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Efeitos do consumo da castanha-do-Brasil (Bertholletia excelsa H.B.K.) na modulação do estresse oxidativo e instabilidade genômica em indivíduos com diabetes mellitus tipo 2
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Abstract(s)
A diabetes mellitus tipo 2 (DM2) é uma doença metabólica cada vez mais prevalente que ocorre, em grande parte, devido às mudanças ambientais e no estilo de vida. Os estados crônicos de hiperglicemia, hiperlipidemia e hiperinsulinemia podem levar ao estresse oxidativo e consequentemente, à oxidação do ácido desoxirribonucleico (DNA). Uma boa prescrição dietética é considerada essencial no tratamento e prevenção de complicações relacionadas à DM2. A castanha-do-Brasil (Bertholletia excelsa, H.B.K.) é a melhor fonte alimentar de selênio encontrada na natureza e, níveis adequados deste mineral no organismo apresentam diversos benefícios à saúde, incluindo melhora no estado redox celular e modulação da instabilidade genômica. Nesse contexto, o objetivo deste trabalho foi avaliar os efeitos do consumo desta oleaginosa sobre parâmetros bioquímicos, de estresse oxidativo e instabilidade genômica em indivíduos com DM2. Participaram deste estudo 37 homens e 37 mulheres, que consumiram 1 castanha-do-Brasil por dia (»210 μg de selênio) durante 6 meses. Foram coletadas amostras de sangue periférico e células esfoliadas da mucosa bucal imediatamente antes do início e ao final do estudo. Foram analisados os perfis glicêmico, lipídico, inflamatório, hepático e renal, além dos níveis séricos de selênio. Em relação ao estresse oxidativo, foram determinados os níveis de 2',7'-diclorofluoresceína (DCF), nitritos, tióis totais, grupamentos carbonila, malondialdeído (MDA), glutationa (GSH), glutationa peroxidase (GPx) e catalase (CAT). O ensaio cometa nas versões alcalina e modificada com o uso de formamidopirimidina glicosilase foi utilizado para análise dos danos basal e oxidativo ao DNA, respectivamente. O teste de micronúcleo em células esfoliadas da mucosa bucal foi utilizado para caracterização dos tipos celulares, anormalidades nucleares e presença de dano nuclear. As análises estatísticas foram feitas usando os testes t pareado ou de Wilcoxon e, correlação Spearman. Ao analisar os parâmetros bioquímicos, foram observados aumento dos níveis de glicemia de jejum, colesterol HDL e LDL e gama-glutamiltransferase. Os níveis de insulina e a relação triglicerídeos/HDL-colesterol foram diminuídos. O consumo de castanha-do-Brasil durante seis meses foi capaz de aumentar significativamente os níveis de selênio, GSH, GPx e CAT, sugerindo uma melhora do sistema antioxidante dos pacientes. Em relação à produção de oxidantes, os níveis de DCF e nitritos foram diminuídos. Observou-se um aumento dos níveis de tióis totais e diminuição do conteúdo de grupamentos carbonila e níveis de MDA, sugerindo uma redução na oxidação de proteínas e lipídios. Quanto à instabilidade genômica, os 16 danos ao DNA, avaliados através do ensaio cometa foram significativamente diminuídos, assim como a frequência de micronúcleos e brotos nucleares também. Os testes estatísticos revelaram que os níveis de selênio foram negativamente associados aos níveis de MDA, danos ao DNA e frequência de micronúcleos. Por outro lado, houve uma associação positiva entre os níveis de selênio e tióis totais, GSH, GPx e CAT. Os resultados do presente trabalho sugerem que a ingestão diária de castanha-do-Brasil pode ser uma aliada na modulação da instabilidade genômica em indivíduos com DM2, provavelmente através de mudanças no estado redox celular.
Type 2 diabetes mellitus (T2DM) is a metabolic disease, occurring largely due to environmental and lifestyle changes. Chronic conditions of hyperglycaemia, hyperlipidaemia and hyperinsulinemia can lead to oxidative stress, and consequently damage to lipids, proteins and DNA. Dietary interventions are considered essential for the treatment and prevention of T2DM-related complications. Brazil nuts (Bertholletia excelsa, H.B.K.) are the richest source of selenium known in nature. The adequate selenium status presents several health benefits, including improve of redox cellular status and maintenance of genomic stability. Based on this, the aim of this study was to assess biochemical and oxidative stress parameters and genomic instability in T2DM patients before and after 6-month consumption of selenium through Brazil nut. Thirty-seven men and thirty-seven women with T2DM were included. Participants consumed 1 Brazil nut a day (»210 µg of selenium) for 6 months. Samples of blood and exfoliated buccal cells (EBC) were collected at the beginning and at the end of treatment. The glycaemic, lipidic, inflammatory, hepatic and renal serum profiles were analyzed. In relation to oxidative stress, the levels of 2',7'-dichlorofluorescein (DCF), nitrites, total thiols, protein carbonyl, malondialdehyde (MDA), glutathione (GSH), gluthatione peroxidase (GPx) and catalase (CAT) were determined. The alkaline version of the comet assay was the method selected to measure basal DNA damage. In order to measure oxidative DNA damage, the comet assay was coupled with a lesion-specific endonuclease (formamidopyrimidine glycosylase) to detect oxidized purines. The EBC were evaluated for the characterization of cell types (basal and differentiated) and nuclear abnormalities (binucleated cells, pyknosis, karyolysis, karyorrhexis, condensed chromatin) and the presence of cellular damage (micronuclei and nuclear buds). Finally, selenium levels were quantified in serum of participants. The data were processed and statistically analyzed using paired t test or Wilcoxon test and Spearman correlation. The data relative to biochemical parameters presents an increased in fasting glucose levels, HDL- and LDLcholesterol and gama glutamyl transferase levels. Insulin levels and triglycerides/HDL-cholesterol ratio were decreased. Six-month Brazil nut consumption proved to be enough to significantly increase selenium and GSH levels, GPx and CAT activity, improving the antioxidant system of patients. In relation to oxidant production, DCF and nitrites levels were decreased. Besides, were observed an increase in total thiols, and a decrease in protein carbonyl and MDA levels, suggesting a reduction of proteins and lipids oxidized. Relative to genomic instability, the levels of basal and oxidative DNA damage in T2DM were significantly decreased after Brazil nut consumption, as well as the frequency of micronuclei and nuclear buds. The statistic tests revealed that selenium levels were negatively associated with MDA, basal and oxidative DNA damage and micronuclei frequency. On the other hand, there was a positive association between selenium levels and total thiois, GSH, GPx and CAT. Taken together, the results of the present work indicate that Brazil nut consumption could be an ally to module the genomic instability in T2DM patients, probably through changes in oxidative status.
Type 2 diabetes mellitus (T2DM) is a metabolic disease, occurring largely due to environmental and lifestyle changes. Chronic conditions of hyperglycaemia, hyperlipidaemia and hyperinsulinemia can lead to oxidative stress, and consequently damage to lipids, proteins and DNA. Dietary interventions are considered essential for the treatment and prevention of T2DM-related complications. Brazil nuts (Bertholletia excelsa, H.B.K.) are the richest source of selenium known in nature. The adequate selenium status presents several health benefits, including improve of redox cellular status and maintenance of genomic stability. Based on this, the aim of this study was to assess biochemical and oxidative stress parameters and genomic instability in T2DM patients before and after 6-month consumption of selenium through Brazil nut. Thirty-seven men and thirty-seven women with T2DM were included. Participants consumed 1 Brazil nut a day (»210 µg of selenium) for 6 months. Samples of blood and exfoliated buccal cells (EBC) were collected at the beginning and at the end of treatment. The glycaemic, lipidic, inflammatory, hepatic and renal serum profiles were analyzed. In relation to oxidative stress, the levels of 2',7'-dichlorofluorescein (DCF), nitrites, total thiols, protein carbonyl, malondialdehyde (MDA), glutathione (GSH), gluthatione peroxidase (GPx) and catalase (CAT) were determined. The alkaline version of the comet assay was the method selected to measure basal DNA damage. In order to measure oxidative DNA damage, the comet assay was coupled with a lesion-specific endonuclease (formamidopyrimidine glycosylase) to detect oxidized purines. The EBC were evaluated for the characterization of cell types (basal and differentiated) and nuclear abnormalities (binucleated cells, pyknosis, karyolysis, karyorrhexis, condensed chromatin) and the presence of cellular damage (micronuclei and nuclear buds). Finally, selenium levels were quantified in serum of participants. The data were processed and statistically analyzed using paired t test or Wilcoxon test and Spearman correlation. The data relative to biochemical parameters presents an increased in fasting glucose levels, HDL- and LDLcholesterol and gama glutamyl transferase levels. Insulin levels and triglycerides/HDL-cholesterol ratio were decreased. Six-month Brazil nut consumption proved to be enough to significantly increase selenium and GSH levels, GPx and CAT activity, improving the antioxidant system of patients. In relation to oxidant production, DCF and nitrites levels were decreased. Besides, were observed an increase in total thiols, and a decrease in protein carbonyl and MDA levels, suggesting a reduction of proteins and lipids oxidized. Relative to genomic instability, the levels of basal and oxidative DNA damage in T2DM were significantly decreased after Brazil nut consumption, as well as the frequency of micronuclei and nuclear buds. The statistic tests revealed that selenium levels were negatively associated with MDA, basal and oxidative DNA damage and micronuclei frequency. On the other hand, there was a positive association between selenium levels and total thiois, GSH, GPx and CAT. Taken together, the results of the present work indicate that Brazil nut consumption could be an ally to module the genomic instability in T2DM patients, probably through changes in oxidative status.
Description
Tese de doutoramento apresentada em Ciências da Saúde, apresentada à Universidade do Extremo Sul Catarinense, 2017
Keywords
Stress Oxidativo Diabetes mellitus tipo 2 Castanha-do-Brasil Selênio Instabilidade Genômica Ensaio Cometa Brazilian Nut Selenium Type 2 Diabetes mellitus Oxidative Stress Genomic Instability Comet Assay Genotoxicidade Ambiental