Inhibitory effect of the gallotannin corilagin on dextran sulfate sodium-induced murine ulcerative colitis

p-Coumaric Acid Protects Human Lens Epithelial Cells against Oxidative Stress-Induced Apoptosis by MAPK Signaling

To protect against oxidative stress-induced apoptosis in lens epithelial cells is a potential strategy in preventing cataract formation. The present study aimed at studying the protective effect and underlying mechanisms of p-coumaric acid (p-CA) on hydrogen peroxide- (H₂O₂-) induced apoptosis in human lens epithelial (HLE) cells (SRA 01–04). Cells were pretreated with p-CA at a concentration of 3, 10, and 30 μM before the treatment of H₂O₂ (275 μM). Results showed that pretreatment with p-CA significantly protected against H₂O₂-induced cell death in a dose-dependent manner, as well as downregulating the expressions of both cleaved caspase-3 and cleaved caspase-9 in HLE cells. Moreover, p-CA also greatly suppressed H₂O₂-induced intracellular ROS production and mitochondrial membrane potential loss and elevated the activities of T-SOD, CAT, and GSH-Px of H₂O₂-treated cells. As well, in vitro study showed that p-CA also suppressed H₂O₂-induced phosphorylation of p-38, ERK, and JNK in HLE cells. These findings demonstrate that p-CA suppresses H₂O₂-induced HLE cell apoptosis through modulating MAPK signaling pathways and suggest that p-CA has a potential therapeutic role in the prevention of cataract.

Carnosic acid prevents dextran sulfate sodium-induced acute colitis associated with the regulation of the Keap1/Nrf2 pathway

Crohn's disease and ulcerative colitis are inflammatory bowel diseases (IBDs) with high prevalence in humans. Carnosic acid (CA) has been reported to possess antioxidative properties; however, its role in IBDs has not been determined. In the present study, we found that CA significantly prevented the loss of body weight and shortening of colon length in acute colitis induced by dextran sodium sulfate (DSS). Pronounced infiltration of immune cells and a loss of crypt architecture and goblet cells were ameliorated by CA. CA significantly decreased the activity of MPO and infiltration of F4/80⁺ macrophages in the colon. DSS-induced pro-inflammatory cytokine mRNA and protein levels in the colon were also attenuated by CA. CA decreased the activation of p65 and c-Jun signalling. CA inhibited DSS-induced NLRP3 inflammasome activation by reducing caspase 1 activity. In addition, CA increased the level of Nrf2 and prevented the degradation of Nrf2 via ubiquitination by blocking the interaction between Cullin3 and Keap1, which resulted in the decrease of Nrf2 target genes. Finally, GSH levels and SOD activity were increased after CA treatment, while MDA and iNOS levels were significantly reduced. Taken together, our data showed that CA may be useful as a potential therapeutic candidate for IBDs.

Magnolol, a Natural Polyphenol, Attenuates Dextran Sulfate Sodium-Induced Colitis in Mice

Magnolol is a lignan with anti-inflammatory activity identified in Magnolia officinalis. Ulcerative colitis (UC), one of the types of inflammatory bowel disease (IBD), is a disease that causes inflammation and ulcers in the colon. To investigate the effect of magnolol in dextran sulfate sodium (DSS)-induced experimental UC model, male C57 mice were treated with 2% DSS drinking water for 5 consecutive days followed by intragastric administration with magnolol (5, 10 and 15 mg/kg) daily for 7 days. The results showed that magnolol significantly attenuated disease activity index, inhibited colonic shortening, reduced colonic lesions and suppressed myeloperoxidase (MPO) activity. Moreover, colonic pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) induced by colitis were dramatically decreased by magnolol. To further unveil the metabolic signatures upon magnolol treatment, mass spectrometry-based metabolomic analysis of the small molecular metabolites in mice serum were performed. Compared with controls, abnormality of serum metabolic phenotypes in DSS-treated mice were effectively reversed by different doses of magnolol. In particular, magnolol treatment effectively elevated the serum levels of tryptophan metabolites including kynurenic acid (KA), 5-hydroxyindoleacetic acid, indoleacetic acid (IAA), indolelactic acid and indoxylsulfuric acid, which are potential aryl hydrocarbon receptor (AHR) ligands to impact colitis. These findings suggest that magnolol exerts anti-inflammatory effect on DSS-induced colitis and its underlying mechanisms are associated with the restoring of tryptophan metabolites that inhibit the colonic inflammation.

Anti-inflammatory effect of Chang-An-Shuan on TNBS-induced experimental colitis in rats

Background

Inflammatory bowel disease (IBD), denominated by Crohn’s disease and ulcerative colitis, is often associated with abdominal pain, diarrhea and bloody stool. The standard protocols for treating colitis conditions are not satisfactory; thus, complementary and alternative medicines have been increasingly accepted by IBD sufferers worldwide. In this study, we aimed to elucidate the anti-inflammatory effect of Chang-An-Shuan (CAS), a 6-herb Chinese medicinal formula, on 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats and the underlying mechanisms.

Methods

Sprague-Dawley rats were administered with rectal gavage of 2.5% TNBS in 50% ethanol for the induction of experimental colitis which is considered as a model for Crohn’s disease. Upon the TNBS induction, rats were given CAS at 0.5 g/kg/day or 5 g/kg/day for 10 days. The application of salicylazosulfapyridine (0.5 g/kg/day) was served as a positive reference drug for the colitis condition. The efficacy and mechanistic action of CAS were evaluated by means of histopathological and biochemical approaches such as histological staining, real-time polymerase chain reaction, Western blotting analysis and enzyme-linked immunosorbent assay.

Results

Oral administration of CAS at 5 g/kg/day, but not 0.5 g/kg/day, significantly ameliorated the severity of TNBS-induced colitis as evidenced by the reduced loss of body weight, alleviated diarrhea and decreased bloody stool. While lowering the disease activity index, the administration of CAS lessened mucosal lesions thus mucosal integrity of the colitis rats was notably improved. Further, the CAS treatment also significantly suppressed the mRNA and protein levels of pro-inflammatory cytokines, namely interleukin-1β and tumor necrosis factor-α while enhancing the level of anti-inflammatory cytokine IL-10 in the TNBS-treated rats. Importantly, the ameliorative effect of CAS was related to an inhibition of the nuclear factor-κB (NF-κB) signaling pathway by downregulating the expression levels of NF-κBp-65, p-38 and p-AKT.

Conclusions

We suggest that CAS is a potential alternative remedial approach for treating IBD conditions, and the anti-inflammatory effect of CAS is associated with the down-regulation of the NF-κB signaling pathway and the balanced production of pro- and anti-inflammatory cytokines.

Antiinflammatory and immunomodulatory activity of an ethanolic extract from the stem bark of Terminalia catappa L. (Combretaceae): In vitro and in vivo evidences

ETHNOPHARMOCOLOGICAL RELEVANCE

Terminalia catappa Linn (Combretaceae) is a medicinal plant with anti-inflammatory, anti-diarrhoeal and antioxidant properties, frequently found in tropical regions. Considering its characteristics, it could be useful for the treatment of inflammatory bowel disease, which is associated with inflammation, oxidative stress and an immune dysfunction. Thus this study evaluates the immunomodulatory properties and the intestinal anti-inflammatory effect of an ethanolic extract of the stem bark of T. catappa (ETCB) both in vitro (in RAW 264.7 macrophages) and in vivo, in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis.

MATERIALS AND METHODS

The phenolic compounds in ETCB were identified and quantified using HPLC-DAD-qTOF-MS. The immunomodulatory activity ETCB was tested in vitro by determining the macrophage production of IL-1β and nitrites. In vivo studies were performed in the TNBS model of rat colitis. ETCB was given (25, 50 and 100mg/kg/day) orally for two days prior to colitis induction and thereafter for 7 days. Response to treatment was assessed by scoring the gross appearance of the colon, and determining myeloperoxidase activity, gene expression of pro-inflammatory cytokines like TNF-α, IL-23 and IL-6, chemokines, inducible nitric oxide synthase and proteins crucial in the maintenance of the intestinal mucosal barrier integrity like mucins (MUC-2, MUC-3) and villin.

RESULTS

ETCB was able to inhibit IL-1β and nitrite production in vitro in RAW 264.7 macrophages. Moreover, treatment of TNBS colitic rats with ETCB resulted in a decreased colonic damage score and weight/length ratio. It also reduced the colonic neutrophil infiltration indicated by a lower myeloperoxidase activity and prevented the depletion of colonic glutathione levels in colitic rats. In addition, treatment with ETCB down-regulated the gene expression of pro-inflammatory mediators (TNF-α, IL-23, IL-6 and CINC-1) and iNOS in colitic rats. Moreover, the gene expression of mucosal barrier proteins like MUC-2, MUC-3 and villin were up-regulated in colitic rats treated with ETCB. The dose of ETCB that produced the most significant beneficial effect was 100mg/kg. Regarding the chemical composition of ETCB, 31 phenolic compounds were identified, including ellagic acid, catalagin and gallic acid.

CONCLUSION

The beneficial effect of ETCB in the TNBS induced colitis in rats could be related to its antioxidant, immunomodulatory and anti-inflammatory activities, which could be attributed to the phenolic compounds identified.

Inflammatory bowel disease: exploring gut pathophysiology for novel therapeutic targets

Ulcerative colitis and Crohn's disease are the 2 major phenotypes of inflammatory bowel disease (IBD), which are influenced by a complex interplay of immunological and genetic elements, though the precise etiology still remains unknown. With IBD developing into a globally prevailing disease, there is a need to explore new targets and a thorough understanding of the pathophysiological differences between the healthy and diseased gut could unearth new therapeutic opportunities. In this review, we provide an overview of the major aspects of IBD pathogenesis and thereafter present a comprehensive analysis of the gut pathophysiology leading to a discussion on some of the most promising targets and biologic therapies currently being explored. These include various gut proteins (CXCL-10, GATA-3, NKG2D, CD98, microRNAs), immune cells recruited to the gut (mast cells, eosinophils, toll-like receptors 2, 4), dysregulated proinflammatory cytokines (interleukin-6, -13, -18, -21), and commensal microbiota (probiotics and fecal microbiota transplantation). We also evaluate some of the emerging nonconventional therapies being explored in IBD treatment focusing on the latest developments in stem cell research, oral targeting of the gut-associated lymphoid tissue, novel anti-inflammatory signaling pathway targeting, adenosine deaminase inhibition, and the beneficial effects of antioxidant and nutraceutical therapies. In addition, we highlight the growth of biologics and their targets in IBD by providing information on the preclinical and clinical development of over 60 biopharmaceuticals representing the state of the art in ulcerative colitis and Crohn's disease drug development.

Protective Role of Corilagin on Aβ25-35-Induced Neurotoxicity: Suppression of NF-κB Signaling Pathway

Aggregation and deposition of beta-amyloid peptides (Aβ), a pathological hallmark of Alzheimer's disease, has been recognized as a potent activator of neuroinflammation and neuronal dysfunction. In this study, the underlying molecular mechanisms responsible for the neuroprotective effects of corilagin against Aβ_25-35-triggered neurotoxicity and inflammatory responses were investigated in PC12 cells. Pretreatment with corilagin effectively protected PC12 cells against Aβ_25-35-induced damage and apoptosis. Aβ_25-35 induced damage in PC12 cells as revealed by increased production of reactive oxygen species, caspase-3 activity, and cell cycle arrest was attenuated by corilagin pretreatment. Corilagin not only significantly suppressed the production of neurotoxic inflammatory mediators such as tumor necrosis factor-α, nitric oxide, and prostaglandin E₂ but also downregulated cyclooxygenase-2 and inducible nitric oxide synthase expression in PC12 cells. It also exerted a beneficial effect by suppressing the degradation of inhibitor of κB (IκB)-α and subsequent activation of transcription factor nuclear factor κB (NF-κB), mostly through inhibition of extracellular signal-regulated kinase activity in comparison to c-Jun N-terminal kinase and p38 MAP kinase (p38) mitogen-activated protein kinase activity. These findings suggest that attenuation of Aβ_25-35-induced inflammatory responses by downregulating the NF-κB signaling pathway might be a valuable strategy for both Alzheimer's disease prevention and/or treatment.

Anti-inflammatory Actions of (+)-3'α-Angeloxy-4'-keto-3',4'-dihydroseselin (Pd-Ib) against Dextran Sulfate Sodium-Induced Colitis in C57BL/6 Mice

The immunoregulatory protective properties of (+)-3'α-angeloxy-4'-keto-3',4'-dihydroseselin (Pd-Ib) isolated from Bupleurum malconense has not been reported. In the present study, the therapeutic effect of Pd-Ib (30, 60, and 120 mg/kg/day) was examined in a mouse model of dextran sulfate sodium (DSS)-induced acute colitis. Administration of Pd-Ib significantly reduced the disease activity index, inhibited the shortening of colon length, reduced colonic tissue damage, and suppressed colonic myeloperoxidase activity and nitric oxide levels in mice with DSS-induced colitis. Moreover, Pd-Ib greatly suppressed the secretion of pro-inflammatory cytokines TNF-α, IFN-γ, IL-6, and IL-17A while enhancing the level of anti-inflammatory cytokine IL-4. The protein levels of phosphorylated STAT3 (p-STAT3) and phosphorylated p38 (p-p38) were down-regulated in the colonic tissues of DSS-treated mice. Importantly, the anti-inflammatory effect of Pd-Ib against acute colitis was comparable to the anti-inflammatory sulfa drug sulfasalazine (300 mg/kg). Furthermore, the in vitro study showed that the inhibitory effect of Pd-Ib on p-STAT3 and IL-6 protein levels was accompanied by the reduction of MAPKs (JNK and p38). In conclusion, this study suggested that Pd-Ib attenuated DSS-induced acute colitis via the regulation of interleukins principally through the STAT3 and MAPK pathways.

A review of the efficacy of dietary polyphenols in experimental models of inflammatory bowel diseases

Crohn's disease and ulcerative colitis presently have no cure and are treated with anti-inflammatory drugs or monoclonal antibodies targeting pro-inflammatory cytokines. A variety of rodent models have been used to model chronic and acute colitis. Dietary polyphenols in foods and botanicals are of considerable interest for prevention and treatment of colitis. Many dietary polyphenols have been utilized for prevention of colitis in rodent models. Berries, green tea polyphenols, curcumin, and stilbenes have been the most extensively tested polyphenols in rodent models of colitis. The majority of polyphenols tested have inhibited colitis in rodents, but increasing doses of EGCG and green tea, isoflavones, flaxseed, and α-mangostin have exacerbated colitis. Few studies have examined combination of polyphenols or other bioactives for inhibition of colitis. Translating polyphenol doses used in rodent models of colitis to human equivalent doses reveals that supplemental doses are most likely required to inhibit colitis from a single polyphenol treatment. The ability to translate polyphenol treatments in rodent models is likely to be limited by species differences in xenobiotic metabolism and microbiota. Given these limitations, data from polyphenols in rodent models suggests merit for pursuing additional clinical studies for prevention of colitis.

A novel coumarin, (+)-3'-angeloxyloxy-4'-keto-3',4'-dihydroseselin, isolated from Bupleurum malconense (Chaihu) inhibited NF-κB activity

Background

This study aims to identify the major anti-inflammatory components in the petroleum ether extract of Bupleurummalconense (Chaihu), by bioassay-guided fractionation, and to investigate the anti-inflammatory mechanisms of active components in lipopolysaccharide (LPS)-stimulated murine macrophage RAW-Blue cells.

Methods

A QUANTI-Blue assay was used to guide fractionation of B.malconense root extract. The petroleum ether extract which exerted significant secreted embryonic alkaline phosphatase (SEAP) inhibition effect was purified by silica gel column chromatography and assisted with reverse phase HPLC. The major bioactive compound which significantly inhibited SEAP activity was obtained and its anti-inflammatory effects in LPS-induced RAW-Blue cells were measured by the overproduction of NO (Griess method), gene expression of Il-1β, Tnf-α and iNos (real-time PCR). In parallel, protein expressions of COX-2, iNOS and IκB-α were determined by western blot.

Results

In bioassay-guided fractionation using LPS-stimulated mouse macrophage RAW-Blue cells, (+)-3′-angeloxyloxy-4′-keto-3′,4′-dihydroseselin (Pd-Ib) was identified by MS and NMR spectral analyses. Pd-Ib (5, 10, 20 μg/mL) suppressed the gene expression of Il-1β (P < 0.0001, P < 0.0001, P < 0.0001 for three respective concentrations), Tnf-α (P = 0.006, P = 0.001, P < 0.0001 for three respective concentrations) and iNos (P = 0.009, P < 0.0001, P < 0.0001 for three respective concentrations) in LPS-stimulated macrophages. The production of cyclooxygenase-2 (P = 0.019, P = 0.002, P < 0.0001), iNOS (P < 0.0001, P < 0.0001, P < 0.0001 for three respective concentrations) and NO (P < 0.0001, P < 0.0001, P < 0.0001 for three respective concentrations) significantly decreased when macrophages were treated with Pd-Ib (5, 10, 20 μg/mL) in the presence of LPS. Pd-Ib (5, 10, 20 μg/mL) suppressed the nuclear activation of NF-κB while it up-regulated the IκB-α level (P = 0.028, P = 0.013, P = 0.005 for three respective concentrations) in LPS-stimulated macrophages.

Conclusions

Pd-Ib isolated from B.malconense suppressed LPS-induced inflammatory responses in macrophages by inhibiting NF-κB activity and reducing the expression of iNOS, COX-2 as well as pro-inflammatory cytokines.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-016-0077-x) contains supplementary material, which is available to authorized users.

Drug Discovery of Host CLK1 Inhibitors for Influenza Treatment

The rapid evolution of influenza virus makes antiviral drugs less effective, which is considered to be a major bottleneck in antiviral therapy. The key proteins in the host cells, which are related with the replication cycle of influenza virus, are regarded as potential drug targets due to their distinct advantage of lack of evolution and drug resistance. Cdc2-like kinase 1 (CLK1) in the host cells is responsible for alternative splicing of the M2 gene of influenza virus during influenza infection and replication. In this study, we carried out baculovirus-mediated expression and purification of CLK1 and established a reliable screening assay for CLK1 inhibitors. After a virtual screening of CLK1 inhibitors was performed, the activities of the selected compounds were evaluated. Finally, several compounds with strong inhibitory activity against CLK1 were discovered and their in vitro anti-influenza virus activities were validated using a cytopathic effect (CPE) reduction assay. The assay results showed that clypearin, corilagin, and pinosylvine were the most potential anti-influenza virus compounds as CLK1 inhibitors among the compounds tested. These findings will provide important information for new drug design and development in influenza treatment, and CLK1 may be a potent drug target for anti-influenza drug screening and discovery.

Qing-dai powder promotes recovery of colitis by inhibiting inflammatory responses of colonic macrophages in dextran sulfate sodium-treated mice

Background

Qing-dai powder (QDP), comprising Indigo naturalis (Qing-dai) and dried alum (Ku-fan), was used in Chinese medicine to treat the conditions associated with mucosal hemorrhage, such as ulcerative colitis (UC). This study aims to investigate the effects and potential mechanism of QDP on dextran sulfate sodium (DSS)-induced acute colitis in mice and to examine the regulatory effects of QDP on macrophages.

Methods

Seven- to eight-week-old male C57BL/6 mice were challenged with 2.0 % DSS in drinking water for 5 days and then the colitic mice were arbitrarily allocated into five groups (n = 10 for each group). QDP (0.77, 1.54 and 3.08 g/kg) and sulfasalazine (SASP) (0.20 g/kg) were orally administered for 7 days. The disease activity index was determined by scores of body weight loss, diarrhea and rectal bleeding; histological signs of damage was analyzed by H&E staining; myeloperoxidase activity was measured by colorimetric method, levels of proinflammatory cytokines were determined by ELISA; changes in macrophages in the colon were analyzed by immunohistochemistry (IHC) and flow cytometry. Lipopolysaccharide (LPS)-induced RAW264.7 cells were treated with or without QDP, then the production of TNF-α and IL-6 were measured by ELISA; and protein molecules such as COX-2, iNOS, IкB-α were determined by Western blot.

Results

Oral administration of QDP at dosages of 1.54 and 3.08 g/kg significantly reduced disease activity index on day 12 (P < 0.001 for 1.54 g/kg and P < 0.0008 for 3.08 g/kg), colon shortening (P = 0.012 for 1.54 g/kg, P = 0.001 for 3.08 g/kg), histological damage (P < 0.001 for 1.54 g/kg, P < 0.001 for 3.08 g/kg) and colonic myeloperoxidase activity (P = 0.002 for 1.54 g/kg, P < 0.001 for 3.08 g/kg) of DSS-treated mice. Moreover, QDP treatment (1.54 and 3.08 g/kg) significantly decreased DSS-induced infiltration of macrophages, and production of TNF-α (P = 0.005 for 1.54 g/kg, P = 0.002 for 3.08 g/kg), IL-1β (P = 0.008 for 1.54 g/kg, P = 0.002 for 3.08 g/kg) and IL-6 (P = 0.011 for 1.54 g/kg, P = 0.004 for 3.08 g/kg) in colonic tissues, and also reduced serum MCP-1 levels (P = 0.001 for 1.54 g/kg, P < 0.001 for 3.08 g/kg). In RAW264.7 cells, QDP significantly suppressed LPS-induced production of TNF-α and IL-6 (Both P < 0.001 for 1.0 μg/mL QDP treatment) and expression levels of COX-2 (P = 0.002 and P = 0.001 for 1 and 3 μg/mL QDP treatment, respectively) and iNOS (P < 0.001 for 3 μg/mL QDP treatment) by inhibiting IкB-α degradation (P = 0.007 and P = 0.004 for 1 and 3 μg/mL QDP treatment, respectively) and NF-кB p65 nuclear translocation.

Conclusion

QDP suppressed the inflammatory responses of colonic macrophages in DSS-induced UC in mice and LPS-induced RAW264.7 cells.

Anomeric selectivity and influenza A virus inhibition study on methoxylated analogues of Pentagalloylglucose

Anomeric selectivity in galloylation of D-glucose and D-mannose with carboxylic acid was explored under steglich conditions. Base catalyst 4-dimethylaminopyridine favored the formation of alpha-anomers, while adding an acid and carbodiimide favored the formation of beta-anomers. Steric hindrance between α,β-unsaturated acid and C-2 OH stereochemistry (adjacent carbon to anomeric) influenced anomeric selectivity for both D-glucose and D-mannose. The influenza A virus inhibition activities of the synthesized compounds were evaluated in Madin-Darby canine kidney cell line using the cytopathic effect inhibition assay. All the synthetic methoxylated analogues showed more considerable activity against influenza A virus than their corresponding acids, which indicated the sugar core as key functionality for anti-viral activity. The activities of trimethoxy-cinnamic acid Pentagalloylglucose analogues, 3α, 3β, 4α, and 4β (IC50, 109.1 μM, 134.4 μM, 119.5 μM, 111.1 μM, respectively) were better than those of trimethoxy-benzoic acid Pentagalloylglucose analogues, 1-αβ and 2α, 2β (IC50, 209.8 μM, 132.9 μM, 161.2 μM, respectively), which suggested that the double bond in cinnamic acid Pentagalloylglucose analogues makes the major contribution for influenza A virus inhibitory activity. Notably, several anomeric mixtures showed better activities than pure alpha or beta anomer and were almost two times more effective than Ribavirin, a clinically used anti-viral drug.

Murine model of dextran sodium sulfate induced ulcerative colitis

Ulcerative colitis (UC) is an idiopathic, chronic inflammatory disorder of the colonic mucosa, and its etiology remains unclear. Animal models are commonly used to study UC, including the murine model of colitis induced with dextran sulfate sodium (DSS). The murine model of DSS-induced colitis is well appreciated and widely used because of its simplicity, cheapness and high success rate. DSS-induced colitis has many similarities to human UC in location, clinical and histological features. In view of its indispensable position in the study of UC, we provide a brief overview of the animal model of DSS-induced colitis in terms of its features, modelling methods, pathogenesis and influencing factors.