Antitumor activity of an Artemisia annua herbal preparation and identification of active ingredients

Background: Artemisia annua L. has gained increasing attention for its anticancer activity. However, beside artemisinin, less is known about the possible bioactive ingredients of Artemisia annua and respective herbal preparations. We hypothesized that, in addition to artemisinin, Artemisia annua preparations might contain multiple ingredients with potential anticancer activity. Methods: MDA-MB-231 triple negative human breast cancer (TNBC) cells along with other treatment resistant, metastatic cancer cell lines were used to investigate in vitro and in vivo the anticancer efficacy of an Artemisia annua extract marketed as a herbal preparation, which contained no detectable artemisinin (limit of detection = 0.2 ng/mg). The extract was characterized by HPLC-DAD and the most abundant compounds were identified by H-1- and C-13 NMR spectroscopy and quantified by UHPLC-MS/MS. Cell viability and various apoptotic parameters were quantified by flow cytometry. In vitro data were validated in two in vivo cancer models, the chick chorioallantoic membrane (CAM) assay and in orthotopic breast cancer xenografts in nude mice. Results: The Artemisia annua extract, the activity of which could be enhanced by acetonitrile maceration, inhibited the viability of breast (MDA-MB-231 and MCF-7), pancreas (MIA PaCa-2), prostate (PC-3), non-small cell lung cancer (A459) cells, whereas normal mammary epithelial cells, lymphocytes, and PBMC were relatively resistant to extract treatment. Likewise, the extracts most abundant ingredients, chrysosplenol D, arteannuin B, and casticin, but not arteannuic acid or 6,7-dimethoxycoumarin, inhibited the viability of MDA-MB-231 breast cancer cells. The extract induced accumulation of multinucleated cancer cells within 24 h of treatment, increased the number of cells in the S and G(2)/M phases of the cell cycle, followed by loss of mitochondrial membrane potential, caspase 3 activation, and formation of an apoptotic hypodiploid cell population. Further, the extract inhibited cancer cell proliferation, decreased tumor growth, and induced apoptosis in vivo in TNBC MDA-MB-231 xenografts grown on CAM as well as in nude mice. Conclusion: An extract of an artemisinin-deficient Artemisia annua herbal preparation exhibits potent anticancer activity against triple negative human breast cancer. New active ingredients of Artemisia annua extract with potential anticancer activity have been identified.