Cinnamaldehyde targets TLR-4 and inflammatory mediators in acetic-acid induced ulcerative colitis model

Narirutin mitigates dextrose sodium sulfate-induced colitis in mice by modulating intestinal flora

BACKGROUND

Ulcerative colitis (UC) is a prolonged inflammatory disease of the gastrointestinal tract. Current therapeutic options remain limited, underscoring the imperative to explore novel therapeutic strategies. Narirutin (NR), a flavonoid naturally present in citrus fruits, exhibits excellent anti-inflammatory effects in vitro, yet its in vivo efficacy, especially in UC, remains underexplored.

OBJECTIVE

This work examined the effect of NR on dextrose sodium sulfate (DSS)-induced UC in mice in vivo, with a specific focus on the role of gut flora in it.

METHODS

The effects of NR (10, 20, and 40 mg/kg) on DSS-induced UC in mice were investigated by monitoring changes in body weight, disease activity index (DAI) scores, colon length, and histological damage. Colonic levels of pro-inflammatory mediators, tight junction (TJ) proteins, and inflammation-related signaling pathway proteins were analyzed via enzyme-linked immunosorbent assay, western blot, and immunofluorescence. The role of gut microbiota in NR against colitis was analyzed through 16S rRNA sequencing, flora clearance assays, and fecal microbiota transplantation (FMT) assays.

RESULTS

NR administration suppressed DSS-induced colitis as reflected in a decrease in body weight loss, DAI score, colon length shortening, and histological score. Furthermore, NR administration preserved the integrity of the DSS-induced intestinal barrier by inhibiting the reduction of TJ proteins (claudin3, occludin, and zonula occludens-1). Moreover, NR administration markedly repressed the activation of the toll-like receptor 4-mitogen-activated protein kinase/nuclear factor-κB pathway and reduced the amount of pro-inflammatory mediators in the colon. Importantly, the results of 16S rRNA sequencing showed that the intestinal flora of mice with colitis exhibited richer microbial diversity following NR administration, with elevated abundance of Lactobacillaceae (Lactobacillus) and decreased abundance of Bacteroidaceae (Bacteroides) and Shigella. In addition, the anti-colitis effect of NR almost disappeared after gut flora clearance. Further FMT assay also validated this gut flora-dependent protective mechanism of NR.

CONCLUSION

Our findings suggest that NR is a prospective natural compound for the management of UC by modulating intestinal flora.

Protective effect of freeze-dried extract of Persicaria bistorta Samp. on acetic acid-induced colitis model in rats: Involvement of nitric oxide and opioid system

Inflammatory bowel disease is a chronic inflammatory disorder accompanied by occasional flare-ups, abdominal pain, and rectal bleeding. Persicaria bistorta Samp. is a medicinal plant repeatedly mentioned in traditional Persian medicine for the treatment of bleeding and tissue damage in different organs, including the intestines. The current study aimed to evaluate the effect of bistort root in an animal model of colitis. Freeze-dried aqueous extract of the plant (PB) was prepared and analyzed using liquid chromatography-mass spectrometry and high-performance liquid chromatography. The anti-inflammatory effect of oral PB (300, 500, and 700 mg/kg) was evaluated in acetic acid-induced colitis in Wistar rats compared with negative control and positive control (dexamethasone). The role of nitric oxide (NO), opioid receptors, Toll-like receptors (TLR-4), interleukin (IL)-1β, IL-6, TNF-α, NF-κB, myeloperoxidase, and intestinal tissue damage using immunohistochemistry staining for cyclooxygenase-2 (COX-2) were also assessed. A total of 29 compounds were identified in the extract. The gallic acid content of the extract was 4.973 ± 1.102 mg/g. PB significantly ameliorated the gross morphological damage from 4.66 ± 0.577 in negative control to 1.33 ± 0.56 in PB 700 (p < 0.001). Also, PB 700 lowered the levels of TNF-α (p < 0.01), TLR-4 (p < 0.001), NF-κB (p < 0.0001), IL-1β (p < 0.0001), and IL-6 (p < 0.0001) compared to the negative control. Additionally, while blocking NO and opioid pathways, the therapeutic effect of the extract was not significant, compared to the negative control, suggesting that PB 700 has exerted its therapeutic effect via these two pathways. However, further mechanistic and clinical studies are recommended to confirm PB as a natural treatment for colitis.

Amygdalin Alleviates DSS-Induced Colitis by Restricting Cell Death and Inflammatory Response, Maintaining the Intestinal Barrier, and Modulating Intestinal Flora

Inflammatory bowel disease (IBD) refers to a cluster of intractable gastrointestinal disorders with an undetermined etiology and a lack of effective therapeutic agents. Amygdalin (Amy) is a glycoside extracted from the seeds of apricot and other Rosaceae plants and it exhibits a wide range of pharmacological properties. Here, the effects and mechanisms of Amy on colitis were examined via 16S rRNA sequencing, ELISA, transmission electron microscopy, Western blot, and immunofluorescence. The results showed that Amy administration remarkably attenuated the signs of colitis (reduced body weight, increased disease activity index, and shortened colon length) and histopathological damage in dextran sodium sulfate (DSS)-challenged mice. Further studies revealed that Amy administration significantly diminished DSS-triggered gut barrier dysfunction by lowering pro-inflammatory mediator levels, inhibiting oxidative stress, and reducing intestinal epithelial apoptosis and ferroptosis. Notably, Amy administration remarkably lowered DSS-triggered TLR4 expression and the phosphorylation of proteins related to the NF-κB and MAPK pathways. Furthermore, Amy administration modulated the balance of intestinal flora, including a selective rise in the abundance of S24-7 and a decline in the abundance of Allobaculum, Oscillospira, Bacteroides, Sutterella, and Shigella. In conclusion, Amy can alleviate colitis, which provides data to support the utility of Amy in combating IBD.

Cinnamic Acid Ameliorates Acetic Acid-induced Inflammatory Response through Inhibition of TLR-4 in Colitis Rat Model

BACKGROUND

Cinnamic acid, an active compound in cinnamon spp., has anti-inflammatory and antioxidant characteristics and is favorable in managing inflammatory bowel diseases.

OBJECTIVES

Evaluate cinnamic acid's effects on colitis in rats.

METHODS

To induce colitis in experimental rats, excluding the sham group, a 4% intrarectal solution of acetic acid was administered. The rats were then given oral doses of cinnamic acid at 30, 45, and 90 mg/kg for two days. The animals were assessed for macroscopic and microscopic changes, and the levels of inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and myeloperoxidase (MPO) were measured using Eliza kits. Additionally, real-time PCR was performed to examine the gene level of toll-like receptor 4 (TLR-4) in the colon.

RESULTS

Effective reduction of inflammation in acetic acid-induced colitis was achieved through Cinnamic acid administration at doses of 45 and 90 mg/kg. The decrease was achieved by inhibiting the activities of TNF-α, IL-6, and MPO while downregulating the expression of TLR-4. It is important to note that macroscopic and microscopic evaluations were significant in determining the effectiveness of cinnamic acid in reducing inflammation.

CONCLUSION

Downregulation of inflammatory cytokines and TLR-4 expression may contribute to cinnamic acid's anti-inflammatory effect.

Toll-like receptors in inflammatory bowel disease: A review of the role of phytochemicals

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammation within the gastrointestinal tract with a remarkable impact on patients' quality of life. Toll-like receptors (TLR), as a key contributor of immune system in inflammation, has a critical role in the pathogenesis of IBD and thus, can be a suitable target of therapeutic agents. Medicinal plants have long been considered as a source of bioactive agents for different diseases, including IBD.

PURPOSE

This review discusses current state of the art on the role of plant-derived compounds for the management of IBD with a focus on TLRs.

METHODS

Electronic database including PubMed, Web of Science, and Scopus were searched up to January 2023 and all studies in which anticolitis effects of a phytochemical was assessed via modulation of TLRs were considered.

RESULTS

Different categories of phytochemicals, including flavonoids, lignans, alkaloids, terpenes, saccharides, and saponins have demonstrated modulatory effects on TLR in different animal and cell models of bowel inflammation. Flavonoids were the most studied phytochemicals amongst others. Also, TLR4 was the most important type of TLRs which were modulated by phytochemicals. Other mechanisms such as inhibition of pro-inflammatory cytokines, nuclear factor-κB pathway, nitric oxide synthesis pathway, cyclooxygenase-2, lipid peroxidation, as well as induction of endogenous antioxidant defense mechanisms were also reported for phytochemicals in various IBD models.

CONCLUSION

Taken together, a growing body of pre-clinical evidence support the efficacy of herbal compounds for the treatment of IBD via modulation of TLRs. Future clinical studies are recommended to assess the safety and efficacy of these compounds in human.

Anti-inflammatory natural products modulate interleukins and their related signaling markers in inflammatory bowel disease: A systematic review

This review aims to identify in vivo studies investigating the potential of plant substances and their natural molecules in managing inflammatory bowel disease (IBD). Specifically, the objective is to examine the impact of these substances on interleukins and other key inflammatory signaling markers. Relevant articles published up to December 2022 were identified through a search of the PubMed, Scopus, Web of Science, and Embase databases. The search used keywords including "inflammatory bowel disease", "medicinal plants", "natural molecules", "anti-inflammatory", and "ulcerative colitis", and identified 1,878 potentially relevant articles, of which 89 were included in this review after completion of the selection process. This study provides preclinical data on natural products (NPs) that can potentially treat IBD, including ulcerative colitis. The main actions of these NPs relate to their effects on nuclear factor kappa B (NF-κB), the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway, the regulation of T helper 17/regulatory T cells balance, and oxidative stress. The ability of these NPs to inhibit intestinal inflammation appears to be dependent on lowering levels of the pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and IL-17, via the Jun N-terminal kinase (JNK)1, NF-κβ-p65, and STAT3 pathways. In addition, NPs were shown to reduce oxidative stress and the severity of ulcerative colitis, as well as increase the activity of antioxidant enzymes. These actions suggest that NPs represent a promising treatment for IBD, and potentially have greater efficacy and safety than current treatments.

Plausible Protective Role of Encephalartos villosus Extract in Acetic-Acid-Induced Ulcerative Colitis in Rats

Ulcerative colitis (UC) is an inflammatory ailment of the intestine associated with the upregulation of oxidative stress and pro-inflammatory cytokines. Here, we aimed to assess the consequences of Encephalartos villosus (EV) Lem extract on acetic acid (AA)-induced UC. Rats were randomly classified into five groups, as follows: control, AA, AA + mesalazine, AA + EV (50 mg/kg), and AA + EV (100 mg/kg) groups. EV (50 mg/kg and 100 mg/kg) and mesalzine (100 mg/kg) were administered orally for 14 days before the induction of UC. On the last day of the experiment, colitis was provoked via the intra-rectal delivery of 3% AA. Then, after 24 h, the rats were sacrificed and their colon tissues were isolated and inspected. Interestingly, EV pretreatment substantially (p < 0.05) reduced the elevated colon weight/length ratio and ulcer area and normalized the histological changes and immunohistochemical features. In addition, EV efficiently reduced the levels of myeloperoxidase (MPO) and increased the activity of glutathione peroxidase (GS-PX) and catalase (CAT). EV (100 mg/kg) resulted in a downregulation of toll-like receptor 4 (TLR-4) and upregulation of heme oxygenase 1 (HO-1) and occludin expression levels. Concerning the anti-inflammatory mechanisms, EV reduced the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nuclear transcription factor kappa B (NF-ĸB) and inhibited cyclooxygenase-2 (COX-2) expression levels. It also decreased caspase-3 levels. Our results indicate that the oral intake of EV improves AA-induced colitis in rats through its antioxidative effects and the modulation of pro-inflammatory cytokines, as well as the restoration of mucosal integrity. Consequently, EV may be an efficient therapeutic candidate for UC.

Xianglian Zhixie Tablet Antagonizes Dextran Sulfate Sodium-Induced Ulcerative Colitis by Attenuating Systemic Inflammation and Modulating Gut Microbiota

Purpose

Xianglian Zhixie Tablet (XLZXT), a classical traditional Chinese medicine formulation, is commonly used to treat Ulcerative Colitis (UC) in China. However, the therapeutic mechanisms of XLZXT for UC have yet to be fully understood. This study aimed to investigate the curative benefits of XLZXT and its associated mechanisms for healing UC in mice.

Methods

In the present study, the 1% dextran sulfate sodium (DSS) solution was used to establish the UC model in C57BL/6N mice. To investigate the therapeutic effects of XLZXT on DSS-induced UC mice, several parameters were measured, including DAI score, colon length, spleen index, pathological changes in colon tissue, and levels of inflammatory factors in plasma and colon tissue. By investigating the gut microbiota, assessing the levels of intestinal mucosal protein expression, and looking at the proteins involved in the TLR4/MyD88/NF-B p65 signaling pathway, the mechanisms of XLZXT impact on UC were investigated. Mouse feces were examined for patterns of gut microbiota expression using high-throughput sequencing of 16S rRNA.

Results

XLZXT effectively alleviated UC symptoms and colon pathological damage in DSS-induced UC mice. It improved body weight loss, stool consistency, and hematochezia, while also repairing colon damage. Moreover, it down-regulated pro-inflammatory cytokines (such as TNF-α, IL-1β, and IL-6), and up-regulated anti-inflammatory cytokines (such as IL-10). XLZXT also increased the expression of MUC-2, Occludin and ZO-1, while decreasing the expression of NF-κB, MyD88 and TLR4. Additionally, it regulated gut microbiota disorder by increasing the abundance of beneficial bacteria and reducing the adhesion of intestinal harmful bacteria.

Conclusion

XLZXT demonstrated therapeutic effects on DSS-induced UC mice. The mechanisms may be associated with repairing the intestinal mucosal barrier, regulating the TLR4/MyD88/NF-κB p65 signaling pathway, and restoring the balance of gut microbiota.

Antioxidant, anti-inflammatory and analgesic activity of Mimosa acutistipula (Mart.) Benth

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants belonging to the genus Mimosa, such as Mimosa tenuiflora, M. caesalpinifolia, and M. verrucosa are known for their popular use for asthma, bronchitis and fever. Ethnopharmacological studies report that Mimosa acutistipula is used to treat alopecia and pharyngitis, conditions that can be related to oxidative stress, inflammatory processes and painful limitations. However, there is no studies on its efficacy and mechanism of action.

AIM OF THE STUDY

To elucidate the antioxidant, anti-inflammatory, analgesic and antipyretic activity of M. acutistipula leaves.

MATERIALS AND METHODS

Phytochemical profile of M. acutistipula extracts was evaluated by several reaction-specific methods. Secondary metabolites such as tannins, phenols and flavonoids were quantified with colorimetric assays. In vitro antioxidant potential was evaluated using DPPH and ABTS + as free radical scavenging tests, FRAP and phosphomolybdenum as oxide-reduction assays, and anti-hemolytic for lipid peroxidation evaluation. In vivo anti-inflammatory evaluation was performed by paw edema, and peritonitis induced by carrageenan. Analgesic effect and its possible mechanisms were determined by acetic acid-induced abdominal writhing and the formalin test. Antipyretic activity was evaluated by yeast-induced fever.

RESULTS

Cyclohexane, chloroform, ethyl acetate and methanol extracts of leaves had presence of tannins, flavonoids, phenol, alkaloids, terpenes (except methanolic extract), and saponins (only for methanolic and chloroformic extracts). In phenols, flavonoids and tannins quantification, methanolic and ethyl acetate extract had higher amounts of this phytocompounds. Ethyl acetate extract, due to its more expressive quantity of phenols and flavonoids, was chosen for carrying out the in vivo tests. Due to the relationship between oxidative stress and inflammation, antioxidant tests were performed, showing that ethyl acetate extract had a high total antioxidant activity (70.18%), moderate activity in DPPH radical scavenging, and a moderate ABTS + radical inhibition (33.61%), and FRAP assay (112.32 μg Fe²⁺/g). M. acutistipula showed anti-inflammatory activity, with 54.43% of reduction in paw edema (50 mg/kg) when compared to the vehicle. In peritonitis test, a reduction in the concentration of NO could be seen, which is highly involved in the anti-inflammatory activity and is responsible for the increase in permeability. In the analgesic evaluation, most significant results in writhing test were seen at 100 mg/kg, with a 34.7% reduction of writhing. A dual mechanism of action was confirmed with the formalin test, both neurogenic and inflammatory pain were reduced, with a mechanism via opioid route. In the antipyretic test, results were significantly decreased at all concentrations tested.

CONCLUSION

M. acutistipula leaves ethyl acetate extract showed expressive concentrations of phenolic compounds and antioxidant activity. It also exhibited anti-inflammatory and analgesic activity, besides its antipyretic effect. Thus, these results provide information regarding its popular use and might help future therapeutics involving this specimen.

Molecular mechanism of the anti-inflammatory effects of plant essential oils: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Plant essential oils (PEOs) extracted from aromatic compounds of the plant contain complex mixtures of volatile and lipophilic bioactive compounds. In ancient Egypt, Arabia, Greece, and China, PEOs were traditional used in aromatherapy for various health disorders, including pain and inflammation.

AIM OF THE STUDY

In this review, we provide an overview of the anti-inflammatory effects of PEOs and the underlying mechanisms associated with anti-inflammatory effects using in vitro and in vivo models. Further, clinical trials associated with PEOs were explored.

MATERIALS AND METHODS

The literature search was performed using various web-based tools and databases like Google Scholar, Web of Science, PubMed, CNKI and SCOPUS. The keywords used for conducting the literature review were general terms like "essential oils" followed by (AND) the subject of interest like "in vitro and/or in vivo anti-inflammatory models," "inflammatory response," "inflammatory indicators," "pro-inflammatory cytokines," "signaling pathway," "anti-inflammatory mechanism," "toxicology and side effects" and "clinical trials." The articles selected were published between 2017 and 2022. The articles prior to 2017 were only considered if they were associated with molecular mechanisms or signaling pathways involved in the inflammatory responses.

RESULTS

In vitro and in vivo inflammation models have been used to study the anti-inflammatory effects of 48 PEOs. Studies have reported that PEOs targets and inhibit multiple dysregulated signaling pathways associated with inflammation, including Toll-like receptors, nuclear transcription factor-κ B, mitogen-activated protein kinases, Nod-like receptor family pyrin domain containing 3, and auxiliary pathways like the nuclear factor erythroid 2-related factor 2/antioxidant response element and Janus kinase/signal transducers and activators of transcription) signaling pathways.

CONCLUSION

PEOs extracted from different plant materials had varied qualitative and quantitative compositions of biologically active compounds. Different anti-inflammatory potentials and different molecular signal transduction have been attributed to PEOs-derived bioactive compounds with different chemical structures. The data on therapeutic efficacy and the long-term side effects of PEOs as an anti-inflammatory drug are still unknown due to the lack of clinical trials on PEOs. There is still insufficient evidence to draw conclusions on anti-inflammatory properties of PEOs without promising outcomes from clinical trials.

A systematic review of preclinical studies on the taurine role during diabetic nephropathy: focused on anti-oxidative, anti-inflammation, and anti-apoptotic effects

Diabetic nephropathy is one of the most important and growing diseases globally and the leading cause of cardiovascular mortality in these patients. Taurine is an amino acid that has pleiotropic protective properties on some diseases. This study aimed to investigate the potential role of taurine in the treatment of diabetes-induced nephropathy. To achieve the aim of the present study, a comprehensive systematic search based on PRISMA guidelines has been conducted up to August 2021. A total of 382 articles were found in the electronic databases based on search keywords. After doing the screening, 14 articles were included in the present systematic review. The dated demonstrated elevation of oxidative stress, inflammatory and apoptotic pathways, and changes in other molecules' function plays an essential role in diabetes-induced renal tissue damage. Due to its multiple protective effects, taurine significantly prevented the activation of the pathways mentioned above and altered the function of molecules involved in these pathways, resulting in alleviating diabetic nephropathy. According to the obtained results, it was found that taurine can mitigate diabetes-induced nephropathy, mainly through its anti-oxidant activity, which is an essential factor in activating inflammation and apoptosis pathways.

Preventive Effect of Lycopene in Dextran Sulfate Sodium-Induced Ulcerative Colitis Mice through the Regulation of TLR4/TRIF/NF-κB Signaling Pathway and Tight Junctions

The preventive effect and molecular mechanism of lycopene (LP) in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice were evaluated. Compared to the DSS group, the LP prevention groups not only significantly inhibited the DSS-induced weight loss, decreased the disease activity index (DAI) score, increased the colon length, and improved inflammation in the colon but also significantly increased the levels of superoxide dismutase (SOD),catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione (GSH) in the colon and reduced inflammatory cytokine, myeloperoxidase (MPO), and malondialdehyde (MDA) levels. Notably, when compared to the DSS group, the protein expression levels of TLR4, TRIF, and p-NF-κB p65 in the mice colon tissue were downregulated and those of tight junction-related proteins were upregulated in the LP + DSS group, with the most significant effect observed in the 10 mg/kg LP + DSS group. These results confirmed that the upregulation of tight junction-related protein expression after blocking the TLR4/TRIF/NF-κB signaling pathway may be one of the mechanisms through which LP prevents UC.

The TRPA1 Agonist Cinnamaldehyde Induces the Secretion of HCO3- by the Porcine Colon

A therapeutic potential of the TRPA1 channel agonist cinnamaldehyde for use in inflammatory bowel disease is emerging, but the mechanisms are unclear. Semi-quantitative qPCR of various parts of the porcine gastrointestinal tract showed that mRNA for TRPA1 was highest in the colonic mucosa. In Ussing chambers, 1 mmol·L^-1 cinnamaldehyde induced increases in short circuit current (ΔI_sc) and conductance (ΔG_t) across the colon that were higher than those across the jejunum or after 1 mmol·L^-1 thymol. Lidocaine, amiloride or bumetanide did not change the response. The application of 1 mmol·L^-1 quinidine or the bilateral replacement of 120 Na⁺, 120 Cl^- or 25 HCO₃^- reduced ΔG_t, while the removal of Ca²⁺ enhanced ΔG_t with ΔI_sc numerically higher. ΔI_sc decreased after 0.5 NPPB, 0.01 indometacin and the bilateral replacement of 120 Na⁺ or 25 HCO₃^-. The removal of 120 Cl^- had no effect. Cinnamaldehyde also activates TRPV3, but comparative measurements involving patch clamp experiments on overexpressing cells demonstrated that much higher concentrations are required. We suggest that cinnamaldehyde stimulates the secretion of HCO₃^- via apical CFTR and basolateral Na⁺-HCO₃^- cotransport, preventing acidosis and damage to the epithelium and the colonic microbiome. Signaling may involve the opening of TRPA1, depolarization of the epithelium and a rise in PGE2 following a lower uptake of prostaglandins via OATP2A1.