Avaliação toxicológica de nanocápsulas de núcleo lipídico e estudo da eficiência de nanocápsulas contendo melatonina na proteção frente ao dano causado pelo paraquat

De acordo com dados da Organização Mundial da Saúde (OMS) estimam-se que os agrotóxicos causam anualmente 70 mil intoxicações agudas e crônicas que evoluem para óbito. Dentre eles, o paraquat (PQ) é o que apresenta maior taxa de mortalidade, sendo responsável por cerca de 13% de todos os casos registrados, principalmente devido a falta de um tratamento efetivo. O principal mecanismo de toxicidade proposto está associado ao ciclo redox do PQ, onde ocorre a formação de espécies reativas (ERs) de oxigênio e nitrogênio, levando ao estresse oxidativo (EO). Na literatura há relatos do uso de antioxidantes para casos de intoxicação do PQ. Dessa maneira, nesse trabalho avaliou-se o uso de melatonina associada a nanocápsulas de núcleo lipídico (Mel-LNC) na proteção contra os danos causados pelo PQ, uma vez que o uso da nanotecnologia melhorou a atividade antioxidante dessa molécula. Para tal utilizou-se o sistema in vitro, linhagem celular de adenocarcinoma pulmonar (A549), e o modelo alternativo in vivo, Caenorhabditis elegans. Mel-LNC e nanocápsulas de núcleo lipídico (LNC) foram preparadas de acordo com o método de deposição do polímero pré-formado. Ambas as formulações foram caracterizadas avaliando tamanho de partícula, potencial zeta e pH, e para Mel-LNC foram determinadas a concentração de melatonina e porcentagem de encapsulação. Os resultados encontrados estão de acordo com os parâmetros já validados para essas formulações. Foi possível verificar que as formulações MEL-LNC e LNC se mantiveram estáveis nos meios de cultura utilizados nos ensaios in vitro e in vivo. No estudo in vitro foi observado que o tratamento com ambas as formulações não causaram diminuição da viabilidade nem dano de DNA na linhagem celular utilizada. Além disso, foi verificado a internalização da Mel-LNC utilizando-se a formulação marcada com rodamina B, sendo possível verificar uma intensa fluorescência vermelha ao redor do núcleo da célula. O pré-tratamento com Mel-LNC foi capaz de aumentar a viabilidade celular e diminuir o dano oxidativo de DNA causado pelo paraquat após 24 horas de exposição, porém isso não ocorreu quando as células foram pré-tratadas com melatonina livre. No estudo com o modelo alternativo C. elegans, foi utilizada uma formulação de Mel-LNC marcada com rodamina B (Mel-LNC-RoB), a fim de verificar a absorção dessa formulação pelo nematoide. Foi possível observar que a internalização da Mel-LNC no C. elegans ocorre principalmente pela via oral, uma vez que se verificou uma intensa fluorescência no intestino do nematoide após o tratamento com a Mel-LNC-RoB e após três horas, essa fluorescência se distribuiu pelo restante do corpo, apresentando inúmeros pontos de fluorescência fora do intestino. Com relação à avaliação do efeito protetor nesse modelo alternativo in vivo, pode-se inferir que o pré-tratamento com Mel-LNC aumentou a sobrevida, diminuiu a produção de espécies reativas (ERs) e manteve o desenvolvimento normal dos nematoides após a exposição ao PQ, sendo que isso não foi verificado quando os mesmos foram pré-tratados com melatonina livre. Além disso, verificou-se que as nanocápsulas de núcleo lipídico (LNC) são seguras para o uso no modelo C. elegans, uma vez que apresentou alto valor para a dose letal 50 (DL50), e alterações no desenvolvimento e produção de ERs somente ocorreram em doses mais elevadas que as utilizadas em nossos experimentos. Dessa maneira, a formulação de Mel-LNC mostrou-se um promissor candidato para estudos futuros nos casos de intoxicação por paraquat.According to estimations by World Health Organization (WHO), pesticides are responsible for 70 thousand acute intoxication cases that lead to death per year. Among these compounds, paraquat (PQ) presents the highest mortality rate, about 13% of all registered cases, especially for the lack of effective treatment. The major mechanism of toxicity proposed is associated to its redox cycle, in which oxygen and nitrogen reactive species (RS) are generated culminating in oxidative stress (OS). Some reports in the literature support the use of antioxidants for PQ intoxication cases. The present study aimed to evaluate the use of melatonin-loaded lipid-core nanocapsules (Mel-LNC) in the protection against PQ-induced damages, considering that nanotechnology has improved the antioxidant activity of this molecule. For this purpose, an in vitro system composed by lung adenocarcinoma (A549) cell line, and the in vivo alternative model of Caenorhabditis elegans have been utilized. Mel-LNC and unloaded lipid-core nanocapsules were prepared by self-assembly and characterized by particle sizing, zeta potential and pH, and for Mel-LNC formulation it was determined the drug content and encapsulation efficiency. The results are in agreement with the parameters already validated for these formulations. It was possible verify that Mel-LNC and LNC formulations remained stable in the culture medium utilized in in vitro and in vivo experiments. Results from in vitro studies showed that none of the formulations induced reduction in cell viability or DNA damage in treated cells. Besides, it was observed the internalization of Mel-LNC marked with rhodamine B, showing an intense red fluorescence around the cell nucleus. Pretreatment with Mel-LNC was able to enhance cell viability and diminish DNA oxidative damage caused by paraquat after 24h exposure, which could not be observed when cells were pretreated with Mel. In the study with the alternative model C. elegans, a rhodamine (Ro)-linked Mel-LNC formulation was prepared in order to assess the absorption of the formulation by the nematode. Mel-LNC uptake in C. elegans was found to occur mainly by the oral route, once an intense fluorescence was observed in the intestine after treatment with Mel-LNC-RoB, which after 3h distributed to the rest of the body, presenting numerous fluorescence dots outside the intestine. In relation to the evaluation of protection with the in vivo alternative model, results indicate that pretreatment with Mel-LNC increased survival rate, reduced the production of reactive species and maintained the normal development of nematodes after paraquat exposure, while the same observations were not found after pretreatment with free melatonin. In addition, the lipid-core nanocapsules (LNC) were found to be safe in the C. elegans model, due to its high lethal dose (LD50) value, and development alterations and RS production only occurred in the higher doses than those utilized in our experiments. Therefore, the Mel-LNC formulation demonstrated to be a promising candidate for future studies aiming treatment of paraquat intoxication cases

Neurotoxicity evaluation of meloxicam in the alternative in vivo model, Caenorhabditis elegans

Inflammatory processes cause changes in the permeability of the blood brain barrier. Non-steroidal anti-inflammatory drugs (NSAID) are most commonly used to treat these inflammatory processes, including meloxicam, and they can reach the central nervous system (CNS) and cause neurotoxicity. Since there are no studies evaluating the neurotoxicity of NSAID in alternative models of toxicity, the aim of this study was to evaluate the acute neurotoxicity (through nematodes changes in behavior) of meloxicam in an alternative in vivo model, Caenorhabditis elegans, as well as, to determine meloxicam toxicity through LD50 and development assessments. Meloxicam LD50 was high (50.03 mg/mL) and only the highest dose (100 mg/mL) caused a decrease in the nematode body size, indicating low toxicity in this alternative model. Besides, a neurological effect was observed only in the highest dose. Meloxicam showed neurotoxicity only at a very high dose, suggesting low potential to cause toxicity in the CNS. However, further studies are necessary to evaluate meloxicam neurotoxicity

Evaluation of the potential toxicity of haloperidol, clozapine and a new putative antipsychotic molecule, PT-31, in an alternative toxicity model, C. elegans

Schizophrenia is a disabling mental illness that affects approximately 1% of the world population. The treatment of this disorder is based on two generations of substances, typical antipsychotics, such as haloperidol, and atypical antipsychotics, such as clozapine, which can cause severe adverse effects. Therefore, the development of novel molecules that are safe and efficacious to treat the disease is crucial. PT-31 is a putative α2-adrenoceptor agonist effective against schizophrenia positive and cognitive symptoms in mice. C. elegans is an alternative model that has been successfully used to investigate the toxicity of a variety of substances. The present study aimed to evaluate the potential toxicity of the new molecule PT-31 and the antipsychotics haloperidol and clozapine in C. elegans. The evaluation was carried out based on toxicity endpoint tests, survival, developmental and behavioral assays. The antipsychotics haloperidol and clozapine decreased nematode survival by 30 and 40%, respectively, exposing the potential toxicity of these substances whereas PT-31 was safer based on this parameter. Similar results were obtained in the nematode developmental assay: haloperidol and clozapine significantly reduced nematode body length and area, whereas PT-31 preserved the normal development of the nematodes. The behavioral assessment was based on the frequency of body bends; none of the antipsychotics affected the locomotion rate of the nematodes, and PT-31 also did not compromise this parameter, demonstrating the safety of this new compound and reinforcing the recognized toxicity of antipsychotics

Antioxidantes sanguíneos provenientes da dieta em ribeirinhos da Amazônia Brasileira : suas relações com sazonalidade e determinantes sociodemográficos

This study associates blood antioxidants like copper (Cu), manganese (Mn), selenium (Se), zinc (Zn), β-carotene, lycopene and vitamins (A and E) to sociodemographic features and seasonality in communities from the Tapajós River region, Brazilian Amazon. We observed increased Mn, Se and Zn levels compared to the average Brazilian population, whereas this is only the case for β-carotene in the rainy season. Lycopene levels fall within the reference range, although lower than those found in other Brazilian regions. Cu, Se, Zn, β-carotene, lycopene and vitamin E levels vary among seasons. β-carotene, Mn and Se vary among communities. Se and Zn vary with smoking habits and sex, respectively. In addition, β-carotene and vitamins (A and E) are altered by alcohol consumption. Villagers who both farmed and fished present higher Cu and lower β-carotene levels than participants with a single occupation. Vitamin E levels depend upon the individual state of origin. These data provide important baseline information for antioxidant status in this Amazonian riparian population.O presente estudo reporta as concentrações plasmáticas dos antioxidantes cobre (Cu), manganês (Mn), selênio (Se), zinco (Zn), β-caroteno, licopeno e vitaminas (A e E) em moradores da região do Rio Tapajós, Pará, Amazônia, e as relaciona com características sociodemográficas e sazonalidade (seca e cheia). Os teores de Mn, Se e Zn foram acima dos valores de referência (VR) e daqueles achados em outras regiões do Brasil, enquanto para o β-caroteno tal achado ocorreu apenas na estação da cheia. Os valores de licopeno foram dentro dos VR, porém abaixo dos achados em outras regiões do Brasil. Os níveis de Cu, Se, Zn, β-caroteno, licopeno e vitamina E variaram entre as estações. Variação intercomunitária foi constatada para β-caroteno, Mn e Se. Os teores de Se e Zn foram alterados, respectivamente, por tabagismo e sexo. Os níveis de β-caroteno e vitaminas (A e E) alteraram-se com o consumo de bebida alcoólica. A vitamina E foi dependente do estado de origem. Participantes que desempenhavam ambas as profissões de agricultor e pescador apresentavam teores de Cu superiores e de β-caroteno inferiores comparativamente àqueles que desempenhavam uma única profissão. Esses dados fornecem informações sobre os teores de antioxidantes para essa população amazônica

Acute Toxicity Evaluation of Phosphatidylcholine Nanoliposomes Containing Nisin in <i>Caenorhabditis elegans</i>

Liposomes are among the most studied nanostructures. They are effective carriers of active substances both in the clinical field, such as delivering genes and drugs, and in the food industry, such as promoting the controlled release of bioactive substances, including food preservatives. However, toxicological screenings must be performed to ensure the safety of nanoformulations. In this study, the nematode Caenorhabditis elegans was used as an alternative model to investigate the potential in vivo toxicity of nanoliposomes encapsulating the antimicrobial peptide nisin. The effects of liposomes containing nisin, control liposomes, and free nisin were evaluated through the survival rate, lethal dose (LD50), nematode development rate, and oxidative stress status by performing mutant strain, TBARS, and ROS analyses. Due to its low toxicity, it was not possible to experimentally determine the LD50 of liposomes. The survival rates of control liposomes and nisin-loaded liposomes were 94.3 and 73.6%, respectively. The LD50 of free nisin was calculated as 0.239 mg mL−1. Free nisin at a concentration of 0.2 mg mL−1 significantly affected the development of C. elegans, which was 25% smaller than the control and liposome-treated samples. A significant increase in ROS levels was observed after exposure to the highest concentrations of liposomes and free nisin, coinciding with a significant increase in catalase levels. The treatments induced lipid peroxidation as evaluated by TBARS assay. Liposome encapsulation reduces the deleterious effect on C. elegans and can be considered a nontoxic delivery system for nisin

Simultaneous quantification of organic solvent biomarkers by high performance liquid chromatography

Biological monitoring is very important to guarantee health to workers. This method was developed for simultaneous determination of xylene, toluene, styrene and ethylbenzene metabolites. It involves only dilution and centrifugation of urine samples and improved chromatographic conditions. Analyses show recovery ≥ 95%; r2 > 0.99; intermediate precision CV% < 6% and % bias < ±10. Exposed subjects presented at least three metabolites in urine. The method proved to be feasible, reliable and important in biological monitoring, especially in exposure to organic solvent mixtures

Simultaneous quantification of organic solvent biomarkers by high performance liquid chromatography

Biological monitoring is very important to guarantee health to workers. This method was developed for simultaneous determination of xylene, toluene, styrene and ethylbenzene metabolites. It involves only dilution and centrifugation of urine samples and improved chromatographic conditions. Analyses show recovery ≥ 95%; r2 > 0.99; intermediate precision CV% < 6% and % bias < ±10. Exposed subjects presented at least three metabolites in urine. The method proved to be feasible, reliable and important in biological monitoring, especially in exposure to organic solvent mixtures