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Euphorbia seguieriana ssp. seguieriana Necker (ES) and Euphorbia cyparissias (EC) with a habitat in the Deliblato Sands were the subject of this examination. The latexes of these so far insufficiently investigated species of the Euphorbia genus are used in traditional medicine for the treatment of wounds and warts on the skin. To determine their chemical composition, non-targeted screening of the latexes’ chloroform extracts was performed using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry employing an electrospray ionization source (LC-ESI QTOF MS). The analysis of the obtained results showed that the latexes of ES and EC represent rich sources of diterpenes, tentatively identified as jatrophanes, ingenanes, tiglianes, myrsinanes, premyrsinanes, and others. Examination of the anticancer activity of the ES and EC latex extracts showed that both extracts significantly inhibited the growth of the non-small cell lung carcinoma NCI-H460 and glioblastoma U87 cell lines as well as of their corresponding multi-drug resistant (MDR) cell lines, NCI-H460/R and U87-TxR. The obtained results also revealed that the ES and EC extracts inhibited the function of P-glycoprotein (P-gp) in MDR cancer cells, whose overexpression is one of the main mechanisms underlying MDR.

Chemotaxonomy presents various challenges that need to be overcome in order to obtain valid and reliable results. Individual genetic and environmental variations can give a false picture and lead to wrong conclusions. Applying a holistic approach, based on multivariate data analysis, these challenges can be overcome. Thus, a metabolomics approach has to be optimized depending on the subject of research. We used 1H NMR-based metabolomics as a potential chemotaxonomic tool on the selected Euphorbia species growing wild in Serbia. Principal components analysis (PCA), soft independent modeling by class analogy (SIMCA) and Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) were used to analyze obtained NMR data in order to reveal chemotaxonomic biomarkers. The standard protocol for plant metabolomics was optimized aiming to extract more specific metabolites, which are characteristic for the Euphorbia genus. The obtained models were validated, which revealed that variables unique for each species were associated with certain classes of molecules according to literature data. In E. salicifolia, acacetin-7-O-glycoside (not found before in the species) was detected, and the structure of the aglycone part was solved based on 2D NMR data. In the presented paper, we have shown that metabolomics can be successfully used in Euphorbia chemotaxonomy.