STRUCTURAL CHARACTERIZATION OF ALGINATE-BASED MATERIAL EXTRACTED FROM PERUVIAN KELP MACROCYSTIS PYRIFERA

This research is focused on the preparation of an alginate-based material through a purification process of sodium alginate extracted from a Peruvian kelp: Macrocystis Pyrifera. In this work, the starting material was purified with n-butanol and characterized by UV-Vis, 1H-NMR and HSQC. As shown Figure 1, the 1H NMR spectrum of AlgP (purified alginate) was acquired for evaluating the M/G ratio according to the method described by S. Pawar & K. Edgar [1]. This parameter was calculated from the signals in the anomeric region 4.4 – 5.5 ppm through the relationship of G and M block distribution [2]. For a better understanding of AlgP structure, Figure 2 displays the 13C/1H HSQC spectrum of AlgP in order to evaluate the correlation between 13C–1H. As can be observed, the 103.92/4.67 ppm correlation was assigned to C1/H1 of β-D-mannuronic acid residues, whereas the signal at 102.70/5.06 ppm was attributed to C1/H1 of α-L-guluronic acid residue. Besides, the 80.78/3.91 ppm and 82.63/4.13 ppm correlations were assigned to C4/H4 of manuronic (AlgPa) and guluronic (AlgPb) acid residues in AlgP. Finally, it was observed that guluronic acid blocks of alginate are preferentially oxidized using sodium metaperiodate in dark conditions at room temperature as is reported in the literature. This fact a clear evidence that alginate-based materials could be applied in different field such as biomedical and cosmetic due to the wide range of structual functionalization that can be achieved through amino-reductive reactions.