The objectives of the doctoral dissertation "Effect of C19H16ClN3O2S on the expression of glycosphingolipids, cytotoxicity, apoptosis and metabolomics in the ovarian adenocarcinoma cell lines" are to investigate the potential of the antitumor compound on the ovarian cell lines SK-OV-3 and OVCAR-3 with a focus on cytotoxicity, apoptosis, percentage of cancer stem cells (CSC), glycosphingolipid (GSL) expression and metabolomics. The studied compound, 3-amino-N-(3-chloro-2-methylphenyl)-5-oxo-5,6,7,8-tetrahydrothieno[2,3-b]quinoline-2-carboxamide (Compound 1), is artificially synthesized and we used it to evaluate its potential inhibitory effects on ovarian cancer cell lines. The cytotoxicity of the compound was performed using the MTT assay which showed that Compound 1 was significantly toxic to both cell lines, with IC50 values of 5.5 μM for SK-OV-3 and 5.0 μM for OVCAR-3 cell lines when exposed to the compound in duration of 48 hours. Furthermore, Compound 1 leads to the induction of apoptosis, with a statistically significantly higher proportion of both early and late apoptotic cells observed in both lines after treatment. In addition, CSCs show that their proportion significantly decreased after treatment with Compound 1, thus indicating the important role of Compound 1 in tumor recurrence and treatment failure. Changes in the expression of GSLs were noted in both CSCs and non-CSCs. In the SK-OV-3 cell line, seven of the eight observed GSLs showed a decrease in CSCs, while non-CSCs showed increased GSL expression. The OVCAR-3 cell line showed similar trends, although the changes were less statistically significant. Metabolic profiling performed with GC-MS on ovarian cancer cell lines before and after treatment with Compound 1 found specific metabolic changes only in treated cells. Metabolomics revealed 20 metabolites in OVCAR-3 and 21 in SK-OV-3 cell lines. OVCAR-3 cells showed more significant changes, with eight metabolites significantly different in treated versus untreated cells, while only two metabolites showed significant differences in the SK-OV-3 line. The results show that Compound 1 not only induces significant cell death, but also affects several key signaling pathways responsible for the regulation of GSL expression in ovarian cancer cell lines. Emphasizing its ability to induce apoptosis, reduce the population of CSCs, and alter the metabolic pathways of tumor cells, the potential of Compound 1 as a therapeutic agent against ovarian cancer is exceptional.