Exploring the Chemical Profile and Biological Activities of Eryngium dichotomum: UHPLC–MS/NMR Characterization, and In Vitro Antioxidant Activity Along with the Antitumor Effect of Falcarinol

Qualitative liquid chromatography–mass spectrometry (UHPLC–MS) and NMR analysis of the diethyl ether extract of the aerial part of Eryngium dichotomum plant belonging to the Apiaceae family led to the putative identification of phenolic acids, flavonoid glycosides, triterpenoid saponins, fatty acids, and oxylipins. The tentative identification of several secondary metabolites by UHPLC–MS analysis was further confirmed by compound isolation and comprehensive spectroscopic characterization using 2D NMR and mass spectrometry, leading to the elucidation of seven compounds, a mixture of two hydroxy fatty acids, namely (Z,E)-13-hydroxyoctadeca-9,11-dienoic acid (1) and (E)-13-hydroxyoctadec-11-enoic acid (2); two C17 polyacetylenes, (E)-heptadeca-1,10-dien-4,6-diyne-3,8,9-triol (3), and falcarinol ((Z)-1,9-heptadeca-1,9-dien-4,6-diyn-3-ol) (4); glycerol monopalmitate (5) and two flavonoid glycosides, kaempferol 3-O-β-D-glucopyranosyl-(1 → 6)-O-β-D-galactopyranoside (6), and quercetin 3-O-β-D-glucopyranosyl-(1 → 6)-O-β-D-galactopyranoside (7). Furthermore, the antioxidant activity of the n-butanol and the diethyl ether extracts of the species were evaluated using the DPPH, FRAP, and ABTS assays. In addition, the anticancer activity of the major falcarinol-type polyacetylene was assessed against A375 human melanoma cells.