Chemical composition and selective cytotoxic activity of Euphorbia leucocephala essential oil

This study investigates the chemical composition and cytotoxic activity of the essential oil from Euphorbia leucocephala. 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 E. leucocephala essential oil as a source of selective anticancer agents.