Gastroprotective effect of Neem (Azadirachta indica) bark extract: possible involvement of H(+)-K(+)-ATPase inhibition and scavenging of hydroxyl radical

The antisecretory and antiulcer effects of aqueous extract of Neem (Azadirachta indica) bark have been studied along with its mechanism of action, standardisation and safety evaluation. The extract can dose dependently inhibit pylorus-ligation and drug (mercaptomethylimidazole)-induced acid secretion with ED(50) value of 2.7 and 2 mg Kg(-1) b.w. respectively. It is highly potent in dose-dependently blocking gastric ulcer induced by restraint-cold stress and indomethacin with ED(50) value of 1.5 and 1.25 mg Kg(-1) b.w. respectively. When compared, bark extract is equipotent to ranitidine but more potent than omeprazole in inhibiting pylorus-ligation induced acid secretion. In a stress ulcer model, it is more effective than ranitidine but almost equipotent to omeprazole. Bark extract inhibits H(+)-K(+)-ATPase activity in vitro in a concentration dependent manner similar to omeprazole. It offers gastroprotection against stress ulcer by significantly preventing adhered mucus and endogenous glutathione depletion. It prevents oxidative damage of the gastric mucosa by significantly blocking lipid peroxidation and by scavenging the endogenous hydroxyl radical ((z.rad;)OH)-the major causative factor for ulcer. The (z.rad;)OH-mediated oxidative damage of human gastric mucosal DNA is also protected by the extract in vitro. Bark extract is more effective than melatonin, vitamin E, desferrioxamine and alpha-phenyl N-tert butylnitrone, the known antioxidants having antiulcer effect. Standardisation of the bioactive extract by high pressure liquid chromatography indicates that peak 1 of the chromatogram coincides with the major bioactive compound, a phenolic glycoside, isolated from the extract. The pharmacological effects of the bark extract are attributed to a phenolic glycoside which is apparently homogeneous by HPLC and which represents 10% of the raw bark extract. A single dose of 1g of raw extract per kg b.w. (mice) given in one day and application of 0.6g raw extract per kg b.w. per day by oral route over 15 days to a cumulative dose of 9g per kg was well tolerated and was below the LD(50). It is also well tolerated by rats with no significant adverse effect. It is concluded that Neem bark extract has therapeutic potential for the control of gastric hyperacidity and ulcer.     

Curcumin regulates expression and activity of matrix metalloproteinases 9 and 2 during prevention and healing of indomethacin-induced gastric ulcer

Matrix metalloproteinases (MMPs) are suggested to play a critical role in extracellular matrix degradation and remodeling during inflammation and wound healing processes. However, the role of MMPs in indomethacin-induced gastric ulcer and its healing process are not clearly understood. This study is aimed at determining the regulation of MMP-9 and -2 activities in indomethacin-induced acute gastric ulceration and healing. Indomethacin-ulcerated stomach extracts exhibit significant up-regulation of pro-MMP-9 (92 kDa) activity and moderate reduction of MMP-2 activity, which strongly correlate with indomethacin dose and severity of ulcer. The anti-inflammatory and antioxidant properties of curcumin, an active component of turmeric, suggest that curcumin may exert antiulcer activity through scavenging reactive oxygen species, by regulating MMP activity, or both. To test these possibilities, the effect of curcumin in indomethacin-induced gastric ulcer is examined by biochemical and histological methods. The results show that curcumin exhibits potent antiulcer activity in acute ulcer in rat model by preventing glutathione depletion, lipid peroxidation, and protein oxidation. Denudation of epithelial cells during damage of gastric lumen is reversed by curcumin through re-epithelialization. Furthermore, both oral and intraperitoneal administration of curcumin blocks gastric ulceration in a dose-dependent manner. It accelerates the healing process and protects gastric ulcer through attenuation of MMP-9 activity and amelioration of MMP-2 activity. Omeprazole, an established antiulcer drug does not inhibit MMP-9 while protecting indomethacin-induced gastric ulcer. We conclude that antiulcer activity of curcumin is primarily attributed to MMP-9 inhibition, one of the major path-ways of ulcer healing.     

Lansoprazole protects and heals gastric mucosa from non-steroidal anti-inflammatory drug (NSAID)-induced gastropathy by inhibiting mitochondrial as well as Fas-mediated death pathways with concurrent induction of mucosal cell renewal

We have investigated the mechanism of antiapoptotic and cell renewal effects of lansoprazole, a proton pump inhibitor, to protect and heal gastric mucosal injury in vivo induced by indomethacin, a non-steroidal anti-inflammatory drug (NSAID). Lansoprazole prevents indomethacin-induced gastric damage by blocking activation of mitochondrial and Fas pathways of apoptosis. Lansoprazole prevents indomethacin-induced up-regulation of proapoptotic Bax and Bak and down-regulation of antiapoptotic Bcl-2 and Bcl(xL) to maintain the normal proapoptotic/antiapoptotic ratio and thereby arrests indomethacin-induced mitochondrial translocation of Bax and collapse of mitochondrial membrane potential followed by cytochrome c release and caspase-9 activation. Lansoprazole also inhibits indomethacin-induced Fas-mediated mucosal cell death by down-regulating Fas or FasL expression and inhibiting caspase-8 activation. Lansoprazole favors mucosal cell renewal simultaneously by stimulating gene expression of prosurvival proliferating cell nuclear antigen, survivin, epidermal growth factor, and basic fibroblast growth factor. The up-regulation of Flt-1 further indicates that lansoprazole activates vascular epidermal growth factor-mediated controlled angiogenesis to repair gastric mucosa. Lansoprazole also stimulates the healing of already formed ulcers induced by indomethacin. Time course study of healing indicates that it switches off the mitochondrial death pathway completely but not the Fas pathway. However, lansoprazole heals mucosal lesions almost completely after overcoming the persisting Fas pathway, probably by favoring the prosurvival genes expression. This study thus provides the detailed mechanism of antiapoptotic and prosurvival effects of lansoprazole for offering gastroprotection against indomethacin-induced gastropathy.     

Omeprazole as a potent activator of human cytosolic aldehyde dehydrogenase ALDH1A1

BackgroundAccumulation of lipid aldehydes plays a key role in the etiology of human diseases where high levels of oxidative stress are generated. In this regard, activation of aldehyde dehydrogenases (ALDHs) prevents oxidative tissue damage during ischemia-reperfusion processes. Although omeprazole is used to reduce stomach gastric acid production, in the present work this drug is described as the most potent activator of human ALDH1A1 reported yet.MethodsDocking analysis was performed to predict the interactions of omeprazole with the enzyme. Recombinant human ALDH1A1 was used to assess the effect of omeprazole on the kinetic properties. Temperature treatment and mass spectrometry were conducted to address the nature of binding of the activator to the enzyme. Finally, the effect of omeprazole was evaluated in an in vivo model of oxidative stress, using E. coli cells expressing the human ALDH1A1.ResultsOmeprazole interacted with the aldehyde binding site, increasing 4–6 fold the activity of human ALDH1A1, modified the kinetic properties, altering the order of binding of substrates and release of products, and protected the enzyme from inactivation by lipid aldehydes. Furthermore, omeprazole protected E. coli cells over-expressing ALDH1A1 from the effects of oxidative stress generated by H₂O₂ exposure, reducing the levels of lipid aldehydes and preserving ALDH activity.ConclusionOmeprazole can be repositioned as a potent activator of human ALDH1A1 and may be proposed for its use in therapeutic strategies, to attenuate the damage generated during oxidative stress events occurring in different human pathologies.     

Involvement of reactive oxygen species in gastric ulceration: protection by melatonin

Uncontrolled hydrochloric acid secretion and ulceration in the stomach due to various factors are serious global problems today. Although the mechanism of acid secretion from the parietal cell is now fairly known, the mechanism of gastric ulceration is still not clear today. Among various causes of gastric ulceration, lesions caused by stress, alcohol consumption, Helicobacter pylori infection and use of nonsteroidal antiinflammatory drugs have been shown to be mediated largely through the generation of reactive oxygen species especially hydroxyl radical (*OH). A number of excellent drugs have been proved useful in controlling hyperacidity and ulceration but their long term uses are not devoid of disturbing side-effects. Hence, the search is still on to find out a compound possessing antisecretory, antiulcer and antioxidant properties which will serve as a powerful therapeutic agent to cure gastric hyperacidity and ulcer. This article describes the role of reactive oxygen species in gastric ulceration, drugs controlling them with their merits and demerits and, the role of melatonin, a pineal hormone in protecting the gastric lesions with a final commentary on how melatonin research with respect to gastric pathophysiology can be taken forward with a view to projecting this indole as a promising therapeutic agent to control gastric ulceration in humans.     

Evaluation of the antiulcerogenic activity of violacein and its modulation by the inclusion complexation with beta-cyclodextrin

The effects of beta-cyclodextrin (betaCD) inclusion complexation on the ability of violacein to prevent gastric ulceration in mice were studied. Violacein-betaCD inclusion complexes were prepared in 1:1 and 1:2 molar ratios and analysed by differential scanning calorimetry and powder X-ray diffractometry. Violacein previously administered orally at 10 mg/kg significantly reduced indomethacin-induced gastric lesions, as well as 100 mg/kg of cimetidine (positive control). However, betaCD complexation in both molar ratios significantly potentiated the protective action of violacein. In the HCl--ethanol-induced gastric ulcer model, violacein and the 1:2 inclusion complex (10 mg/kg, p.o.) inhibited gastric damage by almost 85%, whereas a 63% reduction was observed for the positive control, lansoprazole, at 30 mg/kg. In contrast, treatment with the 1:1 inclusion complex resulted in almost total disappearance of the antiulcer activity in this model. No significant changes in stress-induced gastric injury were found. In addition, the 1:2 inclusion complex improved the antilipoperoxidant activity of violacein in rat liver cells exposed to t-butyl hydroperoxide, whereas the 1:1 complex was less active than violacein. In summary, the 1:2 betaCD inclusion complex has gastroprotective properties similar to or higher than that of violacein. An increase in mucosal defensive mechanisms and protection against peroxidative damage might be involved.     

Histamine in stress ulcer prophylaxis in rats.

BACKGROUND: Gastrin and its analogues increase the gastric acid secretion, but also enhance mucosal defense mechanisms. On the other hand, increased formation of histamine leading to an increase in gastric acid secretion is accompanied with gastroprotection and acceleration of gastric ulcer healing. AIM: Of this study was to examine the effect of histamine on stress induced gastric ulcers in rats. METHODS: Male Wistar rats were exposed to water immersion and restrain stress (WRS) for 3.5 h at 23 degrees C. Before WRS rats were pretreated with saline, histamine, ranitidine or omeprazole. RESULTS: WRS produces gastric lesions which were strongly reduced by ranitidine or omeprazole. Also treatment with histamine markedly reduced ulcer area evoked by WRS. Addition of histamine to ranitidine or omeprazole caused an additional reduction in ulcer area. Gastroprotective effect of histamine was accompanied with the increase in gastric blood flow (GBF). Administration of omeprazole or ranitidine alone was without significant effect on GBF. Histamine caused an slight decrease in gastric luminal pH, whereas ranitidine or omeprazole significantly increased gastric luminal pH. Plasma interleukin-1beta was significantly reduced after administration of omeprazole, ranitidine, or histamine, however, the effect of histamine was less pronounced. DNA synthesis was increased after administration of omeprazole, ranitidine or histamine when compared with WRS alone. Administration of histamine in combination with ranitidine or omeprazole caused an additional increase in DNA synthesis. CONCLUSIONS: Histamine exhibits protective effect and increases gastroprotective effect of ranitidine and omeprazole against stress-induced gastric lesions. This effect of histamine seems to be independent on gastric acid secretion but related to the increase in gastric blood flow and the reduction in activation of cytokine cascade.     

The pharmacological differences and similarities between stress- and ethanol-induced gastric mucosal damage.

Stress- and ethanol-induced gastric mucosal damage are the two commonly used ulcer models in animals. They share some of the similarities but also have differences in the etiology of gastric ulceration. This article reviews the influences of various protective drugs on these two types of gastric damage in rats. Verapamil (a calcium antagonist) or N-ethylmaleimide (a sulfhydryl depletor) prevents cold restraint-, but potentiates ethanol-provoked gastric lesion formation. N-Acetylcysteine (a mucolytic agent) and acetaminophen (an antipyretic analgesic) have the opposite actions. Prostaglandins provide a much better antiulcer effect on ethanol-induced lesions. Cimetidine (a histamine H2-receptor antagonist) prevents only stress-induced mucosal damage. These differences in drug actions indicate that stress and ethanol may have dissimilar ulcerogenic mechanisms in rats. On the other hand, carbenoxolone (a mucus inducer), histamine H1-receptor antagonists, leukotriene inhibitors (FPL 55712 and nordihydroguaiaretic acid) and mast cell stabilizers (like zinc compounds, sodium cromoglycate, FPL 52694 and ketotifen), all protect against gastric mucosal damage by stress or ethanol in rats. However, the role of gastric sulfhydryls in both types of gastric lesions is still controversial. These findings imply that the two types of lesion formation share some of the ulcerogenic mechanisms. This communication attempts to analyze the various findings and to relate them to the etiology of stress and ethanol-induced gastric lesions. It also summarizes the uses, and the antiulcer mechanisms, of the drugs that have been studied utilizing these two animal ulcer models, and suggests their possible implications in man.     

The role of reactive oxygen species and capsaicin-sensitive sensory nerves in the pathomechanisms of gastric ulcers induced by stress.

Gastric microcirculation plays an important role in the maintenance of the gastric mucosal barrier and mucosal integrity. Sensory nerves are involved in the regulation of mucosal blood circulation and mucosal defense. Therefore, the ablation of these nerves by neurotoxic doses of capsaicin provides the possibility of determination of their role in gastric mucosal integrity. Stress ulceration represents a serious gastric lesions. Results of our previous experiments have indicated that water immersion and restraint stress (WRS) led to increased oxidative metabolism. Ablation of sensory nerves by high doses of capsaicin retards healing of gastric ulcers, but the role of reactive oxygen species (ROS) in the healing process has been little studied. Therefore, the aim of our present investigations was to determine the participation of ROS in sensory nerve activity during WRS. Experiments were carried out on 90 male Wistar rats and the area of gastric lesions was measured by planimetry. Colorimetric assays were used to determine gastric mucosal levels of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), as well as superoxide dismutase (SOD) activity. We demonstrated that inactivation of sensory nerves resulted in magnification of gastric mucosal damage induced by the WRS. In this process, oxidative stress, as reflected by an increase of MDA and 4-HNE tissue concentrations (an index of lipid peroxidation), as well as decrease of SOD activity, could play an important role. Aspirin, applied in a low dose, exerts a protective activity, possibly due to its metabolites, which possess the anti-oxidant and ROS scavanging properties. Pentoxyfilline-induced gastroprotection and hyperemia depends upon attenuation of the oxidative stress. This protection and hyperemia were, at least in part, attenuated by ASA.     

Adenosine: a novel ulcer modulator in stomachs.

Adenosine has been demonstrated for its actions on gastric secretion and stress-induced gastric ulceration in animals. We examined the pharmacological actions of adenosine on ethanol-evoked gastric lesions and gastric mucosal blood flow (GMBF) in rats, because both of them are closely related. Adenosine pretreatment, in dose of 7.5 mg/kg increased GMBF and protected against ethanol-evoked gastric lesion formation. However, this antiulcer action was followed by an aggravation of gastric lesions and reduction in GMBF. We further investigated whether these actions could act through the adenosine A1 or A2 receptors, therefore L-phenylisopropyladenosine (L-PIA) or N-ethylcarboxamidoadenosine (NECA), the adenosine A1 or A2 receptor agonists, respectively, were used. The drugs given in doses of 10 or 50 micrograms/kg for L-PIA and 1 or 5 micrograms/kg for NECA, dose-dependently inhibited GMBF and potentiated ethanol-induced gastric damage. When the two drugs were given together to animals, they did not further aggravate the severity of ulceration and reduction of GMBF. These findings indicate that the antiulcer action of adenosine is not mediated via the adenosine A1 and A2 receptors but if acts through different adenosine receptor subtypes. It was because the lesion worsening effects of adenosine at the second stage of the biphasic responses were similar to the actions of L-PIA and NECA, the ulcer potentiating effect is probably acting through adenosine A1 and A2 receptors in anaesthetised rats.     

Evaluation of gastric anti-ulcer activity of fixed oil of Ocimum basilicum Linn. and its possible mechanism of action

Fixed oil of O. basilicum was found to possess significant antiulcer activity against aspirin, indomethacin, alcohol, histamine, reserpine, serotonin and stress-induced ulceration in experimental animal models. Significant inhibition was also observed in aspirin-induced gastric ulceration and secretion in pylorus ligated rats. The lipoxygenase inhibiting, histamine antagonistic and antisecretory effects of the oil could probably contribute towards antiulcer activity. O. basilicum fixed oil may be considered to be a drug of natural origin which possesses both antiinflammatory and anti-ulcer activity.     

The membrane-stabilizing action of zinc carnosine (Z-103) in stress-induced gastric ulceration in rats

Zinc compounds have been shown to antagonize various types of gastric ulceration in rats. Zinc carnosine (Z-103), a newly developed agent was, therefore, examined for its antiulcer effect in stress-induced ulceration and also its membrane stabilizing action in rat stomachs. Cold-restraint (restrained at 4 degrees C for 2 h) stress induced severe hemorrhagic lesions together with increased mast cell degranulation and beta-glucuronidase release in the gastric glandular mucosa. Z-103 pretreatment with a single oral dose (3, 10 or 30 mg/kg) reversed these actions in a dose-dependent manner. When the compound was incubated in concentrations of 10(-7, 10(-6), 10(-5) or 10(-4) M, with isolated hepatic lysosomes, it significantly reduced the spontaneous release of beta-glucuronidase in the medium. The present study not only demonstrates the antiulcer effect of Z-103 but also indicates that the protective action is likely to be mediated by its membrane-stabilizing action on mast cells and lysosomes in the gastric glandular mucosa.     

Gastric toxicity and mucosal ulceration induced by oxygen-derived reactive species: protection by melatonin

Uncontrolled hydrochloric acid secretion and ulceration of the stomach mucosa due to various factors are serious global problems. Although the mechanism of acid secretion from the parietal cell is now well understood, the processes involved in gastric ulceration are still not clear. Among various causes of gastric ulceration, lesions caused by stress, alcohol consumption, Helicobacter pylori infection and due to use of nonsteroidal antiinflammatory drugs have been shown to be mediated largely through the generation of reactive oxygen species, especially the hydroxyl radical. A number of excellent drugs have proven useful in controlling hyperacidity and ulceration but their long-term use is associated with disturbing side-effects. Hence, the search is still on to find a compound possessing antisecretory, antiulcer and antioxidant properties which will serve as a therapeutic agent to reduce gastric hyperacidity and ulcers. This article describes the role of reactive oxygen species in gastric ulceration, drugs controlling them with their merits and demerits and, the role of melatonin, a pineal secretory product, in protecting against gastric lesions. In experimental studies, melatonin has been shown to be effective in reducing mucosal breakdown and ulcer formation in a wide variety of situations. Additionally, the low toxicity of melatonin supports further investigation of this molecule as a gastroprotective agent. Finally, we include a commentary on how melatonin research with respect to gastric pathophysiology can move forward with a view of eventually using this indole as a therapeutic agent to control gastric ulceration in humans.     

Attenuation of stress-induced gastric lesions by lansoprazole, PD-136450 and ranitidine in rats

Combining restraint with cold temperature (4°C) consistently induces gastric ulceration in rats after 3.5 h. The cold restraint-stress (CRS) method provides a suitable model for acute ulcer investigations. This study compares the antiulcer activities of lansoprazole (a proton pump inhibitor), PD-136450 (CCK(2)/gastrin receptor antagonist) and ranitidine (histamine H(2) receptor antagonist) on CRS-induced gastric ulcers in rats. The results have shown that lansoprazole, which is a potent anti-secretory agent, provides complete protection in this model of ulcer formation. The use of indomethacin pretreatment to inhibit the prostaglandin (PG) synthesis and N(G)-nitro L-arginine methyl ester (L-NAME) pretreatment to inhibit nitric oxide synthase did not alter the lansoprazole-induced inhibition of ulcer index obtained in the untreated Wistar rats indicating that these two systems were not involved in the activation of lansoprazole. PD-136450, an effective anti-secretory agent against gastrin- but not dimaprit-induced stimulation, evoked a dose-dependent inhibition of CRS-induced gastric ulcers. The results show that both PG and nitric oxide pathways can influence the inhibitory effect of PD-136450 against CRS-induced gastric ulcer. The antiulcer activities of both lansoprazole and PD-136450 were compared to that of ranitidine. The results showed that ranitidine was more potent than lansoprazole and PD-136450 in inhibiting CRS-induced gastric ulcers and its effect was shown to be influenced by PG as well as nitric oxide synthase. The results of this study have demonstrated that although lansoprazole, PD-136450 and ranitidine were protective against CRS-induced gastric ulcers, the antiulcer activities of PD-136450 and ranitidine involved both PG and nitric oxide pathways, while lansoprazole acted independently of these two systems during CRS.     

Antiulcer Effects of the Tripeptide PGP and Its Possible Metabolites (PG, GP, Glycine, and Proline) in Different Models of Ulcer Induction in Rats

The study of the effect of equimolar concentrations (3.7 mol/kg) of the tripeptide PGP and its possible metabolites—PG, GP, proline, and glycine—on ethanol-, stress-, and indomethacin-induced ulcer development in rats showed that only PGP exhibited consistent antiulcer effects on all three ulceration models. Glycine and proline tended to increase the area of indomethacin-induced lesions in the stomach. PG reduced the ethanol- and indomethacin-induced lesions approximately twofold but was considerably less effective in stress-induced ulcer. GP decreased the stress- and indometacin-induced ulcer but tended to stimulate the ethanol-induced lesions. The results of this study indicate that the antiulcer activity of PGP may be related to the effect of this tripeptide itself and to proteolysis of PGP to dipeptides and amino acids as well.     

Repair of Oxidative DNA Damage in Saccharomyces cerevisiae

Malfunction of enzymes that detoxify reactive oxygen species leads to oxidative attack on biomolecules including DNA and consequently activates various DNA repair pathways. The nature of DNA damage and the cell cycle stage at which DNA damage occurs determine the appropriate repair pathway to rectify the damage. Oxidized DNA bases are primarily repaired by base excision repair and nucleotide incision repair. Nucleotide excision repair acts on lesions that distort DNA helix, mismatch repair on mispaired bases, and homologous recombination and non-homologous end joining on double stranded breaks. Post-replication repair that overcomes replication blocks caused by DNA damage also plays a crucial role in protecting the cell from the deleterious effects of oxidative DNA damage. Mitochondrial DNA is also prone to oxidative damage and is efficiently repaired by the cellular DNA repair machinery. In this review, we discuss the DNA repair pathways in relation to the nature of oxidative DNA damage in Saccharomyces cerevisiae.     

Role of polyamines in gastroprotection induced by epidermal growth factor.

Polyamines have been shown to stimulate cellular growth and differentiation, though their role in the prevention of acute gastric lesion induced by various noxious agents has been little studied. Epidermal growth factor (EGF) exhibits gastroprotective and ulcer healing properties due to its potent mitogenic and growth promoting action. This study was designed to compare the gastroprotective effects of spermine and EGF against gastric damage induced by absolute ethanol, acidified aspirin and stress and to determine the role of endogenous polyamines in EGF-induced gastroprotection. Spermine and EGF significantly reduced the lesions induced by all three ulcerogens. Oral administration of spermine or subcutaneous infusion of EGF in 24 h fasted rats with chronic gastric fistula resulted in similar inhibition of gastric acid and pepsin secretion. Pretreatment with difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), a key enzyme in the biosynthesis of polyamines, did not affect ethanol lesions, but reversed the protective effect EGF but not spermine against ethanol. This finding indicates that polyamines mediate, at least in part, EGF-induced gastroprotection. In tests with oral administration of aminoguanidine that is known to suppress the activity of diamino-oxidase (DAO) and to inhibit the degradation of polyamines, EGF showed a markedly enhanced gastroprotective activity against ethanol damage. Since indomethacin failed to affect the gastroprotective effects of spermine and EGF and neither of these agents influenced the mucosal generation of PGE2 in intact or injured gastric mucosa, we conclude that prostaglandins are not the major factors in spermine- and EGF-induced gastroprotection. This study demonstrates that polyamines are highly effective against gastric lesions induced by various ulcerogens and that they act as primary mediators of EGF-induced gastroprotection.     

Protective role of ellagitannins from Eucalyptus citriodora against ethanol-induced gastric ulcer in rats: Impact on oxidative stress,inflammation and calcitonin-gene related peptide

The gastroprotective activity of an ellagitannin-rich fraction obtained from Eucalyptus citriodora (ECF) was investigated against ethanol-induced gastric ulceration in rats. The rats were pretreated with ECF (25, 50 and 100 mg/kg) 1 h before the administration of absolute ethanol to induce acute gastric ulceration. The gastric lesions were significantly reduced by all doses of ECF. Notably, pre-treatment with ECF (100 mg/kg) conferred 99.6% gastroprotection, which is significantly higher than that produced by omeprazole. Moreover, ECF administration markedly increased the mucin content in a dose-dependent manner. The potent gastroprotective effect of ECF could be partly mediated by attenuating ethanol-induced oxidative stress. ECF-pre-treatment markedly increased the depleted GSH and SOD levels in a dose-dependent manner. Moreover, ECF significantly decreased the elevated MDA tissue levels induced by ethanol administration. The results demonstrated that ECF administration exerted a powerful anti-inflammatory activity as evidenced by the reduction in the pro-inflammatory markers; IL-1β, TNF-α, 5-LO and COX-2. Additionally, the caspase-3 tissue levels were significantly reduced in the groups pre-treated with ECF. These results suggest that ECF could exert a beneficial gastroprotective effect through their antioxidant, anti-inflammatory and anti-apoptotic properties. Furthermore, ECF pre-treatment significantly attenuated the ethanol-induced decrease in CGRP expression, which has a protective role against gastric ulceration. Histopathological examination revealed intact mucosal layer, absence of hemorrhage and necrosis in groups treated with ECF. Ellagitannins were identified as the major active constituents responsible for the marked antioxidant and gastroprotective properties of ECF. The HPLC–PDA–ESI/MS/MS technique was employed to identify the ellagitannins of E. citriodora.