Descoberta de novos produtos naturais de cianobactérias com bioatividade

Dissertação de mestrado em Genética MolecularO cancro e a resistência antimicrobiana são dois dos principais problemas de saúde na sociedade atual, sendo por isso imprescindível a procura de novos tratamentos mais eficazes nestas áreas terapêuticas. Os produtos naturais têm sido um importante recurso para obtenção de compostos com atividade biológica, incluindo compostos com propriedades anticancerígenas e antimicrobianas. Neste contexto, as cianobactérias têm demonstrado uma elevada taxa de descoberta de novos produtos naturais, alguns dos quais com relevante atividade farmacológica. Este trabalho foi realizado no CIIMAR, em Matosinhos, Portugal, especificamente no grupo de investigação CNP. Diferentes metodologias foram aplicadas para encontrar novos compostos produzidos por cianobactérias com atividade biológica. A atividade citotóxica e antimicrobiana foi avaliada por métodos de referência. No primeiro capítulo uma nova estratégia para a descoberta de produtos naturais produzidos por cianobactérias, desenvolvida recentemente no CNP, foi usada em seis estirpes de cianobactérias. Adicionalmente, três novos compostos previamente descobertos no laboratório, os nocuolactilatos A, B e C, foram avaliados quanto à sua atividade citotóxica e antimicrobiana. Os nocuolactiliatos A e B demonstraram ter atividade citotóxica em 5 linhas celulares (valores de GR50 entre 1,73 e 5,90 µM) e adicionalmente o nocuolactilato A revelou ter atividade contra Bacillus subtilis (halo difuso com 8 mm). No segundo capítulo uma amostra ambiental foi fracionada e as frações resultantes foram avaliadas quanto à sua atividade citotóxica e antimicrobiana. Posteriormente, as frações bioativas escolhidas foram novamente fracionadas e duas vias distintas foram seguidas de forma a isolar os compostos responsáveis pela atividade citotóxica e antimicrobiana. Vários fracionamentos se seguiram até que um composto quase puro foi obtido.Cancer and antimicrobial resistance are two of the main health problems in today's society, which is why it is essential to seek new and more effective treatments in these therapeutic areas. Natural products have been an important resource for obtaining compounds with biological activity, including compounds with anti-cancer and anti-microbial properties. In this context, cyanobacteria have shown a high rate of discovery of new natural products, some of which have relevant pharmacological activity. This work was carried out at the Interdisciplinary Center for Marine and Environmental Research (CIIMAR), Matosinhos, Portugal, specifically in the research group Cyanobacterial Natural Products (CNP). Different methodologies were applied to find new compounds produced by cyanobacteria with biological activity. Cytotoxic and antimicrobial activity was evaluated by reference methods. In the first chapter, a new strategy for the discovery of natural products produced by cyanobacteria, recently developed at CNP, was used in six strains of cyanobacteria. In addition, three new compounds previously discovered in the laboratory, nocuolactylates A, B and C, were evaluated for their cytotoxic and antimicrobial activity. Nocuolactylates A and B have been shown to have cytotoxic activity against 5 cell lines (Half Maximal Growth Rate Inhibition (GR50) values between 1.73 and 5.90 µM) and in addition nocuolactylate A has been shown to have activity against Bacillus subtilis (diffuse halo with 8 mm).In the second chapter, an environmental sample was fractionated by Vacuum Liquid Chromatography (VLC) and the resulting fractions were evaluated for their cytotoxic and antimicrobial activity. Subsequently, the chosen bioactive fractions were fractionated by Flash Chromatography (FC) and two distinct pathways were followed in order to isolate the compounds responsible for cytotoxic and antimicrobial activity. Several High Pressure Liquid Chromatography (HPLC) fractionations followed until an almost pure compound was obtained.This work was also supported by the HALVERSITY project (PTDC/BIA-BQM/29710/2017) which is co-financed by COMPETE 2020, PORTUGAL 2020, European Union through European Regional Development Fund (ERDF) and Science and Technology Foundation (FCT). Part of the work was also included in the ERC funded project FattyCyanosThis work was integrated in the Blue Young Talent (BYT) program, namely BYT Plus, at Interdisciplinary Center of Marine and Environmental Research (CIIMAR) which is a program for the realization of the master’s dissertation in this institute. For that, I would also like to thank CIIMAR, where the work that led to this dissertation was conducted, the BYT program that allowed for this to be possible, to Dr. Sandra, Dr. Pedro and Dr. Ralph (my supervisors in this program) and to Fundação Amadeu Dias for the financial support