Chemical composition and cytotoxic activities of <i>Rhodomyrtus tomentosa</i> (Aiton) Hassk. essential oil extracted by microwave-assisted hydrodistillation

<i>Rhodomyrtus tomentosa</i> (Aiton) Hassk. has been widely used in traditional medicine; however, limited attention has been paid to its essential oil's chemical profile and biological activities. In this study, essential oil was extracted from fresh leaves of <i>R. tomentosa</i> using microwave-assisted hydrodistillation. The oil yield was 0.72% (<i>v/w</i>), and gas chromatography-mass spectrometry (GC-MS) analysis revealed a composition highly enriched in monoterpene hydrocarbons, with α-pinene comprising approximately 79.73% of the total content. Minor constituents included <i>β</i>-caryophyllene, <i>α</i>-terpineol, and d-limonene. The cytotoxic potential of <i>R. tomentosa</i> essential oil (RtEO) was evaluated against three human cancer cell lines: breast adenocarcinoma (MCF-7), epidermoid carcinoma (KB), and lung carcinoma (A549) using the WST-1 assay. RtEO exhibited significant dose-dependent cytotoxicity, with IC₅₀ values of 14.30 <i>µ</i>g/mL, 19.91 <i>µ</i>g/mL, and 20.63 <i>µ</i>g/mL, respectively. These results suggest that RtEO possesses promising broad-spectrum anticancer activity, warranting further investigation as a potential natural source of bioactive compounds for cancer therapy.