Evaluation of the anti-cancer potential of extracts of the Australian native plant Haemodorum spicatum R. Br (Mardja, bloodroot)

Haemodorum spicatum is a bulbous, perennial herb native to Western Australia. It is known as Mardja by indigenous Aboriginal people, for whom the tubers were an important food and medicine. It is also commonly called bloodroot due to the deep red colour of its rhizomes. The compound responsible for the red pigmentation, haemocorin, is believed to have anti-tumour activity. The aim of this study was to investigate whether methanol extracts of H. spicatum tubers could inhibit the growth of cultured human cancer cells. A panel of cell lines representing colorectal (Caco-2), breast (MCF-7 and MDA-MB-468), prostate (PC-3 and DU-145), skin (MM-253) and lung (A549) cancers were exposed to a range of concentrations of methanol extracts of H. spicatum tubers. These samples were obtained from distinct geographical regions and contained different levels of haemocorin. The MTT assay was used to assess inhibition of cancer cell proliferation after 48h exposure to extracts. Initial results showed that 6mg/mL (w/v) of crude methanolic extracts from tubers of H. spicatum containing high levels of haemocorin did, indeed, inhibit the proliferation of two cancer cell lines (PC-3 and MCF-7) by over 50%. However, experiments using tubers obtained on other occasions and from other locales failed to show significant inhibition of any cell type. These data suggest that further purification of haemocorin from H. spicatum tubers may be worthwhile in the ongoing search for compounds to treat cancer, but that the location and season of collection of tubers may be important determinants in bioactivity.