approximately 3 mg/g, followed by isoorientin, vitexin-2-O-rhamnoside, and vicenin II, each with a content of approximately 2 mg/g. Furthermore, the cytotoxic potential of the plant against human colorectal adenocarcinoma (HT29) and human cervical cancer (HeLa) cells was investigated using the normal epithelial colon cell line (CCD 841CoTr) as a reference. It has been demonstrated that the ethyl acetate fraction was the most abundant in polyphenolic compounds and had the most promising anticancer activity. Further fractionation allowed for the obtaining of some subfractions that differed in phytochemical composition. The subfractions containing polyphenolic acids and flavonoids were characterized by low cytotoxicity against cancer and normal cell lines. Meanwhile, the subfraction with fatty acids was active and decreased the viability of HeLa and HT29 with minimal negative effects on CCD 841CoTr. The effect was probably linked to traumatic acid, which was present in the fraction at a concentration of 147 mg/g of dried weight. The research demonstrated the significant potential of C. acaulis as a plant with promising attributes, thus justifying further exploration of its biological activity.
Keywords: anticancer; pinellic acid; polyphenols; stemless carline thistle; traumatic acid.