Cytotoxic isoeleutherol of <i>Eleutherine bulbosa</i> (Mill.) Urb onion bulb from Simalungun, North Sumatera against human cancer cells

The moderate cytotoxic of isoeleutherol reported, a naphthalene-derived compound, from <i>Eleutherine bulbosa</i> bulbs collected in Simalungun, North Sumatra. The isolated compound, identified as (3S)-4-hydroxy-5-methoxy-3-methyl-3H-benzo[f][2] benzofuran-1-one, was characterised through FTIR, NMR and EIMS analyses, confirming its structural integrity and molecular formula C₁₄H₁₂O₄. Methanolic extraction of the bulb yielded the highest isoeleutherol concentration (17.35 ± 1.72 ppm), indicating that the bulb serves as the primary storage tissue. The cytotoxic evaluation revealed moderate antiproliferative activity against HeLa, A549 and MCF-7 cancer cell lines, with IC₅₀ values of 27.63 ± 2.52, 32.68 ± 1.60 and 50.13 ± 1.49 μM, respectively, showing the highest sensitivity in HeLa cells. The observed activity is attributed to the naphthoquinone-type framework. These findings provide scientific validation of <i>E. bulbosa</i>'s ethnomedicinal use and establish isoeleutherol as a potential lead compound for traditional herb medicine development.