Antioxidant Mechanisms Underlying the Gastroprotective Effect of Menthofuran on Experimentally Induced Gastric Lesions in Rodents.

Menthofuran is a monoterpene present in various essential oils derived from species from Mentha genus, and in Brazil, those species are widely used in treating gastrointestinal and respiratory disorders. Considering the wide pharmacological potential of monoterpenes, including their antioxidant activity, this study aimed to evaluate menthofuran-gastroprotective activity, as well as the involvement of antioxidant mechanisms in this effect. The acute toxicity was evaluated according to the fixed dose method. The antiulcerogenic activity was investigated by using experimental models of gastric ulcers induced by ethanol, indomethacin, and ischemia/reperfusion in rats. The antisecretory gastric activity, the catalase activity, and the gastric wall mucus were determined in pylorus ligated rats. Gastric wall nonprotein sulfhydryl (NPSH) group content, myeloperoxidase (MPO) activity, and malondialdehyde (MDA) content were evaluated in ethanol-induced the gastric ulcer model. Menthofuran (2 g/kg) presented low acute toxicity and showed gastroprotective activity against ethanol-, indomethacin-, and ischemia/reperfusion-induced ulcers. Moreover, menthofuran presented antisecretory activity, reduced the total acidity, and increased pH of gastric secretion. On the other hand, a decrease in mucus content of gastric wall without alteration of gastric juice volume and catalase activity was observed. Interestingly, menthofuran increased NPSH levels and reduced MDA levels and MPO activity. Gastroprotective effects of menthofuran appear to be mediated, at least in part, by the NOS pathway, endogenous prostaglandins, reduced gastric juice acidity, increased concentration of the NPSH groups, and reduced lipidic peroxidation. These findings support the menthofuran as an effective gastroprotective agent, as well as the marked participation of antioxidant mechanisms in this response.

Antiulcerogenic and Antibacterial Effects of Chitosan Derivatives on Experimental Gastric Ulcers in Rats.

Gastric ulcer is an injury that develops on the lining of the stomach due to an imbalance between aggressive and defensive agents. Chitosan derivatives demonstrate promising biological activities in accelerating the healing activity of gastric lesions. Thus, this study aimed at investigating the healing activity of gastric lesion, induced by acetic acid (80%), of the chitosan derivative with acetylacetone (Cac) modified with ethylenediamine (Cacen) or diethylenetriamine (Cacdien). The biological activity was determined based on cytotoxicity, antibacterial activity, and gastroprotective activities. The results showed no significant difference in the cytotoxicity, a better antibacterial activity against S. aureus and E. coli, and a positive result on the healing of gastric lesions of the materials (Cac 18.4%, Cacen 55.2%, and Cacdien 68.1%) compared to pure chitosan (50.7%). Therefore, the results indicate that derivatives of chitosan are promising biomaterials for application in the control of lesions on the gastric mucosa.

Gastroprotective Activity of Neoglaziovia variegata (Arruda) Mez. (Bromeliaceae) in Rats and Mice.

Neoglaziovia variegata (Arruda) Mez (Bromeliaceae) is a medicinal plant popularly known as "caroá." The leaves are made up of highly resistant fibers, which is of great commercial value to the handicraft and textile industry. Some studies have demonstrated that ethanolic extract of N. variegata have gastroprotective properties. This study aimed to investigate the gastroprotective activity and cytoprotective mechanisms of ethyl acetate (Nv-AcOEt), hexane (Nv-Hex), and chloroform (Nv-CHCl3) fractions of N. variegata leaves. The gastroprotective activity of Nv-AcOEt, Nv-Hex, and Nv-CHCl3 was evaluated using the ethanol and ethanol/HCl-induced gastric injury model. To elucidate the gastroprotective mechanisms, the functions of prostaglandins (PGs), nitric oxide (NO), and KATP channels were evaluated. In addition, the nonprotein sulfhydryl groups and the mucus content in the gastric tissues were analyzed. All fractions of N. variegata leaves at oral doses of 100, 200, and 400 mg/kg significantly decreased ethanol and ethanol/HCl-induced gastric lesions, leading to gastroprotection, accompanied by an increase in reduced glutathione (GSH) and gastric mucus. Gastroprotective activity of Nv-AcOEt was inhibited after pretreatment with ibuprofen and N(G)-nitro-L-arginine (L-NOARG). Gastroprotective effect of Nv-Hex and Nv-CHCl3 was also inhibited after pretreatment with L-NOARG and with glibenclamide. The results indicate that N. variegata (Arruda) Mez exhibits promising gastroprotective activity with the possible participation of NO, PGs, mucus, sulfhydryl groups, and KATP.

Gastroprotective effect of (-)-myrtenol against ethanol-induced acute gastric lesions: possible mechanisms.

OBJECTIVES: (-)-Myrtenol is a natural fragrance monoterpenoid structurally related to α-pinene found in diverse plant essential oils. This study was aimed to assess the anti-ulcerogenic potential of (-)-myrtenol against ethanol-induced gastric lesions and to elucidate the underlying mechanism(s). METHODS: Gastroprotective activity of (-)-myrtenol was evaluated using the mouse model of ethanol-induced gastric damage. To elucidate the gastroprotective mechanism(s), the roles of GABA, prostaglandins, nitric oxide and KATP channels were assessed. Besides, the oxidative stress-related parameters and the mucus content in gastric tissues were analysed. KEY FINDINGS: (-)-Myrtenol at oral doses of 25, 50 and 100 mg/kg significantly decreased the severity of ethanol-induced gastric lesions affording gastroprotection that was accompanied by a decrease in the activity of myeloperoxidase and malondialdehyde, an increase in GPx, SOD, and catalase activity in gastric tissues, and with well-maintained normal levels of nitrite/nitrate, gastric mucus and NP-SHs. Pretreatment with GABA-A receptor antagonist flumazenil, the COX inhibitor indomethacin, and NO synthesis inhibitor L-NAME but not with KATP channel blocker glibenclamide significantly blocked the (-)-myrtenol gastroprotection. CONCLUSION: These results provide first-time evidence for the gastroprotective effect of (-)-myrtenol that could be related to GABAA -receptor activation and antioxidant activity.