Wogonin but not Nor-wogonin inhibits lipopolysaccharide and lipoteichoic acid-induced iNOS gene expression and NO production in macrophages

Protective effect of wogonin on inflammatory responses in BisGMA-treated macrophages through the inhibition of MAPK and NFκB pathways

Composites, resins, and sealants that are commonly used in orthopedics and dentistry are based on 2,2-bis[p-(2'-hydroxy-3'-methacryloxypropoxy)phenylene]propane (BisGMA), which induces proinflammatory responses in macrophages. The present study aimed to explore the anti-inflammatory responses of wogonin, which is a natural dihydroxyl flavonoid compound, in BisGMA-treated macrophages. According to the findings, wogonin exhibits anti-inflammatory, antiallergic, anticancer, and antioxidative properties. The generation of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) were noted to be inhibited by wogonin in BisGMA-treated macrophages. Furthermore, the production of proinflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 was reduced. In addition, BisGMA-induced nuclear factor (NF)-κB p65 phosphorylation and inhibitor of κB (IκB) degradation were inhibited. Finally, the BisGMA-induced phosphorylation of mitogen-activated protein kinases (MAPKs), including p38 MAPK, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) was inhibited. All these effects were induced by wogonin in the macrophages in a concentration-dependent manner. Similar inhibitory effects of wogonin were observed on the production of NO and proinflammatory cytokines, expression of iNOS, phosphorylation of NF-κB p65 and MAPK, and degradation of IκB. These results indicated that rutin is a potential anti-inflammatory agent for BisGMA-treated macrophages that undergo NFκB p65 phosphorylation and IκB degradation through upstream MAPK phosphorylation. Therefore, wogonin inhibits BisGMA-induced proinflammatory responses in macrophages through the regulation of the NFκB pathway and its upstream factor, MAPK.

Structure-Activity Relationship (SAR) of Flavones on Their Anti-Inflammatory Activity in Murine Macrophages in Culture through the NF-κB Pathway and c-Src Kinase Receptor

Flavones benefit human health through their anti-inflammatory activity; however, their structure-activity relationship is unclear. Herein, we selected 15 flavones with the same backbone but different substituents and systematically assessed their anti-inflammatory activities in RAW 264.7 regarding cellular-Src kinase (c-Src) affinity, suppression of IκBα phosphorylation, inhibition of nitric oxide (NO) and inducible nitric oxidase (iNOS) production, and downregulation of genes of proinflammatory cytokines interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor α (TNF-α). Overall, our results showed that the double bond between C2-C3 and C3'- and C4'-OH promoted anti-inflammatory activity, while C8- and C5'-OH and the methoxy group on C4' attenuated the overall anti-inflammatory and antioxidant activities. The hydroxyl groups at other positions exhibited more complicated functions. The two most effective flavones are 3',4'-dihydroxyflavone and luteolin with inhibitory concentration (IC₅₀) values for inhibiting the LPS-induced nitric oxide level are 9.61 ± 1.36 and 16.90 ± 0.74 μM, respectively. Furthermore, they suppressed the production of iNOS by approximately 90% and inhibited IL-1β and IL-6 by more than 95%. Taken together, our results established a relationship between the flavone structure and anti-inflammatory activity in vitro.

Anti-Inflammation Activity of Flavones and Their Structure-Activity Relationship

Flavones are an important class of bioactive constituents in foods, and their structural diversity enables them to interact with different targets. In particular, flavones are known for their anti-inflammatory activity. Herein, we summarized commonly applied in vitro, in vivo, and clinical models in testing anti-inflammatory activity of flavones. The anti-inflammatory structure-activity relationship of flavones was systematically mapped and supported with cross comparisons of that with flavanones, flavanols, and isoflavones. Hydroxyl groups (-OH) are indispensable for the anti-inflammatory function of flavones, and -OH at the C-5 and C-4' positions enhance while -OH at the C-6, C-7, C-8, and C-3' positions attenuate their activity. Moreover, the C2-C3 single bond, -OH at the C-3 and B-ring positions undermine flavone aglycones' activity. Most of the flavone aglycones function through NF-κB, MAPK, and JNK-STAT pathways, and their possible cell binding targets are kinase, aryl hydrocarbon receptor (AhR), G-protein coupled receptors, and estrogen receptors. However, the structure and anti-inflammatory activity relationship of flavones were unclear, and further research shall be conducted to close the gap in order to guide development of evidence-based functional foods.

Norwogonin attenuates hypoxia-induced oxidative stress and apoptosis in PC12 cells

Background

Norwogonin is a natural flavone with three phenolic hydroxyl groups in skeletal structure and has excellent antioxidant activity. However, the neuroprotective effect of norwogonin remains unclear. Here, we investigated the protective capacity of norwogonin against oxidative damage elicited by hypoxia in PC12 cells.

Methods

The cell viability and apoptosis were examined by MTT assay and Annexin V-FITC/PI staining, respectively. Reactive oxygen species (ROS) content was measured using DCFH-DA assay. Lactate dehydrogenase (LDH), malondialdehyde (MDA) and antioxidant enzyme levels were determined using commercial kits. The expression of related genes and proteins was measured by real-time quantitative PCR and Western blotting, respectively.

Results

We found that norwogonin alleviated hypoxia-induced injury in PC12 cells by increasing the cell viability, reducing LDH release, and ameliorating the changes of cell morphology. Norwogonin also acted as an antioxidant by scavenging ROS, reducing MDA production, maintaining the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and decreasing the expression levels of HIF-1α and VEGF. In addition, norwogonin prevented cell apoptosis via inhibiting the expression levels of caspase-3, cytochrome c and Bax, while increasing the expression levels of Bcl-2 and the ratio of Bcl-2/Bax.

Conclusions

Norwogonin attenuates hypoxia-induced injury in PC12 cells by quenching ROS, maintaining the activities of antioxidant enzymes, and inhibiting mitochondrial apoptosis pathway.

Anti-Inflammatory Activity and Mechanism of Isookanin, Isolated by Bioassay-Guided Fractionation from Bidens pilosa L

Bidens pilosa L. (Asteraceae) has been used historically in traditional Asian medicine and is known to have a variety of biological effects. However, the specific active compounds responsible for the individual pharmacological effects of Bidens pilosa L. (B. pilosa) extract have not yet been made clear. This study aimed to investigate the anti-inflammatory phytochemicals obtained from B. pilosa. We isolated a flavonoids-type phytochemical, isookanin, from B. pilosa through bioassay-guided fractionation based on its capacity to inhibit inflammation. Some of isookanin’s biological properties have been reported; however, the anti-inflammatory mechanism of isookanin has not yet been studied. In the present study, we evaluated the anti-inflammatory activities of isookanin using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We have shown that isookanin reduces the production of proinflammatory mediators (nitric oxide, prostaglandin E₂) by inhibiting the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. Isookanin also inhibited the expression of activator protein 1 (AP-1) and downregulated the LPS-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-jun NH₂-terminal kinase (JNK) in the MAPK signaling pathway. Additionally, isookanin inhibited proinflammatory cytokines (tumor necrosis factor-a (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1β (IL-1β)) in LPS-induced THP-1 cells. These results demonstrate that isookanin could be a potential therapeutic candidate for inflammatory disease.

Rutin prevents inflammation induced by lipopolysaccharide in RAW 264.7 cells via conquering the TLR4-MyD88-TRAF6-NF-κB signalling pathway

OBJECTIVES

Inflammation widely exists in many diseases and poses a great threat to human and animal health. Rutin, quercetin-3-rhamnosyl glucoside, has a variety of pharmacological effects, including anti-oxidant, anti-inflammatory, antibacterial, anticancer and radioresistance effects. The current study focused on evaluation of its anti-inflammatory activity and described the mechanism of rutin in lipopolysaccharide-induced RAW 264.7 cells.

METHODS

The related gene and protein expression levels were investigated by quantification real-time PCR and western blotting, respectively.

KEY FINDINGS

This study revealed that rutin can decrease inducible nitric oxide synthase (iNOS) gene and protein expression levels, effectively increase IκB gene expression, reduce toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), tumour necrosis factor receptor-associated factor 6 (TRAF6) and p65 gene expression and inhibit the phosphorylation of IκB and p65 and the proteins expression of TLR4, MyD88 and TRAF6.

CONCLUSIONS

These results suggest that rutin might exert anti-inflammatory effect on LPS-stimulated RAW 264.7 cells and will be potentially useful as an adjuvant treatment for inflammatory diseases.

The main bioactive compounds of Scutellaria baicalensis Georgi. for alleviation of inflammatory cytokines: A comprehensive review

Scutellaria baicalensis Georgi., a plant used in traditional Chinese medicine, has multiple biological activities, including anti-inflammatory, antiviral, antitumor, antioxidant, and antibacterial effects, and can be used to treat respiratory tract infections, pneumonia, colitis, hepatitis, and allergic diseases. The main active substances of S. baicalensis, baicalein, baicalin, wogonin, wogonoside, and oroxylin A, can act directly on immune cells such as lymphocytes, macrophages, mast cells, dendritic cells, monocytes, and neutrophils, and inhibit the production of the inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α, and other inflammatory mediators such as nitric oxide, prostaglandins, leukotrienes, and reactive oxygen species. The molecular mechanisms underlying the immunomodulatory and anti-inflammatory effects of the active compounds of S. baicalensis include downregulation of toll-like receptors, activation of the Nrf2 and PPAR signaling pathways, and inhibition of the nuclear thioredoxin system and inflammation-associated pathways such as those of MAPK, Akt, NFκB, and JAK-STAT. Given that in addition to the downregulation of cytokine production, the active constituents of S. baicalensis also have antiviral and antibacterial effects, they may be more promising candidate therapeutics for the prevention of infection-related cytokine storms than are drugs having only antimicrobial or anti-inflammatory activities.

Systems Pharmacology Based Strategy for Q-Markers Discovery of HuangQin Decoction to Attenuate Intestinal Damage

The quality control research of traditional Chinese medicine (TCM) is lagged far behind the space of progress in modernization and globalization. Thus the concept of quality marker (Q-marker) was proposed recently to guide the quality investigations of TCM. However, how to discover and validate the Q-marker is still a challenge. In this paper, a system pharmacology based strategy was proposed to discover Q-marker of HuangQin decoction (HQD) to attenuate Intestinal Damage. Using this strategy, nine measurable compounds including paeoniflorin, baicalin, scutellarein, liquiritigenin, norwogonin, baicalein, glycyrrhizic acid, wogonin, and oroxylin A were screened out as potential markers. Standard references of these nine compounds were pooled together as components combination according to their corresponding concentration in HQD. The bioactive equivalence between components combination and HQD was validated using wound healing test and inflammatory factor determination experiment. The comprehensive results indicated that components combination is almost bioactive equivalent to HQD and could serve as the Q-markers. In conclusion, our study put forward a promising strategy for Q-markers discovery.

Extraction Process, Component Analysis, and In Vitro Antioxidant, Antibacterial, and Anti-Inflammatory Activities of Total Flavonoid Extracts from Abutilon theophrasti Medic. Leaves

The flavonoid fraction was extracted from the leaves of Abutilon theophrasti Medic., which are usually used as a traditional Chinese herbal medicine for the treatment of inflammation and joint pain. The current study focused on the extraction process, component analysis, and in vitro antioxidant, antibacterial, and anti-inflammatory activities of the flavonoid fraction as a part of ongoing research on bioactive substances from natural plant sources. This study evaluated the antioxidant activities via assays of DPPH radical scavenging capacity, ABTS radical scavenging capacity, and reducing power and investigated inhibitory activities against Escherichia coli, Salmonella, Staphylococcus aureus, and Streptococcus. Moreover, the inflammatory activity of the flavonoid fraction was estimated by measurement of the content of tumor necrosis factor alpha, interleukin-1-beta, interleukin-6, interleukin-10, nitric oxide, and cyclooxygenase-2 and the gene expression levels of several inflammation markers, such as inducible nitric oxide synthase and cyclooxygenase-2, in RAW 264.7 macrophages after LPS treatment. In addition, the underlying anti-inflammatory mechanisms, that is, the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways, were also revealed from the gene and protein expression levels. Taken together, these results suggested that the flavonoid fraction might exert in vitro antioxidant, antibacterial, and anti-inflammatory effects on LPS-stimulated RAW 264.7 macrophages and will be potentially useful as an adjuvant treatment for oxidative stress and bacterial and inflammatory diseases.

Heat-Processed Scutellariae Radix Protects Hepatic Inflammation through the Amelioration of Oxidative Stress in Lipopolysaccharide-Induced Mice

The present study evaluated the effects of heat-processed Scutellariae Radix (Scutellaria baicalensis) on lipopolysaccharide (LPS)-induced liver injury in mice. Scutellariae Radix heat-processed at 160[Formula: see text]C or 180[Formula: see text]C was orally administered at a dose of 100 mg/kg body weight for three days before the intraperitoneal injection of LPS, and the effects were compared with those of vehicle-treated LPS administered to control mice. The administration of Scutellariae Radix decreased the elevated serum monocyte chemotactic protein-1 (MCP-1), interleukin-6 (IL-6), reactive oxygen species (ROS), nitrite/nitrate, peroxynitrite, and hepatic functional parameters, and reduced the increased ROS in the liver. The augmented expressions of hepatic oxidative stress and inflammation-related proteins, phospho-p38, phosphorylated extracellular signal-regulated kinase, phosphorylated c-Jun N-terminal kinase, nuclear factor-[Formula: see text] B p65, activator protein-1, cyclooxygenase-2, inducible nitric oxide synthase, MCP-1, intercellular adhesion molecule-1, tumor necrosis factor-[Formula: see text], and IL-6, were downregulated by the heat-processed Scutellariae Radix. Hematoxylin-eosin staining showed that the increased hepatocellular damage in the liver of LPS-treated mice improved with the administration of heat-processed Scutellariae Radix. Overall, the ameliorative effects of Scutellariae Radix were superior to those when heat-processed at 180[Formula: see text]C. Our results indicate that heat-processed Scutellariae Radix acts as an anti-inflammatory agent by ameliorating oxidative stress in the liver of mice with LPS-induced liver injury.

4'-Hydroxywogonin suppresses lipopolysaccharide-induced inflammatory responses in RAW 264.7 macrophages and acute lung injury mice

4'-Hydroxywogonin (4'-HW), a flavonoid, has been isolated from various plants and shown to inhibit NO production in macrophages. However, the molecular mechanisms and its in vivo activity have not been determined. Our study aimed to investigate the mechanisms underlying the anti-inflammatory effects of 4'-HW in vitro and in vivo. We showed that 4'-HW potently reduced the expression levels of COX-2 and iNOS as well as their products, prostaglandin E2 (PGE2) and nitric oxide (NO) respectively, in LPS-stimulated RAW 264.7 macrophages. 4'-HW also suppressed LPS-induced pro-inflammatory cytokines at mRNA and protein levels. Moreover, 4'-HW blocked the interaction of TAK1 and TAB1 in LPS-stimulated RAW 264.7 macrophages, resulting in an inhibition of the TAK1/IKK/NF-κB signaling pathway. Furthermore, 4'-HW also reduced the phosphorylation of MAPKs and PI3/Akt signaling pathways in LPS-stimulated RAW 264.7 macrophages. 4'-HW was also significantly decreased the intracellular reactive oxygen species (ROS) level. The effect of 4'-HW was confirmed in vivo. 4'-HW exhibited potent protective effect against LPS-induced ALI in mice. These findings indicate that 4'-HW suppresses the LPS-induced response in vitro and in vivo. It is likely that the inhibition of the TAK1/IKK/NF-κB, MAPKs and PI3/AKT signaling pathways contribute to the anti-inflammatory effects of 4'-HW. Our study suggests that 4'-HW may be an important functional constituent in the plants and has the potential value to be developed as a novel anti-inflammatory agent.

Wogonin suppresses inflammatory response and maintains intestinal barrier function via TLR4-MyD88-TAK1-mediated NF-κB pathway in vitro

AIMS AND OBJECTIVE

Wogonin has multiple pharmacological effects, including anti-inflammatory effects. Here, we hypothesize that wogonin can protect intestinal barrier function in lipopolysaccharide (LPS)-induced Caco-2 cells, which is an in vitro model of intestinal inflammation.

METHODS

We measured intestinal barrier function in LPS-induced Caco-2 cells by using transepithelial electrical resistance (TEER) and transport of fluorescent markers. A quantitative (q) RT-PCR and immunofluorescent staining analysis was used to detect the expression of tight junction proteins (claudin-1 and ZO-1) in LPS-induced Caco-2 cells. We measured inflammatory molecules in LPS-induced Caco-2 cells using ELISA and qRT-PCR. In addition, the expression of TLR4, MyD88 and TAK1 and their interaction, and NF-κB activity in LPS-induced Caco-2 cells were investigated by western blot analysis and immune-precipitation.

RESULTS

We found that exposing Caco-2 cells to wogonin (10 and 50 μM for 24 h) attenuated the LPS-induced changes in TEER and transport of fluorescent markers. In addition, wogonin suppressed LPS-induced down-regulation of tight junction proteins (claudin-1 and ZO-1). Furthermore, LPS-induced up-regulation of inflammatory mediators, including interleukin (IL)-1β, IL-6 and IL-8, cyclooxygenase-2 (COX-2), inducible nitric oxide synthases (iNOS) were reduced after being pre-treated with wogonin. Moreover, wogonin not only inhibited the expression of TLR4, MyD88 and TAK1 and the interaction between these molecules, but also reduced NF-κB translocation to nucleus and its DNA-binding activity in LPS-induced Caco-2 cells.

CONCLUSION

Our results suggested that pre-treatment with wogonin could attenuate the TLR4-mediated inflammatory response and maintain intestinal barrier function in LPS-induced Caco-2 cells, thus might be a potential therapy for treating IBD.

Wogonin inhibits LPS-induced inflammatory responses in rat dorsal root ganglion neurons via inhibiting TLR4-MyD88-TAK1-mediated NF-κB and MAPK signaling pathway

Recent studies showed that the activation of toll-like receptor 4 (TLR4) on dorsal root ganglion (DRG) neurons might underlie neuropathic and inflammatory pain states. This study was undertaken to investigate the effects of wogonin, a flavonoid with potent anti-inflammatory properties on the inflammatory reaction and TLR4 dependent pathways in lipopolysaccharide (LPS)-treated DRG neurons. Our results showed that wogonin not only inhibited the expression and interaction of TLR4, MyD88, and TAK1, but also reduced the activation of nuclear factor kappa B and mitogen-activated protein kinases pathway in LPS-treated DRG neurons. Moreover, wogonin significantly suppressed the release of pro-inflammatory mediators in LPS-induced DRG neurons, including cyclooxygenase-2, inducible nitric oxide synthases, interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha. Our results suggested that pre-treatment with wogonin could attenuate the TLR4-mediated inflammatory response in LPS-induced DRG neurons, thus might be beneficial for the treatment of neuropathic and inflammatory pain.

Genkwanin inhibits proinflammatory mediators mainly through the regulation of miR-101/MKP-1/MAPK pathway in LPS-activated macrophages

Genkwanin is one of the major non-glycosylated flavonoids in many herbs with anti-inflammatory activities. Although its anti-inflammatory activity in vivo has been reported, the potential molecular mechanisms remain obscure. In this study, by pharmacological and genetic approaches, we explore the anti-inflammatory effects of genkwanin in LPS-activated RAW264.7 macrophages. Genkwanin potently decreases the proinflammatory mediators, such as iNOS, TNF-α, IL-1β and IL-6, at the transcriptional and translational levels without cytotoxicity, indicating the excellent anti-inflammatory potency of genkwanin in vitro. Mechanism study shows that genkwanin significantly suppresses the p38- and JNK-mediated AP-1 signaling pathway and increases the mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) expression at the posttranscriptional level. We also confirmed that microRNA-101 (miR-101) is a negative regulator of MKP-1 expression. Moreover, regardless of miR-101-deficient cells or miR-101-abundant cells, the suppression effects of genkwanin on supernatant proinflammatory mediators' levels are far less than that in respective negative control cells, suggesting that genkwanin exerts anti-inflammatory effect mainly through reducing miR-101 production. However, genkwanin can't affect the level of phospho-Akt (p-Akt), indicating that the phosphorylation of Akt may be not responsible for the effect of genkwanin on miR-101 production. We conclude that genkwanin exerts its anti-inflammatory effect mainly through the regulation of the miR-101/MKP-1/MAPK pathway.

Myricetin blocks lipoteichoic acid-induced COX-2 expression in human gingival fibroblasts

Periodontitis is an infectious disease caused by microorganisms present in dental bacterial plaque. Lipoteichoic acid (LTA) is a component of the external membrane of Gram-positive bacteria. It causes septic shock. Ingested flavonoids have been reported to directly affect the regulation of cyclooxygenase-2 (COX-2) expression induced by bacterial toxins. In this study, we examined the effects of four flavonoids (luteolin, fisetin, morin and myricetin) on the activation of ERK1/2, p38 and AKT, and on the synthesis of COX-2 in human gingival fibroblasts treated with LTA from Streptococcus sanguinis. We found that luteolin and myricetin blocked AKT and p38 activation and that myricetin blocked LTA-induced COX-2 expression. The results of our study are important for elucidating the mechanism of action of flavonoid regulation of inflammatory responses.

Pharmacological effects of active compounds on neurodegenerative disease with gastrodia and uncaria decoction, a commonly used poststroke decoction

Neurodegenerative diseases refer to the selective loss of neuronal systems in patients. The diseases cause high morbidity and mortality to approximately 22 million people worldwide and the number is expected to be tripled by 2050. Up to now, there is no effective prevention and treatment for the neurodegenerative diseases. Although some of the clinical therapies target at slowing down the progression of symptoms of the diseases, the general effectiveness of the drugs has been far from satisfactory. Traditional Chinese medicine becomes popular alternative remedies as it has been practiced clinically for more than thousands of years in China. As neurodegenerative diseases are mediated through different pathways, herbal decoction with multiple herbs is used as an effective therapeutic approach to work on multiple targets. Gastrodia and Uncaria Decoction, a popular TCM decoction, has been used to treat stroke in China. The decoction contains compounds including alkaloids, flavonoids, iridoids, carotenoids, and natural phenols, which have been found to possess anti-inflammatory, antioxidative, and antiapoptotic effects. In this review, we will summarize the recent publications of the pharmacological effects of these five groups of compounds. Understanding the mechanisms of action of these compounds may provide new treatment opportunities for the patients with neurodegenerative diseases.

Protective effect of wogonin on proinflammatory cytokine generation via Jak1/3-STAT1/3 pathway in lipopolysaccharide stimulated BV2 microglial cells

Wogonin is a flavonoid compound which exhibits antioxidation, anti-inflammation, neuroprotection, and antitumorgenesis functions. However, the mechanism of how wogonin reduces proinflammatory cytokine generation in activated microglia is unclear. At present, we found wogonin inhibited lipopolysaccharide (LPS)-/interferon-γ (INF-γ)-induced generation of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Wogonin exhibited parallel inhibition on LPS-/INF-γ-induced expression of IL-6 and TNF-α messenger RNA at the same concentration range. LPS-/INF-γ-induced phosphorylation of signal transduction and transcription 1 and 3 (STAT1/3) were also inhibited by wogonin. Although wogonin expressed only weak inhibitory effect on LPS-/INF-γ-induced phosphorylation of Janus kinase-2 (Jak-2) and tyrosine kinase (Tyk)-2, it significantly attenuated the phosphorylation of Jak-1 and Jak-3. These results indicated that the blockade of IL-6 and TNF-α production by wogonin in LPS-/INF-γ-stimulated BV2 microglial cells was attributed mainly to the interference in Jak-1/-3-STAT1/3 signaling pathway.

Wogonin induces reactive oxygen species production and cell apoptosis in human glioma cancer cells

Glioma is the most common primary adult brain tumor with poor prognosis because of the ease of spreading tumor cells to other regions of the brain. Cell apoptosis is frequently targeted for developing anti-cancer drugs. In the present study, we have assessed wogonin, a flavonoid compound isolated from Scutellaria baicalensis Georgi, induced ROS generation, endoplasmic reticulum (ER) stress and cell apoptosis. Wogonin induced cell death in two different human glioma cells, such as U251 and U87 cells but not in human primary astrocytes (IC 50 > 100 μM). Wogonin-induced apoptotic cell death in glioma cells was measured by propidine iodine (PI) analysis, Tunnel assay and Annexin V staining methods. Furthermore, wogonin also induced caspase-9 and caspase-3 activation as well as up-regulation of cleaved PARP expression. Moreover, treatment of wogonin also increased a number of signature ER stress markers glucose-regulated protein (GRP)-78, GRP-94, Calpain I, and phosphorylation of eukaryotic initiation factor-2α (eIF2α). Treatment of human glioma cells with wogonin was found to induce reactive oxygen species (ROS) generation. Wogonin induced ER stress-related protein expression and cell apoptosis was reduced by the ROS inhibitors apocynin and NAC (N-acetylcysteine). The present study provides evidence to support the fact that wogonin induces human glioma cell apoptosis mediated ROS generation, ER stress activation and cell apoptosis.

Wogonin improves histological and functional outcomes, and reduces activation of TLR4/NF-κB signaling after experimental traumatic brain injury

Background

Traumatic brain injury (TBI) initiates a neuroinflammatory cascade that contributes to neuronal damage and behavioral impairment. This study was undertaken to investigate the effects of wogonin, a flavonoid with potent anti-inflammatory properties, on functional and histological outcomes, brain edema, and toll-like receptor 4 (TLR4)- and nuclear factor kappa B (NF-κB)-related signaling pathways in mice following TBI.

Methodology/Principal Findings

Mice subjected to controlled cortical impact injury were injected with wogonin (20, 40, or 50 mg·kg⁻¹) or vehicle 10 min after injury. Behavioral studies, histology analysis, and measurement of blood-brain barrier (BBB) permeability and brain water content were carried out to assess the effects of wogonin. Levels of TLR4/NF-κB-related inflammatory mediators were also examined. Treatment with 40 mg·kg⁻¹ wogonin significantly improved functional recovery and reduced contusion volumes up to post-injury day 28. Wogonin also significantly reduced neuronal death, BBB permeability, and brain edema beginning at day 1. These changes were associated with a marked reduction in leukocyte infiltration, microglial activation, TLR4 expression, NF-κB translocation to nucleus and its DNA binding activity, matrix metalloproteinase-9 activity, and expression of inflammatory mediators, including interleukin-1β, interleukin-6, macrophage inflammatory protein-2, and cyclooxygenase-2.

Conclusions/Significance

Our results show that post-injury wogonin treatment improved long-term functional and histological outcomes, reduced brain edema, and attenuated the TLR4/NF-κB-mediated inflammatory response in mouse TBI. The neuroprotective effects of wogonin may be related to modulation of the TLR4/NF-κB signaling pathway.

Effects of flavonoids and other polyphenols on inflammation

Flavonoids are a family of polyphenolic compounds which are widespread in nature (vegetables) and are consumed as part of the human diet in significant amounts. There are other types of polyphenols, including, for example, tannins and resveratrol. Flavonoids and related polyphenolic compounds have significant antiinflammatory activity, among others. This short review summarizes the current knowledge on the effects of flavonoids and related polyphenolic compounds on inflammation, with a focus on structural requirements, the mechanisms involved, and pharmacokinetic considerations. Different molecular (cyclooxygenase, lipoxygenase) and cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) have been identified. In addition, many flavonoids display significant antioxidant/radical scavenging properties. There is substantial structural variation in these compounds, which is bound to have an impact on their biological profile, and specifically on their effects on inflammatory conditions. However, in general terms there is substantial consistency in the effects of these compounds despite considerable structural variations. The mechanisms have been studied mainly in myeloid cells, where the predominant effect is an inhibition of NF-κB signaling and the downregulation of the expression of proinflammatory markers. At present there is a gap in knowledge of in vitro and in vivo effects, although the pharmacokinetics of flavonoids has advanced considerably in the last decade. Many flavonoids have been studied for their intestinal antiinflammatory activity which is only logical, since the gastrointestinal tract is naturally exposed to them. However, their potential therapeutic application in inflammation is not restricted to this organ and extends to other sites and conditions, including arthritis, asthma, encephalomyelitis, and atherosclerosis, among others.

Aciculatin inhibits lipopolysaccharide-mediated inducible nitric oxide synthase and cyclooxygenase-2 expression via suppressing NF-κB and JNK/p38 MAPK activation pathways

OBJECTIVES

Natural products have played a significant role in drug discovery and development. Inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) have been suggested to connect with various inflammatory diseases. In this study, we explored the anti-inflammatory potential of aciculatin (8-((2R,4S,5S,6R)-tetrahydro-4,5-dihydroxy-6-methyl-2H-pyran-2-yl)-5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-4H-chromen-4-one), one of main components of Chrysopogon aciculatis, by examining its effects on the expression and activity of iNOS and COX-2 in lipopolysaccharide (LPS)-activated macrophages.

METHODS

We used nitrate and prostaglandin E2 (PGE2) assays to examine inhibitory effect of aciculatin on nitric oxide (NO) and PGE2 levels in LPS-activated mouse RAW264.7 macrophages and further investigated the mechanisms of aciculatin suppressed LPS-mediated iNOS/COX-2 expression by western blot, RT-PCR, reporter gene assay and confocal microscope analysis.

RESULTS

Aciculatin remarkably decreased the LPS (1 μg/mL)-induced mRNA and protein expression of iNOS and COX-2 as well as their downstream products, NO and PGE2 respectively, in a concentration-dependent manner (1-10 μM). Such inhibition was found, via immunoblot analyses, reporter gene assays, and confocal microscope observations that aciculatin not only acts through significant suppression of LPS-induced NF-κB activation, an effect highly correlated with its inhibitory effect on LPS-induced IκB kinase (IKK) activation, IκB degradation, NF-κB phosphorylation, nuclear translocation and binding of NF-κB to the κB motif of the iNOS and COX-2 promoters, but also suppressed phosphorylation of JNK/p38 mitogen-activated protein kinases (MAPKs).

CONCLUSION

Our results demonstrated that aciculatin exerts potent anti-inflammatory activity through its dual inhibitory effects on iNOS and COX-2 by regulating NF-κB and JNK/p38 MAPK pathways.

The flavonoids luteolin and quercetagetin inhibit lipoteichoic acid actions on H9c2 cardiomyocytes

Dental focal infections are infections in the mouth that cause subsequent infection and symptoms in other parts of the body. Dental conditions such as periodontitis have been associated with coronary heart disease. In this study, we investigated the effect of flavonoids on activation of mitogen-activated protein kinase (MAPK) family members, protein kinase B (AKT), and IL-1 beta expression by rat heart embryonic (H9c2) cells upon stimulation with LTA. Pretreatment with four flavonoids, including quercetin, genistein, quercetagetin, and luteolin diminished LTA-induced ERK1/2, JNK, p38, and AKT phosphorylation and IL-1 beta gene expression. Our findings indicate that flavonoids interfere with LTA signal transduction.