biostudies-literatureUnknown9Tuasha N<i>Vernonia leopoldi</i> (Sch. Bip. ex Walp.) Vatke (Asteraceae) is one of the widely used anti-cancer traditional medicinal plants in Ethiopia, despite the lack of data to support its therapeutic efficacy. Here we describe the isolation of compounds from the plant and the investigation of their cytotoxicity and other bioactivities. We identified the novel sesquiterpene lactone (SL) 11ß,13-dihydrovernodalol along with the three other SLs (vernomenin, vernolepin, and 11ß,13-dihydrovernodalin) and three flavonoids (apigenin, eriodyctiol, and luteolin) isolated from this plant for the first time. The structures of all the compounds were established based on extensive analysis of nuclear magnetic resonance spectroscopic data and confirmed by high-resolution electrospray ionization mass spectroToxicology reports382-392https://www.ebi.ac.uk/biostudies/studies/S-EPMC8920872biostudies-literatureCytotoxic and other bioactivities of a novel and known sesquiterpene lactones isolated from <i>Vernonia leopoldi</i> (Sch. Bip. ex Walp.) Vatke in breast cancer cell lines.PMC8920872Gadisa EPetros BOredsson SSeifu DTuasha NEscobar ZSterner OfalseCytotoxic and other bioactivities of a novel and known sesquiterpene lactones isolated from <i>Vernonia leopoldi</i> (Sch. Bip. ex Walp.) Vatke in breast cancer cell lines.<i>Vernonia leopoldi</i> (Sch. Bip. ex Walp.) Vatke (Asteraceae) is one of the widely used anti-cancer traditional medicinal plants in Ethiopia, despite the lack of data to support its therapeutic efficacy. Here we describe the isolation of compounds from the plant and the investigation of their cytotoxicity and other bioactivities. We identified the novel sesquiterpene lactone (SL) 11ß,13-dihydrovernodalol along with the three other SLs (vernomenin, vernolepin, and 11ß,13-dihydrovernodalin) and three flavonoids (apigenin, eriodyctiol, and luteolin) isolated from this plant for the first time. The structures of all the compounds were established based on extensive analysis of nuclear magnetic resonance spectroscopic data and confirmed by high-resolution electrospray ionization mass spectro2022-01-01T00:00:00Z20222025-04-04T08:53:32.285Z2025-04-04T08:53:32.285ZS-EPMC89208723529987110.1016/j.toxrep.2022.02.011