RESUMO
BACKGROUND: Brea gum (BG) is an exudate from the Cercidium praecox tree that grows in semi-arid regions of Argentina. Some previous studies on BG have shown physicochemical characteristics and functional features similar to those of gum arabic. However, there is a need to elucidate the molecular structure of BG to understand the functionality. In this sense, BG was fractionated using hydrophobic interaction chromatography and the obtained fractions were analyzed by size exclusion chromatography. RESULTS: Analysis of the fractions showed that the bulk of the gum (approx. 84% of the polysaccharides) was a polysaccharide of 2.79 × 10(3) kDa. The second major fraction (approx. 16% of the polysaccharides) was a polysaccharide-protein complex with a molecular mass of 1.92 × 10(5) kDa. A third fraction consisted of protein species with a wide range of molecular weights. The molecular weight distribution of the protein fraction was analyzed by size exclusion chromatography. Comparison of the elution profiles of the exudates in native and reducing conditions revealed that some of the proteins were forming aggregates through disulfide bridges in native conditions. Further analysis of the protein fraction by SDS-PAGE showed proteins with molecular weight ranging from 6.5 to 66 kDa. CONCLUSIONS: The findings showed that BG consists of several fractions with heterogeneous chemical composition and polydisperse molecular weight distributions. © 2016 Society of Chemical Industry.
Assuntos
Fabaceae/química , Gomas Vegetais/química , Proteínas de Plantas/análise , Polissacarídeos/análise , Argentina , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Clima Desértico , Ditiotreitol/farmacologia , Eletroforese em Gel de Poliacrilamida , Fabaceae/crescimento & desenvolvimento , Aditivos Alimentares/análise , Aditivos Alimentares/química , Goma Arábica/química , Interações Hidrofóbicas e Hidrofílicas , Peso Molecular , Oxirredução , Fenóis/análise , Fenóis/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Proteínas de Plantas/química , Polissacarídeos/química , Agregados Proteicos/efeitos dos fármacos , Substâncias Redutoras/farmacologia , Reagentes de Sulfidrila/farmacologiaRESUMO
UNLABELLED: Bioactive compounds from natural plant sources are becoming increasingly important to the food industry. Ilex paraguariensis is used in the preparation of a widely popular tea beverage (Yerba Mate) in the countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, extracts of 4 brands of commercial tea, derived from the holly plant species, Ilex paraguariensis, were evaluated for their ability to inhibit or inactivate bacterial foodborne pathogens. The ultimate goal was to evaluate potential use of the extracts in commercial applications. Dialyzed aqueous extracts were screened for antimicrobial activity against Escherichia coli O157:H7 and Staphylococcus aureus. S. aureus was found to be the more sensitive to extracts than E. coli O157:H7. Minimum bactericidal concentrations (MBCs) were determined to be approximately 150 to 800 µg/mL and 25 to 50 µg/mL against E. coli O157:H7 and S. aureus, respectively. A Uruguayan brand had reduced activity against E. coli O157:H7 compared to the Argentinean brands tested. It was concluded that Yerba Mate could be used as a potential antimicrobial in foods and beverages against these pathogenic bacteria. PRACTICAL APPLICATION: Soluble extracts from Yerba Mate are natural antimicrobials that can be incorporated into food products to achieve longer shelf life.