Chemical composition and selective cytotoxic activity of <i>Euphorbia leucocephala</i> essential oil

This study investigates the chemical composition and cytotoxic activity of the essential oil from <i>Euphorbia leucocephala</i>. Gas chromatography coupled with mass spectrometry (GC-MS) and flame ionisation detection (GC-FID) identified thirty-nine constituents, representing 96.2% of the oil. Sesquiterpenes were predominant (61.7%), with spathulenol (18.0%) as the major compound. Cytotoxicity was evaluated against three human cancer cell lines: cervical adenocarcinoma (HeLa), breast adenocarcinoma (MCF-7), and glioblastoma (U-251MG), as well as non-tumour fibroblasts (GM07492A). The essential oil exhibited IC₅₀ values of 19.6 ± 1.7 μg/mL (HeLa), 14.1 ± 1.2 μg/mL (MCF-7), 83.0 ± 2.3 μg/mL (U-251MG), and 122.7 ± 1.5 μg/mL (GM07492A), indicating low toxicity to normal cells. The selectivity index was 6.2 for HeLa, 8.7 for MCF-7, and 1.4 for U-251MG, demonstrating strong selectivity for breast and cervical cancer cells and moderate selectivity for glioblastoma. These findings suggest the potential of <i>E. leucocephala</i> essential oil as a source of selective anticancer agents.