Luteolin and luteolin-7-O-glucoside inhibit lipopolysaccharide-induced inflammatory responses through modulation of NF-κB/AP-1/PI3K-Akt signaling cascades in RAW 264.7 cells

Free Radical Scavenging Principles of Salvia reuterana Boiss. Aerial Parts

Salvia reuterana Boiss. is an aromatic perennial plant traditionally used for its anxiolytic and sedative properties. In the present study, various fractions and essential oil of S. reuterana aerial parts were investigated to find its free radical scavenging principles. Hydroalcoholic fraction with IC₅₀ value of 112.6 ±3.2 μg mL^-1 in DPPH assay demonstrated the highest free radical scavenging activity and was selected to further phytochemical investigation. RP-18 and Sephadex LH-20 column chromatography of the hydroalcoholic fraction resulted in the isolation and structural elucidation of four phenolic derivatives, including apigenin-7-O-β-D-glucopyranoside (1), luteolin-7-O-β-D-glucopyranoside (2), rosmarinic acid (3), and luteolin (4). Isolated compounds showed potent free radical scavenging activities (5.1-34.2 μg mL^-1), compared with BHT (21.30 ± 1.9 μg mL^-1). Twenty four compounds were also identified in GC-MS analysis of the plant essential oil, of which benzyl benzoate (26.64%), n-hexyl benzoate (22.99%) and n-hexyl isovalerate (6.04%) were the main compounds. The results of the present study introduced S. reuterana as a valuable source of natural phenolic antioxidants which can be utilized in prevention of oxidative stress related diseases. Moreover, interesting composition of S. reuterana essential oil, dominated by non-terpenes compounds (76.17%) especially aromatic derivatives, make it an appropriate candidate for more detailed studies.

Luteolin and luteolin-7-O-glucoside protect against acute liver injury through regulation of inflammatory mediators and antioxidative enzymes in GalN/LPS-induced hepatitic ICR mice

BACKGROUND/OBJECTIVES

Anti-inflammatory and antioxidative activities of luteolin and luteolin-7-O-glucoside were compared in galactosamine (GalN)/lipopolysaccharide (LPS)-induced hepatitic ICR mice.

MATERIALS/METHODS

Male ICR mice (6 weeks old) were divided into 4 groups: normal control, GalN/LPS, luteolin, and luteolin-7-O-glucoside groups. The latter two groups were administered luteolin or luteolin-7-O-glucoside (50 mg/kg BW) daily by gavage for 3 weeks after which hepatitis was induced by intraperitoneal injection of GalN and LPS (1 g/kg BW and 10 µg/kg BW, respectively).

RESULTS

GalN/LPS produced acute hepatic injury by a sharp increase in serum AST, ALT, and TNF-α levels, increases that were ameliorated in the experimental groups. In addition, markedly increased expressions of cyclooxygenase (COX)-2 and its transcription factors, nuclear factor (NF)-κB and activator protein (AP)-1, were also significantly attenuated in the experimental groups. Compared to luteolin-7-O-glucoside, luteolin more potently ameliorated the levels of inflammatory mediators. Phase II enzymes levels and NF-E2 p45-related factor (Nrf)-2 activation that were decreased by GalN/LPS were increased by luteolin and luteolin-7-O-glucoside administration. In addition, compared to luteolin, luteolin-7-O-glucoside acted as a more potent inducer of changes in phase II enzymes. Liver histopathology results were consistent with the mediator and enzyme results.

CONCLUSION

Luteolin and luteolin-7-O-glucoside protect against GalN/LPS-induced hepatotoxicity through the regulation of inflammatory mediators and phase II enzymes.

Relative protective activities of quercetin, quercetin-3-glucoside, and rutin in alcohol-induced liver injury

Alcoholic liver diseases has been known to be one of the major health risks worldwide. The purpose of this study was aimed to demonstrate the relative protective effect of quercetin, quercetin-3-glucoside, and rutin on alcohol-induced damage in hepatocytes. The hepatotoxicity, antioxidant enzymatic defense mechanisms, and pro-inflammatory mediators were examined for evaluating the hepatoprotective effects of quercetins in hepG2 cells. The results revealed that quercetin and its glucoside derivatives significantly prevented ethanol-induced hepatotoxicity by decreasing hepatic aminotransferase activities and inflammatory response in HepG2 cells. Moreover, the quercetins significantly induced detoxifying enzymes via the nuclear accumulation of the NF-E2-related factor 2 (Nrf2) and induction of antioxidant response element (ARE) gene. These hepatoprotective activities were observed to be more effective with quercetin aglycone than quercetin glucosides. From the above findings, the present study imply that quercetin aglycone may have a vital function in the therapeutic and preventive strategies of alcoholic liver diseases. PRACTICAL APPLICATIONS: Quercetin is commonly present in fruits and vegetables as aglycone and glucoside-derived forms. In the present study, quercetin and its glycosides was shown to alleviate oxidative stress, glutathione depletion, and pro-inflammatory cytokines in alcohol-induced HepG2 cells via the Nrf2/ARE antioxidant pathway. Moreover, quercetin aglycone had better protective effects against alcohol-induced liver damage in vitro, compared to its glycosylated form. The present study proposed that quercetin aglycone may be a more efficient hepatoprotective agent than its glucoside derivatives such as rutin in the amelioration of alcohol-induced liver diseases.

Protective effects of luteolin on injury induced inflammation through reduction of tissue uric acid and pro-inflammatory cytokines in rats

Background and aim

Luteolin belongs to flavone group of flavonoids, present in many plants with potent antioxidant, anti-inflammatory and anti-proliferative effects. The objective of present study was to investigate protective effect of luteolin on injury induced inflammation via Monosodium urate (MSU) crystals induced and Acetaminophen (AMP) induced liver injury in rats.

Experimental procedure

Protective effect of luteolin was observed by measurement of rat paw edema, lysosomal enzymes, antioxidants status and cytokine level. Measurement of uric acid level and neutrophil infiltration were done in AMP induced liver injury in rats. Luteolin was tested at 30 and 50 mg/kg doses and compare with colchicine.

Results and conclusion

Luteolin significantly decreases paw edema in dose dependent manner compare to control group in MSU crystal-induced rats. Luteolin (50 mg/kg) was showed significant decrease in serum level of oxidative and lysosomal enzymes, proinflammatory cytokines i.e. tumor necrosis factor (TNF)-α (39.28 ± 3.17), interleukin (IL)-1β (12.07 ± 1.24), and IL-6 (24.72 ± 2.52) in MSU crystal-induced rats. In AMP induced liver injury, tissue uric acid level and myeloperoxidase were decreased significantly after treatment with luteolin as well as N-acetylcysteine. Serum level of liver enzymes was significantly reduced after treatment with luteolin. Histological observation of ankle joints and liver was support to protective effect of luteolin at both doses. In conclusion, luteolin showed anti-inflammatory effect through restoration of cytokine level, lysosomal enzymes level and antioxidants status. The reduction of liver tissue uric acid content may be one of the mechanisms for protective effect of luteolin. It can contribute to reduce injury induced inflammation.

Aspalathus linearis (Rooibos) - a functional food targeting cardiovascular disease

Increasing consumer bias toward natural products and the considerable wealth of indigenous knowledge has precipitated an upturn in market-driven research into potentially beneficial medicinal plants. In this context, Aspalathus linearis (Rooibos) has been identified to be a promising candidate which may impact cardiovascular disease (CVD), which is one of the most widely studied chronic diseases of modern times. Despite these efforts, ischemic heart disease remains the number one cause of mortality globally. Apart from genetic predisposition and other aetiological mechanisms specific to particular types of CVD, co-factors from interlinked systems contribute significantly to disease development and the severity of its clinical manifestation. The bioactivity of Rooibos is directed towards multiple therapeutic targets. Experimental data to date include antioxidant, anti-inflammatory and anti-diabetic effects, as well as modulatory effects in terms of the immune system, adrenal steroidogenesis and lipid metabolism. This review integrates relevant literature on the therapeutic potential of Rooibos in the context of CVD, which is currently the most common of non-communicable diseases. The therapeutic value of whole plant extracts versus isolated active ingredients are addressed, together with the potential for overdose or herb-drug interaction. The body of research undertaken to date clearly underlines the benefits of Rooibos as both preventative and complementary therapeutic functional food in the context of CVD.

Development of a Cell-Based High-Throughput Screening Assay to Identify Porcine Host Defense Peptide-Inducing Compounds

Novel alternatives to antibiotics are needed for the swine industry, given increasing restrictions on subtherapeutic use of antibiotics. Augmenting the synthesis of endogenous host defense peptides (HDPs) has emerged as a promising antibiotic-alternative approach to disease control and prevention. To facilitate the identification of HDP inducers for swine use, we developed a stable luciferase reporter cell line, IPEC-J2/PBD3-luc, through permanent integration of a luciferase reporter gene driven by a 1.1 kb porcine β-defensin 3 (PBD3) gene promoter in porcine IPEC-J2 intestinal epithelial cells. Such a stable reporter cell line was employed in a high-throughput screening of 148 epigenetic compounds and 584 natural products, resulting in the identification of 41 unique hits with a minimum strictly standardized mean difference (SSMD) value of 3.0. Among them, 13 compounds were further confirmed to give at least a 5-fold increase in the luciferase activity in the stable reporter cell line, with 12 being histone deacetylase (HDAC) inhibitors. Eight compounds were subsequently observed to be comparable to sodium butyrate in inducing PBD3 mRNA expression in parental IPEC-J2 cells in the low micromolar range. Six HDAC inhibitors including suberoylanilide hydroxamine (SAHA), HC toxin, apicidin, panobinostat, SB939, and LAQ824 were additionally found to be highly effective HDP inducers in a porcine 3D4/31 macrophage cell line. Besides PBD3, other HDP genes such as PBD2 and cathelicidins (PG1–5) were concentration-dependently induced by those compounds in both IPEC-J2 and 3D4/31 cells. Furthermore, the antibacterial activities of 3D4/31 cells were augmented following 24 h exposure to HDAC inhibitors. In conclusion, a cell-based high-throughput screening assay was developed for the discovery of porcine HDP inducers, and newly identified HDP-inducing compounds may have potential to be developed as alternatives to antibiotics for applications in swine and possibly other animal species.

Anti-inflammatory effects of luteolin: A review of in vitro, in vivo, and in silico studies

ETHNOPHARMACOLOGICAL RELEVANCE

Luteolin (3', 4', 5,7-tetrahydroxyflavone) has been identified as commonly present in plants. Plants with a high luteolin content have been used ethnopharmacologically to treat inflammation-related symptoms. Both isolated luteolin and extracts from luteolin-rich plants have been studied using various models and exhibited anti-inflammatory activity.

AIM OF THE REVIEW

This paper uses recent research findings with a broad range of study models to describe the anti-inflammatory activity of luteolin, particularly its mechanisms at the molecular level; provide guidance for future research; and evaluate the feasibility of developing luteolin into an anti-inflammatory drug.

MATERIALS AND METHODS

We summarize reports about the anti-inflammatory activity of luteolin published since 2009, which we found in MEDLINE/PubMed, Scopus, Web of Knowledge, and Google Scholar. To acquire broad information, we extended our search to online FDA documents.

RESULTS

Luteolin is a flavonoid commonly found in medicinal plants and has strong anti-inflammatory activity in vitro and in vivo. Some of its derivatives, such as luteolin-7-O-glucoside, have also shown anti-inflammatory activity. The action mechanism of luteolin varies, but Src in the nuclear factor (NF)-κB pathway, MAPK in the activator protein (AP)- 1 pathway, and SOCS3 in the signal transducer and activator of transcription 3 (STAT3) pathway are its major target transcription factors. A clinical trial with a formulation containing luteolin showed excellent therapeutic effect against inflammation-associated diseases.

CONCLUSION

In silico, in vitro, in vivo, and clinical studies strongly suggest that the major pharmacological mechanism of luteolin is its anti-inflammatory activity, which derives from its regulation of transcription factors such as STAT3, NF-κB, and AP-1. Much work remains to ensure the safety, quality, and efficacy of luteolin before it can be used to treat inflammation-related diseases in humans.

Luteolin suppresses the JAK/STAT pathway in a cellular model of intestinal inflammation

Current treatment strategies for inflammatory bowel diseases (IBDs) are associated with a lower efficacy and with several side effects that strongly affect the quality of life of IBD patients. Consequently, the development of new therapies, combining efficacy and safety is an important goal in the field of intestinal inflammation. In this context, evidence supports that polyphenols can be promising candidates due to their ability to modulate intracellular inflammatory signalling cascades. Luteolin, a naturally occurring flavonoid, exhibits anti-inflammatory properties in several models of inflammation. However, its action against intestinal inflammation has been poorly explored. Therefore, there is a lack of scientific knowledge about the potential impact of luteolin in the intestinal inflammation, particularly regarding the underlying molecular mechanisms by which luteolin can exert its anti-inflammatory action. We assessed the potential anti-inflammatory effect of luteolin in a cellular model of intestinal inflammation using cytokine-stimulated HT-29 colon epithelial cells, and the underlying key molecular mechanisms were identified. Luteolin significantly inhibited interleukine-8 (IL-8) production, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression and nitric oxide (˙NO) overproduction induced by cytokines, indicating that luteolin negatively modulates key inflammatory signalling cascades underlying intestinal inflammation. Mechanistically, the inhibition of the JAK/STAT pathway was identified as a critical mechanism by which luteolin exerts its intestinal anti-inflammatory action. This study uncovers novel molecular mechanisms by which luteolin may act against intestinal inflammation, which might support the use of luteolin as a future therapeutic strategy in IBD.

Insights into the importance of dietary chrysanthemum flower (Chrysanthemum morifolium cv. Hangju)-wolfberry (Lycium barbarum fruit) combination in antioxidant and anti-inflammatory properties

Dietary chrysanthemum flower and wolfberry alone or together are widely consumed as a health beverage on a daily basis for centuries. The study aims to evaluate combinative effects of flower heads of Chrysanthemum morifolium cv. Hangju (C) and Lycium barbarum fruit (wolfberry, W) served as tea on chemical compounds, antioxidant and anti-inflammatory activities in RAW 264.7 macrophages. Eight phenolics were mainly detected in chrysanthemum flowers, whereas polysaccharides were dominant in wolfberry. The infusion of five combinations showed significantly antioxidant activities positively associated with the chrysanthemum flower content in chemical methods (ORAC and FRAP). However, the cellular-based CAA assay exhibited the highest antioxidant activities of the infusion at C:W = 1:1, indicating a synergistic interaction (CI = 0.11, P < .01). Additionally, the anti-inflammatory effect of infusion, specifically at a combination of C:W = 1:1, was observed by reducing the LPS-induced nitric oxide production, and inhibiting the expression of iNOS, TNF-α, IL-1β, and IL-6 mRNA (P < .05). The infusion prepared at a C:W = 1:1 was found to inactivate MAPKs (ERK and JNK) and NF-κB. The antioxidant and anti-inflammatory mechanisms might be attributed to acacetin-7-O-rutinoside, luteolin-7-O-glucoside and chlorogenic acid from chrysanthemum flower, and wolfberry polysaccharide via multiple inflammatory pathways.

Suppressive effects of Vochysia divergens aqueous leaf extract and its 5-methoxyflavone on murine macrophages and lymphocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Vochysia divergens Pohl (Vochysiaceae), popularly known as "Cambará", is a tree that is resistant to the seasonal floods in the Pantanal, and usually found in monodominant stands called "Cambarazal". The inhabitants of the Pantanal exploit this tree for medicinal uses. Infusions and decoctions of its leaves are taken as teas, particularly for the treatment of asthma, flu and diarrhea, according to the local tradition transmitted empirically through the generations.

AIM OF THE STUDY

To evaluate the beneficial health effects related to the ethnomedicinal uses of V. divergens (Vd) by using biomonitored fractionation of an aqueous leaf extract.

MATERIALS AND METHODS

The aqueous leaf extract was obtained by decoction, and then the extract was fractionated by a combination of separation techniques including precipitation, organic partition and chromatography. Chromatographic analyses of the active samples were carried out using HPLC-DAD-MS. Flavonoid 1 was isolated from the n-BuOH fraction through classic chromatographic techniques. The inhibitory effects and cytotoxicity of the Vd extract, fractions and flavonoid 1 on NO and TNF-α production were assessed in LPS-stimulated RAW 264.7 macrophage cultures. Additionally, suppression on the proliferation of BALB/c lymphocytes was estimated by [³H] thymidine incorporation. The antioxidant activity of the samples was verified by SNP and DPPH assays and the suppression of the iNOS protein expression was evaluated through Western blotting.

RESULTS

The HPLC-DAD-MS analysis of the Vd extract led to the identification of 5-methoxyluteolin-7-O-β-glucopyranoside (2), rutin (4) and the tannin galloyl-HHDP-glucopyranoside (3), besides the main flavonoid 3',5-dimethoxyluteolin-7-O-β-glucopyranoside (1), which was biologically evaluated in comparison with luteolin aglycone. The Vd extract, n-BuOH fraction and flavonoid 1 inhibited NO and TNF-α production by LPS-stimulated macrophages. The reduction of NO levels was mediated mainly by suppression of the iNOS expression. In addition, both the Vd extract (IC₅₀ 13.6 µg/mL) and flavonoid 1 (IC₅₀ 19.8 µg/mL; 41.6 µM) strongly inhibited stimulated lymphocyte proliferation when compared to the immunosuppressive agent cyclosporin A (IC₅₀ 43.8 µg/mL; 36.4 µM). The Vd extract also showed a scavenging activity toward DPPH and NO free radicals. This is the first report describing the immunomodulatory potential of V. divergens and its major flavonoid (1).

CONCLUSION

Our findings showed that the aqueous leaf extract of V. divergens and its flavonoid reduced the production of excessive pro-inflammatory markers, collaborating with the Pantanal folk medicinal tradition that recommends the tea of cambará leaves for both asthma and flu. In addition, this study contributes to the knowledge of the pharmacological properties of 5-methoxy flavones, a poorly investigated subclass of flavonoids.

Beneficial Effects of Cynaroside on Cisplatin-Induced Kidney Injury In Vitro and In Vivo

Anti-cancer drugs such as cisplatin and doxorubicin are effectively used more than radiotherapy. Cisplatin is a chemotherapeutic drug, used for treatment of various forms of cancer. However, it has side effects such as ototoxicity and nephrotoxicity. Cisplatin-induced nephrotoxicity increases tubular damage and renal dysfunction. Consequently, we investigated the beneficial effect of cynaroside on cisplatin-induced kidney injury using HK-2 cell (human proximal tubule cell line) and an animal model. Results indicated that 10 μM cynaroside diminished cisplatin-induced apoptosis, mitochondrial dysfunction and caspase-3 activation, cisplatin-induced upregulation of caspase-3/MST-1 pathway decreased by treatment of cynaroside in HK-2 cells. To confirm the effect of cynaroside on cisplatin-induced kidney injury in vivo, we used cisplatin exposure animal model (20 mg/kg, balb/c mice, i.p., once a day for 3 days). Renal dysfunction, tubular damage and neutrophilia induced by cisplatin injection were decreased by cynaroside (10 mg/kg, i.p., once a day for 3 days). Results indicated that cynaroside decreased cisplatin-induced kidney injury in vitro and in vivo, and it could be used for improving cisplatin-induced side effects. However, further experiments are required regarding toxicity by high dose cynaroside and caspase-3/MST-1-linked signal transduction in the animal model.

Kaempferol 7-O-β-D-glucoside isolated from the leaves of Cudrania tricuspidata inhibits LPS-induced expression of pro-inflammatory mediators through inactivation of NF-κB, AP-1, and JAK-STAT in RAW 264.7 macrophages

Kaempferol 7-O-β-D-glucoside (KPG), a natural flavonol isolated from Cudrania tricuspidata, has been reported to exert anti-cancer effects; however, its anti-inflammatory effects have not yet been reported. In this study, we demonstrate the suppressive effect of KPG on the production of nitric oxide (NO), prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and mouse bone marrow-derived macrophages. KPG downregulated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein level and iNOS, COX-2, TNF-α, IL-1β, and IL-6 at the mRNA level in LPS-treated RAW 264.7 macrophages. Moreover, we elucidated the underlying molecular mechanism, demonstrating that KPG attenuated LPS-induced nuclear factor-κB (NF-κB) activation by decreasing p65 nuclear translocation, inhibiting κBα (IκBα) phosphorylation/degradation and IκB kinaseα/β (IKKα/β) phosphorylation. KPG additionally reduced LPS-induced activator protein-1 (AP-1) activity by inhibiting c-Fos expression in the nucleus, though c-Jun was not affected. Furthermore, we revealed that KPG significantly abrogated the LPS-induced phosphorylation of signal transducer and activator of transcription (STAT) 1 (Ser 727, Tyr 701) and STAT3 (Tyr 705) through inhibiting the phosphorylation of Janus kinase (JAK) 1 and JAK2, its upstream activating proteins. Taken together, our data suggest that KPG induces anti-inflammatory activity by blocking NF-κB, AP-1, and JAK-STAT signaling pathways in LPS-treated RAW 264.7 macrophages, thus suppressing inflammatory mediators.

Thermal treatment of luteolin-7-O-β-glucoside improves its immunomodulatory and antioxidant potencies

Phytochemicals extracted from flowers, roots and bark, leaves, and other plant sources have been used extensively throughout human history with varying levels of efficacy in prevention and treatment of disease. Recently, advanced methods for characterization and clinical use of these materials have allowed modern understanding of their properties to be used as immunomodulatory agents that act by enhancement of endogenous cytoprotective mechanisms, avoiding interference with normal physiologic signaling and highly effective medical treatment with minimal adverse side effects. Simple methods have been identified for improving their biological effects, such as thermal conditioning by heating or freezing-prominent example being heat treatment of lycopene and tetrahydrocannabinol. The present investigation shows improvement of the ability of heat to augment splenocyte proliferation, natural killer (NK) cell activities, and antioxidant capacity of the flavonoid luteolin-7-O-β-glucoside (L7G) in comparison with the native (non heat-treated) molecule, while further demonstrating that both the native and the heat-treated variants exhibit comparable antioxidant properties, as evidenced by their effects in macrophages by inhibition of nitric oxide production and lysosomal enzyme activity in experiments that strengthen lysosomal membrane integrity. Outcomes of these studies suggest that heat-treated L7G shows promise for use in immunotherapy, including anti-cancer regimens, as shown by its improvement of NK cell cytotoxicity.

Phenolic Composition, Anti-Inflammatory, Antioxidant, and Antimicrobial Activities of Alchemilla mollis (Buser) Rothm

The current study was designed to evaluate the antioxidant, anti-inflammatory and antimicrobial activities of Alchemilla mollis (Buser) Rothm. (Rosaceae) aerial parts extracts. Chemical composition was analyzed by spectrophotometric and chromatographic (HPLC) techniques. The antioxidant properties assessed included DPPH^· and ABTS^·+ radical scavenging, β-carotene-linoleic acid co-oxidation assay. Antimicrobial activity was evaluated with disc diffusion and micro dilution method. In order to evaluate toxicity of the extracts, with the sulforhodamine B colorimetric assay L929 cell line (mouse fibroblast) was used. The anti-inflammatory activities of the potent antioxidant extracts (methanol, 70% methanol, and water extracts) were determined by measuring the inhibitory effects on NO production and pro-inflammatory cytokine TNF-α levels in lipopolysaccharide stimulated RAW 264.7 cells. 70% methanol and water extracts which were found to be rich in phenolic compounds (184.79 and 172.60 mg GAE/g extract) showed higher antioxidant activity. Luteolin-7-O-glucoside was the main compound in the extracts. Ethyl acetate and 70% methanol extracts showed higher antibacterial activity against Staphylococcus aureus and Salmonella enteritidis with MIC value of 125 μg/ml. 70% methanol extract potentially inhibited the NO and TNF-α production (18.43 μm and 1556.22 pg/ml, respectively, 6 h).

Luteolin, a natural flavonoid, inhibits methylglyoxal induced apoptosis via the mTOR/4E-BP1 signaling pathway

Methylglyoxal (MG) accumulation has been observed in human cerebrospinal fluid and body tissues under hyperglycaemic conditions. Recent research has demonstrated that MG-induces neuronal cell apoptosis, which promotes the development of diabetic encephalopathy. Our previous animal study has shown that luteolin, a natural flavonoid, attenuates diabetes-associated cognitive dysfunction. To further explore the neuroprotective properties of luteolin, we investigated the inhibitive effect of luteolin on MG-induced apoptosis in PC12 neuronal cells. We found that MG inhibited cell viability in a dose-dependent manner and induced apoptosis in PC12 cells. Pretreatment with Luteolin significantly elevated cell viability, reduced MG-induced apoptosis, inhibited the activation of the mTOR/4E-BP1 signaling pathway, and decreased pro-apoptotic proteins, Bax, Cytochrome C as well as caspase-3. Furthermore, we found that pretreatment with the mTOR inhibitor, rapamycin, significantly reduced the expression of the pro-apoptotic protein Bax. Therefore, these observations unambiguously suggest that the inhibitive effect of Luteolin against MG-induced apoptosis in PC12 cells is associated with inhibition of the mTOR/4E-BP1 signaling pathway.

Effects of luteolin and luteolin-morphine co-administration on acute and chronic pain and sciatic nerve ligated-induced neuropathy in mice

Background Neuropathic pain (NP) is a common condition accompanied by nerve injury. To date, there is no definite treatment approved for this disorder. In addition, many drugs that are used for NP cause adverse reactions. Luteolin is a naturally occurring flavonoid with diverse pharmacological properties such as anti-inflammatory, antioxidant and anticancer. We sought to investigate luteolin effects on chronic, acute and neuropathic pain as well as its potential to increase morphine anti-nociceptive effects in mice. Methods Albino mice (20-25 g) were randomly divided into 14 groups (n=7) including morphine 1 mg/kg body weight +luteolin (5 mg/kg body weight), morphine (9 mg/kg body weight, i.p.), luteolin (2.5, 5 and 10 mg/kg body weight), imipramine 40 mg/kg body weight and normal saline (NS) (0.9 %) as vehicle and subjected to hot plate test. Formalin test was done in the following groups: NS, diclofenac sodium (10 mg/kg body weight, i.p.), morphine (9 mg/kg body weight, i.p.) and luteolin (2.5, 5 and 10 mg/kg body weight). Results Administration of luteolin single dose (5 and 10 mg/kg body weight) significantly reduced neuropathic pain ( p<0.05$\rm{p}<0.05$) in comparison to negative control. Anti-nociceptive effects of luteolin were comparable to imipramine as the standard positive control ( p<0.001$\rm{p}<0.001$). Co-administration of luteolin and morphine potentiated morphine 1 mg/kg body weight painkilling effects ( p<0.001$\rm{p}<0.001$). Conclusions Our results showed that luteolin alone reduces neuropathic pain. Furthermore, when co-administered with morphine 1 mg/kg body weight, luteolin potentiates morphine effects. Therefore, luteolin-morphine co-administration might be a valuable alternative for the conventional treatment.

Inhibitory effect of the Pseudobrickellia brasiliensis (Spreng) R.M. King & H. Rob. aqueous extract on human lymphocyte proliferation and IFN-γ and TNF-α production in vitro

Pseudobrickellia brasiliensis (Asteraceae) is a plant commonly known as arnica-do-campo and belongs to the native flora of the Brazilian Cerrado. The alcoholic extract of the plant has been used as an anti-inflammatory agent in folk medicine, but the biological mechanism of action has not been elucidated. The present study evaluated the composition of P. brasiliensis aqueous extract and its effects on pro-inflammatory cytokine production and lymphocyte proliferation. The extracts were prepared by sequential maceration of P. brasiliensis leaves in ethanol, ethyl acetate, and water. Extract cytotoxicity was evaluated by trypan blue exclusion assay, and apoptosis and necrosis were measured by staining with annexin V-FITC and propidium iodide. The ethanolic (ETA) and acetate (ACE) extracts showed cytotoxic effects. The aqueous extract (AQU) was not cytotoxic. Peripheral blood mononuclear cells stimulated with phorbol myristate acetate and ionomycin and treated with AQU (100 μg/mL) showed reduced interferon (IFN)-γ and tumor necrosis factor (TNF)-α expression. AQU also inhibited lymphocyte proliferative response after nonspecific stimulation with phytohemagglutinin. The aqueous extract was analyzed by liquid chromatography coupled with photodiode array detection and mass spectrometry. Quinic acid and its derivatives 5-caffeoylquinic acid and 3,5-dicaffeoylquinic acid, as well as the flavonoids luteolin and luteolin dihexoside, were detected. All these compounds are known to exhibit anti-inflammatory activity. Taken together, these findings demonstrate that P. brasiliensis aqueous extract can inhibit the pro-inflammatory cytokine production and proliferative response of lymphocytes. These effects may be related to the presence of chemical substances with anti-inflammatory actions previously reported in scientific literature.

Potential of rooibos, its major C-glucosyl flavonoids, and Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid in prevention of metabolic syndrome

Risk factors of type 2 diabetes mellitus (T2D) and cardiovascular disease (CVD) cluster together and are termed the metabolic syndrome. Key factors driving the metabolic syndrome are inflammation, oxidative stress, insulin resistance (IR), and obesity. IR is defined as the impairment of insulin to achieve its physiological effects, resulting in glucose and lipid metabolic dysfunction in tissues such as muscle, fat, kidney, liver, and pancreatic β-cells. The potential of rooibos extract and its major C-glucosyl flavonoids, in particular aspalathin, a C-glucoside dihydrochalcone, as well as the phenolic precursor, Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid, to prevent the metabolic syndrome, will be highlighted. The mechanisms whereby these phenolic compounds elicit positive effects on inflammation, cellular oxidative stress and transcription factors that regulate the expression of genes involved in glucose and lipid metabolism will be discussed in terms of their potential in ameliorating features of the metabolic syndrome and the development of serious metabolic disease. An overview of the phenolic composition of rooibos and the changes during processing will provide relevant background on this herbal tea, while a discussion of the bioavailability of the major rooibos C-glucosyl flavonoids will give insight into a key aspect of the bioefficacy of rooibos.

Traditional Chinese Medicine Formula "Xiaofeng granules" suppressed gouty arthritis animal models and inhibited the proteoglycan degradation on chondrocytes induced by monosodium urate

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaofeng Granules (XF) is a kind of granules prepared by the famous traditional Chinese medicine formula for its efficiency in treating gouty diseases.

AIM OF THE STUDY

We investigated the relevance between XF that made from Modified simiaowan (MSW) as the anti-gouty arthritis drugs and protective mechanisms for cartilage matrix in order to provide the evidence for new drug application.

MATERIALS AND METHODS

In the present study, we evaluated the anti-gouty arthritis activity of XF in rats and rabbits models induced by MSU together with chondrocytes focusing on the link to proteoglycan degradation in vitro studies.

RESULTS

The results demonstrated that XF significantly reduced the swelling rate and attenuated the pathological changes in joints. The XF-containing serum were used medicated serum in cellular experiments. The in vitro data were in accordance with the in vivo results, showing that the constituents in XF-containing serum had obvious inhibitory effects on the activation of pro-inflammatory mediators in chondrocytes. Moreover, XF-containing serum substantially inhibited MSU-induced expression of glycosaminoglycans(GAG) and hydroxyproline(Hyp), and up regulated proteoglycan, which might be associated with the regulation of the balance of MMP-3/TIMP-1and ADAMTS-4/TIMP-3 inchondrocytes.

CONCLUSION

In conclusion, XF that made from MSW showed obvious effects on acute gouty arthritis, which also provided an effective protection on cartilage matrix degradation.

Anti-atherogenic effect of Humulus japonicus in apolipoprotein E-deficient mice

Humulus japonicus (HJ) is used as a traditional medicine in Korea owing to its multiple properties including anti-mycobacterial, antioxidant and antihypertensive effects. The present study aimed to examine the anti-inflammatory and anti-atherogenic effects of a methanol extract of HJ. In lipopolysaccharide-stimulated RAW 264.7 cells, HJ significantly suppressed the mRNA expression and secretion of pro-inflammatory cytokines [tumor necrosis factor-α, interleukin (IL)-1β and IL-6)], and the release of inflammatory mediators such as nitrite and prostaglandin E₂, together with a concomitant decrease in the mRNA levels of inducible nitric oxide synthase and cyclooxygenase-2. To examine whether HJ is capable of inhibiting experimental atherogenesis in an animal model, we randomly divided apolipoprotein E-deficient (apoE^−/−) mice into three groups: mice fed an atherogenic diet plus vehicle (0.5% carboxymethyl cellulose) as the control vehicle group, and mice fed an atherogenic diet plus either 100 (HJ100) or 500 mg/kg (HJ500) of HJ as the experimental groups. After 12 weeks of HJ administration, lipid accumulation and the formation of atherosclerotic lesions in the aorta (en face) and the aortic sinus markedly decreased in the HJ500 group compared with the corresponding values in the vehicle control group. Moreover, monocyte and macrophage infiltration in the aortic sinus was markedly reduced in the HJ500 group. Reverse transcription-quantitative polymerase chain reaction analysis of the whole aorta showed that the mRNA levels of intercellular adhesion molecule-1, monocyte chemoattractant protein-1, CD68 and IL-18 were significantly decreased in the HJ500 group. Collectively, these findings suggest that HJ may suppress atherosclerosis by inhibiting lipid accumulation and the expression of pro-atherogenic factors, and it may be effective at preventing the development of atherosclerosis.

Anti-diabetic effects of luteolin and luteolin-7-O-glucoside on KK-A y mice

Anti-diabetic potential of luteolin (LU) and luteolin-7-O-glucoside (LUG) were investigated in the amount of equimolar on KK-Ay mice. The results showed that both of LU and LUG significantly improved blood glucose, HbA1c, insulin, and HOMR-IR levels. Anti-inflammatory and anti-oxidative effects of the LU and LUG were also proved. Furthermore, TGs in serum and liver were significantly decreased in the LU and LUG groups, as well as the mRNA expression of fat acid expression-related genes (SREBP-1c), compared to the basal diet group (CON). When compared the effects between the LU and LUG groups, TGs of the LU group were lower than those of the LUG group, accompanied with significantly decreased FAS activity and SREBP-1c expression in liver. These results suggested that both LU and LUG had positive effects of anti-diabetes on KK-Ay mice, but LU more potently ameliorated diabetes than LUG, which might be attributed to the inhibitory of lipid synthesis.

Metabolic Fate of Luteolin in Rats: Its Relationship to Anti-inflammatory Effect

Luteolin is a naturally occurring flavone that reportedly has anti-inflammatory effects. Because most luteolin is conjugated following intestinal absorption, free luteolin is likely present at low levels in the body. Therefore, luteolin metabolites are presumably responsible for luteolin bioactivity. Here we confirmed that luteolin glucuronides, especially luteolin-3'-O-glucuronide, are the major metabolites found in plasma after oral administration of luteolin (aglycone) or luteolin glucoside (luteolin-7-O-glucoside) to rats. Luteolin-4'-O-glucuronide and luteolin-7-O-glucuronide were also detectable together with luteolin-3'-O-glucuronide in the liver, kidney, and small intestine. Next, we prepared these luteolin glucuronides and compared the anti-inflammatory effects of luteolin and luteolin glucuronides on gene expression in lipopolysaccharide-treated RAW264.7 cells. Luteolin glucuronides, especially luteolin-7-O-glucuronide, reduced expression of inflammatory genes in the cells, although their effects were weaker than those of luteolin. These results indicate that the active compound responsible for the anti-inflammatory effect of luteolin in vivo would be luteolin glucuronide and/or residual luteolin.

Luteolin attenuates endotoxin-induced uveitis in Lewis rats

The aim of the present study was to investigate the efficacy of luteolin on endotoxin-induced uveitis (EIU) in rats. EIU was induced in Lewis rats by subcutaneous injections of lipopolysaccharide (LPS). One hr before the LPS injection, 0.1, 1 or 10 mg/kg luteolin or 1 mg/kg prednisolone was intraperitoneally injected. We investigated its effect upon clinical scores, cellular infiltration and protein leakage, as well as on the level of tumor necrosis factor (TNF)-α, nitric oxide (NO) and prostaglandin (PG) E2 in the aqueous humor (AqH). Histologic examination and immunohistochemical analysis in the iris-ciliary body (ICB) were performed to determine the expressions of cyclooxygenase (COX)-2 and inducible NO synthase (iNOS), and then the activated nuclear factor (NF)-κB p65, I kappa B (IκB)-α degradation, phosphorylated (p)-IκB kinase (IKK) α/β and activator protein (AP)-1 c-Jun. Luteolin suppressed, in a dose-dependent manner, the clinical scores, number of inflammatory cells, the protein concentration, and the TNF-α, NO and PGE2 levels in the AqH and improved the histiologic status of the ocular tissue. Luteolin suppressed the expression of iNOS and COX-2 and the activated NF-κB p65, IκB-α degradation, p-IKKα/β and AP-1 p-c-Jun in the ICB. The anti-inflammatory potency of 10 mg/kg luteolin was as strong as that observed with 1 mg/kg prednisolone. These results demonstrate that luteolin attenuates ocular inflammation by inhibiting expression and release of inflammatory markers, along with the inhibition of the activated NF-κB pathway and at least partly AP-1 activity in the ICB.

The ethyl acetate fraction from Physalis alkekengi inhibits LPS-induced pro-inflammatory mediators in BV2 cells and inflammatory pain in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis alkekengi is an edible herb whose fruit and calyx are traditionally used to treat a wide range of diseases including inflammation, toothache, and rheumatism. However, the effects of Physalis alkekengi fruit along with its calyx (PAF) on neuroinflammation and inflammatory pain behavior have not been reported yet.

AIM OF THE STUDY

This study evaluated the anti-inflammatory effect of PAF on lipopolysaccharide (LPS)-induced neuroinflammation and several in vivo model of inflammatory pain in mice.

MATERIALS AND METHODS

Here, first we studied the effects of PAF fractions on the production of pro-inflammatory mediators in LPS-treated BV2 microglial cells using enzyme-linked immunosorbent assay. The translocation of nuclear factor-kappa B (NF-κB) and the involvements of Akt and mitogen-activated protein (MAP) kinases in ethyl acetate fraction of PAF (PAF-EA)-mediated anti-inflammatory effect were measured using Western blotting. In in vivo experiments, the efficacy of PAF-EA was evaluated at the doses of 100 and 200mg/kg using several chemical-induced models of inflammatory pain such as acetic acid-induced writhing, formalin-induced paw licking and edema.

RESULTS

We found that compared to other fractions, the PAF-EA more potently inhibited the LPS-induced generation of nitric oxide, tumor necrosis factor-α, interleukin-6 and reactive oxygen species. It also inhibited LPS-induced nuclear translocation of NF-κB. These actions of EA fraction were found to be associated with a disruption of Akt and MAP kinases signaling pathways. The EA fraction also significantly inhibited acetic acid-induced writhing, formalin-induced licking time and edema in mice.

CONCLUSIONS

Our findings support the ethnopharmacological use of P. alkekengi fruit along with its calyx as an anti-inflammatory agent and suggest that the EA fraction of PAF may serve as a potential candidate to treat different neurological disorders and pain associated with inflammation.

Flavones Inhibit LPS-Induced Atrogin-1/MAFbx Expression in Mouse C2C12 Skeletal Myotubes

Muscle atrophy is a complex process that occurs as a consequence of various stress events. Muscle atrophy-associated genes (atrogenes) such as atrogin-1/MAFbx and MuRF-1 are induced early in the atrophy process, and the increase in their expression precedes the loss of muscle weight. Although antioxidative nutrients suppress atrogene expression in skeletal muscle cells, the inhibitory effects of flavonoids on inflammation-induced atrogin-1/MAFbx expression have not been clarified. Here, we investigated the inhibitory effects of flavonoids on lipopolysaccharide (LPS)-induced atrogin-1/MAFbx expression. We examined whether nine flavonoids belonging to six flavonoid categories inhibited atrogin-1/MAFbx expression in mouse C2C12 myotubes. Two major flavones, apigenin and luteolin, displayed potent inhibitory effects on atrogin-1/MAFbx expression. The pretreatment with apigenin and luteolin significantly prevented the decrease in C2C12 myotube diameter caused by LPS stimulation. Importantly, the pretreatment of LPS-stimulated myoblasts with these flavones significantly inhibited LPS-induced JNK phosphorylation in C2C12 myotubes, resulting in the significant suppression of atrogin-1/MAFbx promoter activity. These results suggest that apigenin and luteolin, prevent LPS-mediated atrogin-1/MAFbx expression through the inhibition of the JNK signaling pathway in C2C12 myotubes. Thus, these flavones, apigenin and luteolin, may be promising agents to prevent LPS-induced muscle atrophy.

The flesh ethanolic extract of Hylocereus polyrhizus exerts anti-inflammatory effects and prevents murine colitis

BACKGROUND & AIMS

IBD is a chronic disorder of the gastrointestinal tract characterized by mucosal inflammation and epithelial damage. Biologic therapy has significantly improved the course of the disease but there are still a high percentage of patients that do not respond to current therapies. We aim to determine the effects of the flesh ethanolic extract of Hylocereus polyrhizus (EH) in a mice model of colitis induced by TNBS.

METHODS

Balb/c mice received TNBS (175 mg/kg, 100 μl, i.r.) and six and thirty hours later were administered with EH (1 g/kg, i.p.). Mice were weighted daily and after sacrificing (2 and 4 days after TNBS) we analyzed mucosal histology, myeloperoxidase activity (MPO), the expression of pro-inflammatory molecules (qPCR) and NF-κB and Iκβ-α protein levels. The chemical characterization of the EH was determined by LC-MS/MS.

RESULTS

The administration of EH to TNBS-treated mice prevented (P < 0.05) the loss of body weight and significantly reduced in the colon: a) histological damage score, b) MPO enzymatic activity c) the expression of pro-inflammatory molecules and d) Iκβ-α degradation and nuclear NF-κβ protein levels. The LC-MS analysis detected metabolites such as polyphenols and fatty acids.

CONCLUSION

Systemic administration of the ethanolic extract of H. polyrhizus exerts an anti-inflammatory effect and prevents murine colitis induced by TNBS.

Dietary Polyphenols as Potential Remedy for Dementia

With increasing life expectancy as a result of better quality of life and improved health care, the incidence of aging related diseases and disorders is heading toward epidemic proportions. Dementia, a spectrum of neurological diseases associated with aging, is an increasingly prevalent disease. No cure exists yet for dementia; however, there are many potential candidates for treatment of dementia that merit more exploration. Polyphenols, which constitute one such class of compounds, are dietary agents that are globally found in commonly consumed food. Many processes that are associated with the pathophysiology of dementia can be modulated by polyphenols. Polyphenolic compounds can alleviate oxidative stress by acting as direct scavengers of free radicals and clearing superoxide and hydroxyl radicals and by increasing the level of antioxidant enzymes such as glutathione peroxidase. They also chelate metal ions to prevent free radical formation. Polyphenols can also combat inflammation by affecting transcription factors such as NF-κB. Some polyphenols may have the potential to inhibit excitotoxicity by regulating intracellular calcium ion concentration, inhibiting glutamate receptors and increasing glutamate reuptake at the synapse. The cognitive decline in dementia due to decreased availability of acetylcholine can also be countered by polyphenols that inhibit acetyl-cholinesterase activity. Taken together, these findings suggest that increasing the consumption of polyphenol rich food may alleviate the effects of dementia. Moreover, their effects on controlling multiple mechanisms that are associated with dementia may also prevent or slow down the onset and progress of this devastating disease.

4-Isopropyl-2,6-bis(1-phenylethyl)aniline 1, an Analogue of KTH-13 Isolated from Cordyceps bassiana, Inhibits the NF-κB-Mediated Inflammatory Response

The Cordyceps species has been a good source of compounds with anticancer and anti-inflammatory activities. Recently, we reported a novel compound (4-isopropyl-2,6-bis(1-phenylethyl)phenol, KTH-13) with anticancer activity isolated from Cordyceps bassiana and created several derivatives to increase its pharmacological activity. In this study, we tested one of the KTH-013 derivatives, 4-isopropyl-2,6-bis(1-phenylethyl)aniline 1 (KTH-13-AD1), with regard to anti-inflammatory activity under macrophage-mediated inflammatory conditions. KTH-13-AD1 clearly suppressed the production of nitric oxide (NO) and reactive oxygen species (ROS) in lipopolysaccharide (LPS) and sodium nitroprusside- (SNP-) treated macrophage-like cells (RAW264.7 cells). Similarly, this compound also reduced mRNA expression of inducible NO synthase (iNOS) and tumor necrosis factor-α (TNF-α), as analyzed by RT-PCR and real-time PCR. Interestingly, KTH-13-AD1 strongly diminished NF-κB-mediated luciferase activities and nuclear translocation of NF-κB family proteins. In accordance, KTH-13-AD1 suppressed the upstream signaling pathway of NF-κB activation, including IκBα, IKKα/β, AKT, p85/PI3K, and Src in a time- and dose-dependent manner. The autophosphorylation of Src and NF-κB observed during the overexpression of Src was also suppressed by KTH-13-AD1. These results strongly suggest that KTH-13-AD1 has strong anti-inflammatory features mediated by suppression of the Src/NF-κB regulatory loop.

Using Bioinformatics Approach to Explore the Pharmacological Mechanisms of Multiple Ingredients in Shuang-Huang-Lian

Due to the proved clinical efficacy, Shuang-Huang-Lian (SHL) has developed a variety of dosage forms. However, the in-depth research on targets and pharmacological mechanisms of SHL preparations was scarce. In the presented study, the bioinformatics approaches were adopted to integrate relevant data and biological information. As a result, a PPI network was built and the common topological parameters were characterized. The results suggested that the PPI network of SHL exhibited a scale-free property and modular architecture. The drug target network of SHL was structured with 21 functional modules. According to certain modules and pharmacological effects distribution, an antitumor effect and potential drug targets were predicted. A biological network which contained 26 subnetworks was constructed to elucidate the antipneumonia mechanism of SHL. We also extracted the subnetwork to explicitly display the pathway where one effective component acts on the pneumonia related targets. In conclusions, a bioinformatics approach was established for exploring the drug targets, pharmacological activity distribution, effective components of SHL, and its mechanism of antipneumonia. Above all, we identified the effective components and disclosed the mechanism of SHL from the view of system.

Comparative study of anti-angiogenic activities of luteolin, lectin and lupeol biomolecules

BACKGROUND

Angiogenesis is a hallmark feature in the initiation, progression and growth of tumour. There are various factors for promotion of angiogenesis on one hand and on the other hand, biomolecules have been reported to inhibit cancer through anti-angiogenesis mechanism. Biomolecules, for instance, luteolin, lectin and lupeol are known to suppress cancer. This study aims to compare and evaluate the biomolecule(s) like luteolin, lupeol and lectin on CAM assay and HT-29 cell culture to understand the efficacy of these drugs.

METHOD

The biomolecules have been administered on CAM assay, HT-29 cell culture, cell migration assay. Furthermore, bioinformatics analysis of the identified targets of these biomolecules have been performed.

RESULT

Luteolin has been found to be better in inhibiting angiogenesis on CAM assay in comparison to lupeol and lectin. In line with this study when biomolecules was administered on cell migration assay via scratch assay method. We provided evidence that Luteolin was again found to be better in inhibiting HT-29 cell migration. In order to identify the target sites of luteolin for inhibition, we used software analysis for identifying the best molecular targets of luteolin. Using software analysis best target protein molecule of these biomolecules have been identified. VEGF was found to be one of the target of luteolin. Studies have found several critical point mutation in VEGF A, B and C. Hence docking analysis of all biomolecules with VEGFR have been performed. Multiple allignment result have shown that the receptors are conserved at the docking site.

CONCLUSION

Therefore, it can be concluded that luteolin is not only comparatively better in inhibiting blood vessel in CAM assay, HT-29 cell proliferation and cell migration assay rather the domain of VEGFR is conserved to be targeted by luteolin, lupeol and lectin.

Quantification of major compounds from Ixeris dentata, Ixeris dentata Var. albiflora, and Ixeris sonchifolia and their comparative anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7 cells

The aim of the present study was to evaluate the comparative anti-inflammatory activities of Ixeris dentata (ID), Ixeris dentata var. albiflora (IDA), and Ixeris sonchifolia (IS) and to identify the main compounds present in extracts. The anti-inflammatory activity was evaluated through lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 murine macrophages. Five main compounds consisting of chlorogenic acid, caffeic acid, luteolin 7-O-glucoside, luteolin 7-O-glucuronide, and luteolin were used for simultaneous high-performance liquid chromatography quantification. The total phenolic content present in ID (30 mg/g GAE), IDA (35.33 mg/g GAE), and IS (43.79 mg/g GAE) was correlated to the corresponding LPS-induced NO production inhibitory effect in RAW 264.7 cells as expressed with IC(50) values 26.19, 21.43, and 7.59 μg/mL, respectively. Luteolin 7-O-glucoside was found as the major compound in ID (8.76 mg/g dry weight) and IDA (10.35 mg/g dry weight) and luteolin 7-O-glucuronide was the major compound in IS (34.66 mg/g dry weight). Luteolin 7-O-glucoside and luteolin 7-O-glucuronide inhibited LPS-induced NO production with IC(50) values of 30 and 4.5 μM, respectively. Furthermore, luteolin, luteolin 7-O-glucoside, and luteolin 7-O-glucuronide suppressed the expression of iNOS and COX-2, and t-BHP-induced ROS generation in LPS-stimulated RAW 264.7 cells. These results clearly showed that the anti-inflammatory potential of ID, IDA, and IS extract are primarily due to their contents of luteolin 7-O-glucoside and luteolin 7-O-glucuronide, respectively.

ATP-Binding Pocket-Targeted Suppression of Src and Syk by Luteolin Contributes to Its Anti-Inflammatory Action

Luteolin is a flavonoid identified as a major anti-inflammatory component of Artemisia asiatica. Numerous reports have demonstrated the ability of luteolin to suppress inflammation in a variety of inflammatory conditions. However, its exact anti-inflammatory mechanism has not been fully elucidated. In the present study, the anti-inflammatory mode of action in activated macrophages of luteolin from Artemisia asiatica was examined by employing immunoblotting analysis, a luciferase reporter gene assay, enzyme assays, and an overexpression strategy. Luteolin dose-dependently inhibited the secretion of nitric oxide (NO) and prostaglandin E₂ (PGE₂) and diminished the levels of mRNA transcripts of inducible NO synthase (iNOS), tumor necrosis factor- (TNF-) α, and cyclooxygenase-2 (COX-2) in lipopolysaccharide- (LPS-) and pam3CSK-treated macrophage-like RAW264.7 cells without displaying cytotoxicity. Luteolin displayed potent NO-inhibitory activity and also suppressed the nuclear translocation of NF-κB (p65 and p50) via blockade of Src and Syk, but not other mitogen-activated kinases. Overexpression of wild type Src and point mutants thereof, and molecular modelling studies, suggest that the ATP-binding pocket may be the luteolin-binding site in Src. These results strongly suggest that luteolin may exert its anti-inflammatory action by suppressing the NF-κB signaling cascade via blockade of ATP binding in Src and Syk.

Effects on Liver Lipid Metabolism of the Naturally Occurring Dietary Flavone Luteolin-7-glucoside

Disruptions in whole-body lipid metabolism can lead to the onset of several pathologies such as nonalcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVDs). The present study aimed at elucidating the molecular mechanisms behind the lipid-lowering effects of the flavone luteolin-7-glucoside (L7G) which we previously showed to improve plasma lipid profile in rats. L7G is abundant in plant foods of Mediterranean diet such as aromatic plants used as herbs. Results show that dietary supplementation with L7G for one week induced the expression of peroxisome proliferator-activated receptor-alpha (PPAR-α) and of its target gene carnitine palmitoyl transferase 1 (CPT-1) in rat liver. L7G showed a tendency to decrease the hepatic expression of sterol regulatory element-binding protein-1 (SREBP-1), without affecting fatty acid synthase (FAS) protein levels. Although SREBP-2 and LDLr mRNA levels did not change, the expression of HMG CoA reductase (HMGCR) was significantly repressed by L7G. L7G also inhibited this enzyme's in vitro activity in a dose dependent manner, but only at high and not physiologically relevant concentrations. These results add new evidence that the flavone luteolin-7-glucoside may help in preventing metabolic diseases and clarify the mechanisms underlying the beneficial health effects of diets rich in fruits and vegetables.

Proinflammatory Pathways: The Modulation by Flavonoids

Inflammation is a natural, carefully orchestrated response of the organism to tissue damage, involving various signaling systems and the recruitment of inflammatory cells. These cells are stimulated to release a myriad of mediators that amplify the inflammatory response and recruit additional cells. These mediators present numerous redundancies of functions, allowing a broad and effective inflammatory response, but simultaneously make the understanding of inflammation pathways much difficult. The extent of the inflammatory response is usually self-limited, although it depends on the balance between the pro- and anti-inflammatory signals. When that equilibrium is dislocated, a more widespread inflammatory response may take place. Flavonoids have been shown to be possible alternatives to the traditionally molecules used as anti-inflammatory agents. In fact, the biological activities of flavonoids include the modulation of the diverse phases of inflammatory processes, from the gene transcription and expression to the inhibition of the enzymatic activities and the scavenging of the reactive species. In the present review, the inflammatory network is widely revised and the flavonoids' broad spectrum of action in many of the analyzed inflammatory pathways is revised. This kind of integrated revision is original in the field, providing the reader the simultaneous comprehension of the inflammatory process and the potential beneficial activities of flavonoids.

Biological evaluation of synthetic chalcone and flavone derivatives as anti-inflammatory agents

Flavonoids and chalcones are natural plant derived compounds with inherent therapeutic value for a range of human pathologies. In this study, a series of 24 substituted chalcones and flavones were synthesized and subsequently screened for anti-inflammatory effects on lipopolysaccharide (1 µg/ml)-activated BV-2 microglial cells by assessing initial production/release of nitric oxide (NO). The data obtained eliminate the majority of compounds as weak or non-effective, whereas 2'-hydroxy-3,4,5,3',4'-pentamethoxychalcone (1) and 2'-hydroxy-3,4,5-trimethoxychalcone (2) were potent, having an IC50 of 1.10 and 2.26 µM, respectively; with greater potency than L-N6-(1-iminoethyl)lysine selective iNOS inhibitor (IC50 = 3.1 µM) but less than steroidal dexamethasone (IC50 < 200 nM). The most potent compound (chalcone 1) attenuated NO parallel to reducing iNOS protein expression, events also corresponding to reduction of IL-1α, IL-10 and IL-6 pro-inflammatory cytokines. These findings suggest that the presence of electron donating groups OH and OCH3 on both A and B rings of synthetic compounds correlate to stronger anti-inflammatory potency.

Modulation of Insulin Sensitivity of Hepatocytes by the Pharmacological Downregulation of Phospholipase D

Background. The role of phospholipase D (PLD) as a positive modulator of glucose uptake activation by insulin in muscle and adipose cells has been demonstrated. The role of PLD in the regulation of glucose metabolism by insulin in the primary hepatocytes has been determined in this study. Methods. For this purpose, we studied effects of inhibitors of PLD on glucose uptake and glycogen synthesis stimulation by insulin. To determine the PLD activity, the method based on determination of products of transphosphatidylation reaction, phosphatidylethanol or phosphatidylbutanol, was used. Results. Inhibition of PLD by a general antagonist (1-butanol) or specific inhibitor, halopemide, or N-hexanoylsphingosine, or by cellular ceramides accumulated in doxorubicin-treated hepatocytes decreased insulin-stimulated glucose metabolism. Doxorubicin-induced hepatocytes resistance to insulin action could be abolished by inhibition of ceramide production. Halopemide could nullify this effect. Addition of propranolol, as well as inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) (wortmannin, LY294002) or suppressors of Akt phosphorylation/activity, luteolin-7-O-glucoside or apigenin-7-O-glucoside, to the culture media could block cell response to insulin action. Conclusion. PLD plays an important role in the insulin signaling in the hepatocytes. PLD is activated downstream of PI3-kinase and Akt and is highly sensitive to ceramide content in the liver cells.

Anti-arthritic activity of luteolin in Freund's complete adjuvant-induced arthritis in rats by suppressing P2X4 pathway

To investigate anti-arthritic activity of luteolin (Lut) in Freund's complete adjuvant (FCA)-induced arthritis (AA) in rats. AA was induced by injecting with Freund's complete adjuvant (FCA). Male rats were randomly divided into five groups with 10 mice in each group: (1) control group (saline), (2) AA group, (3) AA+Diclofenac Sodium (AA+DS, 5 mg/kg), (4) AA+Lut (20 mg/kg), (5) AA+Lut (40 mg/kg). Male SD rats were subjected to treatment with Lut at 10 and 20 mg/kg from days 18 to 24 after immunization. Arthritic scores, tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-17 (IL-17), paw histopathology and the proteins of P2X4 pathway were assessed at the end of the experiment. Lut reduced the severity of arthritic scores during the experimental period as compared with positive control (RA). Lut significantly suppressed TNF-α, IL-6, IL-1β and IL-17 as compared with RA group. Histopathological examination indicated that Lut alleviated infiltration of inflammatory cells and synovial hyperplasia as well as protected joint destruction. Lut significantly suppressed P2X4, NLRP1, ASC, and Caspase-1p10. Lut may be a potential preventive or therapeutic candidate for the treatment of inflammation and arthritis.

Anti-inflammatory potential of newly synthesized 4-[(butylsulfinyl)methyl]-1,2-benzenediol in lipopolysaccharide-stimulated BV2 microglia

In this study, we investigated the anti-inflammatory effects of newly synthesized 4-[(butylsulfinyl)methyl]-1,2-benzenediol (SMBD) in lipopolysaccharide (LPS)-stimulated BV2 microglia and the subsequent signaling events. Following stimulation with LPS, elevated production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) was detected in BV2 cells; however, SMBD pretreatment inhibited the production of NO and PGE₂ through suppressing gene expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), respectively, at non-toxic concentrations. LPS-stimulated gene expression and production of interleukin (IL)-1β and tumor necrosis factor (TNF)-α were also significantly reduced by SMBD. The anti-inflammatory effects of SMBD were associated with suppression of LPS-induced nuclear translocation of nuclear factor-kappa B (NF-κB), and phosphorylation of mitogen-activated protein kinases (MAPKs) and Akt, a phosphatidylinositol 3-kinase (PI3K) downstream effector. Therefore, the present results demonstrate that SMBD down-regulates inflammatory gene expression by inhibiting the activation of NF-κB through interference with the activation of MAPKs and PI3K/Akt signaling. Taken together, our data suggest that SMBD may have potential to be developed into an effective anti-inflammatory agent.