Fitoterapia 100 (2015) 110–117
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Protective effects of pogostone from Pogostemonis Herba against ethanol-induced gastric ulcer in rats Haiming Chen a,1, Huijun Liao c,1, Yuhong Liu a, Yifeng Zheng a, Xiaoli Wu a,d, Zuqing Su a, Xie Zhang a, Zhengquan Lai c, Xiaoping Lai a,b, Zhi-Xiu Lin c,⁎, Ziren Su a,b,⁎⁎ a
College of Chinese Medicines, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China Dongguan Mathematical Engineering Academy of Chinese Medicine, Guangzhou University of Chinese Medicine, Dongguan 523808, People's Republic of China c School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China d Faculty of Health Sciences, University of Macau, Macau 999078, People's Republic of China b
a r t i c l e
i n f o
Article history: Received 5 September 2014 Accepted in revised form 18 November 2014 Accepted 21 November 2014 Available online 3 December 2014 Keywords: Pogostone Ethanol Gastric ulcer Antioxidant Anti-inflammatory Rats
a b s t r a c t We examined the protective effect of pogostone (PO), a chemical constituent isolated from Pogostemonis Herba, on the ethanol-induced gastric ulcer in rats. Administration of PO at doses of 10, 20 and 40 mg/kg body weight prior to ethanol ingestion effectively protected the stomach from ulceration. The gastric lesions were significantly ameliorated by all doses of PO as compared to the vehicle group. Pre-treatment with PO prevented the oxidative damage and the decrease of prostaglandin E2 (PGE2) content. In addition, PO pretreatment markedly increased the mucosa levels of glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT), and decreased gastric malonaldehyde (MDA), relative to the vehicle group. In the mechanistic study, significant elevation of non-protein-sulfhydryl (NP-SH) was observed in the gastric mucosa pretreated by PO. Analysis of serum cytokines indicated that PO pretreatment obviously elevated the decrease of interleukin-10 (IL-10) level, while markedly mitigated the increment of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) secretions in ethanol-induced rats. Taken together, these results strongly indicate that PO could exert a gastro-protective effect against gastric ulceration, and the underlying mechanism might be associated with the stimulation of PGE2, improvement of antioxidant and anti-inflammatory status, as well as preservation of NP-SH. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Peptic ulcers are pathological lesions in the gastrointestinal tract that usually occur in the stomach and duodenum [1]. The gastric ulcer is characterized by necrosis, infiltration of
Abbreviations: CAT, catalase; GSH, glutathione; H&E, hematoxylin and eosin; IL-6, interleukin-6; IL-10, interleukin-10; MDA, malonaldehyde; NP-SH, non-protein-sulfhydryl; NSAIDs, non-steroidal anti-inflammatory drugs; TNF-α, tumor necrosis factor alpha; PO, pogostone; PGE2, prostaglandin E2; SOD, superoxide dismutase. ⁎ Corresponding author. Tel.: +852 3943 6347; fax: +852 2603 7203. ⁎⁎ Correspondence to: Z. Su. Tel.: +86 20 39358517; fax: +86 20 3935 8390. E-mail addresses:
[email protected] (Z.-X. Lin),
[email protected] (Z. Su). 1 These two authors contributed equally to this work.
http://dx.doi.org/10.1016/j.fitote.2014.11.017 0367-326X/© 2014 Elsevier B.V. All rights reserved.
neutrophils, reduction in blood flow, induction of oxidative stress, and secretion of inflammatory mediators [2,3]. Gastric ulcer is one of the major gastrointestinal disorders with increasing incidence and prevalence globally [4,5]. It is estimated that 14.5 million people worldwide are affected by gastric ulcers in 2007, with a mortality of 4.08 million [6–8]. It is well-known that gastric lesions occur primarily due to the imbalance between the harmful and gastro-protective factors of the gastric mucosa [9,10]. Excessive drinking habits, poor diets, stress, smoking, Helicobacter pylori and excessive ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) all contribute to peptic ulcer disease [8,11,12]. To date, a great number of synthetic drugs have been used for the treatment of gastric ulcers, such as anti-acids, proton pump inhibitors, anticholinergics and histamine receptor antagonists
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[13]. However, many of these drugs not only can produce undesirable adverse effects, but also involve high cost in gastric ulcer patients [14,15]. Natural products of plant origin that may present fewer side effects are emerging as a promising therapeutic resource for the development of new drugs in the management of gastrointestinal diseases. To this extent, we look into natural medicinal plants for drug discovery. Pogostemonis Herba, known as “Guang-Huo-Xiang” in Chinese, is originated from the dried aerial part of Pogostemon cablin (Blanco) Benth. (Labiatae). Its therapeutic functions in Chinese medicine are to remove dampness, relieve summerheat and exterior syndrome, stop vomiting and stimulate appetite [16]. Clinically, Pogostemonis Herba has been widely used by traditional Chinese physicians to treat a wide array of medical conditions such as common cold, nausea, diarrhea, headache and fever since time immortal [17]. Moreover, it is also an important component herb of many popular herbal formulae, such as Baoji Pill and Huoxiang Zhengqi Liquid, for the treatment of gastrointestinal diseases. Pogostone (PO, C12H16O4, the chemical structure is shown in Fig. 1) is the major chemical constituent of Pogostemonis Herba and is largely responsible for the intensive aromatic odor of the essential oil of this herb [18,19]. This compound has been demonstrated to exert potent antibacterial [20], anti-fungal [21] and anti-Candida [22] activities. Patchouli alcohol, another major ingredient of Pogostemonis Herba, was reported to exert gastro-protective effect in our previous work [23]. However, so far the antiulcerogenic activity of PO has not been reported in the literature. Therefore, our present study aimed to evaluate the antiulcerogenic potential of PO using the ethanol-induced gastric ulcers in rats as an experimental model, as well as to determine the effects of PO on gastric biochemical parameters and to elucidate its mechanisms of action.
2. Materials and methods
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2.2. Extraction and isolation of PO PO was isolated from P. cablin as previously described [22]. The extraction and isolation procedure was as follows. Briefly, the dried aerial parts of P. cablin (6 kg) were exhaustively extracted through water–steam distillation. Essential oil (20.4 g) was obtained from P. cablin and dissolved in ethyl acetate (100 ml), and then was extracted five times with 4% NaOH (100 ml). The five alkaline extracts were pooled and 10% HCl was added to produce a pH 2 solution. The solution was extracted three times with ethyl acetate (400 ml); then the ethyl acetate extracts were combined, washed five times with distilled water (800 ml), and the organic layer was evaporated in vacuo to get yellow oily liquid. After crystallization from normal hexane, white PO crystal (246.8 mg, yield 0.0041%) was finally obtained. PO was lipid soluble with melt point ranging from 32.6 to 33 °C and molecular weight of 224. Its chemical structure was identified by comparing its spectral data (MS, 1Hand 13C-NMR) with those published previously [21,24], and its purity was above 98% as determined by HPLC-UV using a previously described method [25]. 2.3. Animals Male Sprague–Dawley rats (6–7 weeks old, 180–220 g) were obtained from Laboratory Animal Center of Guangzhou University of Chinese Medicine (Guangzhou, China). Rats were housed in an environmentally controlled condition (22 ± 2 °C, relative humidity of 50 ± 5%) with a 12-h light/dark cycle and allowed free access to food and water. All rats were housed in cages with raised floors of a wide mesh to prevent coprophagy and fasted for 24 h prior to experimentation. Experimental protocols used in the present study were approved by the Animal Experimental Ethics Committee of Guangzhou University of Chinese Medicine (Guangzhou, China). All efforts were made to minimize animal suffering and to reduce the number of animals used in the experiments.
2.1. Plant materials and reagents 2.4. Administration and dose selection The aerial parts of P. cablin were collected in September 2012 in Maoming, Guangdong province, China. It was authenticated by one of the authors (Xiaoping Lai, an experienced Pharmacognosist) at the School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, where a voucher specimen (No. 120911) was deposited. Lansoprazole tablets were purchased from Tuobin Pharmaceutical Factory (Shantou, China) and ethanol was from Guangzhou Chemical Reagent Factory (Guangzhou, China). The ultrapure water was purified using a Milli-Q gradient water purification system (Millipore, Bedford, MA, USA). All other chemicals and reagents were analytical grade.
Fig. 1. The chemical structure of pogostone (PO).
Male Sprague–Dawley rats were randomly divided into six groups, with each containing six animals. The normal and ulcer control groups received distilled water and vehicle respectively throughout the course of the experiment. The prevention groups received lansoprazole (30 mg/kg) and different doses of PO (10, 20 and 40 mg/kg) dissolved in physiological saline, as described in the literature [26], for a period of 7 days. PO dosage was selected based on a preliminary dosing experiment on ethanol induced ulceration. 2.5. Ethanol-induced gastric ulcers All rats were fasted for 24 h with free access to drinking water and were treated as described in Section 2.3 for the last time before the initiation of the ethanol-induced ulceration. One hour after this treatment, the rats except those in the normal group received an oral administration of 1 mL of absolute ethanol. One hour after ethanol administration, all rats were euthanized and the blood samples were obtained with no addition of anticoagulants and centrifuged at 740 g for 10 min to obtain serum for biochemical analysis. Meanwhile, their
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stomachs were removed rapidly and opened along the greater curvature and rinsed with cold saline to remove the gastric contents and blood clots. The flattened stomach samples were photographed and the ulcer area (mm2) was measured using ImageJ software (developed by the National Institutes of Health, USA). The inhibition percentage was calculated using the following formula: [(Ulcer Area(Vehicle) − Ulcer Area(Treated)) / Ulcer Area(Vehicle)] × 100%. The stomach samples were scrapped after the scans and rapidly frozen with liquid nitrogen. Finally, all stomach samples were stored at −80 °C until biochemical analyses.
2.11. Statistical analysis The results were expressed as mean ± SEM and all statistical analyses were performed with Statistical Product and Service Solutions (SPSS) software. The statistical significance of differences for each parameter among groups was analyzed using a one-way analysis of variance (ANOVA) followed by Dunnett's test. A value of P b 0.05 was considered statistical significant. 3. Results 3.1. Ethanol induced gastric ulcers
2.6. Histological analysis Stomach samples removed from each rat were fixed in 10% buffered formalin and embedded in paraffin. Paraffin sections were then cut to a thickness of 5 μm and stained with hematoxylin and eosin (H&E) for histological evaluation according to standard procedures [27]. 2.7. Cytokines evaluations The levels of cytokines (IL-6, IL-10 and TNF-α) in the serum were evaluated using commercial enzyme-linked immunosorbent assay (ELISA) kits (eBioscience, USA) as per the manufacturer's instructions [28]. The absorbance was read at 450 nm with a microplate spectrophotometer (Multiskan GO, Thermo Fisher Scientific, USA). 2.8. Measurement of glutathione (GSH), superoxide dismutase (SOD), malonaldehyde (MDA) level, and catalase (CAT) activity Stomach tissues stored at −80 °C were homogenized in homogenization Tris-buffer (20 mM, pH 7.5) on ice using Ultra Turraks Homogenizer (IKA, Germany) and then were centrifuged at 11,940 g at 4 °C for 10 min. The supernatants were used to determine the activities of CAT and SOD, and levels of GSH and MDA. The concentration of protein in the supernatants was determined by the Bradford method using bovine serum albumin (BSA) as a standard. The activities of CAT and SOD and the levels of GSH and MDA were determined using commercial assay kits according to the manufacturer's instructions (Jiancheng Company, Nanjing, China) [29,30]. 2.9. Determination of non-protein sulfhydryls (NP-SH) Tissue homogenates were prepared from rats of the ethanol-induced gastric ulcer as mentioned in Section 2.8. Non-protein sulfhydryl (NP-SH) content was determined as previously described [31].
The ulcer control group presented severe mucosal injury with an average ulcer area of 260.47 ± 16.89 mm2. A significant decrease (P b 0.01) in ulcer area was observed in the lansoprazole-treated group with an average area of 3.38 ± 1.13 mm2 (98.70% inhibition). For the PO-treated groups, the ulcer area was significantly attenuated (P b 0.01) in a dosedependent manner. The 40 mg/kg of PO group exhibited the smallest ulcer area (12.90 ± 0.87 mm2) and the highest inhibition (95.05% inhibition). The ulcer areas of the 20 and 10 mg/kg PO groups were 60.32 ± 3.83 and 143.60 ± 7.46 mm2 (76.84% and 44.87% inhibition) respectively. A representative stomach of each group is shown in Fig. 2, and the ulcer areas are listed in Fig. 3. 3.2. Histological evaluations Results of histological analyses of the gastric mucosa are depicted in Fig. 4. Rats pre-treated with the vehicle (physiological saline) showed severe damage to the gastric epithelium. In the histological observation of gastric ulcer induced by ethanol, rats pre-treated with PO (10 and 20 mg/kg) showed less mucosal damage when compared with the vehicle group. Rats pre-treated with PO at 40 mg/kg showed normal histology or only very superficial lesions, and the observation was comparable to those treated with lansoprazole. 3.3. Effect of PO on serum cytokines The serum levels of TNF-α and IL-6 were accentuated while IL-10 was reduced in the rats ulcerated by ethanol relative to the control group. However, PO at dose of 20 and 40 mg/kg significantly reduced the levels of the pro-inflammatory cytokines TNF-α (P b 0.05) and IL-6 (P b 0.01). Although the low dose did not achieve statistical significance, decreases in TNF-α and IL-6 productions were also observed compared with the vehicle group. And pretreatment with PO at all tested doses (P b 0.05, P b 0.05 and P b 0.01, respectively) augmented the anti-inflammatory factor IL-10 level in a dose-dependent manner relative to the vehicle group (Table 1).
2.10. Determination of prostaglandin E2 (PGE2) PGE2 levels were determined in stomach tissues obtained from the ethanol-induced gastric ulcer. The stomach tissue was homogenized and centrifuged as described before and the supernatant was used for determination of PGE2 by using an enzyme immunosorbent kit (R&D Systems, Abingdon, UK) [23]. The optical densities were measured at 450 nm and the results were expressed as ng/g protein.
3.4. Effect of PO on SOD, GSH, CAT and MDA levels in the stomach tissue of the ethanol-treated rats Table 2 shows the results of SOD, GSH, CAT and MDA assays. After oral administration with PO of three doses, SOD and GSH activities were elevated obviously (P b 0.05, P b 0.01 and P b 0.01, respectively), which was in concerted with the dosedependent decrease in MDA levels in the stomach tissue
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Fig. 2. Effects of PO on the macroscopic appearance of the gastric mucosa in the ethanol-induced gastric lesions in rats. (A) Control group; (B) Vehicle group; (C) Lansoprazole group (30 mg/kg); (D) PO (10 mg/kg) group; (E) PO (20 mg/kg) group; and (F) PO (40 mg/kg) group.
(P b 0.05, P b 0.01 and P b 0.01, respectively). While PO at doses of 20 and 40 mg/kg significantly increased the CAT activity (P b 0.05, P b 0.05) in parallel to the vehicle group. The low dose also led to an increment in CAT activity, though the variation did not reach the statistical significance. Herewith, the observation indicated that PO might attenuate the ethanolinduced changes via regulation of oxidant–antioxidant balance. Among all the tested doses of PO, 40 mg/kg exhibited the best antioxidant effect.
3.5. Effect of PO on non-protein-sulfhydryl (NP-SH) and prostaglandin E2 (PGE2) levels Administration of rats with PO significantly (P b 0.05) restored the depletion of NP-SH caused by ethanol pretreatment (Table 3). The decreased level (P b 0.01) of PGE2 in the vehicle group when compared to that of the control group provided evidence that ethanol treatment reduced the PGE2 production. Table 3 shows that PO was able to maintain a high PGE2 level in the rats despite being treated with ethanol. 4. Discussion
Fig. 3. Effects of lansoprazole (30 mg/kg) and PO (10, 20 and 40 mg/kg) on the gastric ulcer area (mm2) in rats subjected to ethanol treatment. The results were expressed as mean ± SEM and analyzed by ANOVA followed by Dunnett's test, **P b 0.01 vs. control group.
The present study aimed to evaluate the anti-ulcer activity of PO using an ethanol-induced experimental gastric ulcer model and to investigate its underlying mechanisms of the action associated with its anti-ulcer activity. Alcohol consumption can produce acute hemorrhagic gastric erosions, and excessive ingestion can result in gastritis characterized by mucosal edema, sub-epithelial hemorrhages, cellular exfoliation, and inflammatory cell infiltration [32,33], all are the hallmarks of an acute inflammatory reaction. However, oral administration of PO effectively reversed the ethanol-induced gastric injury in a dose-dependent manner, with significant reduction of the gastric ulcer area. The protective activity of PO was also ascertained with lesser gastric damage magnitude of the rats in PO-treated groups than that of the counterparts in the vehicle group (Fig. 2B). The protective effect of PO towards the rat stomach mucosa exhibited in a dose-dependent manner became apparent (Fig. 2D–F). A week of pretreatment with PO had notably inhibited the mucosal damage of gastric wall (Fig. 4D–F) while
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Fig. 4. Histological evaluation of the ethanol-induced gastric mucosa damage in rats (H&E staining; magnification 100×). (A). Control stomach: intact gastric epithelium with organized glandular structure and normal submucosa could be seen; (B)–(F) ethanol-induced ulcer. (B) Rats pre-treated with vehicle: *indicates damaged mucosal epithelium with disrupted glandular structure and arrow depicts edema of submucosa and inflammatory infiltrate; (C) lanoprazole 30 mg/kg; (D) PO 10 mg/kg; (E) PO 20 mg/kg; (F) PO 40 mg/kg. (C), (D), (E) and (F) depict a recovery in mucosal epithelium and reorganized glandular structure as well as improvement of edema by lansoprazole and PO treatment respectively.
the ulcerated control rats (Fig. 4B) showed severe disruption to the surface epithelium, necrotic lesions penetrated deeply into mucosa, and extensive edema of submucosal layer. This study amply demonstrated that PO had gastroprotective action against the ethanol-induced gastric ulcer. Interleukins play a vital role in the regulation of the mucosal defense barrier. Ethanol ingestion may activate the innate immune system leading to changes in the level of inflammatory cytokines, such as TNF-α, IL-10 and IL-6 [5]. Previous findings
implicated that the levels of pro-inflammatory cytokines IL-6 and TNF-α remarkably increased in the gastric tissue of the ethanol-induced ulcer [34,35] while anti-inflammatory factor IL-10 was significantly reduced in gastric ulceration [36]. TNF-α, a representative inflammatory cytokine with pleiotropic functions, is closely involved in the process of inflammation. The evidence that an aberrant high level of TNF-α is detected in the serum of rats with inflammatory diseases including severe mucosal inflammation [37] and
Table 1 Effect of PO on the serum levels of TNF-α, IL-6 and IL-10 in rats with the ethanol-induced gastric ulcers (n = 6). Group
Dose (mg/kg)
TNF-α (pg/mg protein)
IL-6 (pg/mg protein)
IL-10 (pg/mg protein)
Control Vehicle Lansoprazole PO PO PO
– – 30 10 20 40
11.49 15.53 11.15 13.12 12.15 11.66
6.47 10.30 7.58 8.38 8.02 7.92
18.44 12.97 17.14 14.22 15.64 16.87
± ± ± ± ± ±
0.85** 0.80 0.68** 1.63 0.66* 1.28*
± ± ± ± ± ±
0.45** 0.50 0.73** 0.61 0.45** 0.47**
The results were expressed as mean ± SEM and analyzed by ANOVA followed by Dunnett's test, **P b 0.01, *P b 0.05 vs. the vehicle group.
± ± ± ± ± ±
0.96** 0.88 0.80** 0.88* 0.93* 0.96**
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Table 2 Effect of PO on SOD, GSH, CAT and MDA levels in the stomach tissue of the ethanol-treated rats. Group
Dose (mg/kg)
SOD (pg/mg protein)
GSH (pg/mg protein)
CAT (pg/mg protein)
MDA (pg/mg protein)
Control Vehicle Lansoprazole PO PO PO
– – 30 10 20 40
8.12 5.35 8.37 7.23 7.83 8.17
10.95 6.20 10.00 8.25 8.72 9.16
6.25 3.58 6.18 4.63 5.40 5.40
1.35 2.50 1.65 1.90 1.71 1.63
± ± ± ± ± ±
0.48** 0.71 0.42** 0.50* 0.34** 0.45**
± ± ± ± ± ±
0.34** 0.49 0.65** 0.25* 0.69** 0.75**
± ± ± ± ± ±
0.65** 0.32 0.68** 0.43 0.60* 0.65*
± ± ± ± ± ±
0.16** 0.22 0.19** 0.08* 0.20** 0.12**
The results were expressed as mean ± SEM and analyzed by ANOVA followed by Dunnett's test, **P b 0.01, *P b 0.05 vs. the vehicle group.
in gastric lesion specimens obtained from patients [38], strongly supports the hypothesis that TNF-α has detrimental effects, such as inducing tissue injury and inflammation. IL-6, another key pro-inflammatory cytokine, is known to participate in inflammation process and to modulate the expression of genes involved in cell cycle progression and inhibition of apoptosis [39]. IL-10 plays an important role in downregulating inflammatory cascade by enhancing the production of anti-inflammatory cytokines, mitigating the production of pro-inflammatory cytokines and preventing autoimmune pathologies [40–42]. Therefore, the possible changes in the level of cytokines IL-6, TNF-α and IL-10 were investigated (Table 1). Results indicate that the observed increase in serum IL-6 and TNF-α levels and decrease in IL-10 production can be attributable to the necrotizing effects of ethanol. However, the inflammatory status had been improved favorably in the animals pretreated with lansoprazole and PO at all doses. Despite the widely accepted notion that alcohol abuse leads to detrimental consequences in the gastrointestinal tract, the mechanisms underlying it still remain obscure. There is growing evidence that ethanol-induced gastric mucosal injury is closely related to the increased ROS level and the major source of ROS is from the activated neutrophils [43]. On the other hand, organisms per se have enzymatic and non-enzymatic defenses, including GSH, SOD and CAT against the ROS-induced lipid peroxidation [44]. GSH and SOD are known to be able to scavenge superoxide, hydrogen peroxide, hydroxyl and lipid peroxyl radicals, with a consequence of attenuating the tissue damage. CAT as preventive antioxidant triggers the rapid conversion of peroxyl radical into biologically safe substances, like water [45]. MDA, an index of lipid peroxidation, can usually quantify to identify lipid peroxidation [46]. Thus, to address the role of oxidative stress in our model, we assessed several oxidant–antioxidant parameters in the gastric tissues of rats. The experimental results showed that
Table 3 Effect of PO on the ethanol-induced changes in NP-SH and PGE2 content in gastric tissue homogenate. Group
Dose (mg/kg)
NP-SH (ng/g protein)
PGE2 (ng/g protein)
Control Vehicle Lansoprazole PO PO PO
– – 30 10 20 40
53.60 31.87 51.13 46.29 51.86 52.91
73.02 59.38 73.00 71.21 72.71 74.14
± ± ± ± ± ±
6.60* 4.27 5.25* 6.08 6.36* 6.90*
± ± ± ± ± ±
3.52* 4.61 3.98* 2.99* 3.58* 3.17**
The results were expressed as mean ± SEM and analyzed by ANOVA followed by Dunnett's test, **P b 0.01, *P b 0.05 vs. the vehicle group.
ethanol markedly increased MDA level, accompanied by a decrease of GSH, CAT and SOD activities, all of which are endogenous antioxidants. Our data support a critical role of oxidative stress in the pathogenesis of the ethanol-induced gastric ulcer. Nevertheless, pretreatment with PO resulted in significant increases in the activities of SOD and the levels of GSH, as well as a decrease in MDA formation, indicating its antioxidant activity. Our experimental results indicate that PO potentially exerted gastroprotective effect via an antioxidant mechanism. It has been reported that the endogenous NP-SH is important in the maintenance of mucosal integrity against the ethanol-induced gastric injury [47]. Its continuous adherence to mucus layer is a barrier to luminal pepsin and creates a stable, undisturbed layer to support the surface neutralization of acid, preventing the underlying mucosa from proteolytic digestion [48]. If disulfide bridges, which can connect the mucus subunits, are reduced, the mucus may become watersoluble and easily withdrawn by ulcerogenic agent, including ethanol [49]. Our study indicated that PO-treated groups effectively elevated the gastric NP-SH content when compared to the vehicle group. PO significantly increased basal levels of NP-SH groups, confirming the involvement of these groups in the gastroprotective effect. PGE2, which is crucial in the regulation of gastric mucus secretion, can be reduced by ethanol [50]. PGE2 acts via improving blood flow to maintain the cellular integrity in the mucosa [50,51], increasing mucus secretion, and bicarbonate and sulfhydryl compounds to strengthen the resistance of gastric mucosal cells to the necrotizing effect of strong irritants [52,53]. Our results showed that PO was able to increase PGE2 levels in a dose-dependent manner after the administration of ethanol, which might explain why PO exhibited a reducing effect on ethanol-induced ulceration in a dose-dependent fashion. In conclusion, the results of the present study amply demonstrated that PO pre-treatment was able to exert protective effects in the ethanol-induced gastric ulcer model. PO administration not only significantly increased CAT, SOD and GSH activities and decreased MDA level in gastric tissue, but also reduced the secretions of proinflammatory mediators such as IL-6 and TNF-α and raised the level of anti-inflammatory cytokine IL-10 in serum in rats exposed to ethanol. The experimental findings render PO as a promising chemical constituent for the treatment of gastric ulcer. Moreover, the elucidation of the underlying mechanisms of action also helps put the traditional use of Pogostemonis Herba for gastrointestinal diseases on a solid scientific footing.
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Conflict of interest The authors declare that they have no competing interests. Acknowledgments This work was supported by grants from the National Natural Science Foundation of China (No. 81173534), Guangdong International Cooperation Project (No. 2012B050300002), Science and Technological Program for Dongguan's Higher Education, Science and Research, and Health Care Institutions (No. 2012105102009), Ph.D. Programs Foundation of Ministry of Education of China (No. 20134425110009) and Science and Technology Innovation Project of Guangdong Provincial Department of Education (No. 2013KJCX0045), and Science and Technology Planning Project of Guangdong Province (No. 2012A080202002), and Central Finance of China in Support of the Development of Local Colleges and University [Educational finance Grant No. 276(2014)], and Science and technology cooperation projects among Hong Kong, Macao and Taiwan (No. 2014DFH30010). Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.fitote.2014.11.017. References [1] Rocha Caldas GF, do Amaral Costa IM, Rodrigues da Silva JB, da Nobrega RF, Galvao Rodrigues FF, Martins da Costa JG, et al. Antiulcerogenic activity of the essential oil of Hyptis martiusii Benth. (Lamiaceae). J Ethnopharmacol 2011;137:886–92. [2] Viana AFSC, Fernandes HB, Silva FV, Oliveira IS, Freitas FFBP, Machado FDF, et al. Gastroprotective activity of Cenostigma macrophyllum Tul. var. acuminata Teles Freire leaves on experimental ulcer models. J Ethnopharmacol 2013;150:316–23. [3] de Souza Almeida ES, Cechinel Filho V, Niero R, Clasen BK, Balogun SO, de Oliveira Martins DT. Pharmacological mechanisms underlying the antiulcer activity of methanol extract and canthin-6-one of Simaba ferruginea A. St-Hil. in animal models. J Ethnopharmacol 2011;134:630–6. [4] Brucker MC, Faucher MA. Pharmacologic management of common gastrointestinal health problems in women. J Nurse Midwifery 1997; 42:145–62. [5] Salga MS, Ali HM, Abdulla MA, Abdelwahab SI. Gastroprotective activity and mechanism of novel dichlorido-zinc(II)-4-(2-(5methoxybenzylideneamino)ethyl)piperazin-1-iumphenolate complex on ethanol-induced gastric ulceration. Chem Biol Interact 2012;195:144–53. [6] Srikanta BM, Siddaraju MN, Dharmesh SM. A novel phenol-bound pectic polysaccharide from Decalepis hamiltonii with multi-step ulcer preventive activity. World J Gastroenterol 2007;13:5196–207. [7] Maity B, Chattopadhyay S. Natural antiulcerogenic agents: an overview. Curr Bioact Compd 2008;4:20. [8] Laloo D, Prasad SK, Krishnamurthy S, Hemalatha S. Gastroprotective activity of ethanolic root extract of Potentilla fulgens Wall. ex Hook. J Ethnopharmacol 2013;146:505–14. [9] Laine L, Takeuchi K, Tarnawski A. Gastric mucosal defense and cytoprotection: bench to bedside. Gastroenterology 2008;135:41–60. [10] Sairam K, Priyambada S, Aryya NC, Goel RK. Gastroduodenal ulcer protective activity of Asparagus racemosus: an experimental, biochemical and histological study. J Ethnopharmacol 2003;86:1–10. [11] Vonkeman HE, Klok RM, Postma MJ, Brouwers JRBJ, van de Laar MAFJ. Direct medical costs of serious gastrointestinal ulcers among users of NSAIDs. Drugs Aging 2007;24:681–90. [12] Konturek SJ, Konturek PC, Brzozowski T, Konturek JW, Pawlik WW. From nerves and hormones to bacteria in the stomach; Nobel prize for achievements in gastrology during last century. J Physiol Pharmacol 2005;56:507–30. [13] Malfertheiner P, Chan FK, McColl KE. Peptic ulcer disease. Lancet 2009; 374:1449–61. [14] Chan FKL, Leung WK. Peptic-ulcer disease. Lancet 2002;360:933–41.
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