Estudos metabolômicos e biossintéticos visando contribuições para a química e taxonomia de microorganismos da família Xylariaceae

• Ano de defesa: 2014
• Autor(a) principal: Amaral, Luciana da Silva
• 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; Fungo endofítico; Citocalasinas; Biossíntese; Química microbiana
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufscar.br/handle/ufscar/6331

The PhD work aimed the exploration of fungal metabolism of NICL3 and NICL5, both initially identified as Xylaria sp., isolated as endophytic fungi from Cupressus lusitanica. The investigation of the NICL3 metabolism allowed the isolation and identification of new compounds, one unpublished eremophilane sesquiterpene and a mixture of two cyclic peptides. In addition, from NICL5 were isolated cytochalasins C, D, Q, 18- desoxy cytochalasin Q and trichodepsipeptide. The production of this depsipeptide by NICL5 is very relevant, since there is only one paper in the literature that reports the production of this class of compounf by fungi belonging to Xylaria genus. Another aspect applied in this work was the use of OSMAC approach, through supplementation of different nitrogen sources in the culture medium of NICL5, to obtain new cytochalasins. However, only the administration of NH4Br was promising since it allowed the isolation of 4- hydroxymethyl cytochalasin C a new metabolite. The secondary metabolism NICL5 is strongly guided to the production of cytochalasins C, D and Q, independently of the nitrogen source administered in the culture medium, suggesting that the microorganism is able to perform de novo biosynthesis. Mass spectrometry studies demonstrated that administration of Na15NO3, 15NH4Cl and 15N-glycine led to incorporation of labeled nitrogen into cytochalasin D. Supplementation of the culture medium with 2-13C glycine showed the incorporation of labeled carbon in positions in which the enzyme S-adenosyl methionine is responsible for introducing two methyl groups and one methylene. However, genomic and proteomic studies are essential to prove this process. The NICL5 fungus has an interesting enzymatic potential because it was able to promote reductions of carboxylic acid into alcohol and performs the incorporation of GABA and glucose to the substrate core, when the substrate was p-bromo benzoic acid. This enzymatic potencial appears to be closely related to the eletronic nature of the substrate, since similar reaction occurred with p-cloro benzoic acid and bioreduction occurred also with p-nitro benzoic acid. A collection of fungi belonging to Xylariaceae family, which were identified according to molecular techniques was created. Interestingly NICL3 was classified as Nemania aff. primolutea and NICL5 as Xylaria aff. arbuscula. The identification techniques based on molecular biology, biomarkers profile by MALDI-TOF and metabolic profile by high resolution mass spectrometry of all members of the collection were confronted, and it was verified a good level of agreement between three different techniques.