Rodrigo Rezende Kitagawa

Anti-Helicobacter pylori activity and oxidative burst inhibition by the naphthoquinone 5-methoxy-3,4-dehydroxanthomegnin from Paepalanthus latipes

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.

Anti-ulcer mechanisms of polyphenols extract of Euphorbia umbellata (Pax) Bruyns (Euphorbiaceae).

ETHNOPHARMACOLOGICAL RELEVANCE Euphorbia umbellata (leitosinha) is used in southern Brazilian folk medicine to treat gastric problems, as well as for its analgesic and anti-inflammatory properties. AIM OF STUDY To evaluate the anti-ulcer effects of methanolic bark fraction (MF) against in vivo and in vitro assays, as well as an antioxidant, antibacterial and chromatographic study of this fraction. MATERIALS AND METHODS In vivo anti-ulcer activity was performed using ethanol and indomethacin models with different MF concentrations (50, 100 or 200mg/Kg). The stomachs of the animals were applied to histological evaluation, and the serum to evaluate the ABTS(•+) radical capture. The 200mg/Kg dose was used to analyze the mechanisms involved in antiulcerogenic properties of methanolic fraction. The in vitro activity was performed using several different antioxidant assays, in addition to anti-Helicobacter pylori and anti-urease experiments. The chromatographic study was carried out by LC-MS analysis. RESULTS Pharmacological investigation of the MF showed an anti-ulcer potential in ethanol and indomethacin in vivo assays. The material presented a high antioxidant activity for several oxidant in vitro systems (DPPH(•), ABTS(•+), O2(•-), HOCl, TauCl and HRP), as well as an ABTS(•+) capture increasing (7.5%) by the treated animals serum (when compared to the negative control). Prostaglandins, nitric oxide/ cyclic guanosine monophosphate pathway and involvement of the protein components of the glutathione complex are some of the mechanisms related with this potential anti-ulcer action. The histological examination of the stomachs of the animals showed that the MF also prevents local action of offensive agents. Chemical analysis using LC-QTOF-MS revealed the presence of ellagic and gallic acid derivatives and flavonols. CONCLUSION The findings provide scientific basis to the ethnopharmacological purpose of the studied plant and the biological activities of MF of E. umbellata stem bark may be due to the presence of phenolic compounds.

Ascorbic acid potentiates the cytotoxicity of the naphthoquinone 5-methoxy-3,4-dehydroxanthomegnin

The interaction of ascorbic acid with 5-methoxy-3,4-dehydroxanthomegnin, an 1,4-naphthoquinone, was investigated using the cytotoxic index for McCoy cells by neutral red assay. The synergistic effect was observed when such compounds were added simultaneously, most probably due to hydrogen peroxide being generated by ascorbate-driven 5-methoxy-3,4-dehydroxanthomegnin redox cycling. Incubation of cells in the presence of 5-methoxy-3,4-dehydroxanthomegnin/ascorbic acid/catalase, an enzyme that destroys H2O2, resulted in an increase of cell survival, reinforcing the involvement of hydrogen peroxide generated as an important oxidizing agent that kills McCoy cells.

Comparison of Brazilian plants used to treat gastritis on the oxidative burst of helicobacter pylori -stimulated neutrophil

Ten Brazilian medicinal plants used to treat gastritis and ulcers were carefully selected on the basis of ethnopharmacological importance and antiulcerogenic activity previously described. The antioxidant activity of the methanolic extracts was determined in analysis conditions that simulate a real biological activity on inhibition of the oxidative burst induced in neutrophils using Helicobacter pylori as activator, by a luminol-amplified chemiluminescence assay. The extracts, at low concentration (5 μg/mL), exhibited a large variation in inhibitory effects of H. pylori-induced oxidative burst ranging from 48% inhibition to inactive, but all extracts, excluding Byrsonima intermedia, had inhibitory activity over 80% at the concentration of 100 μg/mL. The total suppressive antioxidant capacity measured as the effective concentration, which represents the extract concentration producing 50% inhibition of the chemiluminescence induced by H. pylori, varies from 27.2 to 56.8 μg/mL and was in the following order: Qualea parviflora > Qualea multiflora > Alchornea triplinervia > Qualea grandiflora > Anacardium humile > Davilla elliptica > Mouriri pusa > Byrsonima basiloba > Alchornea glandulosa > Byrsonima intermedia. The main groups of compounds in tested extracts are presented. Differences in the phytochemical profile, quantitatively and qualitatively, of these plants can explain and justify their protective effect on the gastric mucosa caused by the neutrophil-generated ROS that occurs when H. pylori displays its evasion mechanisms.

Antitumor and immunomodulatory effects of the naphthoquinone 5-methoxy-3,4-dehydroxanthomegnin

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.

Anti-Helicobacter pylori effect of the antioxidant extract from Baccharis trimera Less. (DC)

One of the main risk factors for the development of stomach ulcers and cancer is infection with Helicobacter pylori bacteria, which is accompanied by considerable oxidative stress. Therefore, the aim of the present study was to assess the anti-Helicobacter pylori activity of B. trimera hydroalcoholic extract (HE) and aqueous (AqF), hexanic (HxF), and acetonitrile/chloroform (ACF) fractions, as well as their oxidant potentials. A preliminary phytochemical screening was carried out. Anti-Helicobacter pylori activity was assessed using a microdilution assay. After exposure to the investigated samples, the bacterial morphology was analysed under a scanning electron microscope (SEM). The antioxidant activity was evaluated in hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 •- ), hypochlorous acid (HOCl), hydroxyl radical (HO • ) and nitric oxide (NO • ) assays. The highest concentration of polyphenols was found in HE, the highest concentration of flavonoids was found in ACF, and of tannins was found in AqF. In the anti-H. pylori assay, the MIC 90 was 512 µg/mL for HE and 1024 µg/mL for ACF, which was bactericidal. The SEM showed morphological alterations such as cell lysis in the tested samples. In the O 2 •- inhibition assay, the EC 50 of AqF was 5.85 ± 0.86. In the HOCl, HO • radical, NO • and H 2 O 2 scavenging assays, the best results were in ACF, with an EC 50 of 15.50 ± 0.80, 2.90 ± 0.48, 132.13 ± 7.38 and 66.70 ± 2.30 µg/mL, respectively. The analyses indicate that compounds present in B. trimera, especially in HE and ACF, are promising candidates for the prevention and treatment of diseases caused by H. pylori.

Effect of biotransformation by liver S9 enzymes on the mutagenicity and cytotoxicity of melanin extracted from Aspergillus nidulans.

Abstract Context: A mutant that exhibited increased melanin pigment production was isolated from Aspergillus nidulans fungus. This pigment has aroused biotechnological interest due to its photoprotector and antioxidant properties. In a recent study, we showed that melanin from A. nidulans also inhibits NO and TNF-α production. Objective: The present study evaluates the mutagenicity and cytotoxicity of melanin extracted from A. nidulans after its exposure to liver S9 enzymes. Materials and methods: The cytotoxicity of multiple concentrations of melanin (31.2–500 μg/mL) against the McCoy cell line was evaluated using the Neutral Red assay, after incubation for 24 h. Mutagenicity was assessed using the Ames test with the Salmonella typhimurium strains TA98, TA97a, TA100, and TA102 at concentrations ranging from 125 μg/plate to 1 mg/plate after incubation for 48 h. Results: The cytotoxicity of A. nidulans melanin after incubation with S9 enzymes was less than (CI50 value= 413.4 ± 3.1 μg/mL) that of other toxins, such as cyclophosphamide (CI50 value = 15 ± 1.2 μg/mL), suggesting that even the metabolised pigment does not cause significant damage to cellular components at concentrations up to 100 μg/mL. In addition, melanin did not exhibit mutagenic properties against the TA 97a, TA 98, TA 100, or TA 102 strains of S. typhimurium, as shown by a mutagenic index (MI) <2 in all assays. Discussion and conclusion: The significance of these results supports the use of melanin as a therapeutic reagent because it possesses low cytotoxicity and mutagenic potential, even when processed through an external metabolising system.AbstractContext: A mutant that exhibited increased melanin pigment production was isolated from Aspergillus nidulans fungus. This pigment has aroused biotechnological interest due to its photoprotector and antioxidant properties. In a recent study, we showed that melanin from A. nidulans also inhibits NO and TNF-α production.Objective: The present study evaluates the mutagenicity and cytotoxicity of melanin extracted from A. nidulans after its exposure to liver S9 enzymes.Materials and methods: The cytotoxicity of multiple concentrations of melanin (31.2–500 μg/mL) against the McCoy cell line was evaluated using the Neutral Red assay, after incubation for 24 h. Mutagenicity was assessed using the Ames test with the Salmonella typhimurium strains TA98, TA97a, TA100, and TA102 at concentrations ranging from 125 μg/plate to 1 mg/plate after incubation for 48 h.Results: The cytotoxicity of A. nidulans melanin after incubation with S9 enzymes was less than (CI50 value= 413.4 ± 3.1 μg/mL) that of other toxins, ...

Antiulcer Activity and Potential Mechanism of Action of the Leaves of Spondias mombin L.

Spondias mombin L. is used in folk medicine for the treatment of inflammation and gastrointestinal diseases. Our study investigated the antiulcer activity of S. mombin ethanolic extract (SmEE) and its majority compounds gallic acid (GA) and ellagic acid (EA). Phytochemical characterization was performed by HPLC. The SmEE was screened for in vitro antioxidant activities using phosphomolybdenum, ABTS, DPPH, and FRAP assays. The antiulcer activity of SmEE, GA, EA, or GA + EA was evaluated by gastric lesion models induced by absolute ethanol and indomethacin. Following this, it is capable of stimulating mucus production, antisecretory capacity, and the influence of −SH groups and NO in the effect of SmEE. Its healing activity was demonstrated by acetic acid-induced chronic ulcer model. Anti-Helicobacter pylori activity was assessed by determining the MIC of the SmEE (64–1024 μg/mL). The HPLC results identified the presence of gallic acid and ellagic acid in SmEE. The extract showed antioxidant activity in vitro. SmEE (50, 100, and 200 mg/kg) reduced the area of ulcerative lesions induced by ethanol in 23.8, 90.3, and 90.2%, respectively. In NSAID model, the SmEE induced protection of 36.8, 49.4, and 49.9%, respectively. GA (10 mg/kg) or EA (7 mg/kg) or the association of GA + EA (10 + 7 mg/kg) inhibited the ethanol-induced lesions in 71.8, 70.9, and 94.9%, respectively, indicating synergistic action. SmEE (100 mg/kg) decreased acid secretion and H+ concentration in the gastric contents, increased levels of mucus, and showed to be dependent of −SH groups and NO on the protection of the gastric mucosa. In chronic ulcer model, SmEE reduced the gastric area lesion. SmEE showed anti-H. pylori activity. In conclusion, our study showed that SmEE has antiulcerogenic activity. GA and EA are isolated gastric protectors and, when associated, acted synergistically to protect the gastric mucosa.

Virola oleifera-capped gold nanoparticles showing radical-scavenging activity and low cytotoxicity

The development of effective nanoparticle therapeutics has been hindered by their surface characteristics, such as hydrophobicity and charge. Therefore, the success of biomedical applications with nanoparticles is governed by the control of these characteristics. In this article, we report an efficient green capping method for gold nanoparticles (AuNPs) by a reduction with sodium citrate and capping with Virola oleifera (Vo), which is a green exudate rich in polyphenols and flavonoids. The Vo-capped AuNPs were characterized by UV, DLS, FTIR, Raman, TEM, DPPH, FRAP and their cytotoxicity was evaluated on the viability of Murine macrophage cell. The AuNPs had an average particle size of 15 nm and were stable over a long time, as indicated by their unchanged SPR and zeta potential values. These nanoparticles were assessed for their antioxidant potential using DPPH and FRAP and demonstrated the highest antioxidant activities and low cytotoxicity. We propose that the Virola oleifera-capped AuNPs have potential biomedical applications.

Avocado seeds (Persea americana Mill.) prevents indomethacin-induced gastric ulcer in mice

The long-term use of anti-inflammatory drugs is the most common cause of gastric ulcer disease, one of the major gastrointestinal disorders affecting people worldwide. Persea americana Mill. (avocado) seed is a by-product generally discarded as waste, but can be used to treat gastric disorder due to its anti-inflammatory, antioxidant and antimicrobial activities. The aim of the present study was to evaluate the potential protective effects of the ethyl acetate fraction of avocado seeds (SEAP) extracts against indomethacin-induced gastric ulcer in mice. It was found that SEAP were effective in mitigating oxidative stress through a decrease on the oxidized products levels (reduction of 90% in lipid peroxidation in plasma) and increasing superoxide dismutase enzyme (SOD) activity (4.25-fold increase compared to the indomethacin group), also preventing the rise in ulcer and lesions areas (92% of protection) and histological changes induced by indomethacin. Chemical analysis using mass spectrometry by (-)-ESI-FT-ICR MS revealed the presence of (-)-epicatechin and (+)-catechin, confirmed by HPLC-DAD, and other important phenolic compounds in avocado seeds, such as caffeoylquinic acid, flavonoids, phenylpropanoids and tannins, substances that promote inhibition of pathways involved in gastric ulcer formation. Thus, avocado seeds extract may be a suitable natural source for the prevention and treatment of gastric ulcer.