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Doctoral Thesis
DOI
https://doi.org/10.11606/T.75.2023.tde-28072023-110212
Document
Author
Full name
Darlon Irineu Bernardi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2023
Supervisor
Committee
Cavalheiro, Eder Tadeu Gomes (President)
Chagas, Fernanda Oliveira das
Curvelo, Antonio Aprigio da Silva
Sarragiotto, Maria Helena
Silva, Maria Fatima das Graças Fernandes da
Title in Portuguese
Metabólitos secundários bioativos produzidos por fungos filamentosos de ambientes extremos
Keywords in Portuguese
desreplicação
fungos filamentosos
peptídeos
produtos naturais
química orgânica
Abstract in Portuguese
A diversidade de metabólitos secundários bioativos produzida por microrganismos em meio de cultura é expressiva. Porém ao longo das últimas décadas a investigação de metabólitos secundários hidrossolúveis, bem como o estudo de linhagens microbianas provenientes de ambientes pouco convencionais tem sido abandonado. Este trabalho objetivou a investigação das condições de cultivo de fungos endofíticos e isolados de solo, evidenciando condições ótimas para o crescimento e produção metabólica. Subsequentemente, foi realizado o screening biológico e químico de frações oriundas de extratos de meio de cultivo de linhagens selecionadas, bem como o isolamento de metabólitos bioativos hidrossolúveis e lipofílicos produzidos por estas linhagens. Duas linhagens de fungos filamentosos foram cultivadas em escala ampliada de crescimento: um fungo endofítico isolado da planta Anthurium alcatrazense, que foi classificada como Byssochlamys spectabilis Aa1 e produziu dois novos metabólitos secundários, a dicetopiperazina ciclo-(D-Trp-L-Glu) e o derivado peptídico formil-L-triptofil-L-alanina, além do composto conhecido N-acetil-quinurenina, que teve seus dados de RMN e configuração absoluta estabelecidos como a (S)-N-acetil-quinurenina. Os compostos ciclo-(D-Trp-L-Glu) e (S)-N-acetil-quinurenina foram avaliados frente células OVCAR-3 e apresentaram IC50 de 1,120 e 1,073 µM, respectivamente. A partir do meio de cultura do fungo Aspergillus sp. SDC28 isolado do solo de caverna foi possível isolar dois compostos lipofílicos, a versicolorina C e o versiconol. Seus potenciais anticancerígenos frente células OVCAR3 também foram determinados com IC50 de 0,24 e 1,07 µM, respectivamente. Estes compostos tiveram suas configurações absolutas determinadas. A fim de se conhecer o poder de seletividade da mistura de resinas XAD-2,-4,-7 na adsorção de metabólitos hidrossolúveis, o metabólito secundário solitumina A produzido pela linhagem fúngica Penicillium solitum IS1-A foi utilizado de maneira que sua captura através das resinas adsortivas pudesse evidenciar com qual resina sua estrutura química teria maior afinidade.
Title in English
Bioactive secondary metabolites produced by filamentous fungi from extreme environments
Keywords in English
dereplication
filamentous fungi
natural products
organic chemistry
peptides
Abstract in English
The diversity of secondary bioactive metabolites produced by microorganisms in culture medium is expressive. However, over the last few decades, the investigation of water-soluble secondary metabolites, as well as the study of microbial strains from unconventional environments, has been abandoned. This work aimed to investigate the cultivation conditions of endophytic fungi and soil isolates, showing optimal conditions for growth and metabolic production. Subsequently, biological and chemical screening of fractions from extracts obtained from the culture medium of selected strains was carried out, as well as the isolation of water-soluble and lipophilic bioactive metabolites produced by these strains. Two strains of filamentous fungi were cultivated on a larger scale: an endophytic fungus isolated from the plant Anthurium alcatrazense, classified as Byssochlamys spectabilis Aa1 and produced two new secondary metabolites, the diketopiperazine cyclo-(D-Trp-L-Glu) and the peptide derivative formyl-L-tryptophyl-L-alanine, in addition to the known compound N-acetyl-kynurenine, which had its NMR data and absolute configuration established as (S)-N-acetyl-kynurenine. The compounds cyclo-(D-Trp-L-Glu) and (S)-N-acetyl-kynurenine were evaluated against OVCAR-3 cells and showed IC50 of 1.120 and 1.073 µM, respectively. The second strain cultived in large scale, the fungus Aspergillus sp. SDC28 isolated from cave soil, produced in its culture medium two lipophilic compounds, versicolorin C and versiconol. Their anticancer potential against OVCAR-3 cells were also determined with IC50 of 0.24 and 1.07 µM, respectively. These compounds had their absolute configuration determined. In order to know the selectivity power of the mixture of XAD-2,-4,-7 resins during the process of water-soluble metabolites adsorption, the natural product solitumine A produced by the fungal strain Penicillium solitum IS1-A was used. The capture of solitumine A through the adsorptive resins allowed us to avaliate with which individual resin its chemical structure have greater affinity.
 
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Publishing Date
2023-08-01
 
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