Mechanisms of action underlying the gastric antiulcer activity of the Rhizophora mangle L

Ethnopharmacological relevance

Rhizophora mangle, the red mangrove, has long been known as a traditional antiulcer medicine. The present work evaluated the mechanisms of action involved in the anti-ulcer properties of the Rhizophora mangle bark extracts.

Materials and methods

Gastroprotection of Rhizophora mangle was evaluated in rodent experimental models (ethanol). To elucidate the mechanisms of action the antisecretory action and involvement of NO, SH, mucus and PGE₂ were evaluated. The acetic acid-induced gastric ulcer model, Western blotting assay (COX-1, COX-2 and EGF) and immunohistochemical localization of HSP-70, PCNA and COX-2 were also used to evaluate the Rhizophora mangle healing properties.

Results

Results showed that Rhizophora mangle bark crude extract (CE), as well as ethyl acetate (EtOAc) and butanolic fractions (BuOH) provided significant gastroprotection at all the tested doses. Thereby, the following protocols were performed using the lowest dose capable of producing the most effective gastroprotection, which was the BuOH 0.5 mg/kg (P < 0.001). Several mechanisms are involved in the antiulcer activity of Rhizophora mangle, such as, participation of NO, SH and mucus. The enhancement of PGE₂ levels and the upregulation of COX-2 and EGF seem to be directly linked to the antisecretory, cytoprotective and healing effects of BuOH. HSP-70 and PCNA are also involved in this cicatrisation process. No sign of toxicity was observed in this study, considering the analyzed parameters.

Conclusion

Our study reinforces its traditional medicinal use. Considering that the current therapies are based on the use of antisecretory or cytoprotective drugs, the Rhizophora mangle arises as a promising alternative antiulcer therapy.     

Centaurium erythrea (Gentianaceae) leaf extract alleviates streptozotocin-induced oxidative stress and β-cell damage in rat pancreas

Aims of the study

The present study was carried out to evaluate the effect of dried mature unripe Morinda citrifolia L. (Rubiaceae) fruit, commonly known as “Noni”, in an aqueous extract preparation (AFE) as used in Thai traditional medicine and its biomarker scopoletin on gastro-esophageal inflammatory models that are related to the claimed pharmacological properties of AFE and/or resembled the human esophagitis or gastric ulcer.

Materials and methods

The powder of dried mature unripe Noni fruit was boiled in water until it became a sticky paste and was then dried into a powder by lyophilization. The pharmacological activity of AFE and pure scopoletin at the same equivalent dose present in AFE was investigated in rat on gastro-esophageal inflammatory models (acid reflux esophagitis, acute gastritis induced by ethanol and serotonin, and chronic gastric ulcer induced by acetic acid); gastric biochemical parameters and gastrointestinal motility.

Results

AFE (0.63-2.50 g/kg) significantly prevented the formation of acid reflux esophagitis, reduced the formation of ethanol-induced acute gastric lesions, suppressed the development of gastric lesions in response to serotonin, and accelerated the healing of acetic acid-induced chronic gastric ulcer in rats with equal potency to those obtained by standard antisecretory agents (ranitidine and lansoprazole). AFE also significantly inhibited gastric acid secretion and pepsin activity in pylorus ligated rats. Additionally, AFE strongly increased the gastrointestinal transit of charcoal meal with a higher potency than cisapride. Pure scopoletin, when compared at the same equivalent dose containing in AFE, possessed similar antiulcer and antisecretory properties to that of AFE although it exerted a less prokinetic activity than AFE.

Conclusion

The findings indicated that AFE as well as its biomarker: scopoletin may be beneficial as a potential preventive and therapeutic agent for gastro-esophageal inflammatory diseases, mainly through its antisecretory and prokinetic activities including an inhibitory activity on serotonin, free radicals, and cytokine-mediated inflammation. Additionally, scopoletin might be one of the biomarker constituents to use for the quality assessment of Noni fruit products used for treating gastro-esophageal inflammatory diseases.     

In vivo antiulcer activity of the aqueous extract of Bauhinia purpurea leaf

Ethnopharmacological relevance

Bauhinia purpurea (Fabaceae) is a medicinal plant traditionally used to treat various ailments, including ulcers. In order to establish pharmacological properties of the leaf of Bauhinia purpurea, studies were performed on antiulcer activity of the plant's aqueous extract.

Materials and methods

The Bauhinia purpurea aqueous extract (BPAE) was prepared in the doses of 100, 500 and 1000 mg/kg. Antiulcer activity of BPAE was evaluated by absolute ethanol- and indomethacin-induced gastric ulcer, and pyloric ligation models. Acute toxicity was also carried out.

Results

BPAE, at the dose of 5000 mg/kg, did not cause any signs of toxicity to rats when given orally. Oral administration of BPAE exhibited antiulcer activity (p < 0.05) in all models used. However, the dose-dependent activity was observed only in the absolute ethanol-induced gastric ulcer model. Histological studies supported the observed antiulcer activity of BPAE. In pyloric ligation assay, BPAE increased the gastric wall mucus secretion.

Conclusions

The BPAE exhibits antiulcer activity, which could be due to the presence of saponins or sugar-free polyphenols, and, thus, confirmed the traditional uses of Bauhinia purpurea in the treatment of ulcers.     

Gastroprotective activity of hydroalcoholic extract obtained from the leaves of Brassica oleracea var. acephala DC in different animal models

Ethnopharmacological relevance

Brassica oleracea var. acephala DC has been extensively used in Brazilian traditional medicine to treat gastric ulcer.

Aim of the study

This study was conducted to evaluate the antiulcerogenic property of hydroalcoholic extract obtained from the leaves of Brassica oleracea.

Materials and methods

Antiulcer assays were performed using the protocol of ulcer induced by ethanol/HCl, and non-steroidal anti-inflammatory drugs (NSAIDs). Parameters of gastric secretion (volume, pH and [H⁺]) were determined by the pylorus ligation model and mucus in gastric contents.

Results

In the ethanol-induced ulcer model, we observed a significant reduction in all the parameters analyzed, obtaining curative ratios of 58.8 ± 11.5, 86.2 ± 12.2 and 42.8 ± 6.6% for the groups treated with 50 and 100 mg/kg of extract and omeprazole (30 mg/kg), respectively. The dose of 25 mg/kg of hydroalcoholic extract of Brassica oleracea showed no significant results. In the indomethacin-induced ulcer, the percentages of ulcer inhibition were 64.3 ± 9.9, 66.4 ± 12.3 and 81.2 ± 7.5% for the groups treated with 50 and 100 mg/kg extract and positive control (cimetidine, 100 mg/kg), respectively. The results showed a significant increase in pH and mucus production in the groups treated with Brassica oleracea when compared with the control group. No sign of toxicity was observed in the acute toxicity study.

Conclusions

The results of the present study show that hydroalcoholic extract of Brassica oleracea displays antiulcer activity, as demonstrated by the significant inhibition of ulcer formation induced using different models. The data suggest that the effectiveness of the extract is based on its ability to stimulate the synthesis of mucus, increase pH and decrease H⁺ ions in the stomach. This work corroborates the ethnopharmacology use of Brassica oleracea preparations, contributing to its pharmacological validation by suggesting that preparations obtained from Brassica oleracea could be used for the development of new phytopharmaceuticals for the treatment of gastric ulcer.     

Indigofera suffruticosa Mill as new source of healing agent: involvement of prostaglandin and mucus and heat shock proteins

Ethnopharmacological relevance

Indigofera suffruticosa is specie typical of the “Cerrado” or Brazilian savannah; it is a member of the Fabaceae family - in folkmedicine is used for gastric disorders, infection and inflammation.

Aim of the study

Ethyl acetate fraction (AcF) and aqueous fraction (AqF) of the methanolic extract of I. suffruticosa leaves were evaluated against acute gastric ulcer. The AcF fraction was selected to assess its activity in ulcer healing and its gastroprotective effects via mucus and gastric secretion.

Materials and methods

The gastroprotective action of AcF and AqF fractions were evaluated in a rodent experimental model. The action mechanisms, involvements of the antisecretory action, mucus and prostaglandin production, toxicological and healing activity of the AcF (100 mg/kg, p.o.) were evaluated. We also used histological analysis (HE and PAS) and immunohistochemical (PCNA and HSP-70) assays to evaluate the effects of I. suffruticosa.

Results

AcF significantly inhibited the gastric mucosal damage caused by ethanol. This effect was statistically significant in 100 mg/kg group compared vehicle. AcF did not interfered with gastric secretion, significantly increased the PGE₂ and mucus production (validated in PAS technique). The gastroprotection was attenuated by pretreatment with N-ethylmaleimide, but not L-NAME. In acid-acetic-induced ulcer model AcF accelerated ulcer healing. Immunohistochemistry analysis showed induction of proliferating cell (PCNA) and heat shock protein (HSP 70).

Conclusions

These results showed that AcF acted as gastroprotective agent stimulating prostaglandin, mucus and HSP70.     

Protective effects of methanolic extract of Hedyotis puberula (G. Don) R. Br. ex Arn. against experimentally induced gastric ulcers in rat

Aim of the study

This study was aimed to evaluate the antiulcer activity of the whole plants of Hedyotis puberula (G. Don) R. Br. ex Arn.

Materials and methods

Gastroprotective potential of the Hedyotis puberula methanol extract (200 and 400 mg/kg body weight) was studied on indomethacin (IND), ethanol and pyloric ligation (PL)-induced gastric ulcer models in rats.

Results

The treatment with Hedyotis puberula extract at 400 mg/kg p.o. protected the rats against the ulceration which was comparable to the reference drug omeprazole. Pretreatment with extract protected rats from gastric lesion development by way of increased pH and decreased volume, acidity and pepsin content of gastric secretion. Furthermore, total carbohydrate: protein ratio of the gastric juice were noticeably increased in pretreated rats.

Conclusion

Results of our study showed that Hedyotis puberula possess significant gastroprotective activity and validate the folklore claim.     

Gastric antisecretory and antiulcer activities of Cyclea peltata (Lam.) Hook. f. & Thoms. in rats

Ethnopharmacological relevance

Cyclea peltata (Lam.) Hook. f. &; Thoms. (Menispermaceae), locally called ‘Padathaali/Padakizhangu’ is used in Ayurvedic medicine to treat peptic ulcer.

Aim of the study

To evaluate the gastric antisecretory and antiulcer activity of Cyclea peltata.

Materials and methods

The ethanolic extract of Cyclea peltata root was used to evaluate its gastric antisecretory and antiulcer effect in the pylorus-ligated rat model and gastric lesions induced by ethanol or ethanol and indomethacin respectively in rats. The levels of gastric wall mucus, non-protein sulfhydryl groups (NP-SH), malondialdehyde, protein and catalase activity in the stomach samples of Cyclea peltata treated and control groups of rats were also quantified.

Results

The ethanolic extract of Cyclea peltata roots showed significant antisecretory activity as evidenced by decreased pepsin secretion, gastric juice volume and acid output in pylorus-ligated rats. Pretreatment with Cyclea peltata extract provided significant protection against the peptic ulceration caused by ethanol administered individually, or in combination with indomethacin. Our studies also revealed that pretreatment with Cyclea peltata significantly increased the gastric protein and catalase concentration of ethanol treated rats. Further, it showed significant gastroprotective effects on the stomach wall of ethanol or ethanol and indomethacin treated rats by decreasing malondialdehyde level, increasing the gastric wall mucus and non-protein sulfhydryl groups.

Conclusion

The present findings demonstrate that Cyclea peltata ethanolic extract has potent antisecretory and antiulcer effects and justify the traditional/ethnic usage of this herb to treat peptic ulcers and consequent stomach ache.     

Pharmacological mechanisms underlying the anti-ulcer activity of methanol extract and canthin-6-one of Simaba ferruginea A. St-Hil. in animal models

Relevance

Simaba ferruginea A. St-Hil. (Simaroubaceae) is a subshrub typical of the Brazilian Cerrado, whose rhizomes are popularly used as infusion or decoction for the treatment of gastric ulcers, diarrhea and fever.

Aim of the study

To evaluate the pharmacological mechanism(s) of action of the antiulcer effects of the methanol extract of Simaba ferruginea and its alkaloid canthin-6-one.

Materials and methods

Rhizome of Simaba ferruginea was macerated with methanol to obtain the methanol extract (MESf) from which was obtained, the chloroform fraction. Canthin-6-one alkaloid (Cant) was purified and then isolated from the chloroform fraction (CFSf). The isolated Cant was identified by HPLC. Anti-ulcer assays were determined using ethanol and indomethacin-induced ulcer models in mice and rats respectively. In order to determine the probable mechanisms of actions of MESf and Cant animals were pretreated with l-NAME prior to anti-ulcer agent treatments and ulcer induction and nitric oxide (NO) level determined in order to assess NO involvement in the gastroprotective effects. Assays of malondialdehyde (MDA), myeloperoxidase (MPO), pro-inflammatory cytokines: interleukin 8 (IL-8) and tumor necrosis factor-alpha (TNF-α) and prostaglandin E₂ (PGE₂) were also carried out according to previously described methods.

Results

The results indicate that the antiulcerogenic effects of MESf and Cant in ethanol-induced ulcer is mediated in part through increase in the production of protective endogenous NO as the antiulcerogenic activity of MESf and Cant was reduced in animals pre-treated with l-NAME. In indomethacin-induced ulcer pre-treatment with MESf and Cant showed reduction in the levels of MPO and MDA in the gastric tissue, thus indicating the participation of the antioxidant mechanisms on the gastroprotective effects. The plasma levels of IL-8 in ulcerated rats with indomethacin were also reduced by Cant, but not by MESf, indicating that inhibition of this cytokine contributes to the gastroprotective effect of Cant. However MESf and Cant had no effect on the mucosal membrane levels of PGE₂, indicating that the gastroprotective effects of these agents is independent of PGE₂ modulation.

Conclusion

The results obtained in this study with MESf and Cant added insights into the pharmacological mechanisms involved in their mode of antiulcer action. The results indicate that Cant is one of the compounds responsible for these effects. Such findings are of extreme importance in the strive for future development of potent, safer and effective antiulcer agent. The efficacy of MESf and Cant in gastroprotection shows that Simaba ferruginea might be a promising antiulcer herbal medicine, in addition to confirming the popular use of this plant against gastric ulcer models utilised in this study.     

Wound repair and anti-inflammatory potential of essential oils from cones of Pinaceae: preclinical experimental research in animal models

Ethnopharmacological relevance

Ethnobotanical surveys revealed that Abies bornmulleriana, Abies cilicica, Abies nordmanniana and Cedrus libani have been used to promote wound healing in Turkish folk medicine. Four different fir species (Abies cilicica subsp. cilicica, Abies nordmanniana subsp. bornmulleriana, Abies nordmanniana subsp. equi-trojani, and Abies nordmanniana subsp. nordmanniana), Cedrus libani and Picea orientalis were assessed for their in vivo wound healing and anti-inflammatory activities.

Materials and methods

The essential oils from six different coniferous cones were used. In vivo wound healing activity of the plants was evaluated by linear incision and circular excision experimental wound models subsequently histopathological analysis. The healing potential was comparatively assessed with a reference ointment Madecassol^®, which contains 1% extract of Centella asiatica. Additionally acetic acid-induced capillary permeability test was used for the oils’ anti-inflammatory activity.

Results

The essential oils from Cedrus libani and Abies cilicica subsp. cilicica demonstrated the highest activities on the both wound models. Moreover, the oil from Abies nordmanniana subsp. bornmulleriana was found generally highly effective. On the other hand, the rest of the species did not show any remarkable wound healing effect. Results of the present study support the continued and expanded utilization of these plant species employed in Turkish folk medicine.

Conclusion

The experimental study revealed that Cedrus libani and Abies cilicica subsp. cilicica display remarkable wound healing and anti-inflammatory activities.     

Evaluation of the antiulcerogenic activity profile of a flavonol diglucoside from Equisetum palustre L.

Ethnopharmacological relevance

The aerial parts of Equisetum palustre L. are used to treat peptic ulcer disease in Turkey. In a previous study, a flavonol diglucoside i.e., kaempferol 3-O-1″-β-d-glucopyranosyl-3-O-1″′-β-d-glucopyranoside (KGG) was isolated as the major antiulcerogenic constituent from the plant.

Aim of the study

The present study was undertaken to evaluate the antiulcer activity profile of KGG using various in vivo experimental ulcer models as well as by assessing gastric biochemical parameters.

Material and methods

KGG was obtained from the ethanol extract of the aerial parts of the plant by successive chromatographical methods. The activity profile of the compound was investigated using several ulcerogenesis models such as indomethacin-, indomethacin plus HCl/EtOH-, cysteamine-, serotonin-, N^G-nitro-l-arginine methyl ester plus EtOH-, diethyldithiocarbamate-, N-ethylmaleimide plus EtOH-, water immersion and restraint stress-, pyloric ligation-induced ulcers. In addition, effects of KGG on the biochemical parameters of gastric juice; i.e., inhibition of titratable gastric acidity, acid output, gastric pH, gastric secretion volume and peptic activity were studied.

Results

KGG exerted statistically significant gastroprotective activity against indomethacin-, indomethacin plus HCl/EtOH- and N-ethylmaleimide plus EtOH-induced ulcerogenesis. Moreover, KGG demonstrated weak activity against N^G-nitro-l-arginine methyl ester plus EtOH, water immersion and immobilization-induced stress, pyloric ligation-induced and diethyldithiocarbamate-induced gastric ulcer models, and also it was ineffective in the prevention of ulcers induced by serotonin and cysteamine. On the other hand, among the gastric biochemical parameters studied, KGG was only found to increase the gastric acid pH from 2.03 to 3.35.

Conclusion

Results of this investigation have clearly demonstrated that KGG was found to improve the cytoprotective mechanisms of the gastric mucosa. On the other hand, a weak activity profile was observed on the parameters affecting the gastric acidity (water immersion and restraint-induced-, pyloric ligation-induced-ulcerogenesis and titratable acidity).     

Chemical composition, antinociceptive and anti-inflammatory effects in rodents of the essential oil of Peperomia serpens (Sw.) Loud

Ethnopharmacological relevance

Peperomia serpens (Piperaceae), popularly known as “carrapatinho”, is an epiphyte herbaceous liana grown wild on different host trees in the Amazon rainforest. Its leaves are largely used in Brazilian folk medicine to treat inflammation, pain and asthma.

Aim of the study

This study investigated the effects of essential oil of Peperomia serpens (EOPs) in standard rodent models of pain and inflammation.

Materials and methods

The antinociceptive activity was evaluated using chemical (acetic acid and formalin) and thermal (hot plate) models of nociception in mice whereas the anti-inflammatory activity was evaluated by carrageenan- and dextran-induced paw edema tests in rats croton oil-induced ear edema, as well as cell migration, rolling and adhesion induced by carrageenan in mice. Additionally, phytochemical analysis of the EOPs has been also performed.

Results

Chemical composition of the EOPs was analyzed by gas chromatography and mass spectrometry (GC/MS). Twenty-four compounds, representing 89.6% of total oil, were identified. (E)-Nerolidol (38.0%), ledol (27.1%), α-humulene (11.5%), (E)-caryophyllene (4.0%) and α-eudesmol (2.7%) were found to be the major constituents of the oil. Oral pretreatment with EOPs (62.5-500 mg/kg) significantly reduced the writhing number evoked by acetic acid injection, with an ED₅₀ value of 188.8 mg/kg that was used thereafter in all tests. EOPs had no significant effect on hot plate test but reduced the licking time in both phases of the formalin test, an effect that was not significantly altered by naloxone (0.4 mg/kg, s.c.). EOPs inhibited the edema formation induced by carrageenan and dextran in rats. In mice, EOPs inhibited the edema formation by croton oil as well as the leukocyte and neutrophil migration, the rolling and the adhesion of leukocytes.

Conclusions

These data show for the first time that EOPs has a significant and peripheral antinociceptive effect that seems unrelated to interaction with the opioid system. EOPs also displays a significant anti-inflammatory effect in acute inflammation models. This effect seems to be related to components which inhibit the production of several inflammatory mediators. These results support the widespread use of Peperomia serpens in popular medicine to treat inflammation and pain.     

Anti-diabetic activity of Chiliadenus iphionoides

Ethnopharmacological relevance

Chiliadenus iphionoides (Boiss. & Blanche) Brullo (Asteraceae), a small aromatic shrub found throughout Israel, is used traditionally in the treatment of diabetes mellitus. In this study, Chiliadenus iphionoides anti-diabetic activity was characterized using cellular and animal models.

Materials and methods

Pancreatic β cells, adipocytes, and skeletal myotubes were treated with an ethanolic extract of Chiliadenus iphionoides to study the extract's effects on insulin secretion and glucose uptake. The sand rat (Psammomys obesus) was used to study Chiliadenus iphionoides acute and long term effects in vivo. An oral starch tolerance test was performed as well as a 30 day feeding study.

Results

Chiliadenus iphionoides extract increased insulin secretion in β cells as well as glucose uptake in adipocytes and skeletal myotubes. The extract also displayed hypoglycemic activity in the diabetic sand rat.

Conclusions

Chiliadenus iphionoides exhibits considerable anti-diabetic activity, although the mechanism of action remains to be determined.     

Antiulcerogenic activity of Lantana camara leaves on gastric and duodenal ulcers in experimental rats

Ethnopharmacological relevance

Lantana camara L. (Verbenaceae), a widely growing shrub has been used in the traditional medicine for treating many ailments. The objective of the present study was to evaluate the effects of methanolic extract of Lantana camara leaves on gastric and duodenal ulcers.

Materials and methods

The antiulcerogenic effect of methanolic extract of Lantana camara was evaluated in aspirin induced gastric ulcerogenesis in pyloric ligated rats, ethanol induced gastric ulcer, and cysteamine induced duodenal ulcer models. The extract was administered orally at two different doses of 250 mg/kg and 500 mg/kg. The lipid peroxidation, reduced glutathione levels of ethanol induced gastric ulcer model and inhibition zone in diameter against Helicobacter pylori also determined.

Results

The L. camara extract significantly (P < 0.01) reduced ulcer index, total acidity and significantly (P < 0.01) increased the gastric pH of aspirin + pylorus-ligation induced ulcerogenesis and ethanol induced gastric ulcer models. The extract also significantly (P < 0.01) reduced the ulcer index of cysteamine induced duodenal ulcer. The L. camara showed significant (P < 0.01) reduction in lipid peroxidation and increase in reduced glutathione levels. The inhibition zone in diameter of extract against H. pylori was 20 mm.

Conclusion

The methanolic extract of Lantana camara leaves shown healing of gastric ulcers and also prevents development of duodenal ulcers in rats.     

Antiulcer principle from Zingiber montanum

Ethnopharmacological relevance

Rhizome of Zingiber montanum has been extensively used as a folk medicine to ameliorate peptic ulcer at northern part of Bangladesh.

Aim of the study

To identify the antiulcer principle of the MeOH extract of the rhizome of Zingiber montanum by an ex vivo bioassay guided chromatographic separation and purification, and structure elucidation of the purified compound by spectroscopic methods.

Materials and methods

Dried powder of Zingiber montanum rhizomes was extracted with MeOH. The antiulcer activity of the crude extract and its chromatographic fractions were evaluated by the inhibition of 1 N HCl induced gastric lesions in Swiss albino mice. The pure compound was purified from the active fraction by crystallization with hexanes. Structure of the pure compound was elucidated by spectroscopic methods. The antiulcer activity of the pure compound was evaluated by the inhibition of 1 N HCl, 95% ethanol and indomethacin induced gastric lesions in mice.

Results

The MeOH extract of Zingiber montanum showed 61.97% and 83.10% inhibition of the 1 N HCl induced gastric lesions at doses of 200 mg/kg and 400 mg/kg, respectively, in mice. Chromatographic separation on silica gel of the extract was yielded seven fractions and the fraction 2 was found to have most potent antiulcer activity in mice. This fraction showed 77.46% inhibition of the 1 N HCl induced gastric lesions at a dose of 40 mg/kg in mice. Crystallization of the fraction yielded 1 (zerumbone, 180 mg). It showed statistically 45.77% and 92.25% inhibition of 1 N HCl induced gastric lesions in mice at doses of 20 mg/kg and 40 mg/kg, respectively. It also showed 29.07% and 45.35% inhibition of 95% ethanol induced gastric mucosal damage, and 64.76% and 72.38% inhibition of indomethacin induced gastric lesions in mice at doses of 20 mg/kg and 40 mg/kg, respectively.

Conclusion

Zerumbone (1) showed potent cytoprotective effect against necrotizing agent (HCl) and non-steroidal anti-inflammatory drug (indomethacin) induced gastric ulceration. It also exhibited moderate cytoprotective effect against noxious agent (EtOH) induced gastric lesions. It can be considered as a promising new antiulcer natural drug lead.     

Evaluation of antiulcer activity and mechanism of action of methanol stem bark extract of Lafoensia pacari A. St.-Hil. (Lytraceae) in experimental animals

Ethnopharmacological relevance

Lafoensia pacari St.-Hil. is a tree native to the Brazilian Cerrado. Its bark macerate is popularly used in Brazilian folk medicine for the treatment of peptic ulcer, wound healing and inflammation.

Aim of the study

To evaluate the antiulcer activities of the methanol extract of Lafoensia pacari (MELP) and possible mechanisms of actions involved.

Materials and methods

The stem bark of Lafoensia pacari was macerated in methanol to obtain the crude methanol extract of Lafoensia pacari (MELP). The gastroprotective and ulcer healing of MELP were evaluated using ethanol, indomethacin, cold-restraint stress-induced (acute) and acetic acid (chronic) ulcer models. The probable mode of action of MELP was also evaluated by determining intestinal transit, involvement of non-protein sulfhyhydryls (NP-SH), gastric mucus secretion, gastric secretory parameters and pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-17 (IL-17). Phytochemical analysis was carried out using classical methods and ellagic acid, one of the most important pharmacological active compounds was confirmed by HPLC.

Results

The results of the pharmacological studies on MELP demonstrated potent and effective gastroprotection against ethanol, indomethacin and cold stress-induced acute ulcers and ulcer healing in acetic acid induced chronic ulcer. MELP had no significant effect on the intestinal motility and it is also independent of mucus production but rather have a mucolytic effect. In pylorus-ligated rats the extract showed anti-secretory activity by decreasing total gastric juice volume and gastric acidity while increasing the gastric pH. The gastroprotection against ethanol is partially attributed to effective attenuation in the decrease in NP-SH levels, inhibition of the increases in the pro-inflammatory cytokines, TNF-α and IL-17. Phytochemical analysis of MELP revealed the presence of pyrrogalic tannins, saponins, steroids, triterpenoids and simple phenols, with ellagic acid being the major components.

Conclusion

The results of this study showed that MELP possesses preventive and curative effects against gastric ulcer in experimental animals. These effects are partly dependent on its anti-oxidant, anti-secretory properties and inhibition of pro-inflammatory cytokines and independent of gastric/intestinal motility and mucus secretion. Ellagic acid, a compound of proven antiulcer activity, was found in MELP as the major component. These results confirmed the traditional use of MELP in Brazilian popular medicine for the treatment of gastric ulcers and shed some light on some of its mechanisms of action.     

In vitro screening on β-amyloid peptide production of plants used in traditional medicine for cognitive disorders

Aim of the study

The aim of the study was to investigate the activity on β-amyloid peptide production of crude extracts of 9 plant species traditionally used in Benin or in Madagascar for the treatment of cognitive disorders, in order to select candidates for Alzheimer's disease treatment.

Materials and methods

For each species, hexane, dichloromethane, ethyl-acetate and water extracts were tested, at non-toxic concentrations, on CHO cells overexpressing the human neuronal β-amyloid peptide precursor (APP695) to measure variations of APP processing (by Western-blotting) and, for the most active, of Aβ-amyloid production (by ECLIA).

Results

We observed, at non-toxic concentrations, a significant increase in CTF/APP ratio with Oldenlandia affinis cyclotide-enriched fraction, Prosopis africana EtOAc extract, Pterocarpus erinaceus aqueous extract and Trichilia emetica hexane extract. We also showed that the Pterocarpus erinaceus extract significantly decreased Aβ production, displaying effects similar to those of DAPT (γ-secretase inhibitor) on APP processing, but may act on another inhibition site.

Conclusion

These active extracts are worth further studies to isolate the compounds responsible for the observed activities, to analyze their mode of action and determine their clinical potentials.     

In vivo anti-tussive activity and structural features of a polysaccharide fraction from water extracted Withania somnifera

Aim of the study

Anti-tussive drugs are amongst the most widely used medications worldwide; however no new class of drugs has been introduced into the market for many years. The present study aims at evaluating the structural features and in vivo anti-tussive activity of a polysaccharide fraction from water extracted Withania somnifera.

Materials and methods

Herein, we have analyzed water extracted material of Withania somnifera using chemical, chromatographic, spectroscopic and biological methods.

Results

A polysaccharide fraction (F3) containing arabinosyl, galactosyl and galacturonosyl residues were obtained by anion exchange chromatography of the water extracted material. This polymer is branched and contained (1,5)-/(1,3,5)-linked arabinofuranosyl, (1,3)-/(1,6)-/(1,3,6)-linked galactopyranosyl residues together with small amount of terminal rhamnopyranosyl and terminal arabinofuranosyl residues. Peroral administration of this pectic arabinogalactan in a dose of 50 mg kg⁻¹ body weight (b.w.) decreased the number of cough efforts induced by citric acid in guinea pigs like that of codeine.

Conclusions

This study provides a scientific basis for the past and present ethnomedical uses of this plant.     

Antisecretory actions of Baccharis trimera (Less.) DC aqueous extract and isolated compounds: analysis of underlying mechanisms

Ethnopharmacological relevance

Baccharis trimera (Less.) DC. (Asteraceae) is a species native to South America used in Brazilian folk medicine to treat gastrointestinal and liver diseases, kidney disorders and diabetes. Previous studies from this laboratory confirmed the antacid and antiulcer activities of the plant aqueous extract (AE) in rat and mouse models.

Aim of the study

To investigate the mechanisms involved in the antacid action of AE and isolated compounds from Baccharis trimera.

Materials and methods

AE was assayed in vivo in cold-restraint stress gastric ulcers and in pylorus-ligated mice. Nine fractions (F2-F10) previously isolated from AE were assayed in vitro on acid secretion measured as [¹⁴C]-aminopyrine ([¹⁴C]-AP) accumulation in rabbit gastric glands, and on gastric microsomal H⁺, K⁺-ATPase preparations. Chlorogenic acids (F2, F3, F6, F7), flavonoids (F9), an ent-clerodane diterpene (F8) and a dilactonic neo-clerodane diterpene (F10) have been identified in these fractions.

Results

Intraduodenal injection of AE (1.0 and 2.0 g/kg) in 4 h pylorus-ligated mice decreased the volume (20 and 50%) and total acidity (34 and 50%) of acid secretion compared to control values. Administered orally at the same doses AE protected against gastric mucosal lesions induced in mice by restraint at 4 °C. Exposure of isolated rabbit gastric glands to fractions F8 (10-100 μM) and F9 (10-300 μg/ml) decreased the basal [¹⁴C]-AP uptake by 50 and 60% of control (Ratio = 6.2 ± 1.1), whereas the remaining fractions were inactive. In the presence of the secretagogues F2 and F4 (30-300 μg/ml) decreased the [¹⁴C]-AP uptake induced by histamine (His) with a 100-fold lower potency than that of ranitidine. F5 and F6 reduced the [¹⁴C]-AP uptake stimulated by carbachol (CCh), but they were 10 to 20-fold less potent than atropine. F8 (diterpene 2) and F9 (flavonoids) decreased both the His- and CCh-induced [¹⁴C]-AP uptake, whereas F10 (diterpene 1) was inactive against the [¹⁴C]-AP uptake stimulated by secretagogues. Diterpene 2 was the most active of all tested compounds being 7-fold less potent than ranitidine and equipotent to atropine in reducing acid secretion in vitro. This compound also reduced the gastric H⁺, K⁺-ATPase activity by 20% of control, while the remaining fractions were inactive on the proton pump in vitro.

Conclusions

The results indicate that Baccharis trimera presents constituents that inhibit gastric acid secretion by acting mainly on the cholinergic regulatory pathway. The plant extract also contains compounds that exert moderate inhibition of the histaminergic regulatory pathway of acid secretion and the gastric proton pump. Altogether these active constituents appear to provide effective inhibition of acid secretion in vivo, which may explain the reputed antiulcer activity of the plant extract.     

Cornus kousa F.Buerger ex Miquel increases glucose uptake through activation of peroxisome proliferator-activated receptor γ and insulin sensitization

Aim of the study

Cornus kousa F.Buerger ex Miquel, an oriental medicinal plant, has been traditionally used for the treatment of hyperglycemia, but its molecular mechanism remains unknown. The goal of this study was to investigate the peroxisome proliferator-activated receptor γ (PPARγ) ligand-binding activity of Cornus kousa and to determine the effects of Cornus kousa on insulin sensitization in 3T3-L1 cells for the treatment of type 2 diabetes.

Materials and methods

PPARγ luciferase transactivation assay was used to evaluate the PPARγ ligand-binding activity of Cornus kousa leaf extract. Western blot analysis, oil Red O staining, and glucose uptake assay were performed to evaluate PPARγ agonistic activity and insulin sensitizing effects of Cornus kousa leaf extract (CKE) in 3T3-L1 cells.

Results

CKE increased PPARγ ligand-binding activity in a dose-dependent manner. In addition, CKE enhanced adipogenesis and the expression of PPARγ target proteins, including glucose transporter 4 (GLUT4) and adiponectin, as well as proteins involved in adipogenesis, including PPARγ and CCAAT/enhancer binding protein α (C/EBPα) in 3T3-L1 adipocytes. Furthermore, CKE led to significant induction of glucose uptake and stimulated insulin signaling, but not to activation of AMP-activated protein kinase (AMPK) signaling. The enhanced glucose uptake by CKE were abolished by treatment with bisphenol a diglycidyl ether (BADGE), a PPARγ antagonist, or LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), but not by compound C, an AMPK inhibitor.

Conclusion

Consistent with the high PPARγ ligand-binding activity, CKE increased glucose uptake through PPARγ activation and insulin signaling. These results suggest that CKE could have pharmacological effects for the treatment of hyperglycemia and type 2 diabetes.