Cytotoxicity Of Silibinin On A375-s2 Cells And Directed Differentiation Of Mouse Es Cells In Vitro

Silibinin is a polyphenolic flavonoid isolated from the fruits and seeds of Silybum marianum L., and exerts potent anti-inflammatory, anticarcinogenic and antioxidant activities. This dissertation reports that silibinin exerts various effects on different cell types through different mechanisms. Immunopathologicaly, silibinin induced A375-S2 cell apoptosis, comparing with silibinin's protective effect against UV irradiation-induced apoptosis; and on developmental biology low dose of silibinin induced mouse embryonic stem cells differentiating into cardiomyocytes in vitro.Photomicroscopical, fluorescence microscopical observation and DNA fragmentation showed that silibinin and agonistic antibody against death receptor Fas CH11 synergistically induced A375-S2 cell apoptosis. After treatment with 200 μM silibinin and 100 ng/mL CH11 treated cells, procaspase-3 decreased followed by the degradation of caspase-3 substrates, ICAD (inhibitor of caspase dependent DNase), indicating caspase-3 activation. Silibinin and CH11 increased the expression of pro-apoptotic protein, Bax and p53, and decreased the expression of anti-apoptotic mitochondrial proteins, Bcl-2 and Bcl-X_L, SIRT1, pAkt.Silibinin exerted inducible effects on mouse embryonic stem cell differentiation. In response to 1 μM silibinin, mouse embryonic stem cells expressed cardiac markers such as Nkx-2.5 and GATA-4. Immunocytochemistry revealed the expression of smooth muscle α-actin, connexin 43 and cardiac troponin I. This demonstrated that silibinin induced differentiation of mouse embryonic stem cells into cardiomyocytes.In conclusion, various concentrations of silibinin have multiple functions in different cell types. Silibinin induced A375-S2 cell apoptosis in high concentration, and protect against UV irradiation-induced apoptosis in the same time. And low dose of silibinin induced mouse embryonic stem cell differentiation into cardiomyocytes in vitro.