RESUMEN

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.

Asunto(s)

Recubrimiento Dental Adhesivo , Galato de Propilo , Galato de Propilo/análisis , Galato de Propilo/farmacología , Recubrimientos Dentinarios/química , Glutaral , Espectroscopía Infrarroja por Transformada de Fourier , Cementos de Resina/química , Dentina , Resistencia a la Tracción , Ensayo de Materiales , Cementos Dentales/farmacología , Resinas Compuestas/química , Agua/química

RESUMEN

Aspergillus ochraceus biofilm, developed on an inert support, can produce tannase in Khanna medium containing 1.5% (w/v) tannic acid as the carbon source, at an initial pH of 5.0, for 72 h at 28 °C. Addition of 0.1% yeast extract increased enzyme production. The enzyme in the crude filtrate exhibited the highest activity at 30 °C and pH 6.0. At 50 °C, the half-life was 60 min and 260 min at pH 6.0. In general, addition of detergents and surfactants did not affect tannase activity significantly. Tannase has potential applications in various biotechnological processes such as the production of propyl gallate and in the treatment of tannin-rich effluents. The content of tannins and total phenolic compounds in effluents from leather treatment was reduced by 56-83% and 47-64%, respectively, after 2 h of enzyme treatment. The content of tannins and total phenolic compounds in the sorghum flour treated for 120 h with tannase were reduced by 61% and 17%, respectively. Interestingly, the same A. ochraceus biofilm was able to produce tannase for three sequential fermentative process. In conclusion, fungal biofilm is an interesting alternative to produce high levels of tannase with biotechnological potential to be applied in different industrial sectors.

Asunto(s)

Aspergillus ochraceus/enzimología , Biopelículas , Hidrolasas de Éster Carboxílico/metabolismo , Proteínas Fúngicas/metabolismo , Aspergillus ochraceus/crecimiento & desarrollo , Biopelículas/crecimiento & desarrollo , Medios de Cultivo/química , Fermentación , Concentración de Iones de Hidrógeno , Fenoles/metabolismo , Galato de Propilo/metabolismo , Sorghum/química , Tensoactivos/metabolismo , Taninos/metabolismo , Temperatura , Contaminantes del Agua/metabolismo

RESUMEN

Avian leukosis virus subgroup J (ALV-J), a member of the retroviridae family, can infect both broilers and layers and induce a spectrum of different neoplasms, resulting in serious economic losses in poultry production. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has demonstrated remarkable anti-inflammatory and cancer chemopreventive effects in many animal tumor bioassays, cell culture systems and epidemiological studies. To assess the antiviral effects of EGCG on ALV-J-induced cell apoptosis in vitro, DF-1 cells were treated with different EGCG concentrations (0, 5, 10, 20 and 40 µg/mL), and their antiviral effects were examined at different time points (0, 24, 48, 72 and 96 h) using a variety of assays. EGCG alleviated the ALV-J-induced apoptosis in a dose-dependent manner. Because high concentrations (20 and 40 µg/mL) inhibited DF-1 cell growth, and low concentration (5 µg/mL) did not suppress the ALV-J virus, 10 µg/mL was the most appropriate concentration. After 96 h of incubation, 10 µg/mL EGCG improved the ALV-J-triggered suppression of the nuclear transcription factor system by enhancing cytoplasmic NF-B p50/p65 expression and inhibiting nuclear NF-B p50/p65 expression, resulting in decreased cell apoptosis. These results demonstrated that EGCG inhibited ALV-J-induced apoptosis in DF-1 cells in a dose-dependent manner via the NF-B signaling pathway, and that 10 µg/mL EGCG is the optimal concentration, which may be useful for therapeutic drug design.

Asunto(s)

Animales , Apoptosis , Galato de Propilo/química , Pollos/virología , FN-kappa B/análisis , Virus de la Leucosis Aviar

RESUMEN

Avian leukosis virus subgroup J (ALV-J), a member of the retroviridae family, can infect both broilers and layers and induce a spectrum of different neoplasms, resulting in serious economic losses in poultry production. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has demonstrated remarkable anti-inflammatory and cancer chemopreventive effects in many animal tumor bioassays, cell culture systems and epidemiological studies. To assess the antiviral effects of EGCG on ALV-J-induced cell apoptosis in vitro, DF-1 cells were treated with different EGCG concentrations (0, 5, 10, 20 and 40 µg/mL), and their antiviral effects were examined at different time points (0, 24, 48, 72 and 96 h) using a variety of assays. EGCG alleviated the ALV-J-induced apoptosis in a dose-dependent manner. Because high concentrations (20 and 40 µg/mL) inhibited DF-1 cell growth, and low concentration (5 µg/mL) did not suppress the ALV-J virus, 10 µg/mL was the most appropriate concentration. After 96 h of incubation, 10 µg/mL EGCG improved the ALV-J-triggered suppression of the nuclear transcription factor system by enhancing cytoplasmic NF-B p50/p65 expression and inhibiting nuclear NF-B p50/p65 expression, resulting in decreased cell apoptosis. These results demonstrated that EGCG inhibited ALV-J-induced apoptosis in DF-1 cells in a dose-dependent manner via the NF-B signaling pathway, and that 10 µg/mL EGCG is the optimal concentration, which may be useful for therapeutic drug design.(AU)

Asunto(s)

Animales , Pollos/virología , Apoptosis , Galato de Propilo/química , FN-kappa B/análisis , Virus de la Leucosis Aviar

RESUMEN

Literature mentions propyl gallate (PG) as a non-toxic synthetic antioxidant that can be used as a food additive due to its high tolerance to heat. It is important to understand the thermal properties and to identify the decomposition products of this substance, since it has been reported to be thermally stable at temperatures as high as 300 °C. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry-photovisual (DSC-photovisual), coupled thermogravimetry-infrared spectroscopy (TG-FTIR) analyses and spectroscopic techniques were used to study the food additive PG. The TG-DTA curves, which were performed with the aid of DSC-photovisual, provided information concerning the thermal stability and decomposition profiles of the compound. From the TG-FTIR coupled techniques, it was possible to identify n-propanol as a possible volatile compound released during the thermal decomposition of the antioxidant. A complete spectroscopic characterization in the ultraviolet, visible, near and middle infrared regions was performed in order to understand the spectroscopic properties of PG.

Asunto(s)

Aditivos Alimentarios/análisis , Galato de Propilo/análisis , Análisis Espectral/métodos , Antioxidantes , Rastreo Diferencial de Calorimetría

RESUMEN

n-Propyl gallate and its analogs are used in foods and other products to prevent oxidation. In the liver the compound exerts several harmful effects, especially gluconeogenesis inhibition. The mode of transport and distribution of n-propyl gallate and its kinetics of biotransformation have not yet been investigated. To fill this gap the transformation, transport and distribution of n-propyl gallate and two analogs were investigated in the rat liver. Isolated perfused rat liver was used. n-Propyl gallate, methyl gallate, n-octyl gallate and transformation products were quantified by high pressure-liquid chromatography coupled to fluorescence detection. The interactions of n-propyl gallate and analogs with the liver presented three main characteristics: (1) the hydrolytic release of gallic acid from n-propyl gallate and methyl gallate was very fast compared with the subsequent transformations of the gallic acid moiety; (2) transport of the esters was very fast and flow-limited in contrast to the slow and barrier-limited transport of gallic acid; (3) the apparent distribution volume of n-propyl gallate, but probably also of methyl gallate and n-octyl gallate, greatly exceeded the water space in the liver, contrary to the gallic acid space which is smaller than the water space. It can be concluded that at low portal concentrations (<50µM) the gallic acid esters are 100% extracted during a single passage through the liver, releasing mainly gallic acid into the systemic circulation. For the latter a considerable time is required until complete biotransformation. The exposure of the liver to the esters, however, is quite prolonged due to extensive intracellular binding.

Asunto(s)

Ácido Gálico/análogos & derivados , Hígado/efectos de los fármacos , Galato de Propilo/farmacocinética , Animales , Biotransformación , Ácido Gálico/farmacocinética , Gluconeogénesis/efectos de los fármacos , Hígado/metabolismo , Masculino , Ratas , Ratas Wistar

RESUMEN

The extracellular tannase from Emericela nidulans was immobilized on different ionic and covalent supports. The derivatives obtained using DEAE-Sepharose and Q-Sepharose were thermally stable from 60 to 75 °C, with a half life (t50) >24 h at 80 °C at pH 5.0. The glyoxyl-agarose and amino-glyoxyl derivatives showed a thermal stability which was lower than that observed for ionic supports. However, when the stability to pH was considered, the derivatives obtained from covalent supports were more stable than those obtained from ionic supports. DEAE-Sepharose and Q-Sepharose derivatives as well as the free enzyme were stable in 30 and 50 % (v/v) 1-propanol. The CNBr-agarose derivative catalyzed complete tannic acid hydrolysis, whereas the Q-Sepharose derivative catalyzed the transesterification reaction to produce propyl gallate (88 % recovery), which is an important antioxidant.

Asunto(s)

Hidrolasas de Éster Carboxílico/metabolismo , Emericella/enzimología , Enzimas Inmovilizadas/metabolismo , Galato de Propilo/metabolismo , Hidrolasas de Éster Carboxílico/química , Estabilidad de Enzimas , Enzimas Inmovilizadas/química , Concentración de Iones de Hidrógeno , Taninos/metabolismo , Temperatura

RESUMEN

The kinetic and mechanistic aspects of the visible-light-mediated photodegradation of the phenolic antioxidants (PA), propyl gallate (PG), and t-butylhydroquinone (TBHQ), employing riboflavin (Rf) as photosensitizer, have been studied by time-resolved and stationary techniques. The photosensitizer Rose Bengal (RB) was used for auxiliary experiments. Results show the occurrence of chemical transformations on PA with the participation of electronically excited states of Rf and different reactive oxygen species (ROS) generated from these states. With 0.02 mM Rf and 1.0 mM PA, the electronically excited triplet state of Rf is quenched by PA, in a competitive manner with the dissolved oxygen. As a consequence, a cascade of photoprocesses produces singlet oxygen (O(2)((1)Δ(g))) and H(2)O(2) in the case of PG and, O(2)((1)Δ(g)), H(2)O(2) and HO(•) in the case of TBHQ. The participation of these species is supported by experiments of oxygen consumption carried out in the presence of specific ROS scavengers. TBHQ has a relatively high capacity for O(2)((1)Δ(g)) physical deactivation and a low photodegradation efficiency by the oxidative species. Comparatively, it can be asserted that TBHQ has a higher antioxidant capacity than PG.

Asunto(s)

Antioxidantes/química , Hidroquinonas/química , Luz , Fotólisis , Galato de Propilo/química , Animales , Fluoroinmunoensayo , Peróxido de Hidrógeno/química , Radical Hidroxilo/química , Mediciones Luminiscentes/métodos , Rosa Bengala/química , Oxígeno Singlete/química

RESUMEN

Antioxidants are currently used as efficient excipients that delay or inhibit the oxidation process of molecules. Excipients are often associated with adverse reactions. Stability studies can guide the search for solutions that minimize or delay the processes of degradation. The ability to predict oxidation reactions in different drugs is important. Methods: This study was conducted to assess the rational use of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), sodium metabisulfite (SMB), propyl gallate (PG) and cysteine (CYS) in tablet formulations of simvastatin and ketoconazole. These antioxidants were evaluated according to stability parameters and the relationship between efficiency of the antioxidant and chemical structure of the drugs. Results were compared with DPPH tests and computational simulations. BHT was most efficient regarding simvastatin stability, and the most effective BHT concentrations for maintaining stability were 0.5 and 0.1%. In relation to ketoconazole, SMB was most efficient for maintaining content and dissolution profile. The evaluation by DPPH showed that the largest percentage of absorbance reduction was observed for PG, while SMB proved most efficient and had lower consumption of DPPH. The same pattern was observed, albeit with lower efficiency, for the other lipophilic antioxidants such as BHT and BHA. The results of the molecular modeling study demonstrated that electronic properties obtained were correlated with antioxidant activity in solution, being useful for the rational development of liquid pharmaceutical formulations but not for solid oral formulations. This study demonstrated the importance of considering stability parameters and molecular modeling to elucidate the chemical phenomena involved in antioxidant activity, being useful for the rational use of antioxidants in the development of pharmaceutical formulations.

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Atualmente, antioxidantes são usados como excipientes eficientes, que retardam ou inibem o processo de oxidação de moléculas. Excipientes são frequentemente associados a efeitos adversos. Estudos de estabilidade podem ajudar na busca por possíveis soluções para minimizar ou retardar os processos de degradação. A habilidade de prever as reações de oxidação em diferentes fármacos é importante. O estudo foi conduzido com o objetivo de avaliar o uso racional de hidroxianisol butilado (BHA), hidroxitolueno butilado (BHT), metabissulfito sódico (SMB), galato de propila (PG) e cisteína (CYS) em formulações de comprimidos de sinvastatina e cetoconazol. Eles foram avaliados por parâmetros de estabilidade e pela relação entre a eficiência dos antioxidantes e a estrutura química do fármaco. Os resultados foram comparados com testes de DPPH e simulações em computador. BHT foi mais eficiente com relação a estabilidade da sinvastatina e às concentrações mais eficientes para manutenção de estabilidade foram 0,5 e 0,1%. Com relação ao cetoconazol, SMB foi mais eficiente em manter o conteúdo e o perfil de dissolução. A avaliação por DPPH mostrou que o maior percentual de redução de absorção foi observado para PG, enquanto que SMB mostrou ser mais eficiente e consumir menos DPPH. A mesma tendência foi observada com menos eficiência em todos os outros antioxidantes lipofílicos como o BHT e BHA. Os resultados do estudo de modelagem molecular demonstraram que as propriedades eletrônicas obtidas podem ser correlacionadas com a atividade antioxidante em solução, sendo útil para o desenvolvimento racional de formulações farmacêuticas líquidas, mas não para formulações sólidas orais. Este estudo demonstrou a importância de considerar parâmetros de estabilidade e modelagem molecular para elucidar os fenômenos químicos envolvidos na atividade antioxidante, sendo úteis para o uso racional de antioxidantes no desenvolvimento de formulações farmacêuticas.

Asunto(s)

Preparaciones Farmacéuticas , Administración Oral , Utilización de Medicamentos/clasificación , Antioxidantes/análisis , Galato de Propilo/farmacocinética , Hidroxianisol Butilado/farmacocinética , Hidroxitolueno Butilado/farmacocinética , Simvastatina/análisis , Cisteína/farmacocinética , Excipientes/clasificación , Cetoconazol/análisis

RESUMEN

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.

Asunto(s)

Gluconeogénesis/efectos de los fármacos , Hígado/efectos de los fármacos , Oxígeno/metabolismo , Galato de Propilo/farmacología , Animales , Cromatografía Líquida de Alta Presión , Hígado/metabolismo , Masculino , Ratas , Ratas Wistar

RESUMEN

The effects of octyl gallate on Ustilago maydis yeast cells were analysed in relation to its capacity to oxidize compounds (pro-oxidant actions). All phenolic compounds tested inhibited the alternative oxidase (AOX). However, only octyl gallate induced a morphological change in yeast cells and collapsed the mitochondrial membrane potential. In contrast to octyl gallate, propyl gallate and nordihydroguaiaretic acid caused only a negligible cell change and the membrane potential was not affected. Our findings show that structurally related phenolic compounds do not necessarily exert similar actions on target cells. Preincubation of U. maydis cells with trolox inhibited the change to pseudohyphal growth produced by octyl gallate. These results suggest that in addition to the inhibitory action of octyl gallate on the AOX, this compound induces a switch from yeast to a mycelium, probably through the formation of lipid peroxides.

Asunto(s)

Ácido Gálico/análogos & derivados , Ustilago/citología , Ustilago/crecimiento & desarrollo , Proteínas Fúngicas/metabolismo , Ácido Gálico/metabolismo , Potencial de la Membrana Mitocondrial , Proteínas Mitocondriales , Oxidorreductasas/metabolismo , Proteínas de Plantas , Galato de Propilo/metabolismo , Ustilago/metabolismo

RESUMEN

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.

Asunto(s)

Antineoplásicos/farmacología , Hepatocitos/efectos de los fármacos , Animales , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Respiración de la Célula/efectos de los fármacos , Células Cultivadas , Ensayos de Selección de Medicamentos Antitumorales , Transporte de Electrón , Ácido Gálico/análogos & derivados , Ácido Gálico/farmacología , Ratones , Mitocondrias Hepáticas/efectos de los fármacos , Mitocondrias Hepáticas/metabolismo , Galato de Propilo/farmacología , Ratas , Pruebas de Toxicidad

RESUMEN

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.

Asunto(s)

Hepatocitos/efectos de los fármacos , Peroxidación de Lípido/fisiología , Extractos Vegetales/farmacología , Especies Reactivas de Oxígeno/metabolismo , Animales , Antioxidantes/farmacología , Derivados del Benceno/farmacología , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ácido Gálico/farmacología , Glucosa Oxidasa/farmacología , Hepatocitos/metabolismo , Hipoxantina/farmacología , Masculino , Mangifera , Oxidantes/farmacología , Estrés Oxidativo/efectos de los fármacos , Galato de Propilo/farmacología , Ratas , Ratas Sprague-Dawley , Superóxidos/metabolismo , Xantina Oxidasa/metabolismo

RESUMEN

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.

Asunto(s)

Aflatoxina B1/biosíntesis , Antioxidantes/farmacología , Arachis/microbiología , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/fisiología , Hidroxianisol Butilado/farmacología , Hidroxitolueno Butilado/farmacología , Medios de Cultivo , Microbiología de Alimentos , Conservantes de Alimentos/farmacología , Germinación , Parabenos/farmacología , Galato de Propilo/farmacología , Microbiología del Agua

RESUMEN

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.

Asunto(s)

Contaminantes Atmosféricos/toxicidad , Antioxidantes/farmacología , Carbono/toxicidad , Epitelio/efectos de los fármacos , Hueso Paladar/efectos de los fármacos , alfa-Tocoferol/análogos & derivados , Enfermedad Aguda , Animales , Anuros , Ceniza del Carbón , Interacciones Farmacológicas , Ácido Edético/farmacología , Epitelio/metabolismo , Exposición por Inhalación , Depuración Mucociliar , Hueso Paladar/citología , Material Particulado , Galato de Propilo/farmacología , Factores de Tiempo , Tocoferoles , alfa-Tocoferol/farmacología

RESUMEN

The antioxidant capacity of butylated hydroxytoluene (BHT; 2,6-di-tert-butyl-p-cresol), propyl gallate (3,4,5-trihydroxybenzoic acid n-propyl ester), resveratrol (trans-3,4',5-trihydroxystilbene), and vitamins C (l-ascorbic acid) and E [(+)-alpha-tocopherol] was studied in chemical and biological systems. The chemical assays evaluated the capacity of these antioxidants to sequester 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS.) and 1,1 diphenyl-2-picrylhydrazyl (DPPH.). A new colorimetric method to determine hydroxyl radical scavenging is also described. The biological tests use the eucaryotic cells of Saccharomyces cerevisiae treated with the antioxidants in the presence of the stressing agents apomorphine, hydrogen peroxide, and paraquat dichloride (methylviologen; 1,1'-dimethyl-4,4'-bipyridinium dichloride). The results in chemical systems showed that all of the antioxidants were able to significantly inhibit the oxidation of beta-carotene by hydroxyl free radicals. The assays in yeast showed that the antioxidant activity of the tested compounds depended on the stressing agent used and the mechanism of action of the antioxidant.

Asunto(s)

Antioxidantes/química , Ácido Ascórbico/química , Hidroxitolueno Butilado/química , Galato de Propilo/química , Estilbenos/química , Vitamina E/química , Antioxidantes/farmacología , Apomorfina/farmacología , Benzotiazoles , Compuestos de Bifenilo , Peróxido de Hidrógeno/farmacología , Radical Hidroxilo/química , Oxidación-Reducción , Paraquat/farmacología , Picratos/química , Resveratrol , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/metabolismo , Ácidos Sulfónicos/química , beta Caroteno/química

RESUMEN

There is considerable interest in the role of the 1-hydroxyethyl radical (HER) in the toxic effects of ethanol. The goal of this study was to evaluate the effects of HER on classical antioxidant enzymes. The interaction of acetaldehyde with hydroxylamine-o-sulfonic acid has been shown to produce 1, 1'-dihydroxyazoethane (DHAE); this compound appears to be highly unstable, and its decomposition leads to the generation of HER. Addition of DHAE into a solution of PBN led to the appearance of the typical EPR spectra of PBN/HER adduct. No PBN/HER spin adduct was detected when DHAE was incubated with 0.1 M PBN in the presence of GSH. In the absence of PBN, DHAE oxidized ascorbic acid to semidehydroascorbyl radical, presumably via an ascorbate-dependent one-electron reduction of HER back to ethanol. Catalase was progressively inactivated by exposure to DHAE-generated HER in a time and HER concentration-dependent manner. Ascorbic acid and PBN gave full protection to catalase against HER-dependent inactivation. The antioxidants 2-tert-butyl-4-methylphenol, propylgallate, and alpha-tocopherol-protected catalase against inactivation by 84, 88, and 39%, respectively. Other antioxidant enzymes were also sensitive to exposure to HER. Glutathione reductase, glutathione peroxidase, and superoxide dismutase were inactivated by 46, 36, and 39%, respectively, by HER. The results reported here plus previous results showing HER interacts with GSH, ascorbate, and alpha-tocopherol suggest that prolonged generation of HER in cells from animals chronically exposed to ethanol may lower the antioxidant defense status, thereby contributing to mechanisms by which ethanol produces a state of oxidative stress and produces toxicity.

Asunto(s)

Antioxidantes/metabolismo , Etanol/metabolismo , Ácido Ascórbico/metabolismo , Compuestos Azo/metabolismo , Hidroxitolueno Butilado/análogos & derivados , Hidroxitolueno Butilado/metabolismo , Catalasa/antagonistas & inhibidores , Catalasa/metabolismo , Ácido Ditionitrobenzoico/metabolismo , Relación Dosis-Respuesta a Droga , Espectroscopía de Resonancia por Spin del Electrón , Etanol/toxicidad , Depuradores de Radicales Libres/metabolismo , Radicales Libres/metabolismo , Glutatión/metabolismo , Glutatión Peroxidasa/antagonistas & inhibidores , Glutatión Peroxidasa/metabolismo , Glutatión Reductasa/antagonistas & inhibidores , Glutatión Reductasa/metabolismo , Oxidación-Reducción , Estrés Oxidativo/efectos de los fármacos , Galato de Propilo/metabolismo , Superóxido Dismutasa/antagonistas & inhibidores , Superóxido Dismutasa/metabolismo , Vitamina E/metabolismo

RESUMEN

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.

Asunto(s)

Aluminio/farmacología , Peroxidación de Lípido/efectos de los fármacos , Agregación Plaquetaria/efectos de los fármacos , Adulto , Aluminio/análisis , Guayacol/análogos & derivados , Guayacol/farmacología , Humanos , L-Lactato Deshidrogenasa/análisis , Lignanos/farmacología , Mediciones Luminiscentes , Galato de Propilo/farmacología , Ristocetina/farmacología , Salicilatos/farmacología

RESUMEN

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.

Asunto(s)

Humanos , Adulto , Aluminio/farmacología , L-Lactato Deshidrogenasa/análisis , Lignanos/farmacología , Peroxidación de Lípido/efectos de los fármacos , Agregación Plaquetaria/efectos de los fármacos , Galato de Propilo/farmacología , Ristocetina/farmacología , Salicilatos/farmacología , Aluminio/análisis , Mediciones Luminiscentes

RESUMEN

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.

Asunto(s)

Amidinas/farmacología , Muramidasa/antagonistas & inhibidores , Triptófano/metabolismo , Radicales Libres , Galato de Propilo/farmacología