RESUMO
Efflux pumps are integral parts of the bacterial plasma membrane that are responsible for many cases of antibiotic resistance. Modulators of drug resistance are regarded as the most suitable new antibacterial therapies. We evaluated the extracts of Sargassum polyceratium and the isolated compound pheophytin (Sp-1) for antibiotic modifying activity in strains of Staphylococcus aureus with efflux pump. The minimum inhibitory concentrations (MICs) for norfloxacin, tetracycline and erythromycin were determined by the microdilution broth method, in the absence and presence of the extract at a sub-inhibitory concentration (MIC/4). The extracts and isolated compounds showed no significant antimicrobial activity, but they changed the antibiotic activity, decreasing bacterial resistance by 2 to 4x. Using a checkerboard method, it was also possible to observe the synergistic effect (ΣFIC ≤ 0.5) between Sp-1 and the antibiotics erythromycin and norfloxacin. The results indicate that the seaweed Sargassum polyceratium and pheophytin are potential sources of an antibiotic adjuvant that modulates bacterial resistance, acting as a putative efflux pump inhibitor.
Assuntos
Proteínas Associadas à Resistência a Múltiplos Medicamentos/antagonistas & inibidores , Feofitinas/farmacologia , Sargassum/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana/efeitos dos fármacos , Sinergismo Farmacológico , Eritromicina/farmacologia , Proteínas de Membrana Transportadoras/metabolismo , Testes de Sensibilidade Microbiana , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Norfloxacino/farmacologia , Feofitinas/metabolismo , Extratos Vegetais/farmacologia , Staphylococcus aureus/metabolismo , Tetraciclina/farmacologiaRESUMO
Abstract Marine algae have been the focus of important studies over the past fifty years, with a considerable number of components important to chemists and taxonomists having been isolated and characterized. The scientific data available on Sargassum polyceratium are extremely limited. The objective of the present study was to evaluate the antinociceptive activity of an ethanol extract of S. polyceratium and to isolate its components. Intraperitoneal treatment with ethanol extract of S. polyceratium reduced the number of acetic acid-induced writhes and the amount of time spent in paw-licking in the second phase of the formalin test. Ethanol extract of S. polyceratium also reduced the amount of time spent in paw-licking in the glutamate test; however, there was no difference in the reaction time in the hot plate test at any of the doses tested. The chemical components isolated from ethanol extract of S. polyceratium were identified using one- and two-dimensional spectroscopic methods such as infrared spectroscopy, mass spectrometry and 1H and 13C nuclear magnetic resonance spectroscopy. The analytical results were also compared with data obtained in the literature. The following porphyrin derivatives were isolated from S. polyceratium: 132-hydroxy-(132-R)-pheophytin-a, 132-hydroxy-(132-S)-pheophytin-a, pheophytin-a, and the steroid fucosterol. The present results indicate that the ethanol extract of S. polyceratium has antinociceptive activity. In addition, four new substances were isolated from the species evaluated.
RESUMO
Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has just started to increase in the last decades. This review describes 101 halogenated substances from 14 species of Aplysina from different parts of the world. These substances can be divided into the following classes: bromotyramines (A), cavernicolins (B), hydroverongiaquinols (C), bromotyrosineketals (D), bromotyrosine lactone derivatives (E), oxazolidones (F), spiroisoxazolines (G), verongiabenzenoids (H), verongiaquinols (I), and dibromocyclohexadienes (J). A compilation of their (13)C NMR data is also part of the review. For this purpose 138 references were consulted.