Lipopolysaccharide-activated BV-2 Microglial Cells Research Articles

Aureonitol Analogues and Orsellinic Acid Esters Isolated from Chaetomium elatum and Their Antineuroinflammatory Activity.

Overexpression of various pro-inflammatory factors in microglial cells tends to induce neurodegenerative diseases, for which there is no effective therapy available. Aureonitol (1) and seven analogues, including six previously undescribed [elatumenol A-F (2-4, 6-8, respectively)], along with two new orsellinic acid esters [elatumone A and B (9 and 10)], were isolated from Chaetomium elatum. The structures of the compounds were established through comprehensive analysis of spectroscopic data, including high-resolution mass spectra and one- and two-dimensional NMR, and absolute configurations determined by the Mosher method, dimolybdenum tetraacetate-induced circular dichroism, and theoretical calculations including electronic circular dichroism and NMR. Metabolites 3, 4, 7, and 8 exhibited antineuroinflammatory activity by attenuating the production of inflammatory mediators, such as nitric oxide, interleukin-6, interleukin-1β, tumor necrosis factor-α, and reactive oxygen species. Western blot results indicated 8 decreases the level of inducible nitric oxide synthase and cyclooxygenase-2 and suppresses the expression of Toll-like receptor 4 and nuclear factor kappa-B (NF-κB) as well as the phosphorylation of the inhibitor of NF-κB and p38 mitogen-activated protein kinases in lipopolysaccharide-activated BV-2 microglial cells.

7-Deoxy-trans-dihydronarciclasine Isolated from Lycoris chejuensis Inhibits Neuroinflammation in Experimental Models.

Overactivated microglia and persistent neuroinflammation hold an important role in the pathophysiology of neurodegenerative diseases. The extract of Lycoris chejuensis (CJ) and its active compound, 7-deoxy-trans-dihydronarciclasine (named E144), attenuated expressions of pro-inflammatory factors, including nitric oxide, prostaglandin E2, inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), tumor necrosis factor α (TNF-α), and interleukin 6, secreted by lipopolysaccharide-activated BV-2 microglial cells, as measured by an enzyme-linked immunosorbent assay or western blotting. In contrast, CJ extract and E144 promoted the secretion of the anti-inflammatory cytokine, interleukin 10. Moreover, we found that E144 attenuated the expression of TNF-α and COX-2 in the cerebral cortex of lipopolysaccharide-treated mice and/or T2576 transgenic mice as well as reduced the reactive immune cells visualized by ionized calcium-binding adaptor molecule 1. Our results suggest the possibility of E144 to serve as a potential anti-neuroinflammatory agent by preventing excess production of pro-inflammatory factors.

Synthesis and anti-neuroinflammatory activity of N-heterocyclic analogs based on natural biphenyl-neolignan honokiol

Novel isoxazole and pyrazole analogs based on natural biphenyl-neolignan honokiol were synthesized and evaluated for their inhibitory activities against nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells. The isoxazole skeleton was constructed via nitrile oxide cycloaddition from oxime 3 and pyrazole was generated by condensation of 4-chromone and alkylhydrazine. Among the analogs, 13b and 14a showed stronger inhibitory activities with IC50 values of 8.9 and 1.2 µM, respectively, than honokiol.

Stachyodin A, a pterocarpan derivative with unusual spirotetrahydrofuran ring from the roots of Indigofera stachyodes

Stachyodin A (1), a rearrangement product of pterocarpan featuring a 6/5/5/6 tetracyclic ring system with an unusual spirotetrahydrofuran ring, and stachyodin B (2), a new dihydrochalcone, along with five known analogues (3–7) were isolated from the roots of Indigofera stachyodes. The structures of 1 and 2 were elucidated on the basis of their HRESIMS and NMR spectroscopic data, and their absolute configurations were determined by X-ray crystallographic analysis and electronic circular dichroism (ECD) data, respectively. Compounds 2–4 showed inhibition of nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells.

Streptocyclinones A and B ameliorate Alzheimer's disease pathological processes in vitro

Alzheimer's disease (AD) is a pathology characterized by the abnormal accumulation of amyloid-beta (Aβ) and hyperphosphorylated tau. Oxidative stress and neuroinflammation are also strongly related to this disease. The ability of two new glycosylated angucyclinones, streptocyclinones A and B (1 and 2), isolated from Streptomyces sp to improve AD hallmarks was evaluated. Compounds were able to protect SH-SY5Y neuroblastoma cells from H2O2-induced oxidative injury by activating the nuclear factor E2-related factor (Nrf2). Their capacity to modulate neuroinflammation was tested in lipopolysaccharide-activated BV2 microglial cells. Compounds reduced the release of pro-inflammatory factors, inhibited the activation of NFκB and mitogen activated kinases (MAPK), and induced the translocation of Nrf2 to the nucleus of microglial cells. A trans-well co-culture was established to determine the effect of microglia treated with streptocyclinones on the survival of SH-SY5Y cells. The cell viability of neuroblastoma cells increased when the compounds were added to BV2 cells. SH-SY5Y-TMHT441 cells were used to determine the effect of compounds on tau phosphorylation. Both compounds reduced tau hyperphophorylation by targeting MAPK kinases. Moreover, streptocyclinone B (2) was able to inhibit the activity of β-secretase 1 and decrease the release of reactive oxygen species in BV2 cells stimulated with Aβ. With the same co-culture trans-well system, the treatment of Aβ-stimulated microglia with compound 2 augmented the viability of SH-SY5Y-TMHT441 cells. The results presented in this work provide evidences of the multitarget activities displayed by these new Streptomyces compounds, making them good candidates for further studies in the treatment of AD.

Histone Deacetylase 2 Inhibitor CAY10683 Alleviates Lipopolysaccharide Induced Neuroinflammation Through Attenuating TLR4/NF-κB Signaling Pathway.

Neuroinflammation involves in the progression of many central nervous system diseases. Several studies have shown that histone deacetylase (HDAC) inhibitors modulated inflammatory responses in lipopolysaccharide (LPS) stimulated microglia. While, the mechanism is still unclear. The aim of present study was to investigate the effect of HDAC2 inhibitor CAY10683 on inflammatory responses and TLR4/NF-κB signaling pathways in LPS activated BV2 microglial cells and LPS induced mice neuroinflammation. The effect of CAY10683 on cell viability of BV2 microglial cells was detected by CCK-8 assay. The expressions of inflammatory cytokines were analyzed by western blotting and RT-PCR respectively. The TLR4 protein expression was measured by western blotting, immunofluorescence, immunohistochemistry respectively. The protein expressions of MYD88, phospho-NF-κB p65, NF-κB-p65, acetyl-H3 (AH3), H3, and HDAC2 were analyzed by western blotting. We found that CAY10683 could inhibit expression levels of inflammatory cytokine TNF-α and IL-1β in LPS activated BV2 microglial cells and LPS induced mice neuroinflammation. It could induce TLR4, MYD88, phospho-NF-κB p65, and HDAC2 expressions. Moreover, CAY10683 increased the acetylation of histones H3 in LPS activated BV2 microglial cells and LPS induced mice neuroinflammation. Taken together, our findings suggested that HDAC2 inhibitor CAY10683 could suppress neuroinflammatory responses and TLR4/NF-κB signaling pathways by acetylation after LPS stimulation.

Anti-Neuroinflammatory Effects of Fucoxanthin via Inhibition of Akt/NF-κB and MAPKs/AP-1 Pathways and Activation of PKA/CREB Pathway in Lipopolysaccharide-Activated BV-2 Microglial Cells.

Microglia play a critical role in controlling the homeostasis of the brain, but over-activated microglia secrete pro-inflammatory mediators and cytokines, which induce neuronal cell death. Fucoxanthin (Fx), a marine carotenoid, has demonstrated a variety of beneficial health effects. Despite accumulating evidence supporting the immune-modulating effects of Fx in vitro, the underlying signaling pathways remain unknown. In the present study, Fx dose-dependently inhibited the secretion of lipopolysaccharide (LPS)-induced pro-inflammatory mediators including interleukin (IL)-6, tumor necrosis factor (TNF)-α, reactive oxygen species (ROS), prostaglandin (PG) E2, and nitric oxide (NO) productions, and also suppressed the expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 enzymes. Further, the reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated IL-6, TNF-α, iNOS, and COX-2 mRNA expression were suppressed by treatment with Fx in a dose-dependently manner. The mechanism studies indicated that Fx blocks protein kinase B (Akt)/nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinase (MAPKs)/transcription factor (AP)-1 pathways. In addition, we demonstrated that Fx increases nuclear factor erythroid 2-related factor (Nrf)-2 activation and heme oxygenase (HO)-1 expression in LPS-activated BV-2 microglia. Subsequently, we found that Fx also mediates the reactive oxygen species (ROS) by activating protein kinase A (PKA)/cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) pathway, and promotes the production of brain-derived neurotrophic factor (BDNF). These results indicate that Fx may be more effective and potential than other candidates via either decreasing the pro-inflammatory factors production or increasing the neuroprotective molecules expression for therapy of neurodegenerative diseases.

Anti-neuroinflammatory constituents from the fungus Penicillium purpurogenum MHZ 111

A new dihydroisocoumarin (1) and a new coumarin (2), along with eight known metabolites (3–10), were isolated from the solid substrate fermentation cultures of the fungus Penicillium purpurogenum MHZ 111. Their structures were elucidated by extensive spectroscopic analysis and comparison of their spectroscopic and physicochemical data with the literature values. Compounds 2 and 8 showed inhibition of nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 26.5 and 52.7 μM, respectively.

Biginkgosides A-I, Unexpected Minor Dimeric Flavonol Diglycosidic Truxinate and Truxillate Esters from Ginkgo biloba Leaves and Their Antineuroinflammatory and Neuroprotective Activities.

Nine unexpected new flavonol glycoside cyclodimers in the truxinate (1-7, biginkgosides A-G, respectively) or truxillate [biginkgosides H (8) and I (9)] forms were isolated as minor components from the extract of Ginkgo biloba leaves. The new dimers possess an unusual cyclobutane ring formed by a [2+2]-cycloaddition between two symmetric (for compounds 1-5 and 7-9) or nonsymmetric (for 6) flavonol coumaroyl glucorhamnosides. A plausible biosynthetic pathway for these new compounds based on the frontier molecular orbital theory of cycloaddition reactions is briefly discussed. An antineuroinflammatory screening revealed that biginkgosides E (5) and H (8) inhibited nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells, with IC50 values of 2.91 and 17.23 μM, respectively. Additionally, biginkgoside F (6) showed a significant neuroprotective effect (34.3% increase in cell viability at 1 μM) against Aβ25-35-induced cell viability decrease in SH-SY5Y neuroblastoma cells.

Nitric Oxide Inhibitory Meroterpenoids from the Fungus Penicillium purpurogenum MHZ 111.

Five new meroterpenoids, purpurogenolides A-E (1-5), and four known metabolites (6-9) were isolated from the solid substrate fermentation cultures of the fungus Penicillium purpurogenum MHz 111. The structures of the new meroterpenoids were elucidated by analysis of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of 1 and 5 were determined by single-crystal X-ray crystallographic analysis, and those of 2-4 were elucidated on the basis of experimental and calculated electronic circular dichroism spectra. Compounds 2-4 and 6 showed inhibition of nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 0.8-30.0 μM.

2-Acetyl-7-hydroxy-6-methoxy-1-methyl-1,2,3,4,-tetrahydroisoquinoline exhibits anti-inflammatory properties and protects the nigral dopaminergic neurons

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by degeneration of dopamine(DA)ergic neurons. Neuroinflammation caused by microglial activation is believed to be involved in the pathogenesis of neurodegenerative diseases including PD. In the present study, we tested the effects of a novel compound 2-acetyl-7-hydroxy-6-methoxy-1-methyl-1,2,3,4,-tetarhydroisoquinoline (AMTIQ) on neuroinflammatory response and DAergic neurodegeneration. In lipopolysaccharide-activated BV-2 microglial cells, AMTIQ lowered nitric oxide and tetrahydrobiopterin levels and downregulated gene expression of inducible nitric oxide synthase and GTP cyclohydrolase I. AMTIQ also repressed gene expression of the proinflammatory cytokines IL-1β and TNF-α, and attenuated nuclear translocation of NF-κB. AMTIQ was stable against liver microsomal enzymes from human and mouse and did not interfere with activities of the cytochrome p450 enzymes 1A2, 2D6, 2C9, 2C19 and 3A4. Pharmacokinetic studies revealed the brain to plasma ratio of AMTIQ to be 45%, suggesting it can penetrate the blood brain barrier. In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mouse PD model, AMTIQ led to decreased microglial activation, increased survival of DAergic neurons and their fibers, and improved behavioral scores on rotarod and vertical grid tests. Taken together, these results suggest that AMTIQ might serve as a candidate preventive-therapeutic agent for neurodegenerative diseases such as PD.

Anti-inflammatory Labdane Diterpenoids from Leonurus macranthus.

Twenty new polyoxygenated labdane diterpenoids (1-20) were isolated from the aerial parts of Leonurus macranthus. Their structures were elucidated on the basis of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of macranthin A (1) and 6-O-deacetylmacranthin A (2) were determined by single-crystal X-ray crystallographic analysis and a modified Mosher's method, respectively. Compounds 1-9, 12, 14, and 19 showed inhibition of nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 10.0-63.7 μM.

A Novel Compound ITC-3 Activates the Nrf2 Signaling and Provides Neuroprotection in Parkinson's Disease Models.

Parkinson's disease (PD) is a progressive neurodegenerative disorder accompanied by a selective loss of the dopamine(DA)ergic neurons residing in the substantia nigra. There is ample evidence that neuroinflammation and oxidative stress are involved in the pathogenesis of PD. In the present study, we aimed at protecting the DAergic neurons by suppressing these cellular events and generated a novel synthetic isothiocyanate ITC-3. The compound led to elevation of nuclear and total levels of the transcription factor Nrf2 and interacted with its binding protein Keap1 with high affinity, suggesting Nrf2 activation. ITC-3 was able to suppress production of the proinflammatory mediators in lipopolysaccharide-activated BV-2 microglial cells. It also increased mRNA and protein levels of the Nrf2-dependent antioxidant enzymes NAD(P)H quinone oxidoreductase, heme oxygenase-1, and glutamylcysteine ligase in both BV-2 and DAergic neuronal CATH.a cells. The compound protected the DAergic cells against oxidative stress. In vivo, ITC-3 attenuated the loss of tyrosine hydroxylase-immunopositive nigrostriatal DAergic neurons, suppressed microglial activation, and abolished PD-associated motor deficits in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-elicited animal model of PD. Taken together, ITC-3 may be useful toward development of neuroprotective therapy for PD.

EOP, a newly synthesized ethyl pyruvate derivative, attenuates the production of inflammatory mediators via p38, ERK and NF-κB pathways in lipopolysaccharide-activated BV-2 microglial cells.

Microglia-induced neuroinflammation is an important pathological mechanism influencing various neurodegenerative disorders. Excess activation of microglia produces a myriad of proinflammatory mediators that decimate neurons. Hence, therapeutic strategies aimed to suppress the activation of microglia might lead to advancements in the treatment of neurodegenerative diseases. In this study, we synthesized a novel ethyl pyruvate derivative, named EOP (S-ethyl 2-oxopropanethioate) and studied its effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in rat primary microglia and mouse BV-2 microglia. EOP significantly decreased the production of NO, inducible nitric oxide synthase, cyclooxygenase and other proinflammatory cytokines, such as interleukin (IL)-6, IL-1β and tumor necrosis factor-α, in LPS-stimulated BV-2 microglia. The phosphorylation levels of extracellular regulated kinase, p38 mitogen-activated protein kinase, and nuclear translocation of NF-κB were also inhibited by EOP in LPS-activated BV-2 microglial cells. Overall, our observations indicate that EOP might be a promising therapeutic agent to diminish the development of neurodegenerative diseases associated with microglia activation.