UPLC-QTOF-MS/MS-based metabolomic approach and gastroprotective effect of two chemotypes of Egletes viscosa (L.) less. against ethanol-induced gastric ulcer in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Egletes viscosa (L.) (macela) is a native wild herb that can be found in different states of northeastern Brazil. The infusions of its flower buds are traditionally used for the treatment of gastrointestinal disorders. E. viscosa possesses two chemotypes (named A and B), distinguishable by the composition of the essential oil from the flower buds. Although there are previous studies of the gastroprotective effect of the isolated constituents of E. viscosa, its infusions have not been investigated yet.

AIM OF THE STUDY

The present study aimed to evaluate and compare the chemical composition and the gastroprotective effect of flower bud infusions of E. viscosa from chemotype A (EVCA) and chemotype B (EVCB).

MATERIALS AND METHODS

Sixteen infusions were brewed with flower buds according to the traditional preparation mode and were analyzed through a UPLC-QTOF-MS/MS based metabolomic approach for determination of their metabolic fingerprints and quantification of bioactive compounds. Afterward, these data were analyzed by chemometric methods (OPLS-DA) for discrimination of the two chemotypes. Additionally, infusions of EVCA and EVCB (50, 100 and 200 mg/kg, p.o.) were evaluated on gastric ulcers induced by absolute ethanol (96%, 0.2 mL, p.o.) in mice. To elucidate the gastroprotective mechanisms, the effect of EVCA and EVCB on gastric acid secretion and gastric wall mucus was determined and the role of TRPV1 channels, prostaglandins, nitric oxide and K_ATP channels were assessed. Moreover, the oxidative stress-related parameters and the histological aspects of the stomach tissue were analyzed.

RESULTS

The chemotypes can be discriminated from each other using UPLC-QTOF-MS/MS chemical fingerprints. Both chemotypes presented similar chemical compositions, consisting basically of caffeic acid derivatives, flavonoids and diterpenes. The quantification of bioactive compounds demonstrated that chemotype A possesses more ternatin, tanabalin and centipedic than chemotype B. EVCA and EVCB (50, 100 and 200 mg/kg, p.o.) significantly decreased the severity of ethanol-induced gastric lesions, as shown by a reduction in histological alterations and leucocyte infiltration in gastric tissue. The gastroprotective mechanism of both infusions involves an antioxidant effect, maintenance of gastric mucus and reduction gastric secretion. Stimulation of endogenous prostaglandins and nitric oxide release, activation of TRPV1 channels, and K_ATP channels are also involved in the gastroprotection of the infusions.

CONCLUSION

The gastroprotective effect of EVCA and EVCB was equivalent and mediated through antioxidant and antisecretory actions, including the activation of TRPV1 receptors, stimulation of endogenous prostaglandins and nitric oxide, and opening of K_ATP channels. The presence of caffeic acid derivatives, flavonoids and diterpenes in both infusions is involved in mediating this protective effect. Our findings support the traditional use of infusions of E. viscosa for gastric disorders regardless of the chemotype.

Effects of centipedic acid on acute lung injury: A dose-response study in a murine model

Centipedic Acid (CPA), a natural diterpene from Egletes viscosa, an endemic species of the Caatinga biome, has shown antioxidant and anti-inflammatory properties. However, no report on the CPA on respiratory system mechanics has been so far advanced. We aimed to investigate the dose-response behavior of CPA on E. coli lipopolysaccharide (LPS)-triggered acute lung injury (ALI). Forty-eight C57BL/6 mice were randomly divided into six groups: control (SS), induced to ALI (LPS), 4 groups induced to ALI pre-treated with 12.5, 25, 50 and 100 mg/kg of CPA (CPA12.5, CPA25, CPA50 and CPA100 groups). CPA 100 mg/kg could prevent inflammatory cell infiltration, alveolar collapse, changes in tissue micromechanics and lung function (airway resistance, tissue elastance, tissue resistance and Static compliance). These results indicate preventive potential of this compound in the installation of ALI.

NIR and 1H qNMR methods coupled to chemometrics discriminate the chemotypes of the gastroprotective herb Egletes viscosa

Egletes viscosa is a Brazilian medicinal herb consumed as flower bud tea due to its gastroprotective properties. This plant possesses two essential oil-based chemical varieties: trans-pinocarveyl acetate-rich chemotype A and cis-isopinocarveyl acetate- rich chemotype B. Therefore, we developed two simple, fast and reliable methods for discrimination of E. viscosa chemotypes using NIR and ¹H qNMR spectroscopies combined with the chemometrics tools (iPLS and PLS-DA). Both methods showed high sensitivity, precision and specificity in the cross-validation tests. The NIR method has the advantages of being non-destructive and analyzable by portable devices, enabling its application for field and industrial evaluations. Meanwhile, the ¹H qNMR method allows the quantification of the bioactive components ternatin, tanabalin, and centipedic acid. These aforementioned compounds were found higher in the chemotype A. Accordingly, our methods showed to be complimentary approaches for authenticity and/or quality control of E. viscosa-derived raw materials and herbal products.

Gastroprotective effect and mechanism of action of Croton rhamnifolioides essential oil in mice

BACKGROUND

Croton rhamnifolioides Pax is a plant species that have been used in the folk medicine to treat ulcers, inflammations and hypertension. However, despite the relevant data obtained from ethnopharmacological studies, the pharmacological properties endorsing the efficacy of this plant to treat ulcer remain to be elucidated.

HYPOTHESIS/PURPOSE

The present study aimed to characterize the chemical profile and evaluate the gastroprotective activity of the essential oil obtained from C. rhamnifolioides Pax (OECC) in mice.

METHODS

The essential oil of Croton rhamnifolioides was obtained by hydrodistillation and analyzed by gas-phase chromatography coupled to mass spectrometry (GC/MS). The median lethal dose was determined employing an acute toxicity test. The gastroprotective activity of the OECC was investigated using animal models of gastric ulcer induced by the administration of absolute ethanol, acidified ethanol or indomethacin. Mechanisms of action were investigated using the physical barrier test and by in vivo evaluation of the involvement of the following molecular pathways: nitric oxide, ATP - dependent potassium channels, α₂ - noradrenergic receptors, capsaicin - sensitive afferent neurons and opioid receptor.

RESULTS

We identified the presence of 21 compounds in OECC, including spathulenol and 1,8 - cineole as major constituents. In orally administered mice, OECC caused no significant toxicity. OECC significantly prevented gastric lesions in all mice models. The barrier test demonstrated that the gastroprotective activity of OECC occurs in a systemic dimension. Our results demonstrated that the gastroprotective effect of OECC involves mechanisms that are related to modulation of opioid receptors and nitric oxide.

CONCLUSION

In conclusion, OECC demonstrated significant gastroprotective activity associated with low toxicity, providing scientific evidences that C. rhamnifolioides have the potential for the development of new antiulcer drugs.

Useful Brazilian plants listed in the manuscripts and publications of the Scottish medic and naturalist George Gardner (1812-1849)

ETHNOPHARMACOLOGICAL RELEVANCE

Information regarding the beneficial use of native Brazilian plants was compiled by a number of European naturalists in the 19th century. The Scottish surgeon botanist George Gardner (1812-1849) was one such naturalist; however, the useful plants recorded in his manuscripts have not yet been studied in depth.

AIM OF THE STUDY

To present data recorded by Gardner in his manuscript Catalogue of Brazilian Plants regarding the use of native plants by Brazilian people and evaluate the extent to which they have been explored.

MATERIALS AND METHODS

Data on useful plants were obtained from Gardner׳s manuscript Catalogue of Brazilian Plants deposited in the Archives of the Royal Botanic Gardens, Kew, UK. The identification of each plant was determined and/or updated by consulting the preserved botanical collections of Gardner deposited in the Herbarium of the Royal Botanic Gardens, Kew (hereafter K), and expert determinations in other herbaria where duplicates are held. Correlated pharmacological studies for each plant were obtained from the PubMed database. Information recorded in Gardner׳s diary and previously published elsewhere complemented these data.

RESULTS

A total of 63 useful plants was recorded from the Catalogue and a further 30 from Gardner׳s book Travels in the Interior of Brazil (Gardner, 1846). Of the recorded names in the Catalogue, 46 (73%) could be identified to species by consulting specimens collected by Gardner and held at Kew. Thirty-six different traditional uses were registered for the identified plants, the most common being as febrifuges, to treat venereal complaints and as purgatives. Fewer than 50% of these species have been the focus of published pharmacological studies, yet for those which have been thus investigated, the efficacies reported by Gardner were confirmed.

CONCLUSION

The data recorded by Gardner represent a rich, relatively unexplored source of information regarding the traditional uses of Brazilian plants which merits further investigation.

Mechanisms involved in the gastroprotective activity of esculin on acute gastric lesions in mice

This work describes the gastroprotective actions of esculin (6,7-dihydroxycoumarin-6-o-glucoside) against indomethacin- or ethanol-induced lesions and verifies the role of nitric oxide, ATP-dependent K(+) channels, prostaglandins, transient receptor potential vanilloid 1 and antioxidant effects in the gastroprotective mechanism of esculin in the ethanol-induced gastric lesion model. The intragastric administration of esculin at doses of 12.5, 25 and 50 mg/kg was able to protect the gastric mucosa against ethanol (0.2 mL/animal p.o.), and esculin at doses of 25 and 50 mg/kg protected against indomethacin-induced lesions (20mg/kg p.o.). Administration of l-NAME (10mg/kg i.p.), glibenclamide (10mg/kg i.p.) or indomethacin (10mg/kg p.o.), but not capsazepine (5mg/kg p.o.), was able to reduce the gastroprotection promoted by esculin (25mg/kg) on the ethanol-induced lesions. Measurements of nitrite, a NO metabolite, were increased in the group that was pretreated with esculin. In terms of antioxidant activity as a gastroprotective mechanism of esculin, the results show that pre-treatment with esculin decreased the amount of GSH, increased SOD activity, did not interfere with the CAT activity and decreased both the MPO activity and the MDA amount. In conclusion, pre-treatment with esculin confers significant gastroprotective and antioxidant activity and leads to a reduction in gastric injury; the mechanisms underlying these effects include stimulation of endogenous prostaglandins, nitric oxide synthesis, opening of K(ATP) channels and reduction of free radicals or modulation of antioxidant enzyme systems.

Gastroprotective activity of isopulegol on experimentally induced gastric lesions in mice: investigation of possible mechanisms of action

The present study investigated whether isopulegol, a monoterpene present in essential oils of several aromatic plants, would be able to promote some gastroprotective effect and also verified the possible mechanisms involved in this action. For this study, ethanol- and indomethacin-induced gastric ulcer models in mice and histopathological assessment were used. The roles of NO, sulfhydryls (glutathione, GSH), ATP-sensitive K(+) channels (K(ATP) channels), and prostaglandins were also investigated. Isopulegol exhibited a dose-related gastroprotective effect against ethanol-induced lesions, while the pretreatment with glibenclamide and indomethacin [but not with N(G)-nitro-L-arginine methyl ester] were able to reverse this action. The pretreatment with isopulegol also restored GSH levels to normal levels and exhibited dose-related gastroprotective effect against indomethacin-induced ulcer. The results suggested that isopulegol presents significant gastroprotective effects in both ethanol- and indomethacin-induced ulcer models, which appear to be mediated, at least in part, by endogenous prostaglandins, K(ATP) channel opening, and antioxidant properties.