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 healing activity of hecogenin acetate in rodents.

Peptic ulcers are lesions in the gastric and duodenal mucosa generated by an imbalance between protective factors (gastroduodenal mucus secretion, bicarbonate production, adequate blood flow) and harmful factors (excess pepsin or hydrochloric acid). Some drugs used in peptic ulcer therapy are associated with adverse effects. The aim of this study was to evaluate the antiulcerogenic and healing activity of hecogenin acetate (HA) in acute and chronic models of gastric lesions in rodents. The antiulcerogenic activity of HA was evaluated in models of gastric lesions induced by absolute ethanol and in acidified ethanol with HA (5, 10, and 20 mg/kg). For the model of gastric lesions induced by ischemia and reperfusion, rats were pre-treated with HA (5, 10, 20 mg/kg). After that, they were submitted to 30 min of ischemia, followed by 1 h of reperfusion. To evaluate the healing activity was induced gastric ulcer using acetic acid (80%) in rats. After 24 h, they were treated for 7 consecutive days with HA (10 and 20 mg/kg). They were evaluated the possible signs of toxicity, measurement of the lesions, collagen deposition, and histological analysis. HA significantly reduced the area of the lesion in models of gastric lesions induced by absolute and acidified ethanol, ischemia-induced gastric lesions and reperfusion, and regarding healing. In the collagen deposition, the presence and increase of collagen demonstrate the healing effect. The AH has antiulcerogenic and healing potential demonstrated by the decrease in gastric injury and presence of collagen fibers, respectively.

In Situ Synthesis of Silver Nanoparticles in a Hydrogel of Carboxymethyl Cellulose with Phthalated-Cashew Gum as a Promising Antibacterial and Healing Agent.

Silver nanoparticles have been shown to possess considerable antibacterial activity, but in vivo applications have been limited due to the inherent, but low, toxicity of silver. On the other hand, silver nanoparticles could provide cutaneous protection against infection, due to their ability to liberate silver ions via a slow release mechanism, and their broad-spectrum antimicrobial action. Thus, in this work, we describe the development of a carboxymethyl cellulose-based hydrogel containing silver nanoparticles. The nanoparticles were prepared in the hydrogel in situ, utilizing two variants of cashew gum as a capping agent, and sodium borohydride as the reducing agent. This gum is non-toxic and comes from a renewable natural source. The particles and gel were thoroughly characterized through using rheological measurements, UV-vis spectroscopy, nanoparticles tracking analysis, and transmission electron microscopy analysis (TEM). Antibacterial tests were carried out, confirming antimicrobial action of the silver nanoparticle-loaded gels. Furthermore, rat wound-healing models were used and demonstrated that the gels exhibited improved wound healing when compared to the base hydrogel as a control. Thus, these gels are proposed as excellent candidates for use as wound-healing treatments.

Beta-cyclodextrin enhanced gastroprotective effect of (-)-linalool, a monoterpene present in rosewood essential oil, in gastric lesion models.

(-)-Linalool is a monoterpene constituent of many essential oils. This particular monoterpene has both anti-inflammatory and antimicrobial activity. Moreover, this compound has been shown to be antinociceptive. However, the poor chemical stability and short half-life prevents the clinical application of (-)-linalool and many other essential oils. Important to the topic of this study, ß-cyclodextrin (ß-CD) has been used to increase the solubility, stability, and pharmacological effects of numerous lipophilic compounds in vivo. In this study, the gastroprotective activities of (-)-linalool (LIN) and linalool incorporated into inclusion complex containing ß-cyclodextrin (LIN-ßCD) were evaluated using models of acute and chronic gastric ulcers in rodents. LIN and LIN-ßCD showed strong gastroprotective activity (p < 0.001). The LIN-ßCD complex revealed that the gastroprotective effect was significantly improved compared with LIN uncomplexed, suggesting that this improvement is related to increased solubility and stability. Taking together the potentiation of the antioxidant profile of this monoterpene, our results suggest that ß-CD may represent an important tool for improved gastroprotective activity of (-)-linalool and other water-insoluble compounds.

α-Phellandrene, a cyclic monoterpene, attenuates inflammatory response through neutrophil migration inhibition and mast cell degranulation.

AIMS: We aimed to investigate the modulating effect of α-phellandrene on neutrophil migration and mast cell degranulation processes. MAIN METHODS: Male Wistar rats or Swiss mice were treated p.o. with vehicle (3% Tween 80, p.o.), α-phellandrene (50, 100, or 200mg/kg, p.o.), or dexamethasone (0.5mg/kg, p.o.) 1h before carrageenan injection. Then, the neutrophil migration in 6-day-old air pouches or peritoneal cavities. The leukocyte rolling and adhesion were measured in real time and assessed by intravital microscopy. ELISA was used to detect TNF-α and IL-6 in peritoneal lavage. Compound 48/80-induced mast cell degranulation was assessed in mesenteric rat tissues. KEY FINDINGS: In all the tested doses, α-phellandrene prevented carrageenan-induced neutrophil accumulation (P<0.05). As detected by intravital microscopy, α-phellandrene also inhibited leukocyte rolling and adhesion, as well as significantly inhibited the production of the pro-inflammatory cytokines TNF-α and IL-6. Moreover, the degranulation of compound 48/80-induced mast cells was also inhibited by α-phellandrene (P<0.001). SIGNIFICANCE: These results suggest that α-phellandrene plays an important role as an anti-inflammatory agent through neutrophil migration modulation and mast cell stabilization.

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.