Prospecção química do metabolismo de fungos endofíticos isolados de maçã (Malus domestica) e goiaba (Psidium guajava)

• Ano de defesa: 2014
• Autor(a) principal: Medeiros, Lívia Soman de
• Orientador(a): Rodrigues Filho, Edson
• Tipo de documento: Tese
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Federal de São Carlos
• Programa de Pós-Graduação: Programa de Pós-Graduação em Química - PPGQ
• País: BR
• Palavras-chave em Português: Química; Metabólitos secundários; Microorganismos; Frutas; Derreplicação
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/6330

Few studies are targeted concerning the chemistry of the secondary metabolism from endophytic fungi associated to edible fruits. In this sense, it is worth to explore the the microbial metabolic skills, particularly from the fungi species naturally present in this host, since a plethora of compounds from different biossintetic groups with diverse bioactivities may have been directly introduced to human diet. Therefore, the aim of the work encompassed the chemical and metabolic investigation of the fungus isolated from sympthomless apple fruits, the specie Talaromyces rugulosus, as well as the fungus Setophoma sp. isolated from healthy guava fruits. The study was based on the chemical prospecting of the fungal metabolism by means of OSMAC approach. In this step, besides the screening of known metabolites, the investigation was carried out in order to encounter new natural products biossintetized by the studied strains. Aiming to reach a fast and effective dectection, the UHPLC-HRMS based dereplication combined to dedicated database queries was extensively applied. The use of these integrated approaches allowed the establishment of a broad chemical profile owned to each microorganism and has led to the identification of seven new depsides produced by Setophoma sp. and novel halogenated alkaloids by T. rugulosus through spectroscopic data, chiefly NMR and HRMS-MS. In addition to these results, the induction of known perilenequinones produced by Setophoma sp. strain was observed when it was submitted to the co-cultive with other fungi species. Some of the novel poliketides showed moderate antimicrobial activity against S.aureus, while the perilenequinones comprised a seeming inhibition of some tested Penicillium species. Concerning T. rugulosus, it was also verified if the fungus showed to be skillfull in biotransformations of compounds naturally owned to apples chemical composition, such as flavonoids and organic acids. Whereas any product from this proposal was detected, a remarkable production of multicolanic acid was observed by the use of the tested substrates into the culture medium, suggesting a likely marker for this specie. Finally, taking into account the fact that fruits represent a rich source of nutrients for its associated microbial inhabitants, it is worth to consider that secondary metabolites biosynthesis in loco be favoured. Therefore it was proposed the monitoring of the most common metabolites produced by T. rugulosus into commercial apple extracts. The detection study was carried out by UHPLC-MS/MS via dynamic MRM experiments, which allowed the detection of compounds potentially produced by the fungus in the evaluated apple extracts.