Navegando por Palavras-chave "Exudates"

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    Cylindrospermopsis raciborskii (Cyanobacteria) exudates: Chemical characterization and complexation capacity for Cu, Zn, Cd and Pb
    (Elsevier B.V., 2014-02-01) Tonietto, Alessandra Emanuele; Lombardi, Ana Teresa; Henriques Vieira, Armando Augusto; Parrish, Christopher C.; Choueri, Rodrigo Brasil [UNIFESP]; Universidade Federal de São Carlos (UFSCar); Mem Univ Newfoundland; Universidade Federal de São Paulo (UNIFESP); Univ Santa Cecilia
    Cylindrospermopsis raciborskii is a cosmopolitan and potentially toxic planktonic Cyanobacteria that produces and exudes copious amounts of dissolved organic materials. This organism dominates the eutrophic reservoir Barra Bonita (Brazil), where it normally blooms throughout the year. This investigation focused on the characterization of such exudates analyzing their capacity to complex copper, zinc, lead and cadmium through the determination of ligand concentration (C-L) and conditional stability constant (logK'mL), as well as elemental composition (C, H, N and S), the content of carbohydrates, proteins, lipids and dissolved organic carbon (DOC). the dissolved organic material was fractionated into 3 molecular weights (>30 kDa; 30-10 kDa; 10-3 kDa) and each fraction was analyzed. the results showed that in the >30 kDa and 30-10 kDa fractions carbohydrates dominate over proteins and lipids. Different CL and logK'mL were obtained for the different molecular weight fractions of the excreted organic materials, suggesting high diversity of ligands. in the >30 kDa, there were more complexing sites (CL) for Cu, but higher affinity (K') for Zn. in the 30-10 kDa fraction, the higher C-L was for Cd, but the greatest affinities were for Cu and Zn. in the 10-3 kDa fraction, higher C-L was obtained for Cd and Zn, while Cu and Cd had the highest strengths of association. in the environment, such diversity of ligands and strengths of association can result in a displacement of metals weakly bound to the EOM, and increase metal buffering capacity of the environment, supporting higher metal inputs before toxic effects are detected in the biota. (C) 2013 Elsevier B.V. All rights reserved.
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    The mystery of the 'resin-of-canuaru': A medicine used by caboclos river-dwellers of the Amazon, Amazonas, Brazil
    (Elsevier B.V., 2012-12-18) Rodrigues, Eliana [UNIFESP]; Santos, Juliana de Faria Lima [UNIFESP]; Souza, Sarah M.; Lago, Joao Henrique Ghilardi [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Ethnopharmacological relevance: 'Resin-of-canuaru' is a medicine utilized by caboclos living in the Amazon Region, Brazil. There is a mystery regarding its origin because the caboclos maintain that this substance is derived only from animal secretions (from a frog called canuaru), whereas the historic literature claims that 'resin-of-canuaru' is derived solely from a plant exudate (resin). Based on our ethnographic studies, we hypothesized that this substance is a combination of both. Because the past reports on this resiniferous material in the literature are based solely on observations, we aimed to present ethnographic, zoological and chemical data to try to elucidate the origin of the 'resin-of-canuaru'.Materials and methods: Ethnographic techniques and methods were applied, including participant observation, the use of field diaries and informal and unstructured interviews. the canuaru frog (Trachycephalus resinifictrix Goeldi, 1907) and 'resin-of-canuaru' were collected for taxonomic identification and chemical analysis, respectively. the resiniferous 'resin-of-canuaru' was extracted using MeOH and then analyzed by silica gel TLC and NMR.Results: Canuaru frogs live in tree cavities and secrete a large amount of substances during spawning, resulting in a resiniferous material. NMR analysis of the MeOH extract of this crude material showed peaks assigned to 3,4-secofriedel-4(23)-en-3-oic acid (putranjuvic acid) and its methyl ester derivative (methyl putranjivate) and to biogenetic precursor of these two compounds (a lactone derivative), which is formed by the oxidation of friedelin. Based on evidence that Protium species accumulate primarily tetracyclic/pentacyclic triterpenoids and that the co-occurrence of the compounds listed above is rarely described in plant species, we suggest that these compounds could be products of the biotransformation of friedelin by the frog.Conclusions: According to our data, the 'resin-of-canuaru' seems to have both animal and vegetal origins. (C) 2012 Elsevier Ireland Ltd. All rights reserved.