Abstract Helicobacter pylori is a bacterium that reaches half of the world population and it’s recognized as the main cause of chronic gastritis and peptic ulcer. In this study, we evaluated the anti-H. pylori, antioxidant and immunomodulatory activities of the methanolic (MeOH) extract of Eugenia uniflora leaves and chemical profile. Anti-H. pylori activity was evaluated by spectrophotometric broth microdilution technique by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), in addition to the evaluation of the effect on the urease enzyme. The antioxidant activity was evaluated by capturing O2 •-, HOCl e NO• radicals. The immunomodulatory effect was evaluated on the cytokines TNF-α, IL-6 and on nitric oxide through inhibition in LPS-stimulated macrophages. The chemical profile was performed by total phenolic, tannin and flavonoid contents and mass spectrometry analysis by ESI-FT-ICR MS. In the anti-H. pylori assay the extract showed MIC of 128 μg/mL, however it did not obtain MBC. The extract also showed ability to inhibit the urease enzyme about 20%. The antioxidant activity of the MeOH extract showed EC50 values of 29.77 µg/mL, 15.71 µg/mL and 442.10 µg/mL to O2 •-, HOCl and NO•, respectively. The extract also showed influence on the release of TNF-α, IL-6 and NO in LPS-stimulated macrophages, ranging from 39% to 97% inhibition. Flavonoids, phenylpropanoids, tannins, triterpenoids and carbohydrates were the major classes of compounds present in the MeOH extract as identified by (-)-ESI-FT-ICR MS. The results indicate important anti-H. pylori, antioxidant and immunomodulatory activities from Eugenia uniflora highlighting its importance in the prevention and treatment of diseases caused by H. pylori infection.

AbstractCoumarins are phenolic compounds and have various biological properties, including antioxidant activity. The isocoumarin paepalantine, isolated from of Paepalanthus bromelioides Silveira, Eriocaulaceae, exhibits a wide range of biological activities, including antimicrobial, anti-inflammatory, antioxidant and cytotoxic properties. Studies on paepalantine often use dimethylsulfoxide as a solvent. However the dimethylsulfoxide interferes with antimicrobial, cytotoxic and antioxidant assays. Thus, this study aims to evaluate alternative solvents for paepalantine and evaluate their potential to interfere with antioxidant assays (ABTS•+, O2•-, HOCl). Of the selected solvents, propylene glycol had good solubility and remained stable throughout the study period. The results suggested that there is no interference from propylene glycol in antioxidant assays, while dimethylsulfoxide significantly interfered with the HOCl assay. The antioxidant assays showed that paepalantine demonstrated similar or even better antioxidant activity than Trolox. Thus, propylene glycol may be the solvent of choice for paepalantine, a compound that has significant biological potential.

Helicobacter pylori is a bacterium recognized as the major cause of chronic gastritis and peptic ulcers. Infection by H. pylori induces inflammatory responses and pathological changes in the gastric microenvironment. The host Keywords: immune cells (especially neutrophils) release inflammatory mediators and large 5-methoxy-3,4-dehydroxanthomegnin amounts of reactive oxygen species (ROS), which are associated with an increased Helicobacter pyloririsk of developing gastric cancer. In this study, we evaluated the anti-H. pylori and oxidative burst antioxidantactivitiesofa1,4-naphthoquinone-5-methoxy-3,4-dehydroxanthomegnin. Paepalanthus latipes The antimicrobial activity was assessed using a spectrophotometric microdilution technique, and antioxidant activity was assessed by noting the effect of 5-methoxy3,4-dehydroxanthomegnin on the neutrophil oxidative burst using luminol-and lucigenin-amplified chemiluminescence. The results showed that 5-methoxy-3,4dehydroxanthomegnin is a potent anti-H. pylori compound (MIC 64 µg/mL and MBC 128 µg/mL) and a strong antioxidant. 5-Methoxy-3,4-dehydroxanthomegnin decreased luminol- and lucigenin-amplified chemiluminescence, with ED50 values of 1.58±0.09 µg/mL and 5.4±0.15 µg/mL, respectively, reflecting an inhibitory effect on the oxidative burst. These results indicate that 5-methoxy-3,4-dehydroxanthomegnin is a promising compound for the prevention and treatment of diseases caused by H. pylori infection, such as gastritis, peptic ulceration, and gastric cancer, because reactive oxygen intermediates are involved in the pathogenesis of gastric mucosal injury induced by H. pylori infections.

Large number of quinones has been associated with antitumor, antibacterial, antimalarial and antifungal activities. In this work we describe the effect of the naphthoquinone, 5-methoxy-3,4-dehydroxanthomegnin, on murine tumor cells (LP07 and LM2) and its immunomodulatory effect on nitric oxide (NO) production on LPS-stimulated macrophages. The results have shown that 5-methoxy-3,4-dehydroxanthomegnin was a significant inhibitor of LPS-stimulated NO generation from macrophage (inhibition percentage ranged from 97.4 to 98.9%) and a strong cytotoxic agent against both tumor cells LP07 and LM2 (CI50 6.2±0.36 µM and 74.6±1.9 µM, respectively). These results indicate that the 5-methoxy-3,4-dehydroxanthomegnin may show promising activity in the treatment of murine breast and lung cancer by immunomodulatory and antiproliferative activities.