Anemonin is one of two anti-mitotic activities present in extracts from the Canadian Prairie Crocus, Pulsatilla nuttalliana

We are investigating plants from the prairie ecological zone of Canada to identify natural products that inhibit mitosis in cancer cells. Extracts prepared from the Canadian prairie plant species Pulsatilla nuttalliana (Ranunculaceae) exhibited anti-mitotic activity on human cancer cell lines. P. nuttalliana-treated cells acquired a rounded morphology and were positive for phospho-histone H3, a mitotic protein. Further investigation revealed that some arrested cells displayed mitotic spindles, whereas others lacked detectable spindles. Fractionation of the extract prepared from plant stems revealed two distinct anti-mitotic activities, each of which exhibited different effects on spindle organization. Using biology-guided fractionation, we isolated one of the anti-mitotic compounds as the natural product anemonin and are the first to report its anti-mitotic activity. In addition, this is the first report of two distinct anti-mitotic activities in one botanical species and contributes to a growing body of evidence that select Canadian prairie plants have a range of anti-mitotic activities.