Nimbolide Targets Multiple Signalling Pathways to Reduce Neuroinflammation in BV-2 Microglia

Nimbolide, a limonoid compound found in the neem plant, was investigated for effects on neuroinflammation in BV-2 microglia activated with lipopolysaccharide (LPS). Cultured BV-2 cells were treated with nimbolide (125, 250 and 500 nM) followed by stimulation with LPS (100 ng/ml). Results showed that nimbolide caused a significant reduction in the levels of TNFα, IL-6, IFNγ, NO/iNOS and PGE2/COX-2 in LPS-activated BV-2 cells. Further experiments revealed that LPS-induced increased expression of phospho-p65 and phospho-IκBα proteins were reduced in the presence of nimbolide. Also, LPS-induced NF-κB acetylation, increased binding to consensus sites and transactivation, as well as phosphorylation of p38 and JNK MAPKs were reduced by nimbolide. Reduction of cellular ROS generation by nimbolide was accompanied by a reduction in gp91phox protein levels, while antioxidant effects were also observed through elevation in protein levels of HO-1 and NQO-1. It was observed that treatment of BV-2 microglia with nimbolide resulted in reduced levels of cytoplasmic Nrf2, which was accompanied by increased levels in the nucleus. Furthermore, treatment with this compound resulted in increased binding of Nrf2 to antioxidant responsive element (ARE) consensus sites accompanied by enhanced ARE luciferase activity. Knockdown experiments revealed a loss of anti-inflammatory activity by nimbolide in cells transfected with Nrf2 siRNA. Treatment with nimbolide resulted in nuclear accumulation of SIRT-1, while siRNA knockdown of SIRT-1 resulted in the reversal of anti-inflammatory activity of nimbolide. It is proposed that nimbolide reduces neuroinflammation in BV-2 microglia through mechanisms resulting in dual inhibition of NF-κB and MAPK pathways. It is also proposed that activation of Nrf2 antioxidant mechanisms may be contributing to its anti-inflammatory activity.

Neuroprotection by Alstonia boonei De Wild., Anacardium occidentale L., Azadirachta indica A.Juss. and Mangifera indica L

ETHNOPHARMACOLOGY RELEVANCE

Alstonia boonei De Wild. (stem bark), Anacardium occidentale L. (stem bark), Azadirachta indica A.Juss (leaves), Enantia chlorantha Oliv. (stem bark), Khaya senegalensis A.Juss (stem bark) Mangifera indica L. (stem bark), and Nauclea latifolia Sm. (stem bark) are used for treating malaria in southwest Nigeria. Surveys revealed that these plants are also employed for treating symptoms of malaria and cerebral malaria in the region.

AIM OF THE STUDY

In this study, the effects of freeze-dried extracts of these plants were investigated on synthetic hemozoin (HZ)-induced neuroinflammation, neuronal damage, and increased permeability of brain microvascular endothelial cells.

MATERIALS AND METHODS

Effects of freeze-dried plant extracts were investigated on neuroinflammation by measuring levels of pro-inflammatory mediators in culture supernatants, while in-cell western assays were used to measure protein levels of iNOS and NLRP3. Effects on HZ-induced neurotoxicity and ROS generation was measured using MTT and DCFDA assays, respectively. HZ-induced permeability of hCMEC/D3 endothelial cells was determined using the in vitro vascular permeability assay kit.

RESULTS

The extracts produced significant (p < 0.05) reduction in TNFα, IL-6, IL-1β, MCP-1, RANTES and iNOS/NO production in HZ-stimulated BV-2 microglia. Pre-treatment with 50 μg/mL of A. boonei, A. indica, A. occidentale, E. chlorantha and M. indica also resulted in the inhibition of NF-κB activation. Pre-treatment with A. indica produced, A. occidentale, M. indica and A. boonei reduced HZ-induced increased NLRP3 protein expression. HZ-induced increased caspase-1 activity was also reduced by A. boonei, A. occidentale, A. indica, E. chlorantha, and M. indica. Freeze-dried extracts of A. boonei, A. occidentale, A. indica and M. indica produced neuroprotective effect in HT-22 neuronal cells incubated with HZ by preventing HZ-induced neurotoxicity, ROS generation, DNA fragmentation and caspase 3/7 activity. Inhibition of HZ-induced increase in permeability of human hCMEC/D3 brain endothelial cells was also observed with A. boonei, A. occidentale, A. indica and M. indica, while reducing the release of TNFα and MMP-9.

CONCLUSIONS

These results suggest that A. boonei, A. occidentale, A. indica and M. indica are neuroprotective through inhibition of neuroinflammation, neuronal damage and increased permeability of blood brain barrier. The outcome of the study provides pharmacological evidence for the potential benefits of plants as herbal treatments for cerebral malaria symptoms.

Iminosugar Amino Acid idoBR1 Reduces Inflammatory Responses in Microglia

(1) Background. Inflammation is reported to be a key factor in neurodegeneration. The microglia are immune cells present in the central nervous system; their activation results in the release of inflammatory cytokines and is thought to be related to aging and neurodegenerative disorders, such as Alzheimer's disease. (2) Methods. A mouse BV-2 microglia cell line was activated using LPS and the anti-inflammatory cucumber-derived iminosugar amino acid idoBR1, (2R,3R,4R,5S)-3,4,5-trihydroxypiperidine-2-carboxylic acid, was used alongside dexamethasone as the control to determine whether it could reduce the inflammatory responses. (3) Results. A dose-dependent reduction in the LPS-induced production of the proinflammatory factors TNFα, IL-6, and nitric oxide and the transcription factor NF-κB was found. (4) Conclusions. Further investigations of the anti-inflammatory effects of idoBR1 in other models of neurodegenerative diseases are warranted.

SARS-CoV-2 Spike Glycoprotein S1 Induces Neuroinflammation in BV-2 Microglia

In addition to respiratory complications produced by SARS‐CoV‐2, accumulating evidence suggests that some neurological symptoms are associated with the disease caused by this coronavirus. In this study, we investigated the effects of the SARS‐CoV‐2 spike protein S1 stimulation on neuroinflammation in BV-2 microglia. Analyses of culture supernatants revealed an increase in the production of TNF-α, IL-6, IL-1β and iNOS/NO. S1 also increased protein levels of phospho-p65 and phospho-IκBα, as well as enhanced DNA binding and transcriptional activity of NF-κB. These effects of the protein were blocked in the presence of BAY11-7082 (1 µM). Exposure of S1 to BV-2 microglia also increased the protein levels of NLRP3 inflammasome and enhanced caspase-1 activity. Increased protein levels of p38 MAPK was observed in BV-2 microglia stimulated with the spike protein S1 (100 ng/ml), an action that was reduced in the presence of SKF 86,002 (1 µM). Results of immunofluorescence microscopy showed an increase in TLR4 protein expression in S1-stimulated BV-2 microglia. Furthermore, pharmacological inhibition with TAK 242 (1 µM) and transfection with TLR4 small interfering RNA resulted in significant reduction in TNF-α and IL-6 production in S1-stimulated BV-2 microglia. These results have provided the first evidence demonstrating S1-induced neuroinflammation in BV-2 microglia. We propose that induction of neuroinflammation by this protein in the microglia is mediated through activation of NF-κB and p38 MAPK, possibly as a result of TLR4 activation. These results contribute to our understanding of some of the mechanisms involved in CNS pathologies of SARS-CoV-2.

Garcinia kola and garcinoic acid suppress SARS-CoV-2 spike glycoprotein S1-induced hyper-inflammation in human PBMCs through inhibition of NF-κB activation

Symptoms and complications associated with severe SARS-CoV-2 infection such as acute respiratory distress syndrome (ARDS) and organ damage have been linked to SARS-CoV-2 spike protein S1-induced increased production of pro-inflammatory cytokines by immune cells. In this study, the effects of an extract of Garcinia kola seeds and garcinoic acid were investigated in SARS-CoV-2 spike protein S1-stimulated human PBMCs. Results of ELISA experiments revealed that Garcinia kola extract (6.25, 12.5, and 25 μg/ml) and garcinoic acid (1.25, 2.5, and 5 μM) significantly reduced SARS-CoV-2 spike protein S1-induced secretion of TNFα, IL-6, IL-1β, and IL-8 in PBMCs. In-cell western assays showed that pre-treatment with Garcinia kola extract and garcinoic acid reduced expressions of both phospho-p65 and phospho-IκBα proteins, as well as NF-κB DNA binding capacity and NF-κB-driven luciferase expression following stimulation of PBMCs with spike protein S1. Furthermore, pre-treatment of PBMCs with Garcinia kola extract prior to stimulation with SARS-CoV-2 spike protein S1 resulted in reduced damage to adjacent A549 lung epithelial cells. These results suggest that the seed of Garcinia kola and garcinoic acid are natural products which may possess pharmacological/therapeutic benefits in reducing cytokine storm in severe SARS-CoV-2 and other coronavirus infections.

Synthesis of novel isoflavone/benzo-δ-sultam hybrids as potential anti-inflammatory drugs

A small series of novel isoflavone/benzo-δ-sultam hybrids was synthesised and evaluated as potential anti-inflammatory and neuroprotective drugs in LPS-activated BV2 microglia. The benzo-δ-sultam core was constructed in a two-step reaction by coupling 2-halobenzenesulfonamide derivatives with terminal alkynes, followed by a 6-endo-dig cyclisation. The synthesised compounds, including precursors and hybrids, were tested for their ability to inhibit NO and TNF-α production in LPS-stimulated BV2 microglial cells, and the results are promising. The most potent hybrid reduces the NO production to 41%, and the TNF-α to 34% at 20 µM final concentration in the well.

New cytotoxic compounds from the leaves of Caesalpinia benthamiana (Baill.) Herend. & Zarucchi (Fabaceae)

OBJECTIVE

The incidence of multi-drug resistant cancer and the adverse effects associated with available chemotherapy have necessitated the search for new drug candidates. This study investigates the cytotoxic activity of Caesalpinia benthamiana.

MATERIALS AND METHODS

Column chromatography (CC) and preparative thin layer chromatography (PTLC) were used to isolate compounds. Structural elucidation was done by spectroscopic analysis. MTT assay was used to evaluate cytotoxicity of the compounds against three human adenocarcinoma cells, using methotrexate and dimethyl sulfoxide (DMSO) as positive and negative controls, respectively. CyQuant direct cell proliferation and caspase-3/7 green detection assays were used to investigate the dichloromethane fraction. IC₅₀ values of isolated compounds were determined from sigmoidal dose-response curve.

RESULTS

Four new cytotoxic compounds, benthamianoate (2), benthamiacone (3), benthamianin (5) and benthamianol (6), and two known compounds, methyl gallate (1) and 2-methoxyacrylic acid (4) were identified. All the compounds were active with the new monoterpenoid characterized as benthamiacone exhibiting the highest activity (IC₅₀ 13.23-21.97 μg/ml) across cancer cell lines investigated. CyQuant direct cell proliferation assay showed significant reduction in the number of live carcinoma cells, while caspase-3/7 green detection assay showed significant increase in the number of dead carcinoma cells.

CONCLUSION

This study revealed potential cytotoxic compounds which are here reported for the first time from C. benthamiana.

Zanthoxylum zanthoxyloides inhibits lipopolysaccharide- and synthetic hemozoin-induced neuroinflammation in BV-2 microglia: roles of NF-κB transcription factor and NLRP3 inflammasome activation

OBJECTIVES

The effects of a root extract of Zanthoxylum zanthoxyloides on neuroinflammation in BV-2 microglia stimulated with LPS and hemozoin were investigated.

METHODS

ELISA, enzyme immunoassay and Griess assay were used to evaluate levels of cytokines, PGE2 and NO in culture supernatants, respectively. Microglia-mediated neurotoxicity was evaluated using a BV-2 microglia-HT-22 neuron transwell co-culture.

KEY FINDINGS

Treatment with Z. zanthoxyloides caused reduced elevated levels of TNFα, IL-6, IL-1β, NO and PGE2, while increasing the levels of IL-10. In addition, there were reduced levels of iNOS and COX-2 proteins. This was accompanied by a prevention of microglia-mediated damage to HT-22 mouse hippocampal neurons. Z. zanthoxyloides reduced elevated levels of phospho-IκB and phospho-p65, while preventing degradation of IκB protein and DNA binding of p65. Further mechanistic studies revealed that Z. zanthoxyloides reduced the levels of pro-IL-1β and IL-1β in hemozoin-activated BV-2 microglia. This was accompanied by a reduction in caspase-1 activity and NLRP3 protein expression. Bioassay-guided fractionation resulted in the isolation of skimmianine as an anti-inflammatory compound in Z. zanthoxyloides.

CONCLUSION

This is the first report showing the inhibition of neuroinflammation in LPS- and hemozoin-activated BV-2 microglia by the root extract of Z. zanthoxyloides by targeting the activation of both NF-κB and NLRP3 inflammasome.

Alzheimer's disease: natural products as inhibitors of neuroinflammation

Alzheimer’s disease (AD) is the most common form of dementia and affects 44 million people worldwide. New emerging evidence from pre-clinical and clinical investigations shows that neuroinflammation is a major pathological component of AD suggesting that anti-inflammatory strategies are important in delaying the onset or slowing the progression of the disease. However, efforts to employ current anti-inflammatory agents in AD clinical trials have produced limited success. Consequently, there is a need to explore anti-inflammatory natural products, which target neuroinflammatory pathways relevant to AD pathogenesis. This review summarises important druggable molecular targets of neuroinflammation and presents classes of anti-neuroinflammatory natural products with potentials for preventing and reducing symptoms of AD.

The tiliroside derivative, 3-O-[(E)-(2-oxo-4-(p-tolyl) but-3-en-1-yl] kaempferol produced inhibition of neuroinflammation and activation of AMPK and Nrf2/HO-1 pathways in BV-2 microglia

Neuroinflammation is now widely accepted as an important pathophysiological mechanism in neurodegenerative disorders, thus providing a critical target for novel compounds. In this study, 3-O-[(E)-(2-oxo-4-(p-tolyl)but-3-en-1-yl] kaempferol (OTBK) prevented the production of pro-inflammatory mediators TNFα, IL-6, PGE₂ and nitrite from BV-2 microglia activated with LPS and IFNγ. These effects were accompanied by reduction in the levels of pro-inflammatory proteins COX-2 and iNOS. Involvement of NF-κB in the anti-inflammatory activity of OTBK was evaluated in experiments showing that the compound prevented phosphorylation, nuclear accumulation and DNA binding of p65 sub-unit induced by stimulation of BV-2 microglia with LPS and IFNγ. Exposure of mouse hippocampal HT22 neurons to conditioned media from LPS + IFNγ-stimulated BV-2 cells resulted in reduced cell viability and generation of cellular reactive oxygen species. Interestingly, conditioned media from LPS/IFNγ-stimulated BV-2 cells which were treated with OTBK did not induce neuronal damage or oxidative stress. OTBK was shown to increase protein levels of phospho-AMPKα, Nrf2 and HO-1 in BV-2 microglia. It was further revealed that OTBK treatment increased Nrf2 DNA binding in BV-2 microglia. The actions of the compound on AMPKα and Nrf2 were shown to contribute to its anti-inflammatory activity as demonstrated by diminished activity in the presence of the AMPK antagonist dorsomorphin and Nrf2 inhibitor trigonelline. These results suggest that OTBK inhibits neuroinflammation through mechanisms that may involve activation of AMPKα and Nrf2 in BV-2 microglia.

Induction of Neuroinflammation and Neurotoxicity by Synthetic Hemozoin

Hemozoin produced by Plasmodium falciparum during malaria infection has been linked to the neurological dysfunction in cerebral malaria. In this study, we determined whether a synthetic form of hemozoin (sHZ) produces neuroinflammation and neurotoxicity in cellular models. Incubation of BV-2 microglia with sHZ (200 and 400 µg/ml) induced significant elevation in the levels of TNFα, IL-6, IL-1β, NO/iNOS, phospho-p65, accompanied by an increase in DNA binding of NF-κB. Treatment of BV-2 microglia with sHZ increased protein levels of NLRP3 with accompanying increase in caspase-1 activity. In the presence of NF-κB inhibitor BAY11-7082 (10 µM), there was attenuation of sHZ-induced release of pro-inflammatory cytokines, NO/iNOS. In addition, increase in caspase-1/NLRP3 inflammasome activation was blocked by BAY11-7082. Pre-treatment with BAY11-7082 also reduced both phosphorylation and DNA binding of the p65 sub-unit. The NLRP3 inhibitor CRID3 (100 µM) did not prevent sHZ-induced release of TNFα and IL-6. However, production of IL-1β, NO/iNOS as well as caspase-1/NLRP3 activity was significantly reduced in the presence of CRID3. Incubation of differentiated neural progenitor (ReNcell VM) cells with sHZ resulted in a reduction in cell viability, accompanied by significant generation of cellular ROS and increased activity of caspase-6, while sHZ-induced neurotoxicity was prevented by N-acetylcysteine and Z-VEID-FMK. Taken together, this study shows that the synthetic form of hemozoin induces neuroinflammation through the activation of NF-κB and NLRP3 inflammasome. It is also proposed that sHZ induces ROS- and caspase-6-mediated neurotoxicity. These results have thrown more light on the actions of malarial hemozoin in the neurobiology of cerebral malaria.

Induction of Autophagy and Activation of SIRT-1 Deacetylation Mechanisms Mediate Neuroprotection by the Pomegranate Metabolite Urolithin A in BV2 Microglia and Differentiated 3D Human Neural Progenitor Cells

SCOPE

Urolithin A is an anti-inflammatory and neuroprotective gut-derived metabolite from ellagitannins and ellagic acid in pomegranate, berries, and nuts. The roles of SIRT-1 and autophagy in the neuroprotective activity of urolithin A are investigated.

METHODS AND RESULTS

Analyses of culture supernatants from lipopolysaccharide-stimulated BV2 microglia show that urolithin A (2.5-10 µm) produced significant reduction in the production of nitrite, tumor necrosis factor (TNF)-α and IL-6. The anti-inflammatory effect of the compound is reversed in the presence of sirtuin (SIRT)-1 and the autophagy inhibitors EX527 and chloroquine, respectively. Protein analyses reveal reduction in p65 and acetyl-p65 protein. Treatment of BV2 microglia with urolithin A results in increased SIRT-1 activity and nuclear protein, while induction of autophagy by the compound is demonstrated using autophagy fluorescent and autophagy LC3 HiBiT reporter assays. Viability assays reveal that urolithin A produces a neuroprotective effect in APPSwe-transfected ReNcell VM human neural cells, which is reversed in the presence of EX527 and chloroquine. Increase in both SIRT-1 and autophagic activities are also detected in these cells following treatment with urolithin A.

CONCLUSIONS

It has been proposed that SIRT-1 activation and induction of autophagy are involved in the neuroprotective activity of urolithin A in brain cells.

Formononetin inhibits neuroinflammation and increases estrogen receptor beta (ERβ) protein expression in BV2 microglia

Formononetin is a bioactive non-steroidal polyphenol found in a variety of plants. In this study we evaluated the effects of formononetin on neuroinflammation in LPS-stimulated BV2 microglia. Results showed that formononetin significantly reduced the production of TNF-α, IL-6 and IL-1β, nitrite and PGE₂, as well as protein levels of iNOS and COX-2. Reporter gene assays showed that formononetin produced inhibition of NF-κB luciferase activity in HEK293 cells stimulated with TNF-α. Immunoblotting experiments revealed an inhibition of IKKα phosphorylation, with the resultant attenuation of phosphorylation and degradation of IκBα following LPS stimulation. Formononetin also produced an inhibition of nuclear translocation and DNA binding by NF-κB following LPS stimulation. RNAi experiments showed that transfection of BV2 microglia with ERβ siRNA resulted in the loss of anti-inflammatory action of formononetin. MTT assay and MAP2 immunoreactivity experiments showed that formononetin produced significant neuroprotective activity by preventing BV2 microglia conditioned media-induced toxicity to HT22 neurons. Investigations on the effect of formononetin on MCF7 breast cancer cells revealed that, while the compound significantly increased ER-luciferase activity, its effects on proliferation were modest. This study has established that formononetin inhibits neuroinflammation by targeting NF-κB signalling pathway in BV2 microglia, possibly through mechanisms involving ERβ. Formononetin appears to modulate ERβ in MCF7 breast cancer cells with limited proliferative effect. Formononetin could therefore serve as a chemical scaffold for the development of novel compounds which have selective neuroprotective actions in the brain.

Agathisflavone isolated from Anacardium occidentale suppresses SIRT1-mediated neuroinflammation in BV2 microglia and neurotoxicity in APPSwe-transfected SH-SY5Y cells

Agathisflavone is a bioactive compound in Anacardium occidentale. In this study, we investigated inhibition neuroinflammation in BV2 microglia by agathisflavone. Neuroprotective activity of the compound was investigated in differentiated SH-SY5Y cells. Experiments in lipopolysaccharide (LPS)-activated BV2 microglia showed that pretreatment with agathisflavone (5-20 μM) produced significant reduction in the release of tumour necrosis factor-α, interleukin-6, interleukin-1β, NO, and PGE₂ from the cells. Immunoblotting experiments also revealed that agathisflavone reduced levels of iNOS and COX-2 protein. Further studies revealed that agathisflavone reduced neuroinflammation by targeting critical steps in NF-κB signalling in BV2 microglia. Treatment of SH-SY5Y cells with conditioned medium from LPS-activated BV2 microglia produced a significant reduction in neuronal viability. However, conditioned medium from BV2 cells that were stimulated with LPS in the presence of agathisflavone did not induce neurotoxicity. Agathisflavone also produced neuroprotection in APPSwe plasmid-transfected SH-SY5Y neurons. The compound further attenuated LPS-induced and APPSwe plasmid-induced reduction in SIRT1 in BV2 microglia and SH-SY5Y, respectively. In the presence of EX527, agathisflavone lost its anti-inflammatory and neuroprotective activities. Our results suggest that agathisflavone inhibits neuroinflammation in BV2 microglia by targeting NF-κB signalling pathway. The compound also reduces neurotoxicity through mechanisms that are possibly linked to SIRT1 in the microglia and neurons.

AMPK and SIRT1 activation contribute to inhibition of neuroinflammation by thymoquinone in BV2 microglia

Thymoquinone is a known inhibitor of neuroinflammation. However, the mechanism(s) involved in its action remain largely unknown. In this study, we investigated the roles of cellular reactive oxygen species (ROS), 5' AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1) in the anti-neuroinflammatory activity of thymoquinone. We investigated effects of the compound on ROS generation in LPS-activated microglia using the fluorescent 2',7'-dichlorofluorescin diacetate (DCFDA)-cellular ROS detection. Immunoblotting was used to detect protein levels of p40^phox, gp91^phox, AMPK, LKB1 and SIRT1. Additionally, ELISA and immunofluorescence were used to detect nuclear accumulation of SIRT1. NAD⁺/NADH assay was also performed. The roles of AMPK and SIRT1 in anti-inflammatory activity of thymoquinone were investigated using RNAi and pharmacological inhibition. Our results show that thymoquinone reduced cellular ROS generation, possibly through inhibition of p40^phox and gp91^phox protein. Treatment of BV2 microglia with thymoquinone also resulted in elevation in the levels of LKB1 and phospho-AMPK proteins. We further observed that thymoquinone reduced cytoplasmic levels and increased nuclear accumulation of SIRT1 protein and increased levels of NAD⁺. Results also show that the anti-inflammatory activity of thymoquinone was abolished when the expressions of AMPK and SIRT1 were suppressed by RNAi or pharmacological antagonists. Pharmacological antagonism of AMPK reversed thymoquinone-induced increase in SIRT1. Taken together, we propose that thymoquinone inhibits cellular ROS generation in LPS-activated BV2 microglia. It is also suggested that activation of both AMPK and NAD⁺/SIRT1 may contribute to the anti-inflammatory, but not antioxidant activity of the compound in BV2 microglia.

Inhibition of neuroinflammation in BV2 microglia by the biflavonoid kolaviron is dependent on the Nrf2/ARE antioxidant protective mechanism

Kolaviron is a mixture of biflavonoids found in the nut of the West African edible seed Garcinia kola, and it has been reported to exhibit a wide range of pharmacological activities. In this study, we investigated the effects of kolaviron in neuroinflammation. The effects of kolaviron on the expression of nitric oxide/inducible nitric oxide synthase (iNOS), prostaglandin E2 (PGE2)/cyclooxygenase-2, cellular reactive oxygen species (ROS) and the pro-inflammatory cytokines were examined in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Molecular mechanisms of the effects of kolaviron on NF-κB and Nrf2/ARE signalling pathways were analysed by immunoblotting, binding assays and reporter assays. RNA interference was used to investigate the role of Nrf2 in the anti-inflammatory effect of kolaviron. Neuroprotective effect of kolaviron was assessed in a BV2 microglia/HT22 hippocampal neuron co-culture. Kolaviron inhibited the protein levels of NO/iNOS, PGE2/COX-2, cellular ROS and the pro-inflammatory cytokines (TNFα and IL-6) in LPS-stimulated microglia. Further mechanistic studies showed that kolaviron inhibited neuroinflammation by inhibiting IκB/NF-κB signalling pathway in LPS-activated BV2 microglia. Kolaviron produced antioxidant effect in BV2 microglia by increasing HO-1 via the Nrf2/antioxidant response element pathway. RNAi experiments revealed that Nrf2 is needed for the anti-inflammatory effects of kolaviron. Kolaviron protected HT22 neurons from neuroinflammation-induced toxicity. Kolaviron inhibits neuroinflammation through Nrf2-dependent mechanisms. This compound may therefore be beneficial in neuroinflammation-related neurodegenerative disorders.

Picralima nitida seeds suppress PGE2 production by interfering with multiple signalling pathways in IL-1β-stimulated SK-N-SH neuronal cells

ETHNOPHARMACOLOGICAL RELEVANCE

The dried seed of Picralima nitida is used in rheumatic fever and as an antipyretic in West Africa. In this study we have investigated the effects of an extract obtained from the seeds of Picralima nitida (PNE) on PGE2 production in IL-1β-stimulated cells.

MATERIALS AND METHODS

Prostaglandin E2 (PGE2) was measured in supernatants of IL-1β-stimulated SK-N-SH cells using enzyme immunoassay (EIA) for PGE2. In Cell ELISA and western blot were used to evaluate the effects of PNE on protein expressions of COX-2, mPGES-1, IκB and IKK. To determine the effect of the extract on NF-κB transactivation, a reporter gene assay was carried out in HEK293 cells stimulated with TNFα. An ELISA was used to measure the roles of p38, ERK1/2 and JNK Mitogen Activated Protein Kinases (MAPKs) on anti-neuroinflammatory actions of PNE.

RESULTS

Results show that PNE significantly inhibited PGE2 production, as well as COX-2 and mPGES-1 protein expressions in IL-1β-stimulated SK-N-SH cells. Molecular targeting experiments showed that PNE interfered with NF-κB signalling pathway through attenuation of TNFα-stimulated NF-κB transcriptional activation in HEK 293 cells. Furthermore, IL-1β-mediated phosphorylation of IκB and IKK were inhibited in SK-N-SH cells. PNE (50-200 μg/ml) also produced significant inhibition of IL-1β-induced p38 MAPK phosphorylation in SK-N-SH cells. However, phosphorylation of ERK1/2 and JNK MAPKs were achieved at 100 and 200 μg/ml of the extract.

CONCLUSIONS

Taken together, these results clearly demonstrate that Picralima nitida suppresses PGE2 production by targeting multiple pathways involving NF-κB and MAPK signalling in IL-1β-stimulated SK-N-SH neuronal cells.

Patients' understanding of how genotype variation affects benefits of tamoxifen therapy for breast cancer

BACKGROUND

CYP2D6 is a critical enzyme in the metabolism of tamoxifen and potentially a key determinant in breast cancer outcomes. Our study examined patients' beliefs about how the CYP2D6 genotype would affect their prognoses.

METHODS

Women enrolled in a pharmacogenomic clinical trial and on tamoxifen for prevention or treatment of breast cancer underwent CYP2D6 genotyping (EM = extensive, IM = intermediate, PM = poor metabolizing alleles). The informed consent said that the purpose of the trial was to examine effects of dose adjustment based on genotype, but that clinical benefits were uncertain. Our embedded sub-study surveyed 320 patients prior to receiving their genotypes. We experimentally manipulated 6 vignettes to describe hypothetical tamoxifen treatment (no or yes) and hypothetical genotype (EM, IM or PM). For each vignette, women gave their perceived recurrence risk (RR; 0-100%).

RESULTS

Women believed that genotype would not affect their RR if they did not take tamoxifen (p = 0.06). However, women believed that if prescribed tamoxifen, genotype would affect their RR (22% if EM, 30% if IM and 40% if PM, p < 0.001).

CONCLUSION

Women believed that extensive tamoxifen metabolizers had better prognoses, despite study materials stating uncertainty about any benefit. The rapidly changing nature of genomic science calls for caution when communicating clinical utility.

Inhibitory effects of St. John's Wort on inflammation: ignored potential of a popular herb

St. John's wort (Hypericum perforatum L., family Hypericaceae) is a flowering herb, which has been used traditionally for decades in Europe and other parts of the world for the treatment of depressive mood disorders. A number of clinical trials support its application in the treatment of depressive mood symptoms. Although not commonly known for this use, St John's wort is also reputed for its usefulness in inflammatory conditions such as sciatica and fibromyalgia. This article discusses evidence from in vitro and in vivo studies supporting a possible use of St. John's wort as an anti-inflammatory remedy, in addition to its well-known antidepressant effects.

Anti-neuroinflammatory properties of synthetic cryptolepine in human neuroblastoma cells: possible involvement of NF-κB and p38 MAPK inhibition

Cryptolepis sanguinolenta and its bioactive alkaloid, cryptolepine have shown anti-inflammatory activity. However, the underlying mechanism of anti-inflammatory action in neuronal cells has not been investigated. In the present study we evaluated an extract of C. sanguinolenta (CSE) and cryptolepine (CAS) on neuroinflammation induced with IL-1β in SK-N-SH neuroblastoma cells. We then attempted to elucidate the mechanisms underlying the anti-neuroinflammatory effects of CAS in SK-N-SH cells. Cells were stimulated with 10 U/ml of IL-1β in the presence or absence of different concentrations of CSE (25-200 μg/ml) and CAS (2.5-20 μM). After 24 h incubation, culture media were collected to measure the production of PGE2 and the pro-inflammatory cytokines (TNFα and IL-6). Protein and gene expressions of cyclooxygenase (COX-2) and microsomal prostaglandin synthase-1 (mPGES-1) were studied by immunoblotting and qPCR, respectively. CSE produced significant (p < 0.05) inhibition of TNFα, IL-6 and PGE2 production in SK-N-SH cells. Studies on CAS showed significant and dose-dependent inhibition of TNFα, IL-6 and PGE2 production in IL-1β-stimulated cells without affecting viability. Pre-treatment with CAS (10 and 20 μM) was also found to inhibit IL-1β-induced protein and gene expressions of COX-2 and mPGES-1. Further studies to determine the mechanism of action of CAS showed inhibition of NF-κBp65 nuclear translocation, but not IκB phosphorylation. At 10 and 20 μM, CAS inhibited IL-1β-induced phosphorylation of p38 MAPK. Studies on the downstream substrate of p38, MAPK-activated protein kinase 2 (MAPKAPK2) showed that CAS produced significant (p < 0.05) and dose dependent inhibition of MAPKAPK2 phosphorylation in IL-1β-stimulated SK-N-SH cells. This study clearly shows that cryptolepine (CAS) inhibits neuroinflammation through mechanisms involving inhibition of COX-2 and mPGES-1. It is suggested that these actions are probably mediated through NF-κB and p38 signalling.

Mechanisms of anti-inflammatory property of Anacardium occidentale stem bark: inhibition of NF-κB and MAPK signalling in the microglia

ETHNOPHARMACOLOGICAL RELEVANCE

Anacardium occidentale is used in traditional African medicine for the treatment of arthritis, fever, aches, pains, and inflammation of the extremities.

AIM OF THE STUDY

In this study, we investigated the molecular mechanisms responsible for anti-inflammatory effects of a stem bark extract of A. occidentale (ANE) in LPS-stimulated microglia.

MATERIALS AND METHODS

Nitric oxide (NO), prostaglandin E(2) and cytokine (TNFα and IL-6) production were evaluated in supernatants from LPS-stimulated BV-2 cells. Cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and microsomal prostaglandin E2 synthase (mPGES-1) protein expressions in rat primary microglia were measured using western blot. The effects of ANE on NF-κB activation and nuclear translocation were evaluated in the luciferase reporter gene assay and ELISA, while ability of ANE to influence IκB phosphorylation was determined using ELISA specific for phospho-IκB. The involvement of MAPK phosphorylation in the anti-inflammatory actions of ANE was evaluated using specific ELISA for phospho-p38, phospho-p42/44 and phospho-JNK. The MTT assay was used to determine the effect of ANE on BV-2 microglia viability.

RESULTS

ANE (25-100 μg/ml) produced significant (p<0.05) reduction in the production of NO, PGE(2), TNFα and IL-6 in BV-2 microglia stimulated with LPS for 24h. Pre-treatment with ANE caused a significant (p<0.05) inhibition of COX-2, iNOS and mPGES-1 protein expressions in the rat primary microglia. Further experiments showed that ANE inhibited COX-2 and iNOS protein expression via IκB-mediated nuclear translocation and transactivation of NF-κB. Our studies also revealed that ANE produced significant (p<0.05) and dose-dependent inhibition of p38, p42/44 and JNK MAPK phosphorylation in LPS-activated BV-2 microglia.

CONCLUSIONS

We conclude that ANE has an anti-inflammatory property related to inhibition of inflammation-associated cytokine production as well as iNOS and COX-2 gene expression by blocking NF-κB and MAPK pathways in the microglia. It is also suggested that mPGES-1 inhibition contributes to the effect of ANE on PGE(2) production in the microglia.

Mangiferin inhibits cyclooxygenase-2 expression and prostaglandin E2 production in activated rat microglial cells

Mangiferin, a naturally occurring glucosylxanthone, has potent antioxidant and anti-inflammatory properties, as demonstrated in several reports. However, very limited information is available on the effects of this natural polyphenol on microglial activation. Thus, the aim of this study was to examine whether mangiferin is able to reduce prostaglandin E(2) (PGE(2)) and 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) production by lipopolysaccharide (LPS)-activated primary rat microglia. Microglial cells were stimulated with 10ng/ml of LPS in the presence or absence of different concentrations of mangiferin (1-50 microM). After 24h incubation, culture media were collected to measure the production of PGE(2) and 8-iso-PGF(2alpha) using enzyme immunoassays. Protein levels of cyclooxygenase (COX)-1 and COX-2 were studied by immunoblotting after 24h of incubation with LPS. Mangiferin potently reduced LPS-induced PGE(2) synthesis and the formation of 8-iso-PGF(2alpha). Interestingly, mangiferin dose-dependently reduced LPS-induced COX-2 protein synthesis without modifying COX-2 transcription. This was due to a decrease in COX-2 transcript stability. However, mangiferin did not modify LPS-mediated phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), a key factor involved in enhancing COX-2 mRNA stability and COX-2 translation in primary microglia. Mangiferin had no effects on LPS-induced expression of inducible nitric oxide synthase (iNOS) or TNF-alpha production. Taken together, results from the present study indicate that mangiferin is able to limit microglial activation, in terms of attenuation of PGE(2) production, free radical formation and reduction in COX-2 synthesis induced by LPS. These data suggest that modulation of microglial activation might contribute to the mechanism of cerebral protection by mangiferin.

Antinociceptive effect of Russelia equisetiformis leave extracts: identification of its active constituents

This study examines the antinociceptive effect of the whole plant extracts of Russelia equisetiformis. The result shows the ethylacetate fraction to be the most active, while the dichloromethane fraction exhibited least activity. The major isolated compound from the ethylacetate showed a tremendous activity on acetic acid induced writhing with less activity on tail-flick response in mice. The structures of the two compounds were assigned on the basis of spectroscopic data. Occurrence of these compounds in Russelia is reported here for the first time, and the results confirm the traditional uses of R. equisetiformis in the treatment of inflammation and pain.

Central nervous system depressant activity of Russelia equisetiformis

The central nervous system depressant activity of the crude methanol extract (REC) and fractions (RE1, RE2, and RE3) of Russelia equisetiformis were evaluated in mice using the following models: amphetamine-induced stereotypy, picrotoxin-induced convulsion and phenobarbitone sleeping time. At 200-400 mg/kg, REC significantly increased phenobarbitone-sleeping time [P < 0.05] in a dose- dependent manner and also reduced the sleep latency significantly [P < 0.05]. The fractions, at doses 1.5 mg/kg for RE1 and 20 mg/kg for RE2 and RE3 also significantly prolonged Phenobarbitone sleeping time and sleep latency [P < 0.05]. Picrotoxin-induced convulsion was not prevented by 100-400 mg/kg of REC but this dose range significantly prolonged seizure latency. A significant reduction [P < 0.05] in amphetamine-induced stereotype behavior was observed with 200 mg/kg REC, but there was no protection against amphetamine-induced mortality. The results of this study suggest that Russelia equisetiformis methanol extract possesses central nervous system depressant activities.

Synthetic cryptolepine inhibits DNA binding of NF-κB

The alkaloid cryptolepine is thought to mediate the anti-inflammatory effects of the climbing shrub, Cryptolepis sanguinoleta. The underlying mechanism of action, however, is largely unknown. In the present study, we show that the synthetic cryptolepine-hydrochloride (2.5-10microM) dose-dependently inhibits lipopolysaccharide (LPS)-induced nitric oxide production in the murine macrophage cell line RAW 264.7. We furthermore demonstrate a strong inhibition of nuclear factor (NF)-kappaB, a transcription factor primarily involved in inflammatory and immune responses, by cryptolepine (2.5-10microM) using a luciferase reporter gene assay in human HEK 293 cells. Examining the individual steps of NF-kappaB activation in the presence of cryptolepine we could exclude an inhibitory effect on degradation of IkappaB or nuclear translocation of NF-kappaB by the alkaloid. However, EMSA of nuclear extracts from LPS-activated RAW cells revealed reduced DNA binding activity of NF-kappaB by cryptolepine in vivo and in vitro. This indicates that cryptolepine may exhibit its anti-inflammatory action by blocking DNA binding of activated NF-kappaB and thus transcription of NF-kappaB-regulated proinflammatory proteins.

Evaluation of the anti-inflammatory and analgesic properties of the extract of Russelia equisetiformis (Schlecht & Cham) Scrophulariacae

A methanolic extract of Russelia equisetiformis whole plant was studied for anti-inflammatory and analgesic activities in rats and mice using carrageenan-induced rat paw oedema, acetic-acid-induced writhing and tail-flick test. The extract, at 10, 20 and 40 mg/kg, significantly (P <0.05) inhibited carrageenan-induced oedema in rats. Abdominal constriction induced by acetic acid was also inhibited by the extract, within the same dose range. The extract at the same dose also prolonged the latency period in the tail-flick response test, which was reverted by naloxone. The results suggested that the extract possesses potential anti-inflammatory and analgesic properties.

Effects of Anacardium occidentale stem bark extract on in vivo inflammatory models

The methanol extract of Anacardium occidentale stem bark was evaluated for activities against the lipopolysaccharide (LPS)-induced septic shock, as well as LPS-induced microvascular permeability in mice. Pre-treatment with Anacardium occidentale extract (25-200 mg/kg) caused a dose-dependent and significant (p < 0.05) reduction in the elevated levels of alanine and aspartate aminotransferases in the sera of D-galactosamine-primed mice injected with LPS. The highest dose of the extract studied (200 mg/kg) produced a 100% protection against death from sepsis. Pentoxifylline (100 mg/kg) and L-NAME (5 mg/kg) offered 100% protection against LPS-induced septic shock, and produced marked reduction in elevated levels of transferases. A dose-related inhibition of LPS-induced microvascular permability in mice was also produced by pentoxifylline, L-NAME and the extract.

Evaluation of the anti-inflammatory property of the extract of Combretum micranthum G. Don (Combretaceae)

A methanol extract of Combretum micranthum leaves was studied for anti-inflammatory activity in rats and mice using the carrageenan-induced rat paw oedema and the acetic acid-induced vascular permeability in mice. The effect of the extract on cellular-type inflammation was also investigated in the cotton pellet granuloma in rats. The extract (50, 100 mg/kg) significantly (P < 0.05) inhibited oedema production induced by carrageenan in rats. Increased vascular permeability caused by acetic acid injection was also inhibited by the extract, within the same dose range. C. micranthum extract (100 mg/kg) inhibited granuloma formation in rats to a similar degree as indomethacin (5 mg/kg). These results provide evidence for the anti-inflammatory property of C. micranthum leaves.

Anti-inflammatory studies on Adenanthera pavonina seed extract

A methanol extract of the seeds of Adenanthera pavonina was evaluated for pharmacological effects in animal models. The extract (50-200 mg/kg) produced statistically significant (P < 0.05) inhibition of the carrageenan-induced paw oedema in the rat, as well as the acetic-acid-induced vascular permeability in mice. At doses of 100 and 200 mg/kg, pleurisy induced with carrageenan was also inhibited. The extract (50-200 mg/kg) exhibited a dose-dependent and significant (P < 0.05) analgesic activity in the acetic-induced writhing in mice. In addition, both early and late phases of the formalin-induced paw licking in mice was inhibited by the extract. Acute toxicity studies revealed that the extract produced reduced motor activity. The LD50 value of the extract was found to be 1.36 g/kg. This study demonstrated the anti-inflammatory and analgesic effects of A. pavonina extract.

Anti-inflammatory properties of Bridelia ferruginea stem bark. Inhibition of lipopolysaccaride-induced septic shock and vascular permeability

The anti-inflammatory activity of the aqueous extract of Bridelia ferruginea stem bark was further evaluated in models which are mediated by tumour necrosis factor-alpha (TNFalpha). The effect of the extract on lipopolysaccharide (LPS)-induced septic shock was evaluated by measuring the number of deaths and the levels of serum alanine and aspartate aminotransferases following intraperitoneal injection of LPS (1 microg/kg) into D-galactosamine-primed mice. LPS-induced vascular permeability on the back skin of mice was measured by the local accumulation of Evan's blue after subcutaneous injection of LPS. Pre-treatment with Bridelia ferruginea extract (10-80 mg/kg) produced a dose-dependent inhibition of the septic shock syndrome in mice, with 80 mg/kg of the extract exhibiting comparable activity as pentoxifylline (100 mg/kg). LPS-induced dye leakage in the skin of mice was also suppressed by the extract (10-80 mg/kg). Our study suggests that one of the mechanisms of the anti-inflammatory effects of Bridelia ferruginea possibly involve the suppression of TNFalpha up-regulation.

Antiinflammatory property of the leaves of Gongronema latifolium

An aqueous extract of the dried leaves of Gongronema latifolium was studied for its antiinflammatory activity. The extract significantly (p < 0.05) inhibited carrageenan-induced rat paw oedema, carrageen-induced leucocyte migration in rats and dye leakage induced by intraperitoneal injection of acetic acid in mice. These results demonstrate the antiinflammatory property of G. latifolium.

Studies on the anti-inflammatory properties of Entada abyssinica

The defatted methanolic extract of Entada abyssinica was evaluated for anti-inflammatory activity in acute and chronic models of inflammation. The extract (50--200 mg/kg, p.o.) exhibited dose-dependent and significant inhibition of both the carrageenan-induced rat paw oedema and granuloma tissue formation in rats. The extract (50--200 mg/kg, p.o.) was also found to inhibit the acetic acid-induced vascular permeability in a dose-dependent fashion in mice. This study demonstrated the anti-inflammatory activity of Entada abyssinica.

Evaluation of the anti-inflammatory and analgesic properties of Chasmanthera dependens leaf methanol extract

A methanol extract of the dried leaves of Chasmanthera dependens was investigated for anti-inflammatory and analgesic activities. The extract (100--400 mg/kg, p.o.) produced dose-related inhibition of carrageenan-induced paw oedema and cotton pellet-induced granuloma in rats. Furthermore, an inhibition in the leakage of Evan's blue induced by acetic acid was observed in mice. At same doses, analgesic effect was also observed on writhing response induced by acetic acid as well as on the early and late phase of formalin-induced paw licking in mice.

Studies on the anti-inflammatory, antipyretic and analgesic properties of Alstonia boonei stem bark

The methanol extract of the stem bark of Alstonia boonei was investigated for anti-inflammatory property. The analgesic and antipyretic properties of the extract was also evaluated. The extract caused a significant (P<0.05) inhibition of the carrageenan-induced paw oedema, cotton pellet granuloma, and exhibited an anti-arthritic activity in rats. Vascular permeability induced by acetic acid in the peritoneum of mice was also inhibited. The extract also produced marked analgesic activity by reduction of writhings induced by acetic acid, as well as the early and late phases of paw licking in mice. A significant (P<0.05) reduction in hyperpyrexia in mice was also produced by the extract. This study has established anti-inflammatory, analgesic and antipyretic activities of the stem bark of A. boonei.

Studies on the anti-inflammatory and related pharmacological properties of the aqueous extract of Bridelia ferruginea stem bark

The anti-inflammatory profile of the aqueous extract of Bridelia ferruginea stem bark was investigated using both in vivo and in vitro models. The extract exhibited strong topical anti-inflammatory effect shown as inhibition of croton oil-induced ear oedema in mice, and reduced hind-paw swelling and growth retardation in the adjuvant-induced arthritis model in rats, following oral administration at 10, 20, 40 or 80 mg/kg. The extract (10-80 mg/kg, p.o.) caused an inhibition of increase in vascular permeability in both cyclophosphamide-induced haemorrhagic cystitis and acetic acid-induced vascular permeability in rats and mice, respectively. B. ferruginea produced stabilization of erythrocytes exposed to heat and stress-induced lysis. Antipyretic and analgesic properties of the extract were also observed.

Evaluation of the anti-diabetic property of Morinda lucida leaves in streptozotocin-diabetic rats

The hypoglycaemic and anti-hyperglycaemic activities of a methanol extract of Morinda lucida Benth. (Rubiaceae) leaves were studied in normal and streptozotocin-diabetic rats. In normal rats, the extract demonstrated a significant (P < 0.05) and dose-dependent hypoglycaemic activity within 4 h after oral administration. The plasma glucose level of 400 mg kg(-1) of the extract at 4 h was 42.5 +/- 0.4 mg/100 mL (control 67.4 +/- 1.2 mg/100 mL). After 12 h, the plasma glucose level of rats administered 50, 100, 200 or 400 mg kg(-1) extract fell to 51.9 +/- 1.2, 47.3 +/- 0.8, 43.1 +/- 0.4 and 40.0 +/- 0.5 mg/100 mL, respectively. In hyperglycaemic rats, the extract produced a significant (P < 0.05) anti-diabetic effect from day 3 after oral administration, with 400 mg kg(-1) extract-treated animals having a plasma glucose level of 248.7 +/- 5.3 mg/100 mL compared with glibenclamide (10 mg kg(-1))-treated animals with a plasma glucose level of 251.5 +/- 5.8 mg/100 mL. These results suggest that the leaves of Morinda lucida have a strong glucose lowering property when administered to streptozotocin-treated rats.

Central nervous system depressant effect of Hoslundia opposita vahl

The chloroform extract of the dried root of Hoslundia opposita has been evaluated for effects on the central nervous system (CNS). The extract significantly potentiated the phenobarbitone sleeping time in mice and produced a 60% protection against leptazol-induced convulsion. Neuropharmacological screening revealed CNS depression.

Effects of the aqueous extract of Bridelia ferruginea stem bark on carrageenan-induced oedema and granuloma tissue formation in rats and mice

The anti-inflammatory activity of the aqueous extract of the stem bark of Bridelia ferruginea was evaluated using carrageenan-induced paw oedema in rats and mice, and the cotton pellet granuloma method. The extract at doses ranging from 10 to 80 mg/kg p.o. significantly inhibited the carrageenan-induced rat paw oedema, with an ID50 value of 36 mg/kg. However, a low activity was produced in the mouse paw oedema. The extract also suppressed the granulomatous tissue formation of chronic inflammation. B. ferruginea therefore proved to be effective in both the acute and chronic phases of the inflammatory process.

Biological effects of Myristica fragrans (nutmeg) extract

The chloroform extract of nutmeg has been evaluated for antiinflammatory, analgesic and antithrombotic activities in rodents. The extract inhibited the carrageenan-induced rat paw oedema, produced a reduction in writhings induced by acetic acid in mice and offered protection against thrombosis induced by ADP/adrenaline mixture in mice.

Investigation of the effects of selected medicinal plants on experimental thrombosis

Six medicinal plants indigenous to Africa were evaluated for their activity on experimental thrombosis in mice. Of the plants screened, the extract of Commiphora molmol exhibited the strongest antithrombotic activity, while the extract of Ageratum conyzoides showed no marked activity. This study established the antithrombotic effect of the extracts of Azadiractha indica, Bridelia ferruginea, Commiphora molmol, Garcinia kola and Curcuma longa.