29 research outputs found
O sistema antioxidante da glautationa como alvo molecular na neurotoxicidade induzida por metilmercĂşrio: efeitos protetores de compostos naturais
Tese (doutorado) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Programa de Pós-Graduação em NeurociênciasO mercurio, em suas formas organicas e inorganicas, e um toxicante ambiental capaz de provocar deficits neurologicos severos em animais e humanos. O sistema nervoso em desenvolvimento apresenta uma maior suscetibilidade aos efeitos deleterios induzidos por mercuriais. Neste contexto, exposicoes durante o periodo pre#]natal e lactacional representam importantes questoes do ponto de vista toxicologico. De fato, pouco se conhece a respeito da contribuicao lactacional para o desenvolvimento de neurotoxicidade frente a intoxicacoes com mercuriais. Alem disso, nao existem tratamentos efetivos capazes de reverter completamente os efeitos toxicos do mercurio. No presente estudo, foi demonstrado que a exposicao exclusivamente lactacional de camundongos jovens ao metilmercurio, uma forma organica de mercurio, causou deficits motores que foram correlacionados com um desequilibrio no estado tiolico cerebelar. Observamos tambem, que o mercurio inorganico causou neurotoxicidade em camundongos expostos a este metal atraves do leite materno. O cerebelo de animais jovens expostos ao mercurio inorganico apresentou uma atividade glutationa redutase aumentada, um efeito que pode estar relacionado a uma resposta de defesa celular frente a acao pro#]oxidativa do mercurio sobre tiois endogenos. Em contrapartida, os camundongos jovens expostos ao metilmercurio nao demonstraram esta resposta, o que aponta para mecanismos moleculares de resposta distintos para as diferentes formas de mercurio, sendo este fenomeno importante do ponto de vista toxicologico. O tratamento de animais adultos com metilmercurio por via oral causou uma diminuicao significativa na atividade glutationa peroxidase cerebral, uma enzima primaria no processo de detoxificacao de peroxidos produzidos endogenamente. Este efeito ocorreu em paralelo a um aumento na proteolise da enzima poli(ADP ribose) polimerase, um indice de apoptose. Em estudos in vitro, nossos dados demonstraram uma participacao importante do peroxido de hidrogenio como mediador da neurotoxicidade induzida por mercuriais e este fato foi acompanhado por uma marcante inibicao da enzima antioxidante glutationa peroxidase mitocondrial. O bloqueio da atividade desta enzima com acido mercaptosuccinico aumentou o estresse oxidativo e a disfuncao mitocondrial induzida pelos mercuriais in vitro. A incubacao de celulas de neuroblastoma humano SH#]SY5Y com metilmercurio causou uma diminuicao significativa na atividade glutationa peroxidase destas celulas. Este efeito tornou as celulas menos eficientes em degradar peroxido de hidrogenio e ocasionou um aumento na expressao de marcadores de dano oxidativo. Alem disso, a inibicao da lutationa peroxidase com acido mercaptosuccinico potencializou a perda de viabilidade celular e aumentou significativamente a expressao de marcadores de apoptose. O tratamento de animais adultos com extrato hidroalcoolico da planta Polygala paniculata preveniu os efeitos comportamentais e relacionados ao estresse oxidativo induzidos pelo tratamento com metilmercurio administrado por via oral. Este efeito se deu provavelmente devido a acao antioxidante do extrato. Em estudos in vitro, demonstramos a participacao do flavonoide quercetina como um importante mediador da neuroprotecao induzida pelo extrato de Polygala frente aos efeitos toxicos do metilmercurio. Alem disso, o flavonoide miricetina tambem apresentou efeito benefico contra a disfuncao mitocondrial e estresse oxidativo induzidos por metilmercurio in vitro. Em conclusao, nossos dados apontam para o sistema antioxidante da glutationa como um importante alvo molecular na neurotoxicidade induzida por mercuriais, onde disturbios no sistema antioxidante, causados por estes agentes, levam a um quadro de estresse oxidativo associado a disfuncao mitocondrial e aumentam a expressao de marcadores de morte celular. O extrato hidroalcoolico da planta Polygala paniculata, bem como os flavonoides quercetina e miricetina, representam potenciais agentes neuroprotetores contra a toxicidade induzida por mercuriais Mercury, in its organic and inorganic forms, is a potent environmental toxicant able to induce neurological deficits in both animals and humans. The developing central nervous system is particularly susceptible to the deleterious effects of mercury compounds. In this regard, mercury exposures during the pre#]natal and lactational periods are main factors from a toxicological point of view. In fact, little is known about the exclusive contribution of the lactational exposure to mercury and its relationship with neurotoxicity. In addition, there are no available treatments able to totally block mercurials#]induced toxicity. In the present study, we demonstrate that the exposure of young mice to methylmercury, an organic form of mercury, exclusively via maternal milk induces motor deficits associated with disturbs in the cerebellar thiol homeostasis. We also show that inorganic mercury caused neurotoxicity by exposure of young mice exclusively through the lactational route. The pups exposed to inorganic mercury presented an increased activity of the antioxidant enzyme glutathione reductase in the cerebellum. This effect appears to be related to an antioxidant response against the well known pro#]oxidative actions of mercury towards endogenous thiols. On the other hand, pups exposed to methylmercury through maternal milk did not show such adaptative response, pointing to different molecular mechanisms of action of the distinct forms of mercury. From a toxicological point of view, this is an important finding. Treatment of adult mice with methylmercury via oral route caused a significant decrease on the glutathione peroxidase activity in the brain. This enzyme is a main antioxidant defence against the deleterious effects of indogenous peroxides. This phenomenon was concomitant with an increase in poly(ADP ribose) polymerase proteolysis, an index of apoptosis. During in vitro studies, our data shows the central role of hydrogen peroxide as an important contributor to the neurotoxicity induced by mercuric compounds. We also show the inhibitory effect of methylmercury on mitochondrial glutathione peroxidase. The blockade of this enzyme with mercaptosuccinic acid caused an increase of oxidative stress markers and mitochondrial dysfunction induced by mercurials in vitro. The incubation of human neuroblastoma cells SH#]SY5Y with methylmercury caused a significant decrease on glutathione peroxidase activity. This effect resulted in a decreased ability of cells to remove hydrogen peroxide from the culture medium, causing an increase in the endogenous formation of peroxides. In addition, the inhibition of glutathione peroxidase improved the methylmercury#]induced anti#]viability effect and potentiated apoptosis. Treatment of adult animals with Polygala paniculata extract prevented the effects of methylmercury in inducing motor deficits and oxidative stress. This effect is probably related to the antioxidant actions of the extract. During in vitro studies, we demonstrated the participation of the flavonoid quercetin as an important mediator on the neuroprotection induced by Polygala extract. In addition, the flavonoid myricetin also displayed beneficial effects against methylmercury induced mitochondrial dysfunction and oxidative stress in vitro. In summary, our data point to the glutathione antioxidant system as an important molecular target for mercury#]induced neurotoxicity. Disturbances in this cellular defence system can induce oxidative stress associated with mitochondrial dysfunction and apoptosis. The Polygala paniculata extract, as well as the flavonoids quercetin and myricetin, may be potential therapeutic agents against mercury induced neurotoxicity
Anacardium microcarpum extract and fractions protect against paraquat-induced toxicity in Drosophila melanogaster
Anacardium microcarpum Ducke (Anacardiaceae) is a native species of Brazil used in folk medicine for the treatment of several illnesses although its antioxidant activity has been reported in vitro, there is no evidence of this effect in an in vivo model. Here, we investigated the potential protective effect of hydroalcoholic extract (AMHE), methanol (AMMF) and acetate (AMAF) fraction of A. microcarpum against paraquat toxicity on survivorship, locomotor performance, antioxidant enzymes activity and reactive species using Drosophila melanogaster. Flies were exposed to the extract or fractions (1 and 10 mg/ml) in the presence or absence of paraquat (5 mM) in sucrose solution for 72 h. In addition, total phenolic content of extract and fractions was evaluated as well as ABTS radical scavenging capacity. Our results demonstrated that AMAF presented higher content of phenols and ABTS chelating potential. Treatment of flies with the extract or fractions did not alter the survivorship, locomotor ability, and acetylcholinesterase (AchE) activity per se. Paraquat caused 85 % mortality of flies and 30 % increase in reactive species generation, which were significantly attenuated by AMHE and AMMF. AAMF increased catalase activity (from 66.77 ± 6.64 to 223.94 ± 25.92 mU/mg of protein), while AMAF increased GST activity (from 477.76 ± 92 to 770.19 ± 147.92 mU/mg of protein) and catalase activity (from 66.77 ± 6.64 to 220.54 ± 26.63 mU/mg of protein). AMHE and AMMF were more effective in protecting against paraquat toxicity. Taken together, the data indicate the potential of this plant in acting as a protective and antioxidant agent in vivo
Determinação dos efeitos de dois suplementos alimentares em Drosophila melanogaster
Pleurotus spp. are considered extremely rich mushroom species from the nutritional pointof view, providing immune-enhancement effects when consumed. However, few mushroomshave been tested for their phenotypic and genotypic responses in animal modelsto ensure the proper dosage for their use. This study aimed to evaluate the effects of twomushroom species on the reproductive capacity of Drosophila melanogaster. Pleurotuscitrinopileatus Singer and Lentinus sajor-caju (Fr.) Fr. were provided separately, in specificconcentrations, as feed supplements to the fruit flies. The total numbers of developedlarvae, pupae, and adults were then measured for each treatment. Inter simple sequencerepeats marker analysis was carried out to infer genotypic changes in the mushroom-fedflies. Our results suggest that Pleurotus spp. can cause positive changes to the flies’ reproductivecapacity, since Pleurotus citrinopileatus in particular accelerated the life cycle andrevealed a higher genetic dissimilarity of the diet-supplemented flies.Keywords: fruitflies, reproductive fitness, edible mushrooms.Pleurotus spp. sĂŁo consideradas espĂ©cies de cogumelo extremamente ricas do ponto de vista nutricional, proporcionando reforço imunolĂłgico quando consumidas. No entanto, poucos cogumelos foram testados quanto Ă sua interferĂŞncia fenotĂpica e genotĂpica em modelos animais para garantir a dosagem adequada para seu uso. Este estudo teve como objetivo avaliar os efeitos de duas espĂ©cies de cogumelos sobre a capacidade reprodutiva de Drosophila melanogaster. Pleurotus citrinopileatus Singer e Lentinus sajor-caju (Fr.) Fr. foram fornecidos separadamente, em concentrações especĂficas, como suplementos alimentares Ă s moscas da fruta. O nĂşmero total de larvas, pupas e adultos desenvolvidos foram entĂŁo avaliados para cada tratamento. Análises de marcadores moleculares do tipo Inter simple sequence repeats foram realizadas para inferir mudanças genotĂpicas nas moscas alimentadas com os cogumelos. Nossos resultados sugerem que Pleurotus spp. podem causar mudanças positivas na capacidade reprodutiva das moscas, uma vez que Pleurotus citrinopileatus, em particular, acelerou o ciclo de vida e revelou uma maior dissimilaridade genĂ©tica das moscas suplementadas com esse fungo em sua dieta.Palavras-chave: moscas das frutas, estĂmulo reprodutivo, cogumelos comestĂveis
Drosophila melanogaster - an embryonic model for studying behavioral and biochemical effects of manganese exposure
Embryonic animals are especially susceptible to metal exposure. Manganese (Mn) is an es-sential element, but in excess it can induce toxicity. In this study we used Drosophila mela-nogaster as an embryonic model to investigate biochemical and behavioral alterations due to Mn exposure. Flies were treated with standard medium supplemented with MnCl2 at 0.1 mM, 0.5 mM or 1 mM from the egg to the adult stage. At 0.5 mM and 1 mM Mn, newly ecloded flies showed significantly enhanced locomotor activity when assessed by negative geotaxis behavior. In addition, a significant increase in Mn levels (p < 0.0001) was observed, while Ca, Fe, Cu, Zn and S levels were significantly decreased. A significant drop in cell viability occurred in flies exposed to 1 mM Mn. There was also an induction of reactive oxygen species at 0.5 mM and 1 mM Mn (p < 0.05). At 1 mM, Mn increased Catalase (p < 0.005), Superoxide Dismutase (p < 0.005) and Hsp83 (p < 0.0001) mRNA expression, without altering Catalase or Superoxide Dismutase activity; the activity of Thioredoxin reductase and Glutatione-S-transferase enzymes was increased. Mn treatment did not alter ERK or JNK1/2 phosphorylation, but at 1 mM caused an inhibition of p38MAPK phosphorylation. Together these data suggest mechanisms of adaptation in the fly response to Mn exposure in embryonic life
Fumigant Activity of the Psidium guajava
The guava fruit, Psidium guajava var. pomifera (Myrtaceae family), is a native plant from South America. Its leaves and fruits are widely used in popular medicine in tropical and subtropical countries. Drosophila melanogaster has been used as one of the main model organisms in genetic studies since the 1900s. The extensive knowledge about this species makes it one of the most suitable organisms to study many aspects of toxic compound effects. Due to the lack of studies on the effects of the bioactive compounds present in the P. guajava var. pomifera essential oil, we performed a phytochemical characterization by CG-MS and evaluated the toxicity induced by the essential oil in the D. melanogaster insect model. In order to understand the biochemical mechanisms of toxicity, changes on the Nrf2 signaling as well as hallmarks of oxidative stress response were followed in the exposed flies. Our results showed that exposure of insects to the P. guajava oil increased mortality and locomotor deficits in parallel with an oxidative stress response signaling. Therefore, it suggested a bioinsecticidal activity for P. guajava volatile compounds by means of oxidative stress. Further studies are ongoing to identify which oil compounds are responsible for such effect
Phytochemical Composition, Antifungal and Antioxidant Activity of Duguetia furfuracea
Background. Duguetia furfuracea is popular plant used in popular medicine. Hypothesis/Purpose. This claim evaluated the phytochemical composition of the hydroethanolic extract (HEDF), fractions of Duguetia furfuracea, and antioxidant and antifungal activity. Methods. The chemical profile was carried out by HPLC-DAD. The total phenolic contents and flavonoid components were determined by Folin-Ciocalteu and aluminium chloride reaction. The antioxidant activity was measured by scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and ferric reducing ability of plasma (FRAP) methods. The antifungal activity was determined by microdilution assay. Results. HPLC analysis revealed caffeic acid and rutin as major compounds (HEDF), caffeic acid and quercitrin (Mt-OH fraction), and quercitrin and isoquercitrin (Ac-OEt fraction). The highest levels of phenols and total flavonoids were found for Ac-OEt fraction, and the crude extract showed higher in vitro antioxidant potential. The antifungal activity showed synergic effect with fluconazole and EHDF against C. krusei, fluconazole and Mt-OH against C. krusei and C. tropicalis, and Ac-OE and fluconazole against C. albicans. Conclusion. The highest levels of phenols and total flavonoids were marked with antioxidant effect. This is the first report of bioactivity of the synergic effect of HEDF and fractions. More studies would be required to better clarify its mechanism of synergic action
Phytochemical Constituents and Toxicity of Duguetia furfuracea
Duguetia furfuracea is frequently used as a medicinal plant in Brazil. However, studies have evidenced its cytotoxic, bactericide, and antitumor activities. In the present study we aimed to evaluate the potential toxicity of hydroalcoholic leaves extracts of D. furfuracea (HEDF) in a Drosophila melanogaster model. Toxicity was assessed as changes in locomotor performance, mitochondrial activity, oxidative stress, MAPKs phosphorylation, and apoptosis induction after exposure to HEDF concentrations (1–50 mg/mL) for 7 days. The phytoconstituents of the plant were screened for the presence of alkaloids, tannins, xanthones, chalcones, flavonoids, aurones, and phenolic acids. Exposure of adult flies to HEDF caused mitochondrial dysfunction, overproduction of ROS, and alterations in the activity of detoxifying enzymes GST, SOD and CAT. Induction of ERK phosphorylation and PARP cleavage was also observed, indicating occurrence of HEDF-induced cell stress and apoptotic cell death. In parallel, alterations in cholinesterase activity and impairments in negative geotaxis behavior were observed. Our study draws attention to the indiscriminate use of this plant by population and suggests oxidative stress as a major mechanism underlying its toxicity
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In
the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost