Milk Thistle: Its Anti-Tumor Potential

Abstract

Milk thistle has been used for treating liver disorders since approximately 2000 years. Silybum marianum and its seeds contain a whole family of natural compounds, called flavonolignans. Silimarin is a dry mixture of these compounds, which are extracted after processing with ethanol, methanol, and acetone. Silimarin contains mainly silibin A, silibin B, taxifolin, isosilibin A, isosilibin B, silichristin A and silidianin. Milk thistle has been suggested to inhibit cell proliferation and to induce apoptosis, while having anti-angiogenic properties, too. Its mechanisms of action involve inhibition of tumor angiogenesis biomarkers (CD31 and nestin) and molecules regulating angiogenesis (VEGF, VEGFR1, VEGFR2, phospho-Akt and HIF-1a), while other pathways such as the Wnt/β-catenin pathway, cyclin-dependent kinases and MAPK have also been implicated in its actions. Ongoing research has focused on the improvement of milk thistle’s bioavailability and its use as an adjuvant in standardized chemotherapy in the near future.