Icaritin(Anhydroicaritin) is a component of Epimedium flavonoid isolated from Herba Epimedii; enhances osteoblastic differentiation of mesenchymal stem cells (MSCs) while it inhibits adipogenic differentiation of MSCs by inhibiting PPAR-g pathway.IC50 value:Target: in vitro: Icaritin was unable to promote proliferation, migration and tube like structure formation by human umbilical vein endothelial cells (HUVECs) in vitro [1]. Icaritin potently inhibited proliferation of K562 cells (IC50 was 8 μM) and primary CML cells (IC50 was 13.4 μM for CML-CP and 18 μM for CML-BC), induced CML cells apoptosis and promoted the erythroid differentiation of K562 cells with time-dependent manner. Furthermore, Icaritin was able to suppress the growth of primary CD34+ leukemia cells (CML) and Imatinib-resistant cells, and to induce apoptosis [2]. icaritin strongly inhibited the growth of breast cancer MDA-MB-453 and MCF7 cells. At concentrations of 2-3 μM, icaritin induced cell cycle arrest at the G(2)/M phase accompanied by a down-regulation of the expression levels of the G(2)/M regulatory proteins such as cyclinB, cdc2 and cdc25C. Icaritin at concentrations of 4-5 μM, however, induced apoptotic cell death characterized by the accumulation of the annexin V- and propidium iodide-positive cells, cleavage of poly ADP-ribose polymerase (PARP) and down-regulation of the Bcl-2 expression [3].in vivo: In mouse leukemia model, Icaritin could prolong lifespan of NOD-SCID nude mice inoculated with K562 cells as effective as Imatinib without suppression of bone marrow. Icaritin could up-regulate phospho-JNK or phospho-C-Jun and down-regulate phospho-ERK, phospho-P-38, Jak-2, phospho-Stat3 and phospho-Akt expression with dose- or time-dependent manner [2].

[1]. Yao D, et al. Icaritin, an exogenous phytomolecule, enhances osteogenesis but not angiogenesis--an in vitro efficacy study. PLoS One. 2012;7(8):e41264. [2]. Zhu Jf, et al. Icaritin shows potent anti-leukemia activity on chronic myeloid leukemia in vitro and in vivo by regulating MAPK/ERK/JNK and JAK2/STAT3 /AKT signalings. PLoS One. 2011;6(8):e23720. [3]. Guo Y, et al. An anticancer agent icaritin induces sustained activation of the extracellular signal-regulated kinase (ERK) pathway and inhibits growth of breast cancer cells. Eur J Pharmacol. 2011 May 11;658(2-3):114-22.