Dietary supplementation of catechins and alpha-tocopherol accelerates the healing of trinitrobenzene sulfonic acid-induced ulcerative colitis in rats

Inflammatory auto-immune diseases of the intestine and their management by natural bioactive compounds

Autoimmune diseases are caused by the overactivity of the immune system towards self-constituents. Risk factors of autoimmune diseases are multiple and include genetic, epigenetic, environmental, and psychological. Autoimmune chronic inflammatory bowel diseases, including celiac and inflammatory diseases (Crohn's disease and ulcerative colitis), constitute a significant health problem worldwide. Besides the complexity of the symptoms of these diseases, their treatments have only been palliative. Numerous investigations showed that natural phytochemicals could be promising strategies to fight against these autoimmune diseases. In this respect, plant-derived natural compounds such as flavonoids, phenolic acids, and terpenoids exhibited significant effects against three autoimmune diseases affecting the intestine, particularly bowel diseases. This review focuses on the role of natural compounds obtained from medicinal plants in modulating inflammatory auto-immune diseases of the intestine. It covers the most recent literature related to the effect of these natural compounds in the treatment and prevention of auto-immune diseases of the intestine.

Therapeutic potential of flavonoids in inflammatory bowel disease: A comprehensive review

The inflammatory process plays a central role in the development and progression of numerous pathological situations, such as inflammatory bowel disease (IBD), autoimmune and neurodegenerative diseases, metabolic syndrome, and cardiovascular disorders. IBDs involve inflammation of the gastrointestinal area and mainly comprise Crohn’s disease (CD) and ulcerative colitis (UC). Both pathological situations usually involve recurring or bloody diarrhea, pain, fatigue and weight loss. There is at present no pharmacological cure for CD or UC. However, surgery may be curative for UC patients. The prescribed treatment aims to ameliorate the symptoms and prevent and/or delay new painful episodes. Flavonoid compounds are a large family of hydroxylated polyphenolic molecules abundant in plants, including vegetables and fruits which are the major dietary sources of these compounds for humans, together with wine and tea. Flavonoids are becoming very popular because they have many health-promoting and disease-preventive effects. Most interest has been directed towards the antioxidant activity of flavonoids, evidencing a remarkable free-radical scavenging capacity. However, accumulating evidence suggests that flavonoids have many other biological properties, including anti-inflammatory, antiviral, anticancer, and neuroprotective activities through different mechanisms of action. The present review analyzes the available data about the different types of flavonoids and their potential effectiveness as adjuvant therapy of IBDs.

Alpha-Tocopheryl Succinate-Conjugated G5 PAMAM Dendrimer Enables Effective Inhibition of Ulcerative Colitis

Ulcerative colitis (UC) is a severe inflammatory disease in colon, however, the therapeutic efficacy of the standard-of-care in clinic for UC patients is unsatisfactory. To explore new drugs for effective and safe treatment of UC, alpha-tocopheryl succinate (α-TOS) is conjugated to generation 5 (G5) poly(amidoamine) (PAMAM) dendrimer to construct a nanodevice of G5-NH-acetamide (Ac)-TOS. The inhibitory effects of the G5-NH-Ac-TOS on UC are evaluated in vivo in a dextran sulfate sodium induced UC mouse model, and its mechanisms are explored in vitro in lipopolysaccharide stimulated mouse peritoneal macrophages. The results indicate that the G5-NH-Ac-TOS exhibits greater inhibitive effects on UC than free α-TOS, through significant attenuation of the disease activity index and reduction of macrophage infiltration in the colon tissues. The protective mechanisms of the G5-NH-Ac-TOS are revealed to be related to inhibition of expression of nuclear translocation of NF-κB, phosphorylation of Akt, and reduction of reactive oxygen species production in the macrophages.

NaOH-induced Crohn's colitis in rats: a novel experimental model

AIM

Several models of experimental ulcerative colitis have been previously reported. To date, only one model of Crohn's colitis that was induced by trinitrobenzene sulfonic acid has been described.

MATERIALS AND METHODS

Twenty-one male albino rats were divided into three groups: group I: sham control group (n = 7), group II: acetic acid group (n = 7), group III: NaOH group (n = 7). On the day of induction, all rats were lightly anesthetized with intramuscular ketamine (8 mg/kg). A 6F plastic catheter was inserted rectally until the tip was 5 cm proximal to the anus. Then, 2 ml of 0.9% saline, 2 ml of 4% acetic acid, and 2 ml of 6.25% NaOH was administered to groups I, II, and III, respectively. All rats were sacrificed 5 days after colitis induction. The distal colon segment was assessed macroscopically and microscopically. In addition, malondialdehyde (MDA) and nitric oxide (NO) levels of the colonic tissue and changes in body weight were measured.

RESULTS

Macroscopic and microscopic examinations of colonic tissue samples showed morphological similarities to human Crohn's disease (CD). The MDA and NO levels of the colonic tissues were significantly higher in the NaOH group compared to the acetic acid and sham control groups (P = 0.001).

CONCLUSION

NaOH may be used to induce Crohn's colitis as an experimental model.

Anti-inflammatory effect of enzymatic hydrolysate of corn gluten in an experimental model of colitis

OBJECTIVES

Intestinal bacteria are thought to be involved in the initiation and perpetuation of inflammatory bowel diseases. Prebiotics (non-digestable dietary carbohydrate) have beneficial properties that alter the intestinal flora and contain glutamine-rich protein. Glutamine significantly decreases indices of inflammation. In this study, an enzymatic hydrolysate of corn gluten (EHCG) was administered by gavage to Sprague-Dawley rats fed an elemental diet to determine whether EHCG can ameliorate experi- mental colitis.

METHODS

Colitis was induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid after 10 days' daily oral administration of EHCG at 100 and 300 mg/kg. Macroscopic damage was assessed using a scoring system. The mucosa homogenate was sonicated and myeloperoxidase activity and histamine levels measured.

KEY FINDINGS

Treatment with EHCG significantly decreased the severity of injury and reduced myeloperoxidase activity and histamine levels in the distal colon mucosa.

CONCLUSIONS

EHCG may have therapeutic benefit as a supplement in enteral nutrition for patients with inflammatory bowel diseases.

Dietary polyphenols can modulate the intestinal inflammatory response

Inflammatory bowel diseases (IBD) arise from multiple causes, including environmental factors, gut microflora, immunity, and genetic predispositions. In the course of IBD, immune homeostasis and intestinal mucosa barrier integrity are impaired. Among natural preventive treatments that have been identified to date, polyphenols appear as promising candidates. They have been shown to protect against several diseases, including cardiovascular diseases and cancers, and they have anti-inflammatory properties in non-intestinal models. This paper will review the literature that has described to date some effects of polyphenols on intestinal inflammation. Studies, conducted using in vivo and in vitro models, provide evidence that pure polyphenolic compounds and natural polyphenolic plant extracts can modulate intestinal inflammation.

Mechanisms of action of green tea catechins, with a focus on ischemia-induced neurodegeneration

Catechins are dietary polyphenolic compounds associated with a wide variety of beneficial health effects in vitro, in vivo and clinically. These therapeutic properties have long been attributed to the catechins' antioxidant and free radical scavenging effects. Emerging evidence has shown that catechins and their metabolites have many additional mechanisms of action by affecting numerous sites, potentiating endogenous antioxidants and eliciting dual actions during oxidative stress, ischemia and inflammation. Catechins have proven to modulate apoptosis at various points in the sequence, including altering expression of anti- and proapoptotic genes. Their anti-inflammatory effects are activated through a variety of different mechanisms, including modulation of nitric oxide synthase isoforms. Catechins' actions of attenuating oxidative stress and the inflammatory response may, in part, account for their confirmed neuroprotective capabilities following cerebral ischemia. The versatility of the mechanisms of action of catechins increases their therapeutic potential as interventions for numerous clinical disorders. However, more epidemiological and clinical studies need to be undertaken for their efficacy to be fully elucidated.

Therapeutic efficacy of pycnogenol in experimental inflammatory bowel diseases

Pycnogenol was administered for 10 days by gavage to Sprague-Dawley rats fed an elemental diet, then inflammatory bowel disease (IBD) was induced by intrarectal administration of ethanol 2,4,6-trinitrobenzene sulfonic acid (TNBS). Twelve hours after TNBS treatment, the rats were killed, the colon was assessed by a macroscopic damage score and mucosa homogenate was assayed for myeloperoxidase (MPO) activity. The supplementation of pycnogenol significantly inhibited the macroscopic damage score and MPO activity in a dose-dependent manner. These results suggested that pycnogenol ameliorates TNBS-induced inflammation by radical scavenging activity, and may have beneficial effects as a supplement in enteral nutrition for IBD.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.

Iron supplementation increases disease activity and vitamin E ameliorates the effect in rats with dextran sulfate sodium-induced colitis

Inflammatory bowel disease is often associated with iron deficiency anemia and oral iron supplementation may be required. However, iron may increase oxidative stress through the Fenton reaction and thus exacerbate the disease. This study was designed to determine in rats with dextran sulfate sodium (DSS)-induced colitis whether oral iron supplementation increases intestinal inflammation and oxidative stress and whether the addition of an antioxidant, vitamin E, would reduce this detrimental effect. Four groups of rats that consumed 50 g/L DSS in drinking water were studied for 7 d and were fed: a control, nonpurified diet (iron, 270 mg, and dl-alpha-tocopherol acetate, 49 mg/kg); diet + iron (iron, 3000 mg/kg); diet + vitamin E (dl-alpha-tocopherol acetate, 2000 mg/kg) and the diet + both iron and vitamin E, each at the same concentrations as above. Body weight change, rectal bleeding, histological scores, plasma and colonic lipid peroxides (LPO), plasma 8-isoprostane, colonic glutathione peroxidase (GPx) and plasma vitamin E were measured. Iron supplementation increased disease activity as demonstrated by higher histological scores and heavier rectal bleeding. This was associated with an increase in colonic and plasma LPO and plasma 8-isoprostane as well as a decrease in colonic GPx. Vitamin E supplementation decreased colonic inflammation and rectal bleeding but did not affect oxidative stress, suggesting another mechanism for reducing inflammation. In conclusion, oral iron supplementation resulted in an increase in disease activity in this model of colitis. This detrimental effect on disease activity was reduced by vitamin E. Therefore, the addition of vitamin E to oral iron supplementation may be beneficial.

The therapeutic potential of flavonoids

Four most widely investigated flavonoids, flavopiridol, catechins, genistein and quercetin are reviewed in this article. Flavopiridol is a novel semisynthetic flavone analogue of rohitukine, a leading anticancer compound from an Indian tree. Flavopiridol inhibits most cyclin-dependent kinases and displays unique anticancer properties. It is the first cyclin-dependent kinase inhibitor to be tested in Phase II clinical trials. Catechin and its gallate are major ingredients in green tea and their anti-oxidant and cancer preventive effects have been widely investigated. A Phase I study of green tea extract GTE-TP91 has been conducted in adult patients with solid tumours. Similarly, genistein is a major ingredient in soybean and has been shown to prevent cancer and have antitumour, anti-oxidant and anti-inflammatory effects. Two antibody-genistein conjugates, B43-genistein and EGF-genistein, are currently in clinical development for the treatment of acute lymphoblastic leukaemia and breast cancer, respectively. Finally, most recent updates of quercetin are briefly described.