Protective effect of embelin against acetic acid induced ulcerative colitis in rats

Effect of piperine on inhibition of FFA induced TLR4 mediated inflammation and amelioration of acetic acid induced ulcerative colitis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Piperine, a main component of Piper longum Linn. and Piper nigrum Linn., is a plant alkaloid with a long history of medicinal use. Piperine exhibits antidepressant, hepatoprotective, anti-metastatic, anti-thyroid, immunomodulatory, antitumor and anti-inflammatory activities, However its therapeutic potential in amelioration of ulcerative colitis and the underlying mechanism for anti-inflammatory activity remains unknown.The objective of the present investigation was to unravel the therapeutic potential of piperine on amelioration of IBD using acetic acid induced experimental animal model for ulcerative colitis and to determine the role of TLR4 receptor in signalling pathway of inflammatory gene expression in ulcerative colitis.

MATERIALS AND METHODS

We induced colitis using acetic acid (150µl of 5% once, intrarectally) in mice and estimated disease activity index (DAI), which took into account weight loss, stool consistency, and occult/gross bleeding. Colon length, spleen weights, ulcer area and ulcer index were measured; histological changes were observed by H&E staining. Effect of piperine on various antioxidant parameter of mice colon such as tissue myeloperoxidase (MPO) accumulation, SOD concentrations, reduced GSH and lipid peroxidation were determined. Pro-inflammatory mediators, namely, nitric oxide (NO), tumour necrosis factor-α (TNF-α) were determined by a TNF-α ELISA kit obtained from Thermo fisher scientific India Pvt. Ltd. Effect of piperine on haematological parameters of mice in acetic acid induced IBD was also determined which involves the estimation of FFA using a commercial free fatty acid fluorometric assay kit.

RESULT

Piperine significantly attenuated acetic acid induced DAI score which implies that it suppresses weight loss, diarrhoea, gross bleeding and infiltration of immune cells. Piperine administration also effectively and dose dependently prevented shortening of colon length and enlargement of spleen size. Histological examination indicated that piperine reduces oedema in sub-mucosa, cellular infiltration, reduced haemorrhages and ulceration as compare to acetic acid induced colitis in mice. Furthermore piperine inhibited abnormal secretion of pro-inflammatory mediators namely NO, cytokines TNF-α and reduces FFA induced TLR4 mediated inflammation.

CONCLUSION

These results suggest that piperine has an anti-inflammatory effect at colorectal sites that is due to down- regulations of the productions and expression of inflammatory mediators and it also reduces FFA induced TLR4 mediated inflammation. Thus it may have therapeutic potential on amelioration of IBD.

Effect of hydroalcoholic extract of Hibiscus rosa sinensis Linn. leaves in experimental colitis in rats

OBJECTIVE

To elucidate the ameliorative effect of hydroalcoholic extract of leaves of Hibiscus rosa sinensis (HRS) in acetic acid induced experimental colitis in male wistar rats.

METHODS

The animals were administered with 2 mL acetic acid (4%) via intra rectal. The animals were divided into various treatment groups (n=6). Prednisolone was used as standard drug and HRS was administered at a dose of 50, 100 and 200 mg/kg p.o. The control group of animals received 1 mL of vehicle (distilled water). Ulcer area, ulcer index, spleen weight, colon weight to length ratio, macroscopic score, haematological parameters, colonic superoxide dismutase (SOD), glutathione (GSH), myeloperoxidase (MPO), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), nitric oxide (NO) and histological changes were recorded after the treatment regimen of 11 days.

RESULTS

Intrarectal instillation of acetic acid caused enhanced ulcer area, ulcer index, spleen weight, colon weight to length ratio, colonic MPO, MDA, NO and TNF-α It caused significant decreased level of SOD and GSH. Pretreatment with HRS for 7 days exhibited significant effect in lowering of oxidative stress, colonic NO, TNF-α and elevation of SOD and GSH at a dose of 100 and 200 mg/kg in acetic acid induced colitis.

CONCLUSIONS

The present investigation demonstrates HRS is of potent therapeutic value in the amelioration of experimental colitis in laboratory animals by inhibiting the proinflammatory mediator like NO and TNF-α.

Oral administration of geraniol ameliorates acute experimental murine colitis by inhibiting pro-inflammatory cytokines and NF-κB signaling

Oral administration of geraniol ameliorates DSS-induced ulcerative colitis in mice.

Myrtle berry seed aqueous extract inhibits human neutrophil myeloperoxidase in vitro and attenuates acetic acid-induced ulcerative colitis in rats

We aimed in the present study to investigate the protective effect of a myrtle (Myrtus communisL.) berry seed aqueous extract (MBSAE) on acetic acid (AA)-induced colitis in rats as well as the mechanism implicated in this coli-protection.

Ameliorative effect of fisetin on cisplatin-induced nephrotoxicity in rats via modulation of NF-κB activation and antioxidant defence

Nephrotoxicity is a dose-dependent side effect of cisplatin limiting its clinical usage in the field of cancer chemotherapy. Fisetin is a bioactive flavonoid with recognized antioxidant and anti-inflammatory properties. In the present study, we investigated the potential renoprotective effect and underlying mechanism of fisetin using rat model of cisplatin-induced nephrotoxicity. The elevation in serum biomarkers of renal damage (blood urea nitrogen and creatinine); degree of histopathological alterations and oxidative stress were significantly restored towards normal in fisetin treated, cisplatin challenged animals. Fisetin treatment also significantly attenuated the cisplatin-induced IκBα degradation and phosphorylation and blocked the NF-κB (p65) nuclear translocation, with subsequent elevation of pro-inflammatory cytokine, TNF-α, protein expression of iNOS and myeloperoxidase activities. Furthermore, fisetin markedly attenuated the translocation of cytochrome c protein from the mitochondria to the cytosol; decreased the expression of pro-apoptotic proteins including Bax, cleaved caspase-3, cleaved caspase-9 and p53; and prevented the decline of anti-apoptotic protein, Bcl-2. The cisplatin-induced mRNA expression of NOX2/gp91phox and NOX4/RENOX and the NADPH oxidase enzyme activity were also significantly lowered by fisetin treatment. Moreover, the evaluated mitochondrial respiratory enzyme activities and mitochondrial antioxidants were restored by fisetin treatment. Estimation of platinum concentration in kidney tissues revealed that fisetin treatment along with cisplatin did not alter the cisplatin uptake in kidney tissues. In conclusion, these findings suggest that fisetin may be used as a promising adjunct candidate for cisplatin use.

A review on chemical-induced inflammatory bowel disease models in rodents

Ulcerative colitis and Crohn's disease are a set of chronic, idiopathic, immunological and relapsing inflammatory disorders of the gastrointestinal tract referred to as inflammatory bowel disorder (IBD). Although the etiological factors involved in the perpetuation of IBD remain uncertain, development of various animal models provides new insights to unveil the onset and the progression of IBD. Various chemical-induced colitis models are widely used on laboratory scale. Furthermore, these models closely mimic morphological, histopathological and symptomatical features of human IBD. Among the chemical-induced colitis models, trinitrobenzene sulfonic acid (TNBS)-induced colitis, oxazolone induced-colitis and dextran sulphate sodium (DSS)-induced colitis models are most widely used. TNBS elicits Th-1 driven immune response, whereas oxazolone predominantly exhibits immune response of Th-2 phenotype. DSS-induced colitis model also induces changes in Th-1/Th-2 cytokine profile. The present review discusses the methodology and rationale of using various chemical-induced colitis models for evaluating the pathogenesis of IBD.

Synthesis and biological evaluation of certain 3-substituted benzylideneamino-2-(4-nitrophenyl)quinazolin-4(3H)-one derivatives

Certain new 3H-quinazolin-4-one Schiff's bases were synthesized and screened for their activities against ulcerative colitis "UC". Their activity against phospholipase A2 and protease enzymes was also investigated. Some compounds possessed remarkable effect with different potentials against acetic acid-induced colitis model in rats. Compound 14 (50 mg/kg) was more effective than dexamesathone (0.01 mg/kg). It produced 79.78% protection of control colitis; however, compound 13 produced 75.80% protection and was considered as effective as dexamesathone with 75.30% protection. The observed results could be explained partially by their anti-inflammatory activities which appear as phospholipase A2 (hGIIA) and/or through protease inhibitor potentials. However, all the compounds under test showed preferential inhibition towards hG-IIA type of PLA2 rather than DrG-IB with varying degrees. Interestingly, compounds 14, 13, 12 and 11 displayed excellent inhibitory activity against phospholipase A2 accompanied by protease inhibitory profile.

Prophylactic and curative anti-ulcerative colitis activity and the possible mechanisms of action of some desert plants

The aim of the present study was to evaluate both prophylactic and curative anti-ulcerative colitis activity and the possible mechanism of action of seven desert plant extracts. Seven desert plants from different families; Conyza dioscoridis (L.) Desf. (Asteraceae), Euphorbia hirta L. (Euphorpiaceae), Origanum syriacum L. and Salvia lanigera L. (Lamiaceae), Sisymbrium irio L., Solanum nigrum Linn. (Solanaceae) and Solenostemma arghel (Del.) Hayne. (Asclepiadaceae) were separately evaluated at three doses (125, 250, and 500 mg/kg) using the acetic acid-induced colitis model. The investigated extracts possessed prophylactic and curative anti-ulcerative colitis activities in a dose-dependent manner, where Salvia lanigera (87.9) and Solenostemma arghel (89.2) were the most effective extracts whereas the dexamesathone produced 68%. These extracts were further investigated for estimation of their mechanism of action. The in vitro potential radical (DPPH) scavenging activities of the investigated extracts were well supported with the reduction of colonic MDA content for both extracts. Suppression of the inflammatory mediator TNF-α and inhibition of both PLA2 and protease enzymes may play an important role in the anti-ulcerative colitis activities. The investigated extracts were safe for use up to 5 g/kg and the total alcohol extracts of Salvia lanigera and Solenostemma arghel (400 mg/kg for 35 d) showed no alteration on liver and kidney functions. Phytochemical screening of the investigated extracts revealed the presence of flavonoids, tannins, unsaturated sterols, and proteins which could be responsible for the activities.

Cardioprotective effect of embelin on isoproterenol-induced myocardial injury in rats: possible involvement of mitochondrial dysfunction and apoptosis

AIMS

Preventive and/or therapeutic interventions using natural products for ischemic heart disease have gained considerable attention worldwide. This study investigated the cardioprotective effect and possible mechanism of embelin, a major constituent of Embelia ribes Burm, using isoproterenol (ISO)-induced myocardial infarction model in rats.

MATERIALS AND METHODS

Rats were pretreated for three days with embelin (50mg/kg, p.o) before inducing myocardial injury by administration of ISO (85 mg/kg) subcutaneously at an interval of 24h for 2 consecutive days. Serum was analyzed for cardiac specific injury biomarkers, lipids and lipoprotein content. Heart tissues were isolated and were used for histopathology, antioxidant and mitochondrial respiratory enzyme activity assays and western blot analysis.

KEY FINDINGS

Results showed that pretreatment with embelin significantly decreased the elevated levels of serum specific cardiac injury biomarkers (CK-MB, LDH and AST), serum levels of lipids and lipoproteins and histopathological changes when compared to ISO-induced controls. Exploration of the underlying mechanisms of embelin action revealed that embelin pretreatment restored the myocardial mitochondrial respiratory enzyme activities (NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and mitochondrial redox activity), strengthened antioxidant status and attenuated ISO-induced myocardial lipid peroxidation. Immunoblot analysis revealed that embelin interrupted mitochondria dependent apoptotic damage by increasing the myocardial expression of Bcl-2 and downregulating the expression of Bax, cytochrome c, cleaved-caspase-3 & 9 and PARP. Histopathology findings further strengthened the cardioprotective findings of embelin.

SIGNIFICANCE

Result suggested that embelin may have a potential benefit in preventing ischemic heart disease like myocardial infarction.

Investigation of sesamol on myeloperoxidase and colon morphology in acetic acid-induced inflammatory bowel disorder in albino rats

Background. Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of gastrointestinal tract of immune, genetic, and environmental origin. In the present study, we examined the effects of sesamol (SES), which is the active constituent of sesame oil in the acetic acid (AA) induced model for IBD in rats. Methods. The groups were divided into normal control, AA control, SES, and sulfasalazine (SS). On day 7, the rats were killed, colon was removed, and the macroscopic, biochemical, and histopathological evaluations were performed. Results. The levels of MPO, TBARS, and tissue nitrite increased significantly (P < 0.05) in the AA group whereas they reduced significantly in the SES and SS treated groups. Serum nitrite levels were found to be insignificant between the different groups. Conclusions. The mucosal protective effects of sesamol in IBD are due to its potential to reduce the myeloperoxidase and nitrite content.

Protective effect of marine mangrove Rhizophora apiculata on acetic acid induced experimental colitis by regulating anti-oxidant enzymes, inflammatory mediators and nuclear factor-kappa B subunits

Ulcerative colitis is a disease that causes inflammation and ulcer in the lining of the large intestine. In this study we investigate the effect of Rhizophora apiculata (R. apiculata) on acetic acid induced colitis in mouse model. Experimental animals were randomized into four groups: normal untreated, colitis control, R. apiculata treated group and sulfasalazine treated group. R. apiculata significantly (p<0.01) decreased macroscopic score and wet weight of damaged colon compared to colitis control. This effect was confirmed biochemically by significant (p<0.01) reduction of colitis associated increase in myeloperoxidase activity. R. apiculata significantly (p<0.05) increased anti-oxidant enzymes such as superoxide dismutase (SOD) and glutathione (GSH) levels compared to colitis control. R. apiculata significantly (p<0.01) reduced lipid peroxides (LPO), nitric oxide (NO) and inflammatory mediators such as myeloperoxidase (MPO), lactate dehydrogenase (LDH), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) expressions compared to colitis control. R. apiculata treatment significantly (p<0.01) inhibits the translocation of NF-kB p65 and p50 subunits. Taken together these findings suggest that R. apiculata prevents acetic acid induced colitis in experimental mouse model and may serve as an excellent anti-oxidant and anti-inflammatory agent that could potentially be useful as a (natural) therapy for inflammatory bowel disease (IBD).

Naringin ameliorates acetic acid induced colitis through modulation of endogenous oxido-nitrosative balance and DNA damage in rats

The aim of this study was to evaluate the effect of naringin on experimentally induced inflammatory bowel disease in rats. Naringin (20, 40 and 80 mg/kg) was given orally for 7 days to Wistar rats before induction of colitis by intrarectal instillation of 2 mL of 4% (v/v) acetic acid solution. The degree of colonic mucosal damage was analyzed by examining mucosal damage, ulcer area, ulcer index and stool consistency. Intrarectal administration of 4% acetic acid resulted in significant modulation of serum alkaline phosphatase, lactate dehydrogenase, superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) and myeloperoxidase (MPO) content along with colonic nitric oxide (NO), xanthine oxidase (XO) level and protein carbonyl content in the colonic tissue as well as in blood. Naringin (40 and 80 mg/kg) exerted a dose dependent (P < 0.05) ameliorative effect, as it significantly increased hematological parameter as well as colonic SOD and GSH. There was a significant (P < 0.05) and dose dependant inhibition of macroscopical score, ulcer area along with colonic MDA, MPO activity by the 7 days of pretreatment of naringin (40 and 80 mg/kg). Biochemical studies revealed a significant (P < 0.05) dose dependant inhibition in serum alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels by pretreatment of naringin. Increased levels of colonic NO, XO, protein carbonyl content and DNA damage were also significantly decreased by naringin pretreatment. The findings of the present investigation propose that naringin has an anti-inflammatory, anti-oxidant and anti-apoptotic potential effect at colorectal sites as it modulates the production and expression of oxidative mediators such as MDA, MPO, NO and XO, thus reducing DNA damage.

Protective effects of hydrogen-rich saline on ulcerative colitis rat model

BACKGROUND

Ulcerative colitis (UC) is associated with enhanced production of reactive oxygen species and altered angiogenesis. Molecular hydrogen has been documented as a novel antioxidant to treat various reactive oxygen species-related diseases. The present study aimed to investigate the effects of hydrogen on UC using a rat model.

MATERIALS AND METHODS

UC in rats was induced with intracolonically administrated acetic acid. Hydrogen was supplied through intraperitoneal injection of 10 or 20 mL/kg hydrogen-rich saline. The hydrogen treatment was performed once every 2 d and lasted 2 wk. The stool consistency and weight loss were used to evaluate UC development. Colonic mucosal damage at the end of the experiment was scored using the macroscopic and microscopic observations. Vascular endothelial growth factor expression in the colonic mucosa was determined using immunohistochemistry.

RESULTS

The administration of acetic acid induced acute rat UC, as indicated by diarrhea, weight loss, and colonic mucosal damage. Treatment with hydrogen-rich saline reduced the weight loss and diarrhea and alleviated the colonic mucosal damage in the UC rats. In addition, the expression of vascular endothelial growth factor in the UC rats increased and could be inhibited by hydrogen treatment.

CONCLUSIONS

Antioxidative hydrogen-rich saline effectively protected the rats from UC, which might be, at least in part, because of inhibition of vascular endothelial growth factor.

Anti-cancer potential of South Asian plants

Phyto-chemicals are increasingly being used in the treatment of cancer because of their availability, potential anti-cancer activity with less adverse effects when compared with chemotherapy. The variation of climate and geography in South Asian countries provides a nursing environment for the growth of versatile plant species, that are repeatedly drawing attention of the scientific community. In this review, we have focused on the anti-cancer potential of thirty plants, which are commonly found in Bangladesh, India, Nepal, Pakistan and Sri Lanka, with their mechanisms of action. In particular, we have discussed the bio-active components that display anti-cancer activity, which have been identified in these plants. This review may help researchers to profile plants with known anti-cancer effect of this region and further investigations of anti-cancer agents in medicinal plants from South Asia.

Potent inhibition of human 5-lipoxygenase and microsomal prostaglandin E₂ synthase-1 by the anti-carcinogenic and anti-inflammatory agent embelin

Embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone) possesses anti-inflammatory and anti-carcinogenic properties in vivo, and these features have been related to interference with multiple targets including XIAPs, NFκB, STAT-3, Akt and mTOR. However, interference with these proteins requires relatively high concentrations of embelin (IC₅₀>4 μM) and cannot fully explain its bioactivity observed in several functional studies. Here we reveal human 5-lipoxygenase (5-LO) and microsomal prostaglandin E₂ synthase (mPGES)-1 as direct molecular targets of embelin. Thus, embelin potently suppressed the biosynthesis of eicosanoids by selective inhibition of 5-LO and mPGES-1 with IC₅₀=0.06 and 0.2 μM, respectively. In intact human polymorphonuclear leukocytes and monocytes, embelin consistently blocked the biosynthesis of various 5-LO products regardless of the stimulus (fMLP or A23187) with IC₅₀=0.8-2 μM. Neither the related human 12- and 15-LO nor the cyclooxygenases-1 and -2 or cytosolic phospholipase A₂ were significantly affected by 10 μM embelin. Inhibition of 5-LO and mPGES-1 by embelin was (I) essentially reversible after wash-out, (II) not impaired at higher substrate concentrations, (III) unaffected by inclusion of Triton X-100, and (IV) did not correlate to its proposed antioxidant properties. Docking simulations suggest concrete binding poses in the active sites of both 5-LO and mPGES-1. Because 5-LO- and mPGES-1-derived eicosanoids play roles in inflammation and cancer, the interference of embelin with these enzymes may contribute to its biological effects and suggests embelin as novel chemotype for development of dual 5-LO/mPGES-1 inhibitors.

Animal models of ulcerative colitis

Ulcerative colitis (UC) is a chronic, recurrent inflammatory disease of the colon, characterized clinically by bloody diarrhea and abdominal pain. UC has been a clinical challenge due to its increasing incidence and prevalence, unknown etiology and pathogenesis, and the lack of effective treatment. Animal models have been widely used to investigate the pathogenesis of various diseases. So far, many animal models of UC have been developed, which play a crucial role in studying the pathogenesis of UC and finding new potential treatments. This article reviews the recent progress in the development of animal models of UC.

Embelin accelerates cutaneous wound healing in diabetic rats

This study reports the effect of embelin (1) on cutaneous wound in streptozotocin (STZ)-induced diabetic rats. The effect was studied using excision, incision, and dead space models. In diabetic rats, topical application of embelin 5% (w/w) ointment showed a significant increase in wound contraction and better epithelialization, thereby facilitating the healing. Embelin was also active by the oral route (25 and 50 mg/kg) in the incision and dead space wound models. In incision wound model, wound granulation tissues were removed on 8th post-wounding day, and the hydroxyproline, hexosamine, total protein, and DNA contents were determined. In STZ diabetic rats, topical and oral applications of embelin showed an increase in hydroxyproline, hexosamine, total protein, and DNA contents. It also showed a significant increase in wound breaking strength. Embelin significantly increased granuloma tissue weight and breaking strength in dead space model. These results indicated that embelin accelerated wound healing in diabetic rat.

Embelin-induced MCF-7 breast cancer cell apoptosis and blockade of MCF-7 cells in the G2/M phase via the mitochondrial pathway

Embelin is a small molecular inhibitor extracted from Myrsinaceae plants that specifically inhibits XIAP, affecting the proliferation and apoptosis of various types of tumor cells. In our previous studies, we have demonstrated that embelin is able to induce the apoptosis of MCF-7 breast cancer cells in a dose-dependent manner. However, its mechanism of action is not yet clear. The purpose of this study was to investigate the involvement of the mitochondrial pathway in embelin-induced apoptosis and the effect of embelin on the cell cycle. Different doses of embelin were added to MCF-7 breast cancer cells and it was found that embelin was able to induce apoptosis of MCF-7 breast cancer cells in a dose- and time-dependent manner. Flow cytometry analysis revealed that embelin caused changes in the MCF-7 cell mitochondrial membrane potential and blocked the cell cycle of MCF-7 cells in the G2/M phase. Moreover, embelin was demonstrated to promote mitochondrial release of cytochrome C via regulation of Bax and Bcl-2, resulting in the activation of caspase-3 and -9, while no significant changes in the level of caspase-8 were observed. The results have demonstrated that embelin-induced apoptosis of MCF-7 breast cancer cells involves the mitochondrial pathway.