Gastroprotective effect of a flavone from Lonchocarpus araripensis Benth. (Leguminosae) and the possible mechanism

Antiulcerogenic activity of the hydroalcoholic extract of leaves of Annona muricata Linnaeus in mice

Annona muricata Linnaeus, popularly known as “graviola” and also called soursop, is a species typical of countries with a tropical climate, and it is used in folk medicine as an anticancer, analgesic and antispasmodic agent. The aim of the present study was to validate the gastroprotective activity of the hydroalcoholic extract of the leaves of A. muricata (HEAM) and to investigate the underlying mechanisms of action for this effect. Gastric lesions were induced in mice by absolute ethanol, acidified ethanol or indomethacin. Before, the animals were pretreated with saline, omeprazole or HEAM orally at doses of 50–400 mg/kg. To determine the mechanism of action of the extract, we investigated, using specific inhibitors, the involvement of nitric oxide (NO), prostaglandins (PGEs), ATP-dependent K⁺ channels and α2-noradrenergic receptors. HEAM showed significant antiulcer activity against lesions induced by absolute ethanol, acidified ethanol or indomethacin, which was mediated by endogenous gastric prostaglandins.

Antiulcerogenic Activity and Toxicity of Bauhinia holophylla Hydroalcoholic Extract

Several species of Bauhinia are used in traditional medicine for the treatment of gastrointestinal diseases, diabetes, and inflammation, among other conditions. The aim of this study was to investigate the antiulcer effect of a hydroalcoholic extract from the leaves of B. holophylla. The chemical profile of the extract was determined by HPLC-PAD-ESI-IT-MS. A dose-effect relation was constructed using the ethanol-induced gastric ulcer model in male Wistar rats. Histological analyses and studies of antioxidant and anti-inflammatory activities were performed in stomach samples. The involvement of SH compounds, NO, K⁺_ATP channels, and α₂-adrenergic receptors in the gastroprotective effect was evaluated. A toxicity study was performed with a single oral dose of 5000 mg/kg. The extract was composed mainly of cyanoglucoside and flavonol-O-glycosides derivatives of quercetin and myricetin. SH compounds, NO release, K⁺_ATP channel activation, and presynaptic α₂-adrenergic receptor stimulation each proved to be involved in the antiulcer effect. The levels of GSH and activity of GR and GPx were increased, and the levels of TNF-α, IL-6 and IL-10 were modulated. There was an antidiarrheal effect and there were no signs of toxicity. B. holophylla presents antiulcer activity mainly by decreasing oxidative stress and attenuating the inflammatory response, without inducing side effects.

Effect of menthol in experimentally induced ulcers: pathways of gastroprotection

Based on ethnopharmacological indications that Mentha species may be used in the treatment of gastrointestinal diseases, this study aimed to characterize the gastroprotective mechanisms of menthol (ME), the major compound of the essential oil from species of the genus Mentha. The gastroprotective action of ME was analyzed in gastric ulcers that were induced by ethanol or indomethacin in Wistar male rats. The mechanisms responsible for the gastroprotective effect were assessed by analyzing the amount of mucus secreted, involvement of non-protein sulfhydryl (NP-SH) compounds, involvement of calcium ion channels and NO/cGMP/K(+)ATP pathway, gastric antisecretory activity and the prostaglandin E2 (PGE2) production. The anti-diarrheal activity and acute toxicity of ME were also evaluated. Oral treatment with ME (50mg/kg) offered 88.62% and 72.62% of gastroprotection against ethanol and indomethacin, respectively. There was an increased amount of mucus and PGE2 production. The gastroprotective activity of ME involved NP-SH compounds and the stimulation of K(+)ATP channels, but not the activation of calcium ion channels or the production of NO. The oral administration of ME induced an antisecretory effect as it decreased the H(+) concentration in gastric juice. ME displayed anti-diarrheal and antiperistaltic activity. There were no signs of toxicity in the biochemical analyses performed in the rats' serum. These results demonstrated that ME provides gastroprotective and anti-diarrheal activities with no toxicity in rats.

Morphologic and pharmacological investigations in the epicatechin gastroprotective effect

Previous studies of the gastroprotective activity of plants have highlighted the importance of the polyphenolic compound epicatechin (EC) in the treatment of gastric ulcers. This paper aimed to evaluate and characterize the gastroprotective mechanism of action of EC using male rats. The gastroprotective action of EC was analyzed in gastric ulcers induced by ethanol or indomethacin. The involvement of sulfhydryl (SH) groups, K⁺_ATP channels, α₂ adrenoceptors, gastric antisecretory activity, and the amount of mucus in the development of gastric ulcers were investigated. The lowest effective dose of EC providing gastroprotective effects was 50 mg/kg in the ethanol-induced gastric ulcers and 25 mg/kg in the indomethacin-induced gastric ulcers. The gastroprotection seen upon treatment with EC was significantly decreased in rats pretreated with a SH compound reagent or an α₂-receptor antagonist, but not with a K⁺_ATP channel blocker. Furthermore, oral treatment with EC increased mucus production and decreased H⁺ secretion. Immunohistochemistry demonstrated the involvement of superoxide dismutase (SOD), nitric oxide (NO), and heat shock protein-70 (HSP-70) in the gastroprotection. These results demonstrate that EC provides gastroprotection through reinforcement of the mucus barrier and neutralization of gastric juice and this protection occurs through the involvement of SH compounds, α₂-adrenoceptors, NO, SOD, and HSP-70.