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Abstract(s)
O aumento da esperança média de vida e do número de casos de pessoas com doenças neurodegenerativas e neuropsiquiátricas tem levado a que haja uma intensificação da preocupação mundial na investigação das causas e dos possíveis tratamentos para doenças como a doença do Alzheimer (DA), a doença de Parkinson (DP) ou de doenças neuropsiquiátricas, como a depressão, de modo a melhorar o nível de vida da população afetada. As algas marinhas como a Undaria pinnatifida (Harvey) Suringar têm sido alvo de vários estudos de investigação devido à presença de compostos naturais com capacidade neuroprotetora contra doenças neurodegenerativas. Assim sendo, o objetivo deste estudo foi testar a bioatividade de extratos da alga marinha U. pinnatifida, recorrendo a ensaios in vitro e in vivo, para determinar as suas propriedades antioxidantes e a sua capacidade de inibição de enzimas do sistema nervoso central (SNC), de modo a avaliar a sua influência no tratamento e prevenção de doenças neurodegenerativas como DA, DP ou de doenças neuropsiquiátricas, como a depressão. As análises in vivo foram realizadas após os ensaios in vitro, de modo a estudar a influência dos extratos no desenvolvimento embrionário dos peixes zebra. Os extratos foram obtidos através da extração assistida por microondas (MAE) após otimização dos parâmetros de extração. Esta otimização foi realizada com base em várias extrações convencionais realizadas com diferentes condições de extração. Como principais resultados in vitro, verificou-se que o extrato de U. pinnatifida, obtido pela extração MAE com a mistura de solventes água: etanol (50:50 v/v) a 40 °C durante 30 min e com uma razão sólido solvente de 1:40 (g:mL), com TPC = 7,39 ± 1,33 mg GAE/g extrato seco, clorofila a = 0,90 ± 0,13 mg/g extrato seco, clorofila c = 0,21 ± 0,040 mg/ g extrato seco, clorofilas totais = 1,21 ± 0,19 mg/g extrato seco e carotenoides = 0,26 ± 0,044 mg/ g extrato seco, apresentou atividade antioxidante em termos de sequestro dos radicais DPPH• , ABTS•+ , •NO, O2 •- e •OH com percentagens de sequestro máxima respetivamente, de 59,4 ± 3,5 % (2,78 mg/mL), 93,7 ± 2,4 % (5,0 mg/mL), 57,5 ± 1,5 % (2,0 mg/mL), 34,4 ± 0,11 % (2,0 mg/mL) e 39,2 ± 0,95 % (4,0 mg/mL). Em termos da inibição das enzimas do SNC, o extrato apresentou baixa capacidade de inibição enzimática, sendo que para a enzima acetilcolinesterase (AChE) apresentou uma inibição máxima de 33,3 ± 6,3 % (4,0 mg/mL), em relação à butirilcolinesterase (BuChE) uma inibição de 33,0 ± 3,3 % (4,0 mg/mL) e por fim em relação à tirosinase apresentou uma inibição de 55,5 ± 2,3 % (4,0 mg/mL). Os resultados in vivo relativos à avaliação do desenvolvimento do peixe-zebra exposto ao mesmo extrato de U. pinnatifida, revelaram que o mesmo não apresentou efeitos negativos significativos nas taxas de eclosão dos embriões expostos. No entanto, para as mesmas concentrações testadas, observou-se uma diminuição no comprimento total das larvas eclodidas com valores significativos para as concentrações de extrato mais altas 10×103 (6,2 %), 50×103 (5,4 %) e 100×103 (5,7 %) µg/L. Para além disso, a concentração de extrato mais alta (100×103 µg/L) foi também responsável pelo aparecimento significativo de malformações a nível dos olhos, pigmentação e a nível da posição lateral da larva às 96 hpf. No futuro seria interessante avaliar também a bioatividade dos extratos de U. pinnatifida nos peixe-zebra para determinar se os resultados são semelhantes ou melhores do que os obtidos in vitro. No entanto, caso se mantivessem os valores de IC50 observados nos ensaios in vitro poderia existir toxicidade, pois teriam de ser usadas concentrações mais elevadas do que 100×103 µg/L. Concluiu-se que o extrato de U. pinnatifida utilizado apresentou moderada atividade antioxidante e inibitória da tirosinase em ensaios in vitro, podendo apresentar efeitos benéficos moderados no tratamento da DA e DP. No entanto, estudos in vivo serão cruciais para averiguar as potencialidades deste extrato.
The increase in the average life expectancy and the number of cases of people with neurodegenerative and neuropsychiatric diseases has led to an intensification of worldwide concern in researching the causes and possible treatments for diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) or neuropsychiatric diseases such as depression, to improve the standard of living of the affected population. Seaweeds such as Undaria pinnatifida (Harvey) Suringar have been the subject of several research studies due to the presence of natural compounds with neuroprotective ability against neurodegenerative diseases. Therefore, the aim of this study was to test the bioactivity of U. pinnatifida seaweed extracts, using in vitro and in vivo assays, to determine their antioxidant properties and their ability to inhibit central nervous system (CNS) enzymes, in order to evaluate their influence in the treatment and prevention of neurodegenerative diseases such as AD, PD or neuropsychiatric diseases such as depression. In vivo analyses were performed after the in vitro assays, to study the influence of the extracts on the embryonic development of zebrafish. The extracts were obtained by microwave assisted extraction (MAE) after optimization of the extraction parameters. This optimization was performed based on several conventional extractions carried out with different extraction conditions. For in vitro studies, it was found that the extract of U. pinnatifida, obtained by MAE extraction with the solvent mixture water: ethanol (50:50 v/v) at 40 °C for 30 min and with a solid/solvent ratio of 1:40 (g: mL), with TPC = 7.39 ± 1.33 mg GAE/g dry extract, chlorophyll a = 0.90 ± 0.13 mg/g dry extract, chlorophyll c = 0.21 ± 0.040 mg/ g dry extract, total chlorophyll = 1.21 ± 0.19 mg/g dry extract and carotenoids = 0.26 ± 0.044 mg/ g dry extract, showed antioxidant activity in terms of scavenging of the DPPH• , ABTS•+ , •NO, O2 •- and •OH radicals with a maximum scavenging percentage, respectively of, 59.4 ± 3.5 % (2.78 mg/mL), 93.7 ± 2.4 % (5.0 mg/mL), 57.5 ± 1.5 % (2.0 mg/mL), 34.4 ± 0.11 % (2.0 mg/mL) and 39.2 ± 0.95 % (4.0 mg/mL),. In terms of CNS enzymes inhibition, the extract showed low enzyme inhibition capacity, and for the enzyme acetylcholinesterase (AChE) it showed a maximum inhibition of 33.3 ± 6.3 % (4.0 mg/mL), for butyrylcholinesterase (BuChE) a maximum inhibition of 33.0 ± 3.3 % (4.0 mg/mL) and finally for tyrosinase a maximum inhibition of 55.5 ± 2.3 % (4.0 mg/mL The in vivo results concerning the evaluation of the development of zebra fish exposed to the same U. pinnatifida extract, revealed that it did not show significant negative effects on the hatching rates of the exposed embryos. However, for the same concentrations tested, a decrease in the total length of hatched larvae was observed with significant values for the highest extract concentrations 10×103 (6.2 %), 50×103 (5.4 %) and 100×103 (5.7 %) µg/L. Furthermore, the highest extract concentration (100×103 µg/L) was also responsible for the significant appearance of eye, pigmentation, and lateral position malformations of the larvae at 96 hpf. In the future, it would be interesting to evaluate the bioactivity of the U. pinnatifida extracts in zebrafish and compare it to in vitro studies, however, considering the in vitro IC50 values, toxicity could exist, since for the existence of bioactivity (IC50) higher concentrations would have to be used than those that proved to cause toxicity in zebrafish. In conclusion, this study demonstrated that U. pinnatifida extract showed moderate antioxidant and tyrosinase inhibitory activity, and may present moderate beneficial effects in the treatment of AD and PD. However, in vivo studies will be crucial to ascertain the potentialities of this extract.
The increase in the average life expectancy and the number of cases of people with neurodegenerative and neuropsychiatric diseases has led to an intensification of worldwide concern in researching the causes and possible treatments for diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) or neuropsychiatric diseases such as depression, to improve the standard of living of the affected population. Seaweeds such as Undaria pinnatifida (Harvey) Suringar have been the subject of several research studies due to the presence of natural compounds with neuroprotective ability against neurodegenerative diseases. Therefore, the aim of this study was to test the bioactivity of U. pinnatifida seaweed extracts, using in vitro and in vivo assays, to determine their antioxidant properties and their ability to inhibit central nervous system (CNS) enzymes, in order to evaluate their influence in the treatment and prevention of neurodegenerative diseases such as AD, PD or neuropsychiatric diseases such as depression. In vivo analyses were performed after the in vitro assays, to study the influence of the extracts on the embryonic development of zebrafish. The extracts were obtained by microwave assisted extraction (MAE) after optimization of the extraction parameters. This optimization was performed based on several conventional extractions carried out with different extraction conditions. For in vitro studies, it was found that the extract of U. pinnatifida, obtained by MAE extraction with the solvent mixture water: ethanol (50:50 v/v) at 40 °C for 30 min and with a solid/solvent ratio of 1:40 (g: mL), with TPC = 7.39 ± 1.33 mg GAE/g dry extract, chlorophyll a = 0.90 ± 0.13 mg/g dry extract, chlorophyll c = 0.21 ± 0.040 mg/ g dry extract, total chlorophyll = 1.21 ± 0.19 mg/g dry extract and carotenoids = 0.26 ± 0.044 mg/ g dry extract, showed antioxidant activity in terms of scavenging of the DPPH• , ABTS•+ , •NO, O2 •- and •OH radicals with a maximum scavenging percentage, respectively of, 59.4 ± 3.5 % (2.78 mg/mL), 93.7 ± 2.4 % (5.0 mg/mL), 57.5 ± 1.5 % (2.0 mg/mL), 34.4 ± 0.11 % (2.0 mg/mL) and 39.2 ± 0.95 % (4.0 mg/mL),. In terms of CNS enzymes inhibition, the extract showed low enzyme inhibition capacity, and for the enzyme acetylcholinesterase (AChE) it showed a maximum inhibition of 33.3 ± 6.3 % (4.0 mg/mL), for butyrylcholinesterase (BuChE) a maximum inhibition of 33.0 ± 3.3 % (4.0 mg/mL) and finally for tyrosinase a maximum inhibition of 55.5 ± 2.3 % (4.0 mg/mL The in vivo results concerning the evaluation of the development of zebra fish exposed to the same U. pinnatifida extract, revealed that it did not show significant negative effects on the hatching rates of the exposed embryos. However, for the same concentrations tested, a decrease in the total length of hatched larvae was observed with significant values for the highest extract concentrations 10×103 (6.2 %), 50×103 (5.4 %) and 100×103 (5.7 %) µg/L. Furthermore, the highest extract concentration (100×103 µg/L) was also responsible for the significant appearance of eye, pigmentation, and lateral position malformations of the larvae at 96 hpf. In the future, it would be interesting to evaluate the bioactivity of the U. pinnatifida extracts in zebrafish and compare it to in vitro studies, however, considering the in vitro IC50 values, toxicity could exist, since for the existence of bioactivity (IC50) higher concentrations would have to be used than those that proved to cause toxicity in zebrafish. In conclusion, this study demonstrated that U. pinnatifida extract showed moderate antioxidant and tyrosinase inhibitory activity, and may present moderate beneficial effects in the treatment of AD and PD. However, in vivo studies will be crucial to ascertain the potentialities of this extract.
Description
Keywords
Doenças neurodegenerativas Neuroinflamação Stress oxidativo U. pinnatifida Propriedades antioxidantes e neuroprotetoras Peixe-zebra Neurodegenerative diseases Neuroinflammation Oxidative stress Antioxidant and neuroprotective properties Zebrafish