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Pesquisa de atividade de lectina e compostos fenólicos no fruto do Kiwi (Actinidia deliciosa var. Hayward)
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Resumo(s)
O fruto do kiwi é conhecido mundialmente pelos seus efeitos benéficos para a saúde digestiva, mas e, se apresentar outras bioatividades que possam contribuir para nosso benefício? Este trabalho teve como objetivo caracterizar a bioatividade de lectina e dos compostos fenólicos do fruto do kiwi, explorando e identificando os compostos fenólicos presentes com avaliação da sua atividade antioxidante, assim como o perfil polipeptídico e a atividade de lectina deste fruto, informação não descrita na literatura, associando à atividade antitumoral.
Obtivemos 193 ± 4,07 mg de equivalentes de ácido gálico/ 100 g de fruto fresco de fenóis totais e 47,7 ± 0,98 mg de equivalentes de catequina/ 100 g de fruto fresco de flavonoides totais no extrato de kiwi. O método do cromatografia líquida de elevada eficiência acopolado a um detetor de díodos e a espectrometria de massa identificou alguns compostos fenólicos presentes no extrato de kiwi. A atividade antioxidante foi determinada pelo método do radical 2,2-difenil1-picril-hidrazil (DPPH) e este apresentou 89,65 %, algo espectável tendo em conta a bibliografia.
Para a componente proteica, identificamos 2 glicoproteínas de aproximadamente de 31 e 48 kDa no perfil polipeptídico do extrato. Exploramos a atividade de lectina (unidade hemaglutinante = 15,6 µg) e a especificidade das lectinas presentes aos hidratos de carbono, com uma elevada especificidade ao ácido siálico (concentração mínima inibitória = 1,56 mM). A partir destes resultados decidimos purificar as lectinas específicas ao ácido siálico por
cromatografia de afinidade com purificação de alguns polipéptidos. O ácido siálico é o principal metastizador nas células tumorais. Foi ainda demonstrada a ligação de vários polipéptidos, pertencentes ao extrato total, aos epítopos glicosilados de membranas de 2 linhagens celulares tumorais: adenocarcinoma colorretal humano (HT-29) e do adenocarcinoma ductal pancreático humano (MIA PaCa-2), sendo alguns destes específicos ao ácido siálico.
Os resultados sugerem que as bioatividades estudadas no fruto do kiwi poderão ser benéficas para a promoção da saúde pública, especialmente devido ao papel na prevenção do cancro e na evasão metástica através do mecanismo de morte celular promovido pelas lectinas.
Kiwifruit is known worldwide for its beneficial effects on digestive health, but what if this fruit has other bioactivities that could contribute to our benefit? The aim of this study was to characterize lectin and phenolic compounds bioactivities from kiwifruit, exploring and identifying the phenolic compounds present and their antioxidant activity, as well as the polypeptide profile and lectin activity, information which has not been published yet in literature, associating with antitumor activity. Total phenolic content of 193 ± 4,07 mg gallic acid equivalents/ 100 g fresh fruit and total flavonoid content of 47,7 ± 0,98 mg catechin equivalents/ 100 g fresh fruit were obtained from kiwifruit extract. The high-performance liquid chromatography coupled with a diode array detector and mass spectrometry identified some phenolic compounds present in kiwifruit extract. The antioxidant activity was determined by DPPH method and showed 89.65 %, which is to be expected based on the literature. For the protein component, two glycoproteins of approximately 31 and 48 kDa were identified in the polypeptide profile of kiwifruit protein extract. The lectin activity (hemagglutination unit = 15.6 µg) and the glycan specificity of the lectins present were explored, highlighting the high specificity to sialic acid (minimum inhibitory concentration = 1.56 mM). Based on these results, it was decided to purify the sialic acid specific lectins by affinity chromatography, with the purification of some polypeptides. Sialic acide is the main metastatic agent in tumour cells. In addition, several polypeptides belonging to the total extract were shown to bind to glycosylated epitopes on the membranes of two tumour cell lines: human colorectal adenocarcinoma (HT-29) and human pancreatic ductal adenocarcinoma (MIA PaCa-2), some of which were specific to sialic acid. The results suggest that the studied bioacitivies present in kiwifruit could be beneficial for promoting public health, especially due to their role in cancer prevention and metastatic evasion through the cell death mechanism promoted by lectins.
Kiwifruit is known worldwide for its beneficial effects on digestive health, but what if this fruit has other bioactivities that could contribute to our benefit? The aim of this study was to characterize lectin and phenolic compounds bioactivities from kiwifruit, exploring and identifying the phenolic compounds present and their antioxidant activity, as well as the polypeptide profile and lectin activity, information which has not been published yet in literature, associating with antitumor activity. Total phenolic content of 193 ± 4,07 mg gallic acid equivalents/ 100 g fresh fruit and total flavonoid content of 47,7 ± 0,98 mg catechin equivalents/ 100 g fresh fruit were obtained from kiwifruit extract. The high-performance liquid chromatography coupled with a diode array detector and mass spectrometry identified some phenolic compounds present in kiwifruit extract. The antioxidant activity was determined by DPPH method and showed 89.65 %, which is to be expected based on the literature. For the protein component, two glycoproteins of approximately 31 and 48 kDa were identified in the polypeptide profile of kiwifruit protein extract. The lectin activity (hemagglutination unit = 15.6 µg) and the glycan specificity of the lectins present were explored, highlighting the high specificity to sialic acid (minimum inhibitory concentration = 1.56 mM). Based on these results, it was decided to purify the sialic acid specific lectins by affinity chromatography, with the purification of some polypeptides. Sialic acide is the main metastatic agent in tumour cells. In addition, several polypeptides belonging to the total extract were shown to bind to glycosylated epitopes on the membranes of two tumour cell lines: human colorectal adenocarcinoma (HT-29) and human pancreatic ductal adenocarcinoma (MIA PaCa-2), some of which were specific to sialic acid. The results suggest that the studied bioacitivies present in kiwifruit could be beneficial for promoting public health, especially due to their role in cancer prevention and metastatic evasion through the cell death mechanism promoted by lectins.
Descrição
Tese de mestrado, Qualidade Alimentar e Saúde, 2024, Universidade de Lisboa, Faculdade de Farmácia.
Palavras-chave
Actinidia deliciosa var. Hayward Kiwi Bioatividades Compostos fenólicos Lectinas Teses de mestrado - 2024