Study Of The Anticancer Activity And Neuroprotective Effects And Mechanisms Of Silibinin

Silibinin is a polyphenolic flavonoid compound extracted from the fruits and seeds of silybum marianum L,which has anti-inflammatory,anti-tumor and anti-oxidation effects.The anti-tumor activity of silibinin in vitro and the protection of neuronal cells were studied in this paper.The mechanism of silibinin-induced apoptosis in human malignant glioma U251was mainly discussed from the perspective of oxidative stress.In addition,the protective effect of silibinin on SH-SY5Y cells treated with H₂O₂ was also described.The experimental results showed that silibinin inhibited the proliferation of U251cells.Nuclear staining demonstrated that silibinin induced U251 cell death as apoptosis.The results of flow cytometry showed that silibinin induced apoptosis of U251 cells at 24h,48h and 72h in a time-and-concentration-dependent manner.At the same time,silibinin increased intracellular ROS level,decreased mitochondrial membrane potential,and caused G2/M and S phase blockade of U251 cells after 24h exposure.Western blot showed that silibinin upregulated the expression of Cleaved-Caspase-3 and Cleaved-Caspase-9 in U251 cells,while Caspase-8 was not activated.After the addition of the antioxidant NAC,silibinin inhibited the apoptosis of U251 cells.The effect of silibinin on the viability of SH-SY5Y cells was limited,while the cell viability reached nearly 50%after treated by 200μM of H₂O₂ for 24h,which was the optimal concentration of oxidative damage.Compared with the model group,pretreatment with 50μM and 100μM of silibinin for 3 h significantly increased cell survival（P<0.05）,decreased apoptosis,reduced intracellular reactive oxygen species（ROS）levels,stabilized mitochondrial membrane potentials,and lowered Cleaved-Caspase-9 and Cleaved-Caspase-3expression associated with apoptosis.Therefore,silibinin had different effects on different cell lines.U251 cells treated for a long time could induce apoptosis and suppress proliferation,while short-time treatment of silibinin could protect SH-SY5Y cells from H₂O₂-induced injury.Silibinin-induced apoptosis in U251cells might increase intracellular ROS levels by blocking cell in G2/M and S phases,which further induced apoptosis in human malignant glioma U251 cells via mitochondrial pathway.Silibinin could protect SH-SY5Y cells from H₂O₂ damage,which might inhibit apoptosis through the anti-oxidative character and stable mitochondrial membrane potentials of silibinin.