Aplicação da Kappa-Carragenana na síntese de materiais híbridos de curcumina natural derivados da incorporação de ferro e cobre.

Abstract

In general, curcumin is an interesting compound, as it is natural and has several properties, such as its antioxidant potential. However, isolated curcumin presents rapid photodegradation, thermal and solution instability. In this sense, new hybrid materials were synthesized in order to overcome such limitations. The synthesis of these materials took place from natural curcumin, iron and copper metals and kappa-carrageenan, which was used as a reducing metal. After the synthesis, a sudden color change could be noticed, indicating the presence of the reduced metal in the final product, as this color change is linked to the coordinated bond between curcumin and the metal. Furthermore, these hybrid materials were characterized by different techniques such as spectroscopy in the infrared region, where characteristic bands were observed in curcumin at 3461 cm-1 (O-H) and 1599 cm-1 (C=O), while in the hybrid materials there were a displacement of these same bands. In Spectroscopy in the Ultraviolet-Visible region, the maximum absorption peak of curcumin was observed at 425 nm, comparing with the peaks of the hybrid materials, a deviation occurred (5-6 nm). In both analyses, the displacements indicate the interaction of the β-diketone fraction of curcumin with the metals. In X-Ray Diffraction (DRX) analysis, an amorphous structure was observed for Kappa-carrageenan, different from curcumin, which presented a crystalline structure, as already reported in the literature. In the thermogravimetric analysis, Kappa-carrageenan showed greater thermal stability when compared to curcumin (30 – 800 ºC). In the natural curcumin sample (commercial Sigma-Aldrich@®), it was possible to identify two more curcuminoids by the High-Performance Liquid Chromatography technique. With this same technique it was possible to verify that curcumin formed degradation products after 24 h in solution. The antioxidant potential was investigated, and in both tests performed, the hybrid materials showed a lower antioxidant potential (2 or 4% lower), equal to or greater than that of curcumin. Finally, the materials were applied as developers of new latent fingerprints, but the results are not presented in this work, since the publication of the patent containing these results is in a confidential process (SEI - UFPel). Thermal stability studies, in solution and DRX analysis, are still being carried out for the hybrid materials. In this sense, the new curcumin-based hybrid materials synthesized in this work will impact the area of Materials Science and Engineering, as they are multifunctional materials and will cause innovation in the area of papiloscopia, specifically as new developers of latent fingerprints.