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J Nat Prod ; 2022 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35427139


Investigation of the marine sponge Agelas dispar MeOH fractions using feature-based molecular networking, dereplication, and isolation led to the discovery of new bromopyrrole-derived metabolites. An in-house library of bromopyrrole alkaloids previously isolated from A. dispar and Dictyonella sp. was utilized, along with the investigation of an MS/MS fragmentation of these compounds. Our strategy led to the isolation and identification of the disparamides A-C (1-3), with a novel carbon skeleton. Additionally, new dispyrins B-F (4-8) and nagelamides H2 and H3 (9 and 10) and known nagelamide H (11), citrinamine B (12), ageliferin (13), bromoageliferin (14), and dibromoageliferin (15) were also isolated and identified by analysis of spectroscopic data. Analysis of MS/MS fragmentation data and molecular networking analysis indicated the presence of hymenidin (16), oroidin (17), dispacamide (18), monobromodispacamide (19), keramadine (20), longamide B (21), methyl ester of longamide B (22), hanishin (23), methyl ester of 3-debromolongamide B (24), and 3-debromohanishin (25). Antibacterial activity of ageliferin (13), bromoageliferin (14), and dibromoageliferin (15) was evaluated against susceptible and multi-drug-resistant ESKAPE pathogenic bacteria Klabsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecalis. Dibromoageliferin (15) displayed the most potent antimicrobial activity against all tested susceptible and MDR strains. Compounds 13-15 presented no significant hemolytic activity up to 100 µM.

J Nat Prod ; 84(3): 790-796, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33371682


Metabolomics analysis detected tambjamine alkaloids in aqueous and EtOAc extracts of the marine invertebrates Virididentula dentata, Tambja stegosauriformis, Tambja brasiliensis, and Roboastra ernsti. Among several tambjamines, the new amino acid derivatives tambjamines M-O (17-19) were identified by Marfey's advanced analysis, UPLC-MS/MS analyses, and total synthesis. The tambjamine diversity increased from the bryozoan V. dentata to its nudibranch predators T. stegosauriformis and T. brasiliensis and attained a higher diversity in R. ernsti, the nudibranch that preys upon T. stegosauriformis and T. brasiliensis. The total tambjamine content also increases among the trophic levels, probably due to biomagnification. Tambjamines A (1), C (3), and D (4) are the major metabolites in the tissues of V. dentata, T. stegosauriformis, T. brasiliensis, and R. ernsti and are likely the main chemical defenses of these marine invertebrates.

Alcaloides/isolamento & purificação , Gastrópodes/química , Pirróis/isolamento & purificação , Animais , Organismos Aquáticos/química , Brasil , Cromatografia Líquida de Alta Pressão , Cadeia Alimentar , Metabolômica , Estrutura Molecular , Espectrometria de Massas em Tandem
Bioorg Chem ; 100: 103921, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32464403


Enterococci are gram-positive, widespread nosocomial pathogens that in recent years have developed resistance to various commonly employed antibiotics. Since finding new infection-control agents based on secondary metabolites from organisms has proved successful for decades, natural products are potentially useful sources of compounds with activity against enterococci. Herein are reported the results of a natural product library screening based on a whole-cell assay against a gram-positive model organism, which led to the isolation of a series of anacardic acids identified by analysis of their spectroscopic data and by chemical derivatizations. Merulinic acid C was identified as the most active anacardic acid derivative obtained against antibiotic-resistant enterococci. Fluorescence microscopy analyses showed that merulinic acid C targets the bacterial membrane without affecting the peptidoglycan and causes rapid cellular ATP leakage from cells. Merulinic acid C was shown to be synergistic with gentamicin against Enterococcus faecium, indicating that this compound could inspire the development of new antibiotic combinations effective against drug-resistant pathogens.

Antibacterianos/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Enterococcus faecium/efeitos dos fármacos , Gentamicinas/farmacologia , Sinergismo Farmacológico , Enterococcus faecium/crescimento & desenvolvimento , Enterococcus faecium/metabolismo , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Hidroxibenzoatos/farmacologia
Rev. bras. farmacogn ; 29(6): 715-719, Nov.-Dec. 2019. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1057861


ABSTRACT Chemical investigation of the aqueous fraction of the ethanol extract from the Brazilian endemic marine sponge Clathria (Clathria) nicoleae Vieira de Barros, Santos & Pinheiro, 2013, Microcionidae, sampled from a 55 m deep rhodolith bed at the Amazon River mouth, led to the isolation of a new hexapeptide, clathriamide (1). HP-20 resin was used to capture compound 1 from the aqueous fraction, which was purified by additional chromatographic steps. The absolute configuration of the amino acids of 1 was determined by advanced Marfey's analysis using 5-fluoro-2,4-dinitrophenyl-Nα-L-tryptophanamide. The amino acid derivatives analyzed by ultra-performance liquid chromatography coupled to a mass spectrometry using a C8 column enabled a good chromatographic resolution of L-Ile and L-allo-Ile, previously unfeasible using C18 column.

Nat Prod Rep ; 36(7): 981-1004, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31049509


Covering: up to 2019The discovery of new bioactive natural products gained momentum during the last few decades, resulting from instrumentation advances, from the expansion of genome mining and regulation, as well as by exploration of untapped biological sources. However, water-soluble, volatile, minor and photosensitive natural products are yet poorly known. This review discusses the literature reporting the isolation strategies for some of these metabolites. Analysis of minor metabolites at sub-milligram level are also presented, since analytical instrumentation enabling structure assignment in minute quantities is now routine. Major trends related to natural products discovery are discussed, under the light of further developments in biodiscovery.

Produtos Biológicos/isolamento & purificação , Produtos Biológicos/química , Produtos Biológicos/efeitos da radiação , Interações Hidrofóbicas e Hidrofílicas , Luz , Estrutura Molecular , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/efeitos da radiação
J Nat Prod ; 81(10): 2296-2300, 2018 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-30281303


The new pyrrole-imidazole and pyrrole-guanidine alkaloids 4-debromooroidin (1), 4-debromougibohlin (2), 5-debromougibohlin (3), and 5-bromopalau'amine (4), along with the known hymenidin (5) and (+)-monobromoisophakellin (6), have been isolated from a Dictyonella sp. marine sponge, collected at the Amazon River mouth. The bromine-substitution pattern observed for compounds 1, 2 and 4 is unusual among bromopyrrole alkaloids isolated from marine sponges. The 20S proteasome inhibitory activities of compounds 1-6 have been recorded, with 5-bromopalau'amine (4) being the most active in this series.

Poríferos/química , Inibidores de Proteassoma/química , Inibidores de Proteassoma/farmacologia , Pirróis/química , Pirróis/farmacologia , Animais , Brasil , Estrutura Molecular , Complexo de Endopeptidases do Proteassoma , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/genética