Oxidized SOD1 accelerates cellular senescence in neural stem cells.

BACKGROUND: Neural stem cells (NSCs), especially human NSCs, undergo cellular senescence characterized by an irreversible proliferation arrest and loss of stemness after prolonged culture. While compelling correlative data have been generated to support the oxidative stress theory as one of the primary determinants of cellular senescence of NSCs, a direct cause-and-effect relationship between the accumulation of oxidation-mediated damage and cellular senescence of NSCs has yet to be firmly established. Human SOD1 (hSOD1) is susceptible to oxidation. Once oxidized, it undergoes aberrant misfolding and gains toxic properties associated with age-related neurodegenerative disorders. The present study aims to examine the role of oxidized hSOD1 in the senescence of NSCs. METHODS: NSCs prepared from transgenic mice expressing the wild-type hSOD1 gene were maintained in culture through repeated passages. Extracellular vesicles (EVs) were isolated from culture media at each passage. To selectively knock down oxidized SOD1 in NSCs and EVs, we used a peptide-directed chaperone-mediated protein degradation system named CT4 that we developed recently. RESULTS: In NSCs expressing the hSOD1 from passage 5, we detected a significant increase of oxidized hSOD1 and an increased expression of biomarkers of cellular senescence, including upregulation of P53 and SA-ß-Gal and cytoplasmic translocation of HMGB1. The removal of oxidized SOD1 remarkably increased the proliferation and stemness of the NSCs. Meanwhile, EVs derived from senescent NSCs carrying the wild-type hSOD1 contained high levels of oxidized hSOD1, which could accelerate the senescence of young NSCs and induce the death of cultured neurons. The removal of oxidized hSOD1 from the EVs abolished their senescence-inducing activity. Blocking oxidized SOD1 on EVs with the SOD1 binding domain of the CT4 peptide mitigated its toxicity to neurons. CONCLUSION: Oxidized hSOD1 is a causal factor in the cellular senescence of NSCs. The removal of oxidized hSOD1 is a strategy to rejuvenate NSCs and to improve the quality of EVs derived from senescent cells.

The Initial Myelination in the Central Nervous System.

Myelination contributes not only to the rapid nerve conduction but also to axonal insulation and protection. In the central nervous system (CNS), the initial myelination features a multistep process where oligodendrocyte precursor cells undergo proliferation and migration before differentiating into mature oligodendrocytes. Mature oligodendrocytes then extend processes and wrap around axons to form the multilayered myelin sheath. These steps are tightly regulated by various cellular and molecular mechanisms, such as transcription factors (Olig family, Sox family), growth factors (PDGF, BDNF, FGF-2, IGF), chemokines/cytokines (TGF-ß, IL-1ß, TNFα, IL-6, IFN-γ), hormones (T3), axonal signals (PSA-NCAM, L1-CAM, LINGO-1, neural activity), and intracellular signaling pathways (Wnt/ß-catenin, PI3 K/AKT/mTOR, ERK/MAPK). However, the fundamental mechanisms for initial myelination are yet to be fully elucidated. Identifying pivotal mechanisms for myelination onset, development, and repair will become the focus of future studies. This review focuses on the current understanding of how CNS myelination is initiated and also the regulatory mechanisms underlying the process.

Cerebral Ischemic Preconditioning Aggravates Death of Oligodendrocytes.

Neurodegeneration can benefit from ischemic preconditioning, a natural adaptive reaction to sublethal noxious stimuli. Although there is growing interest in advancing preconditioning to preserve brain function, preconditioning is not yet considered readily achievable in clinical settings. One of the most challenging issues is that there is no fine line between preconditioning stimuli and lethal stimuli. Here, we show deleterious effect of preconditioning on oligodendrocyte precursor cells (OPCs). We identified Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3), a mitochondrial BH3-only protein specifically involved in OPCs loss after preconditioning. Repeated ischemia stabilized BNIP3 and increased the vulnerability of OPCs to subsequent ischemic events. BNIP3 became mitochondrial-bound and was concurrent with the dysfunction of monocarboxylate transporter 1 (MCT1). Inhibition of BNIP3 by RNAi or necrostatin-1 (Nec-1) and knocking out of BNIP3 almost completely prevented OPCs loss and preserved white matter integrity. Together, our results suggest that the unfavorable effect of BNIP3 on OPCs should be noted for safe development of ischemic tolerance. BNIP3 inhibition appears to be a complementary approach to improve the efficacy of preconditioning for ischemic stroke.

Necrostatin-1 prevents the proapoptotic protein Bcl-2/adenovirus E1B 19-kDa interacting protein 3 from integration into mitochondria.

Necrostatin-1 (Nec-1) has previously been shown to protect neurons from death in traumatic and ischemic brain injuries. This study tests the hypothesis that Nec-1 protects neural cells against traumatic and ischemic brain injuries through inhibition of the Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3). We have used biochemical and morphological techniques to determine the inhibition of Nec-1 on BNIP3-induced cell death and to identify its mechanism of action in in vivo and in vitro models of neurodegeneration. Here we show that Nec-1 significantly increased neuronal viability following prolonged exposure to hypoxia in vitro, and attenuated myelin damage and neuronal death in traumatic brain injury and cerebral ischemia in Sprague-Dawley rats. Nec-1 alleviated traumatic brain injury-induced up-regulation of BNIP3 in mature oligodendrocytes. In isolated mitochondria, Nec-1 prevented BNIP3 from integrating into mitochondria by modifying its binding sites on the mitochondria. Consequently, Nec-1 robustly inhibited BNIP3-induced collapse of mitochondrial membrane potential and reduced the opening probability of mitochondrial permeability transition pores. Nec-1 also preserved mitochondrial ultrastructure and suppressed BNIP3-induced nuclear translocation of apoptosis-inducing factor. In conclusion, Nec-1 protects neurons and oligodendrocytes against traumatic and ischemic brain injuries by targeting the BNIP3-induced cell death pathway, and is a novel inhibitor for BNIP3. Cover Image for this issue: https://doi.org/10.1111/jnc.15056.

Adiponectin regulates bone mass in AIS osteopenia via RANKL/OPG and IL6 pathway.

BACKGROUND: Osteopenia have been well documented in adolescent idiopathic scoliosis (AIS). Adiponectin has been shown to be inversely proportional to body mass index and to affect bone metabolism. However, the circulating levels of adiponectin and the relationship between adiponectin and low bone mass in AIS remain unclear. METHODS: A total of 563 AIS and 281 age-matched controls were recruited for this study. Anthropometry and bone mass were measured in all participants. Plasma adiponectin levels were determined by enzyme-linked immunosorbent assay (ELISA) in the AIS and control groups. An improved multiplex ligation detection reaction was performed to study on single nucleotide polymorphism. Facet joints were collected and used to measure the microstructure, the expression of RANKL, OPG, osteoblast-related genes, inflammatory factors, adiponectin and its receptors by qPCR, western blotting and immunohistochemistry. Furthermore, primary cells were extracted from facet joints to observe the reaction after adiponectin stimulation. RESULTS: Compared with the controls, lower body mass index and a marked increase in circulating adiponectin were observed in AIS osteopenia (17.09 ± 1.09 kg/m2 and 21.63 ± 10.30 mg/L). A significant difference in the presence of rs7639352was detected in the AIS osteopenia, AIS normal bone mass and control groups. The T allele showed a significant higher proportion in AIS osteopenia than AIS normal bone mass and control groups (41.75% vs 31.3% vs 25.7%, p < 0.05). micro-CT demonstrated that the AIS convex side had a significant lower bone volume than concave side. RNA and protein analyses showed that in cancellous bone, higher RANKL/OPG and adipoR1 levels and lower runx2 levels were observed, and in cartilage, higher adipoR1 and IL6 levels were observed in AIS. Furthermore, convex side had higher RANKL/OPG, IL6 and adipoR1 than concave side. Compared with normal primary cells, convex side primary cells showed the most acute action, and concave side primary cells showed the second-most acute action when exposed under same adiponectin concentration gradient. CONCLUSION: Our results indicated that high circulating adiponectin levels may result from gene variations in AIS osteopenia. Adiponectin has a negative effect on bone metabolism, and this negative effect might be mediated by the ADR1-RANKL/OPG and ADR1-IL6 pathways.

Taxifolin Inhibits Receptor Activator of NF-κB Ligand-Induced Osteoclastogenesis of Human Bone Marrow-Derived Macrophages in vitro and Prevents Lipopolysaccharide-Induced Bone Loss in vivo.

It has been reported that taxifolin inhibit osteoclastogenesis in RAW264.7 cells. In our research, the inhibition effects of taxifolin on the osteoclastogenesis of human bone marrow-derived macrophages (BMMs) induced by receptor activator of NF-κB ligand (RANKL) as well as the protection effects in lipopolysaccharide-induced bone lysis mouse model have been demonstrated. In vitro, taxifolin inhibited RANKL-induced osteoclast differentiation of human BMMs without cytotoxicity. Moreover, taxifolin significantly suppressed RANKL-induced gene expression, including tartrate-resistant acid phosphatase, matrix metalloproteinase-9 nuclear factor of activated T cells 1 and cathepsin K, and F-actin ring formation. Further studies showed that taxifolin inhibit osteoclastogenesis via the suppression of the NF-κB signaling pathway. In vivo, taxifolin prevented bone loss in mouse calvarial osteolysis model. In conclusion, the results suggested that taxifolin has a therapeutic potential for osteoclastogenesis-related diseases such as osteoporosis, osteolysis, and rheumatoid arthritis.

Manipulable Permeability of Nanogel Encapsulation on Cells Exerts Protective Effect against TNF-α-Induced Apoptosis.

Cell encapsulation using microgel and nanogel, as a strategy of cell surface engineering, can mimic the niches of cells and organoids. The established niche that seasons cells and tissues for the controllable development underlies the superiority of encapsulation on cells. Encapsulation by layer-by-layer nanogel coating is a bottom-up simulation of extracellular matrices via nano- or micropackaging of cells in a multiscale way. We report the nanogel encapsulation on individual neuronal cell for a basic study and application of permeability tuning to regulate cells' apoptosis. Gelatin and hyaluronic acid (HA) are applied for encapsulating PC12 cells. The permeability of encapsulation on cells can be managed by adjusting different parameters such as material concentration, layer thickness and environmental pH. Eventually, permeability of tumor necrosis factor-α (TNF-α) is controlled by tuning encapsulating parameters for blocking the interaction with TNF-receptor 1, so that cell apoptosis is inhibited. In short, nanogel encapsulation exhibits controllable permeability to different molecules and exerts screen effect on TNF-α for protection. This technique holds great potential in basic biological research and translational research, for example, the protection of transplanted cells against apoptotic factors in target areas.

Taxifolin enhances osteogenic differentiation of human bone marrow mesenchymal stem cells partially via NF-κB pathway.

Taxifolin, a flavonoid compound, has been reported to stimulate osteogenic differentiation in osteoblasts. The present study investigated whether taxifolin affects the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) and the molecular mechanisms involved. The proliferation and osteogenic differentiation of hBMSCs in the presence of taxifolin were examined by CCK-8 assay, alkaline phosphatase (ALP) activity, ALP staining and Alizarin red staining. The expression of osteogenic differentiation markers were detected by real-time quantitative PCR (RT-PCR) analysis and western blot assay. The activation of potential related pathways was examined by luciferase reporter assay, immunofluorescence and western blot analysis. Taxifolin treatment increased osteogenic differentiation of hBMSCs without cytotoxicity. Luciferase reporter assay showed that taxifolin could not activate estrogen receptor pathway, but inhibit TNF-α-induced NF-κB signaling pathway activation in osteogenic induction condition. Moreover, the nucleus translocation of NF-κB under TNF-α treatment was inhibited by taxifolin treatment. The taxifolin-induced osteogenic differentiation effects of hBMSCs were abolished by TNF-α treatment. In conclusion, our results suggested that taxifolin could promote osteogenesis of hBMSCs, partially through antagonism of NF-κB signaling pathway.

Polymorphisms in the SP110 and TNF-α Gene and Susceptibility to Pulmonary and Spinal Tuberculosis among Southern Chinese Population.

OBJECTIVE: To investigate the association of single-nucleotide polymorphisms (SNPs) in SP110 gene and TNF-α gene among pulmonary TB (PTB) and spinal TB (STB) patients. METHODS: In a total of 190 PTB patients, 183 STB patients were enrolled as the case group and 362 healthy individuals at the same geographical region as the control group. The SP110 SNPs (rs722555 and rs1135791) and the promoter -308G>A (rs1800629) and -238G>A (rs361525) polymorphisms in TNF-α were genotyped. Results. TNF-α -238G>A polymorphism was involved in susceptibility to STB, but not to PTB. The TNF-α -238 A allele was a protective factor against STB (A versus G: OR [95% CI] = 0.331 [0.113-0.972], P = 0.044). Furthermore, the presence of the -238 A allele was considered a trend to decrease the risk of STB (AG versus GG: P = 0.062, OR [95% CI] = 0.352 [0.118-1.053]; AA + AG versus GG: P = 0.050, OR [95CI%] = 0.335 [0.113-0.999]). However, SP110 SNPs (rs722555 and rs1135791) and TNF-α -308G>A (rs1800629) showed no association with PTB and STB in all genetic models. CONCLUSION: The TNF-α -238 A allele appeared a protective effect against STB, whereas the SP110 SNPs (rs722555 and rs1135791) and TNF-α -308G>A (rs1800629) showed no association with susceptibility to PTB and STB patients in southern China.

The Aqueous Fraction of Areca catechu Nut Ameliorates Demyelination in Prefrontal Cortex-Induced Depressive Symptoms and Cognitive Decline through Brain-Derived Neurotrophic Factor-Cyclic Adenosine Monophosphate Response Element-Binding Activation.

OBJECTIVE: To investigate if Areca catechu L. treatment could ameliorate depressive symptoms and cognitive decline by facilitating myelination processes in prefrontal cortex. METHODS: A mouse model of cuprizoneinduced demyelination was used to mimic demyelinating disease. Two concentrations of A. catechu nut extract (ANE; 1% and 2%) were administered orally in the diet for 8 weeks. Depressive symptoms and cognition-associated behaviors were evaluated in tests of locomotor activity, tail suspension, and forced swimming; spatial memory was tested with the Y-maze. Expression of myelin basic protein (MBP), 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase), glutathione S-transferases pi (GSTpi), brain-derived neurotrophic factor (BDNF), and the transcription factor cyclic adenosine monophosphate (cAMP) response element-binding (CREB) were evaluated by western blot. RESULTS: Animals subjected to demyelination showed hyperactivity (P<0.01), impaired spatial memory (P<0.01), and depressive behaviors (P<0.05). Internally, they displayed signifificant myelin damage in the cortex, lower expression of CNPase and GSTpi, slightly decreased BDNF (P>0.05), and signifificantly reduced p-CREB (P<0.05). Nevertheless, ANE treatment demonstrated signifificant anti-depressant activity and enhancement of working memory (P<0.05 or 0.01). In addition, ANE treatment increased MBP, CNPase and GSTpi protein expression in prefrontal cortex (P<0.05). Concomitant with increased BDNF production (P<0.05), ANE treatment up-regulated phosphorylated CREB, but without statistical signifificance (P>0.05). CONCLUSION: ANE treatment might ameliorate depressive symptoms and cognitive decline by facilitating myelination processes in prefrontal cortex via induction of BDNF-CREB activation.

Shengmai injection attenuates the cerebral ischemia/reperfusion induced autophagy via modulation of the AMPK, mTOR and JNK pathways.

Context Shengmai injection (SMI) is a patented Chinese medicine originated from the ancient Chinese herbal compound Shengmai san, which is used extensively for the treatment of cardiovascular and cerebrovascular disease in the clinic. Objective To determine the neuroprotective effect of SMI, we investigated the effect of SMI on cerebral ischemia/reperfusion (I/R) injury in mice as well as the mechanisms underlying this effect. Materials and methods Right middle cerebral artery was occluded by inserting a thread through internal carotid artery for 1 h, and then reperfused for 24 h in mice. The neuroprotective effects were determined using transmission electron microscopic examination, the evaluation of infarct volume, neurological deficits and water brain content. Related mechanisms were evaluated by immunofluorescence staining and western blotting. SMI was injected intraperitoneally after 1 h of ischemia at doses of 1.42, 2.84 and 5.68 g/kg. The control group received saline as the SMI vehicle. Results Results showed that SMI (1.42, 2.84 and 5.68 g/kg) could significantly reduce the infarct volume, SMI (5.68 g/kg) could also significantly improve the neurological deficits, decreased brain water content, as well as the neuronal morphological changes. SMI (5.68g/kg) could significantly inhibit the expression of autophagy-related proteins: Beclin1 and LC3. It also reduced the increase in LC3-positive cells. SMI (5.68 g/kg) remarkably inhibited the phosphorylation of adenosine monophosphate activated protein kinase (AMPK), and down-regulated the phosphorylation of mammalian target of rapamycin (mTOR) and Jun N-terminal kinase (JNK) after 24 h of reperfusion. Discussion and conclusion The results indicate that SMI provides remarkable protection against cerebral ischemia/reperfusion injury, which may be partly due to the inhibition of autophagy and related signalling pathways.

Maslinic acid promotes synaptogenesis and axon growth via Akt/GSK-3ß activation in cerebral ischemia model.

Maslinic acid, a natural pentacyclic triterpene from Olea europaea plants, possesses neuroprotective effects both in vivo and in vitro. However, the mechanism of its action is not well understood. In this study, we investigated the potential effects of maslinic acid on synaptogenesis and axonal regeneration, as well as the possible signal pathway involved in a cerebral ischemia mouse model. Adult male C57BL/6J mice were subjected to 1h of cerebral ischemia by middle cerebral artery occlusion (MCAO). Maslinic acid (0.1, 1 and 10mg/kg) was administered intragastrically 24h after MCAO once daily for 7 consecutive days. Axonal loss and synaptophysin expression in the ischemic boundary area was evaluated by histological assay. The Akt/GSK-3ß signal pathway was determined by western blot analysis. Two Akt inhibitors, LY294002 and MK2206, were used to verify the involvement of Akt/GSK-3ß pathway in maslinic acid-mediated neuroprotection. Maslinic acid significantly prevented axonal damage, promoted axonal regeneration and increased synaptophysin expression 7 days after ischemia. In addition, maslinic acid treatment was shown to enhance Akt activity and promote GSK-3ß phorsphorylation in stoke mice. The increased neurite outgrowth and synaptophysin expression by maslinic acid treatment was blocked by the Akt inhibitors both in vivo and in vitro.. These findings suggested that maslinic acid promotes synaptogenesis and axonal regeneration by regulating Akt/GSK-3ß signaling pathway, which may, in turn, provide neuroprotection.

Ruscogenin reduces cerebral ischemic injury via NF-κB-mediated inflammatory pathway in the mouse model of experimental stroke.

Transient cerebral ischemia initiates a complex series of inflammatory events, which has been associated with an increase in behavioral deficits and secondary brain damage. Ruscogenin is a major steroid sapogenin in the traditional Chinese herb Ophiopogon japonicus that have multiple bioactivities. Recent studies have demonstrated that Ruscogenin is involved in down-regulation of intercellular adhesion molecule-1 (ICAM-1) and nuclear factor-κB (NF-κB) activation in anti-inflammatory pathways. We hypothesized that Ruscogenin protects against brain ischemia by inhibiting NF-κB-mediated inflammatory pathway. To test this hypothesis, adult male mice (C57BL/6 strain) were pretreated with Ruscogenin and then subjected to transient middle cerebral artery occlusion (MCAO)/reperfusion. After 1 h MCAO and 24 h reperfusion, neurological deficit, infarct sizes, and brain water content were measured. Ruscogenin markedly decreased the infarct size, improved neurological deficits and reduced brain water content after MCAO. The activation of NF-κB Signaling pathway was observed after 1h of ischemia and 1h of reperfusion, and Ruscogenin significantly inhibited NF-κB p65 expression, phosphorylation and translocation from cytosol to nucleus at this time point in a dose-dependent manner. NF-κB DNA binding activity, and the expression of NF-κB target genes, including ICAM-1, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß), were also suppressed by Ruscogenin pretreatment after 1 h MCAO and 24 h reperfusion. The results indicated that Ruscogenin protected the brain against ischemic damage caused by MCAO, and this effect may be through downregulation of NF-κB-mediated inflammatory responses.

BNIP3 mediates pre-myelinating oligodendrocyte cell death in hypoxia and ischemia.

Developing oligodendrocytes, collectively termed 'pre-myelinating oligodendrocytes' (preOLs), are vulnerable to hypoxic or ischemic insults. The underlying mechanism of this vulnerability remains unclear. Previously, we showed that Bcl-2/E1B-19K-interacting protein 3 (BNIP3), a proapoptotic member of the Bcl-2 family proteins, induced neuronal death in a caspase-independent manner in stroke. In this study, we investigated the role of BNIP3 in preOL cell death induced by hypoxia or ischemia. In primary oligodendrocyte progenitor cell (OPC) cultures exposed to oxygen-glucose deprivation, we found that BNIP3 was upregulated and levels of BNIP3 expression correlated with the death of OPCs. Up-regulation of BNIP3 was observed in preOLs in the white matter in a neonatal rat model of stroke. Knockout of BNIP3 significantly reduced death of preOLs in the middle cerebral artery occlusion model in mice. Our results demonstrate a role of BNIP3 in mediating preOLs cell death induced by hypoxia or ischemia, and suggest that BNIP3 may be a new target for protecting oligodendrocytes from death after stroke. Pre-myelinating oligodendrocytes (preOLs) are known to be highly vulnerable to ischemic insults. It remains unclear, however, how preOLs die. This study shows that BNIP3, a proapoptotic member of the Bcl-2 family proteins, is a mediator of hypoxia/ischemia-induced preOLs death. The BNIP3 cell death pathway may therefore be a new target for protecting oligodendrocytes from death after stroke.

S-nitrosylated protein disulfide isomerase contributes to mutant SOD1 aggregates in amyotrophic lateral sclerosis.

A major hallmark of mutant superoxide dismutase (SOD1)-linked familial amyotrophic lateral sclerosis is SOD1-immunopositive inclusions found within motor neurons. The mechanism by which SOD1 becomes aggregated, however, remains unclear. In this study, we aimed to investigate the role of nitrosative stress and S-nitrosylation of protein disulfide isomerase (PDI) in the formation of SOD1 aggregates. Our data show that with disease progression inducible nitric oxide synthase (iNOS) was up-regulated, which generated high levels of nitric oxide (NO) and subsequently induced S-nitrosylation of PDI in the spinal cord of mutant SOD1 transgenic mice. This was further confirmed by in vitro observation that treating SH-SY5Y cells with NO donor S-nitrosocysteine triggered a dose-dependent formation of S-nitrosylated PDI. When mutant SOD1 was over-expressed in SH-SY5Y cells, the iNOS expression was up-regulated, and NO generation was consequently increased. Furthermore, both S-nitrosylation of PDI and the formation of mutant SOD1 aggregates were detected in the cells expressing mutant SOD1(G93A). Blocking NO generation with the NOS inhibitor N-nitro-L-arginine attenuated the S-nitrosylation of PDI and inhibited the formation of mutant SOD1 aggregates. We conclude that NO-mediated S-nitrosylation of PDI is a contributing factor to the accumulation of mutant SOD1 aggregates in amyotrophic lateral sclerosis.

Anti-inflammatory effects of maslinic acid, a natural triterpene, in cultured cortical astrocytes via suppression of nuclear factor-kappa B.

Maslinic acid (2-α, 3-ß-dihydroxyolean-12-en-28-oic acid) is a natural triterpenoid compound from Olea europaea. This compound prevents oxidative stress and pro-inflammatory cytokine generation in vitro. This study was planned to investigate the anti-inflammatory effects of maslinic acid in central nervous system by using rat astrocyte cultures stimulated with lipopolysaccharide (LPS). We evaluated different proteins implicated in the nuclear factor kappa B (NF-κB) signal transducer pathway employing Western blot and quantitative real time PCR techniques. Results demonstrated that maslinic acid treatment exerted potent anti-inflammatory action by inhibiting the production of Nitric Oxide and tumor necrosis factor alpha (TNF-α). Western blot analysis showed that maslinic acid treatment attenuated LPS-induced translocation of NF-κB p65 subunit to the nucleus and prevented LPS-induced IκBα phosphorylation in a concentration-dependent manner, Moreover, maslinic acid significantly suppressed the expression of cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) at protein and mRNA levels. These results suggest that maslinic acid can potentially reduce neuroinflammation by inhibiting NF-κB signal transducer pathway in cultured cortical astrocytes.

Maslinic acid, a natural triterpenoid compound from Olea europaea, protects cortical neurons against oxygen-glucose deprivation-induced injury.

Maslinic acid is a triterpenoid compound present in plants of Olea europaea. This compound has been reported to have potent antioxidant, anti-cancer, anti-HIV and anti-inflammatory activities. In this study, we investigated the neuroprotective effect of maslinic acid and its mechanism of action. With presence or absence of maslinic acid, cortical neurons were subjected to 1h of oxygen-glucose deprivation and 24h of reoxygenation. Cell injury was determined by lactate dehydrogenase (LDH) measurement and 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay. Neuronal apoptosis was evaluated by flow cytometry assay, caspase-3 expression/activity, caspase-9 activity and Bcl-2/Bax ratio. Nitric Oxide (NO) production and inducible nitric oxide synthase (iNOS) expression were also detected. Results showed that maslinic acid dose-dependently ameliorated neuron injury and apoptosis. Maslinic acid treatment normalized the caspase expression/activation and increased the Bcl-2/Bax ratio. In addition, maslinic acid inhibited oxygen-glucose deprivation-induced NO production and iNOS expression. These results indicated that maslinic acid has beneficial effects on hypoxic neurons by suppressing iNOS activation, which may, in turn, provide neuroprotection.

Cytotoxic effect and apoptotic mechanism of tanshinone A, a novel tanshinone derivative, on human erythroleukemic K562 cells.

Tanshinone A is a novel derivative of phenanthrene-quinone extracted from Salvia miltiorrhiza BUNGE, a traditional herbal medicine. Cytotoxic effect of tanshinone A was observed in this study. Additionally its mechanism of promoting apoptosis was also investigated. MTT and SRB assays were applied to measure the effects of tanshinone A on the cell viability, the cell cycle distribution and cell apoptosis were measured by flow cytometry using PI staining and Annexin V/PI double staining method respectively. The changes of mitochondrial membrane potential were also detected by flow cytometry. Spectrophotometric method was used to detect the changes of caspase-3 activity. Western blotting assay was used to evaluate the expression of bcl-2, bax and c-Myc proteins. Results indicated that tanshinone A displayed a significant inhibitory effect on the growth of K562 cells in a dose- and time-dependent manner, and showed obvious minor damage to LO2 cells. Tanshinone A could arrest K562 cells in the G(0)/G(1) phase and induce apoptosis, decrease the mitochondrial transmembrane potential, decrease the expressions of bcl-2 and c-Myc proteins, increase the expression of bax protein and the activity of caspase-3. Accordingly, it was presumed that the apoptosis induction may be through the endogenous pathway. Subsequently, tanshinone A could be a promising candidate in the development of a novel antitumor agent.