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Doctoral Thesis
DOI
https://doi.org/10.11606/T.75.2021.tde-03122021-115454
Document
Author
Full name
Vítor Fernandes Freire
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2021
Supervisor
Committee
Berlinck, Roberto Gomes de Souza (President)
Vieira, Paulo Cezar
Forim, Moacir Rossi
Lago, João Henrique Ghilardi
Santos Neto, Álvaro José dos
Title in Portuguese
Quimioprospecção de metabólitos secundários de esponjas marinhas do litoral norte do Brasil
Keywords in Portuguese
esponjas marinhas
metabólitos secundários
produtos naturais
quimioprospecção.
Abstract in Portuguese
Pertencentes ao filo Porifera, esponjas são o grupo mais antigo de metazoários existentes. As esponjas apresentam uma grande quimiodiversidade de metabólitos secundários, ainda com vasto universo de compostos a ser explorado. Neste trabalho foram estudadas as esponjas marinhas Clathria (Clathria) nicoleae e Oceanapia sp., coletadas na foz do Rio Amazonas, e Agelas dispar, coletada em Fernando de Noronha. O estudo químico da fração acetato de etila de C. nicoleae possibilitou o isolamento do composto conhecido microcionamida A (1). O estudo da fração aquosa desta mesma esponja levou ao isolamento e a determinação estrutural de um hexapeptídeo inédito, a clathriamida (2), o qual apresentou IC50 de 1,08 µM contra a linhagem de câncer de ovário OVCAR3 . A partir da fração aquosa de espécimes de Oceanapia sp. foi realizado o isolamento de dois peptídeos potencialmente inéditos, oceanapiamidas A e B, ambos compostos com massa molecular acima de 3300 Da. A investigação do perfil de fragmentação por HRMS/MS dos alcalóides bromopirrólicos 4-desbromo-oroidina (3), himenidina (4) 4-desbromougibohlina (5), 5- desbromougibohlina (6) e monobromoisofakelina (7), previamente isolados da esponja Dictyonella sp., possibilitou a diferenciação estrutural de isômeros e proposição de rotas de fragmentação para os compostos estudados. Utilizando as análises por MS/MS desenvolvidas para os alcalóides bromopirrólicos isolados de Dictyonella sp., diferentes ferramentas quimioinformáticas foram utilizadas no estudo da esponja marinha A. dispar. Foi construída uma rede molecular utilizando Feature-Based Molecular Networking (FBMN) a partir de dados de LC-MS2 da fração acetato de etila pré-fracionada. Utilizando a biblioteca pública do GNPS, bibliotecas in-house e in-silico e propagação de anotação, foram anotados os seguintes compostos: himenidina (4), oroidina, undecaetilenoglicol, dispacamida, monobromodispacamida, keramadina, longamida B, o éster-metílico da longamida B, hanishin, o éster metílico da 3-debromolongamida B e a 3-debromohanishin. Após a desreplicação, o estudo químico das frações de Agelas dispar possibilitou o isolamento/identificação dos compostos conhecidos dibromoageliferina (8), bromoageliferina (9), ageliferina (10), nagelamida H (11) e citrinamina B (14), além dos novos compostos nagelamidas H2 e H3 (12) e (13), dispirinas B-F (15-19) e do esqueleto inédito de carbono, as disparamida A-C (20-22). A bromoageliferina (9) apresentou IC50 de 0,010 µM contra a linhagem de células de câncer de ovário OVCAR3.
Title in English
Chemoprospection of secondary metabolites of marine sponges from north coast of Brazil
Keywords in English
chemoprospection
marine sponges
natural products
secondary metabolites
Abstract in English
Belonging to the Porifera phylum, sponges are the oldest known metazoans. Sponges have a large chemodiversity of secondary metabolites and vast universe of compounds to be explored. In this work, the secondary metabolites of the marine sponges Clathria (Clathria) nicoleae and Oceanapia sp., collected at the Amazon River mouth, and Agelas dispar, collected at Fernando de Noronha, were investigated. Fractionation of the ethyl acetate fraction of C. nicoleae led to the isolation of the known compound microcionamide A (1). The fractionation of the aqueous fraction led to the isolation and structural determination of a novel hexapeptide, clathriamide (2), which displayed IC50 of 1,08 µM against the ovarian cancer cell line OVCAR3. From the aqueous fraction of Oceanapia sp. specimens, two peptides were isolated, oceanapamides A and B, both compounds with molecular weight above 3300 Da. The investigation of the fragmentation profile by HRMS/MS of bromopyrrole alkaloids 4-debromooroidin (3), hymenidin (4) 4-debromougibohlin (5), 5-debromougibohlin (6) and monobromoisofakelin (7), previously isolated from Dictyonella sp., enabled the structural differentiation between isomers and the proposal of fragmentation routes for these compounds. Taking advantage of MS/MS analysis developed for the bromopyrrole alkaloids isolated from Dictyonella sp., different chemoinformatic tools were used to assess the identity of secondary metabolites from the marine sponge Agelas dispar. A molecular network was constructed using Feature-Based Molecular Networking (FBMN) with pre-processed LC-MS2 data of a pre-fractionated ethyl acetate fraction. The use of the GNPS public library, in-house and in-silico libraries and by annotation propagation, it was possible to annotated the following compounds: hymenidin (4), oroidin, undecaethyleneglycol, dispacamide, monobromodispacamide, keramadine, longamide B, longamide B methyl ester, hanishin, 3-debromolongamide B and 3-debromohanishin methyl ester. After dereplication, separation of Agelas dispar fractions enabled the isolation and identification of the known compounds dibromoageliferin (8), bromoageliferin (9), ageliferin (10), nagelamide H (11) and citrinamine B (14), in addition to the new nagelamides H2 and H3 (12-13), dispyrins B- F (15-19) and the novel carbon skeleton, disparamides A-C (20-22). Bromoageliferin (9) displayed IC50 of 0,010 µM against the ovarian cancer cell line OVCAR3.
 
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Publishing Date
2021-12-06
 
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