Banca de DEFESA: VALMORE HENRIQUE PEREIRA DOS SANTOS
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : VALMORE HENRIQUE PEREIRA DOS SANTOS
DATA : 14/01/2020
HORA: 09:00
LOCAL: Sala de Seminários
TÍTULO:
Isolated endophytic fungi from the leaves of Handroanthus impetiginosus as efficient stereoselective biocatalysts for the production of chiral building blocks
PALAVRAS-CHAVES:
acetophenone; bioreduction; endophytic fungus; Talaromyces purpurogenus H4
PÁGINAS: 142
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Química dos Produtos Naturais
RESUMO:
Great attention has been paid to the stereoselective synthesis of optically pure compounds using ecological methodologies due to the growing demand for modern drugs, food ingredients, and agrochemicals. Optically pure alcohols are useful as building blocks for the synthesis of bioactive compounds and they can be transformed into other functionalities without racemization. Whole cell-mediated chemical transformations have some advantages over classical chemical procedures, including low cost, high versatility, along with chemo-, regio- and stereoselectivity. The present work consisted in the evaluation of the biocatalytic potential of seven strains of endophytic fungi isolated from the leaves of Handroanthus impetiginosus (Ipê Roxo) in the stereoselective biotransformation of the pro-chiral acetophenone.
Initially, the fungi were isolated from ipê leaves and then cultivated in Petri dishes containing PDA (potato dextrose agar) medium. After seven days of cultivation, in an incubator at 28 ºC, the strains were used for acetophenone bioreduction. The H4-encoded endophytic fungus (later identified by molecular biology as Talaromyces purpurogenus H4) performed the best biotransformation of acetophenone with a conversion rate > 99.9% and leading to an enantiomeric excess of 82.8% of (S)-1-phenylethanol. Aiming to increase the enantiomeric excess resulting from this biotransformation, the reaction parameters were studied: pH of the reaction medium, reaction temperature, amount of substrate used, co-solvent, reaction time, rotation applied in agitation and amount of fungus. As a result of this optimization, we reached conversion rate and enantiomeric excess of 97% and 96%, respectively. Following, the endophyte Talaromyces purpurogenus H4 was also used to evaluate the bioreduction of some acetophenone derivatives: 4'-chloroacetophenone, 4'-bromoacetophenone, 4'-methoxyacetophenone, 4'-nitroacetophenone, 2 'chloroacetophenone, and 2'-bromoacetophenone. These experiments aimed to detail the influences that activating and deactivating groups of the aromatic ring exert on the given bioreduction. Among the evaluated derivatives, 4'-nitro-acetophenone had the best conversion rate (52.2%), and 4'-methoxy-acetophenone had the best enantiomeric excess (90.9% of (S)-1-phenylethanol). Most substrates used led to products with S configuration of the stereogenic center, with the exception of 2-bromine and 2-chloroacetophenone.
Finally, the acetophenone bioreduction was performed on a scale-up using previously optimized conditions. The (S)-1-phenylethanol was then isolated in 73.0% of molar yield and 96.0% of enantiomeric excess. It will be used as a starting point for the synthesis of pharmaceutically useful chemicals.
MEMBROS DA BANCA:
Presidente - 1148522 - ELIANE DE OLIVEIRA SILVA
Interno - 1215450 - SILVIO DO DESTERRO CUNHA
Interno - 1068075 - JORGE MAURICIO DAVID
Interno - 1507716 - MAURICIO MORAES VICTOR
Interno - 3768242 - PAULO ROBERTO RIBEIRO DE JESUS
Interno - 2166886 - ANDRE ALEXANDRE VIEIRA
Externo ao Programa - 1425857 - DOUGLAS FERNANDO RAMBO
Externo ao Programa - 1889116 - SAMUEL SILVA DA ROCHA PITA
Externo ao Programa - 1493023 - MARCELO SANTOS CASTILHO
Externo ao Programa - 1281669 - RENATA BIEGELMEYER DA SILVA RAMBO