RESUMO
This study aimed to evaluate the effect of n-propyl gallate as pre-treatment for resin-dentin bond strength. The dentin pre-treatments evaluated included propyl gallate of concentrations 0.1% (w/v), 1.0% (w/v), and 10.0% (w/v), as well as glutaraldehyde 5.0% (v/v), and distilled water as a control treatment. Dentin specimens were prepared for Fourier Transformed Infrared Spectroscopy (FT-IR) (n = 3/pre-treatment). Pre-treatments were actively applied to dentin blocks before performing the adhesive procedure to composite resin. Microtensile bond strength to dentin (µTBS) (n = 8/pre-treatment) was determined after 24 h and 6 months of storage. Data were submitted to a two-way ANOVA, followed by Tukey's post hoc test. As for FT-IR, propyl gallate 1%-treated specimens presented higher water, carbonate, collagen, and amide absorbance rates compared to other tested groups, while specimens pre-treated with glutaraldehyde and distilled water presented similar absorbance curves. Regarding µTBS, all concentrations of propyl gallate resulted in statistically significant higher bond strength values than distilled water at 24 h. After 6 months of storage, propyl gallate 0.1% was the only group that maintained µTBS over time. Propyl gallate 0.1% might be a suitable dentinal pre-treatment due to being able to present chemical bonds with demineralized dentin and providing resin-dentin bond stability after 6 months of storage.
Assuntos
Colagem Dentária , Galato de Propila , Galato de Propila/análise , Galato de Propila/farmacologia , Adesivos Dentinários/química , Glutaral , Espectroscopia de Infravermelho com Transformada de Fourier , Cimentos de Resina/química , Dentina , Resistência à Tração , Teste de Materiais , Cimentos Dentários/farmacologia , Resinas Compostas/química , Água/químicaRESUMO
In the present study the metabolic actions of n-propyl gallate on hepatic gluconeogenesis, oxygen uptake and related parameters were investigated. Experiments were done in the isolated perfused rat liver. n-Propyl gallate inhibited gluconeogenesis and stimulated oxygen uptake at concentrations up to 200 microM. The inhibitory effects on lactate gluconeogenesis (ED(50) 86.4 microM) and alanine gluconeogenesis were considerably more pronounced than those on glycerol and fructose gluconeogenesis. n-Propyl gallate also stimulated oxygen uptake in both the mitochondrial (63%) and microsomal (37%) electron transport chains. The first one is due mainly to the oxidation of n-propanol, as a metabolite of the first step of n-propyl gallate transformation. The second one results from a direct stimulation of the microsomal electron transport chain. n-Propyl gallate inhibited pyruvate carboxylation (ED(50) 142.2 microM) in consequence of an inhibition of pyruvate transport into the mitochondria an effect not found for gallic acid. This is probably the main cause for glucose output inhibition. Secondary causes are (1) deviation of intermediates for the production of NADPH to be used in microsomal electron transport; (2) deviation of glucose 6-phosphate for glucuronidation reactions; (3) gluconeogenesis inhibition by n-propanol, produced intracellularly from n-propyl gallate. Inhibition of mitochondrial energy metabolism is not significant in the range up to 200 microM, as indicated by the very small effect on the cellular ATP levels (5% decreased). n-Propyl gallate can be considered a kind of metabolic effector, whose actions on the liver metabolism are relatively mild although they can become harmful for the organ and the whole organism at high doses and concentrations.
Assuntos
Gluconeogênese/efeitos dos fármacos , Fígado/efeitos dos fármacos , Oxigênio/metabolismo , Galato de Propila/farmacologia , Animais , Cromatografia Líquida de Alta Pressão , Fígado/metabolismo , Masculino , Ratos , Ratos WistarRESUMO
Alkyl esters of gallic acid inhibited the respiration rate of mouse sarcoma 786A and mouse mammary adenocarcinoma TA3 cell lines and its multiresistant variant TA3-MTX-R more effectively than gallic acid, both in the absence and in the presence of the uncoupler CCCP. The order of inhibition of the respiration rate by gallates in intact cells was n-octyl- approximately iso-amyl- approximately n-amyl- approximately iso-butyl->n-butyl->iso-propyl->n-propyl-gallate>>gallic acid. Sarcoma 786A was significantly more susceptible to all seven esters than the TA3 cell line. Respiration rates of the TA3-MTX-R cell line showed almost the same sensitivity to these esters as the TA3 cell line. However, hepatocytes were significantly less sensitive than all tumor cells tested. These alkyl gallates blocked mitochondrial electron flow, mainly at the NADH-CoQ segment, preventing ATP synthesis, which would lead to cellular death. These esters also inhibited, in the same order of potencies as respiration, the growth of 786A, TA3 and TA3-MTX-R cells in culture. In mice carrying TA3 or TA3-MTX-R tumor cells, an important decrease of the tumor growth rate and an increase of survival were observed when mice were treated with iso-butyl gallate alone or in combination with doxorubicin. These results indicate that alkyl gallates are selectively cytotoxic to tumor cells, which may be due to the mitochondrial dysfunctions of these cells.
Assuntos
Antineoplásicos/farmacologia , Hepatócitos/efeitos dos fármacos , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Respiração Celular/efeitos dos fármacos , Células Cultivadas , Ensaios de Seleção de Medicamentos Antitumorais , Transporte de Elétrons , Ácido Gálico/análogos & derivados , Ácido Gálico/farmacologia , Camundongos , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Galato de Propila/farmacologia , Ratos , Testes de ToxicidadeRESUMO
Vimang is an aqueous extract of Mangifera indica used in Cuba to improve the quality of life in patients suffering from inflammatory diseases. In the present study we evaluated the effects of Vimang at preventing reactive oxygen species (ROS) formation and lipid peroxidation in intact isolated rat hepatocytes. Vimang at 20, 50 and 100 microg/ml inhibited hepatocyte ROS formation induced by glucose-glucose oxidase. Hepatocyte cytotoxicity and lipid peroxidation induced by cumene hydroperoxide was also inhibited by Vimang in a dose and time dependent manner at the same concentration. Vimang also inhibited superoxide radical formation by xanthine oxidase and hypoxanthine. The superoxide radical scavenging and antioxidant activity of the Vimang extract was likely related to its gallates, catechins and mangiferin content. To our knowledge, this is the first report of cytoprotective antioxidant effects of Vimang in cellular oxidative stress models.
Assuntos
Hepatócitos/efeitos dos fármacos , Peroxidação de Lipídeos/fisiologia , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Antioxidantes/farmacologia , Derivados de Benzeno/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ácido Gálico/farmacologia , Glucose Oxidase/farmacologia , Hepatócitos/metabolismo , Hipoxantina/farmacologia , Masculino , Mangifera , Oxidantes/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Galato de Propila/farmacologia , Ratos , Ratos Sprague-Dawley , Superóxidos/metabolismo , Xantina Oxidase/metabolismoRESUMO
AIMS: The effectiveness of the food-grade antioxidants butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB), propyl paraben (PP) and butylated hydroxyanisole (BHA) at 1, 10 and 20 mmol l(-1) concentrations on germination, growth, and aflatoxin B(1) (AFB(1)) production by Aspergillus section Flavi strains was determined. METHODS AND RESULTS: Assays on the lag phase of germination, germination percentage, germ tube elongation rate, lag phase, growth rate and AFB(1) production by three strains of Aspergillus flavus and three of Aspergillus parasiticus were carried out in vitro on peanut extract meal agar conditioned at different water activities (a(w): 0.982, 0.971, 0.955, 0.937). The antioxidants PP and BHA efficiently inhibited the germination of the two species tested at the doses 10 and 20 mmol(-1). The antioxidants PP and BHA at 1 mmol l(-1) and THB at 20 mmol l(-1) reduced the germ tube elongation rate most effectively, regardless of a(w) levels. An increase in the lag time and a reduction in the growth rate of 100% of the strains was observed, this was due to the action of BHT at the doses 10 and 20 mmol(-1) at 0.982, 0.971 and 0.955 a(w), although these treatments stimulated the AFB(1) accumulation in most of the fungi tested. The more effective antioxidants were PP and BHA, which increased the lag phase, reduced the growth rate and AFB(1) production in all of the strains at the four a(w) assayed. At concentrations 10 and 20 mmol l(-1), these antioxidants totally inhibited fungal development. CONCLUSIONS: The study shows that the antioxidants BHA and PP are effective fungal inhibitors to peanut Aspergillus section Flavi in wide range of water activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that phenolic antioxidants, BHA and PP, can be effective fungitoxicants on aflatoxigenic strains in peanut at industrial level.
Assuntos
Aflatoxina B1/biossíntese , Antioxidantes/farmacologia , Arachis/microbiologia , Aspergillus flavus/efeitos dos fármacos , Aspergillus flavus/crescimento & desenvolvimento , Aspergillus flavus/fisiologia , Hidroxianisol Butilado/farmacologia , Hidroxitolueno Butilado/farmacologia , Meios de Cultura , Microbiologia de Alimentos , Conservantes de Alimentos/farmacologia , Germinação , Parabenos/farmacologia , Galato de Propila/farmacologia , Microbiologia da ÁguaRESUMO
There is evidence indicating that oxidants play a pivotal role in determining air pollution-dependent lung injury. In the present study we explored the role of oxidants present in ambient particles in causing damage to the mucociliary epithelium. We explored the protective effects of pretreatment with three substances (n-propyl gallate, DL-alpha-tocopherol acetate, and EDTA) on the frog palate exposed to residual oil fly ash (ROFA). The parameters analyzed were mucociliary transport (MCT) and ciliary beating frequency (CBF) after 0, 10, 20, 30, 60, and 120 min of exposure. MCT was decreased significantly by ROFA (P < 0.001), with a significant interaction effect (P = 0.02) between the duration of exposure and treatment with antioxidants. The inhibitory effects on MCT of the substances tested were significantly different (P = 0.002); vitamin E was similar to control (Ringer) and different from all other groups. CBF showed no significant effect of duration of exposure (P = 0.465), but a significant interaction between duration of exposure and treatments was observed (P = 0.011). Significant differences were detected among treatments (P < 0.001), with ROFA and n-propyl gallate at concentrations of 50 microM presenting a short-lived increase in CBF, which was not observed in the remaining groups. The results showed that both MCT and CBF were affected within a short period (100 min) of exposure to ROFA and that the presence of antioxidant substances, such as vitamin E (4 mg/mL) and n-propyl gallate (300 microM), protected against the mucociliary impairment induced by ROFA on the frog palate.
Assuntos
Poluentes Atmosféricos/toxicidade , Antioxidantes/farmacologia , Carbono/toxicidade , Epitélio/efeitos dos fármacos , Palato/efeitos dos fármacos , alfa-Tocoferol/análogos & derivados , Doença Aguda , Animais , Anuros , Cinza de Carvão , Interações Medicamentosas , Ácido Edético/farmacologia , Epitélio/metabolismo , Exposição por Inalação , Depuração Mucociliar , Palato/citologia , Material Particulado , Galato de Propila/farmacologia , Fatores de Tempo , Tocoferóis , alfa-Tocoferol/farmacologiaRESUMO
Aluminum (Al3+) intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacylglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated that Al(3+) -induced blood platelet aggregation was mediated by lipid peroxidation. Using chemiluminescence (CL) of luminol as an index of total lipid peroxidation capacity, we established a correlation between lipid peroxidation capacity and platelet aggregation. Al3+ (20-100 microM) stimulated CL production by human blood platelets as well as their aggregation. Incubation of the platelets with the antioxidants nor-dihydroguaiaretic acid (NDGA) (100 microM) and n-propyl gallate (NPG) (100 microM), inhibitors of the lipoxygenase pathway, completely prevented CL and platelet aggregation. Acetyl salicylic acid (ASA) (100 microM), an inhibitor of the cyclooxygenase pathway, was a weaker inhibitor of both events. These findings suggest that Al3+ stimulates lipid peroxidation and the lipoxygenase pathway in human blood platelets thereby causing their aggregation.
Assuntos
Alumínio/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Adulto , Alumínio/análise , Guaiacol/análogos & derivados , Guaiacol/farmacologia , Humanos , L-Lactato Desidrogenase/análise , Lignanas/farmacologia , Medições Luminescentes , Galato de Propila/farmacologia , Ristocetina/farmacologia , Salicilatos/farmacologiaRESUMO
Aluminum (Al3+) intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacyglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated that Al3+-induced blood platelet aggregation was mediated by lipid peroxidation. Using chemiluminescence (CL) of luminol as an index of total lipid peroxidation capacity, we established a correlation between lipid peroxidation capacity and platelet aggregation. Al3+ (20-100 muM) stimulated CL production by human blood platelets as well as their aggregation. Incubation of the platelets with the antioxidants nor-dihydroguaiaretic acid (NDGA) (100 muM) and n-propyl gallate (NPG) (100 muM), inhibitors of the lipoxygenase pathway, completely prevented CL and platelet aggregation. Acetyl salicylic acid (ASA) (100 muM), an inhibitor of the cyclooxygenase pathway, was a weaker inhibitor of both events. These findings suggest that Al3+ stimulates lipid peroxidation and the lipoxygenase pathway in human blood platelets thereby causing their aggregation.
Assuntos
Humanos , Adulto , Alumínio/farmacologia , L-Lactato Desidrogenase/análise , Lignanas/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Galato de Propila/farmacologia , Ristocetina/farmacologia , Salicilatos/farmacologia , Alumínio/análise , Medições LuminescentesRESUMO
Thermolysis of 2,2'-azo-bis-(2-amidinopropane) under air in the presence of lysozyme leads to extensive inactivation of the enzyme. The number of inactivated enzyme molecules per radical produced increases with the enzyme concentration up to values considerably larger than one. Enzyme inactivation is accompanied by extensive tryptophan modification. Over the enzyme concentration range considered (1.7 to 130 microM) nearly 4 tryptophan groups are modified per enzyme molecule inactivated. Both the inactivation and tryptophan modification are prevented by micromolar concentrations of propyl gallate. The results are interpreted in terms of an efficient inactivation of the enzyme by the alkylperoxyl radicals generated by thermolysis of the azocompound.
Assuntos
Amidinas/farmacologia , Muramidase/antagonistas & inibidores , Triptofano/metabolismo , Radicais Livres , Galato de Propila/farmacologiaRESUMO
It has been reported that a great part of the deleterious effect caused by ionizing radiations is due to oxidative phenomena. The purpose of this work was to investigate if some antioxidants commonly used in the food industry might have a radioprotecting effect. N propyl-galate (NPG), hydroxyanisol-butylated (HAB) and hydroxytoluene-butylated (HTB) were utilized. Forty BALB/C mice that received 600 rads of gamma irradiation from a 60Co emitter died 17.12 +/- 7.82 days after. Thirteen mice that were injected 5 mg of NPG 24 hours and 30 minutes before radiation survived for more than 90 days. This same effect was observed in 13 mice that were also injected with 10 mg NPC and in other 13 that received 10 mg of HAB in the same way. Doses of 5 mg HAB or 5 and 10 mg HTB did not have a radioprotecting effect. When the radiation dose was increased to 800 rads, the radioprotecting effect was absent with any of the NPG, HAB or HTB doses. In protected mice, preservation of higher numbers of hematopoietic cells were observed in the bone marrow together with slight reduction of chromosomal fractures. There results show that antioxidants used in the food industry have a radioprotecting effect that had not been investigated.