Schisandrin B protects PC12 cells against oxidative stress of neurodegenerative diseases.

Increasing evidence places Schisandrin B (Sch B) at an important position in nerve protection, indicating that Sch B might play a positive role in the therapy of neurodegenerative diseases. However, there is little information on it. Our studies showed that pretreatment with Sch B could reduce lactate dehydrogenase, malondialdehyde, and reactive oxygen species release and significantly increase the cell viability and the superoxide dismutase level. Sch B (10 µM) markedly inhibited cell apoptosis, whereas LY294002 (20 µM), a phosphatidylinositol-3 kinase inhibitor, blocked the antiapoptotic effect. More importantly, Sch B (10 µM) increased the phosphoprotein kinase B/protein kinase B (Akt) and B-cell lymphoma-2/Bcl-2 associated X protein ratios on preincubation with cells for 2 h, which was then inhibited by LY294002 (20 µM). Results indicate that Sch B can protect PC12 cells from apoptosis by activating the phosphatidylinositol-3 kinase/Akt signaling pathway and may emerge as a potential drug for neurodegenerative diseases.

[Effect of Schisandra chinensis lignans on neuronal apoptosis and p-AKT expression of rats in cerebral ischemia injury model].

OBJECTIVE: To observe the effect of Schisandra chinensis lignans (SCL) on neuronal apoptosis and PI3K/AKT signaling pathway of rats in the cerebral ischemia injury model, and study its possible mechanism. METHOD: Rats were orally administered SCL high, middle and low dose groups (100, 50, 25 mg x kg(-1)) for 14 days. The cerebral ischemia injury model was established by using the suture-occluded method to rate the neurological functions. The cerebral infarction area was observed by TTC staining. The pathological changes in brain tissues were determined by HE staining. Bcl-2 and Bax expressions were detected by immunohistochemical assay. The protein expressions of p-AKT and AKT were assayed by Western blotting. RESULT: Compared with the model group, SCL high, middle and low dose groups showed reduction in the cerebral infarction area to varying degrees, improve the pathological changes in brain tissues, promote the expression of apoptin Bcl-2 and p-AKT, and inhibit the expression of apoptin Bax. CONCLUSION: SCL shows a protective effect on rats with cerebral ischemia injury. Its mechanism may be related to the increase in p-AKT ability and antiischemic brain injury capacity and the inhibition of nerve cells.

Induction of apoptosis by shikonin through a ROS/JNK-mediated process in Bcr/Abl-positive chronic myelogenous leukemia (CML) cells.

This study examined the signaling events induced by shikonin that lead to the induction of apoptosis in Bcr/Abl-positive chronic myelogenous leukemia (CML) cells (e.g., K562, LAMA84). Treatment of K562 cells with shikonin (e.g., 0.5 muM) resulted in profound induction of apoptosis accompanied by rapid generation of reactive oxygen species (ROS), striking activation of c-Jun-N-terminal kinase (JNK) and p38, marked release of the mitochondrial proteins cytochrome c and Smac/DIABLO, activation of caspase-9 and -3, and cleavage of PARP. Scavenging of ROS completely blocked all of the above-mentioned events (i.e., JNK and p38 phosphorylation, cytochrome c and Smac/DIABLO release, caspase and PARP cleavage, as well as the induction of apoptosis) following shikonin treatment. Inhibition of JNK and knock-down of JNK1 significantly attenuated cytochrome c release, caspase cleavage and apoptosis, but did not affect shikonin-mediated ROS production. Additionally, inhibition of caspase activation completely blocked shikonin-induced apoptosis, but did not appreciably modify shikonin-mediated cytochrome c release or ROS generation. Altogether, these findings demonstrate that shikonin-induced oxidative injury operates at a proximal point in apoptotic signaling cascades, and subsequently activates the stress-related JNK pathway, triggers mitochondrial dysfunction, cytochrome c release, and caspase activation, and leads to apoptosis. Our data also suggest that shikonin may be a promising agent for the treatment of CML, as a generator of ROS.