Identification and characterization of five anti-mitotic sesquiterpene lactones from <i>Arnica cordifolia</i>

This is the first report of mitotic inhibitors from <i>Arnica cordifolia</i>. Of these five compounds, three have previously undescribed chemical structures, whereas new anti-mitotic activities have been identified for aromaticin and pulchellin-2α-<i>O</i>-isovalerate. Differences in their biological activities suggest that they possess distinct cellular targets. These findings support continued exploration of Canadian botanical species as sources of structurally diverse bioactive compounds.