The Mundaú-Manguaba lagoon estuary complex is the most important ecosystem in the state of Alagoas, and a source of sustenance for a large number of the state’s inhabitants. However, degradation by anthropic sources has been causing impacts on this ecosystem. Understanding the characteristics of the natural organic material of the waters of the mundaú-manguaba lagoon complex is extremely important to understand the interaction dynamics of the contaminants in these lagoons. Thus, the objective of this work was to extract and characterize aquatic humic substances from the Mundau-Manguaba lagoon complex and to evaluate the interaction of this organic material with mercury ions. The profile of the aquatic humic substances of the respective lagoons evidenced the greater influence of aliphatic groups in their structures. The interactions of aquatic humic substances and mercury ions are directly related to the oxygen groups in their structures, corroborated by Principal Component Analysis. Thus, understanding the water and organic matter characteristics present in the Mundaú-Manguaba estuarine lagoon complex is fundamental for establishing strategies, seeking the preservation of this ecosystem and remediation of environmental contamination.

AbstractMany well-established methods for determining the antioxidant capacities in several samples have been described in literature. However, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) are the main two methods that utilize radicals as spectrophotometric probes for analysis. Nevertheless, these methods have certain limitations because of their slower kinetics, solvent polarity effects, the hydrophilicity and lipophilicity of the compounds, chemical costs, etc. In this study, a spectrophotometric method for determining the antioxidant capacity in beverages was developed based on an exploration of the cation radical derived from DEPD. This method was based on the oxidation of aromatic amines with Fe(III) ions at pH 4.0, which leads to their corresponding purple cation radicals (DEPD•+) with λmax values at 500 and 540 nm. The addition of an antioxidant after the formation of the radical leads to a reduction in color intensity that is proportional to the antioxidant concentration in the medium. Results obtained using this method were compared with the Folin-Ciocalteau, ABTS and DPPH methods in terms of applications in wines, teas, and infusions samples. Linear correlation analysis at a 95% confidence level was employed to compare the results, which were in good agreement with a correlation coefficient of r > 0.9000. Thus, the developed method was simple, accurate, and consistent with other assays for the determination of the total amount of phenolic compounds and antioxidant capacity.

NMR is a valuable screening tool for the binding of ligands to proteins providing structural information on both protein and ligands and is thus largely applied to drug-discovery. Among the recent NMR techniques to probe weak binding protein-ligand complexes we have critically evaluated the advantages and disadvantages of STD (Saturation Transfer Difference), WaterLOGSY (Water Ligand Observation with Gradient Spectroscopy), NOE pumping and DOSY-NOESY (Diffusion-Ordered NOESY) using a mixture of BSA (bovine serum albumin) plus salicylic acid, caffeine, citric acid, adipic acid and D-glucose.