The objective of this study was to investigate the sulfonation of （1→6）-β-D-glucan （lasiodiplodan） as a potentiating mechanism for biological functionalities. Lasiodiplodan was sulfonated by the chlorosulfonic a...The objective of this study was to investigate the sulfonation of （1→6）-β-D-glucan （lasiodiplodan） as a potentiating mechanism for biological functionalities. Lasiodiplodan was sulfonated by the chlorosulfonic acid-pyridine method. The modified exopolysaccharide was characterized by FT-IR and 13C NMR spectroscopy, X-ray diffraction and SEM. Antioxidant activity was assessed by the methods of H2O2 and OH radical removal and reducing power. Antimicrobial potential was evaluated by the broth-microdilution method. Sulfonation resulted in a derivative with DS of 0.24. FT-IR analysis indicated the introduction of sulfonyl groups in the macromolecule structure through specific bands in the regions of 1,240 cm-1 and 810 cm-1. 13C NMR analysis suggested that sulfonation occurred at carbon 2 of the glucose residue. Sulfonation led to morphological changes in the structure of the biopolymer resulting in a heterogeneous structure with the presence of fibrils. Derivatization promoted an increase in the antioxidant ability of the macromolecule, with a high OH removal potential （74.32%）. Bacteriostatic activity against E. coli （Escherichia coli） and S. enterica （Salmonella enterica） typhimurium and fungicidal activity against C. albicans （Candida albicans） and C. tropicalis （Candida tropicalis） were found in the sulfonated sample. Sulfonation potentiated the antioxidant and antimicrobial activities of the biomacromolecule, suggesting that it is a potentiating mechanism of biological functions.展开更多
β-Glucans are biomacromolecules that present biological properties of medical and pharmacological interest, The chemical modification of the primary structure of these carbohydrate biopolymers is a way to enhance or ...β-Glucans are biomacromolecules that present biological properties of medical and pharmacological interest, The chemical modification of the primary structure of these carbohydrate biopolymers is a way to enhance or achieve new biological properties. Acetylated derivatives of （1→6）-β-D-glucan （lasiodiplodan） with different degrees of substitution （0.48, 0.66, 1.03 and 1.26） were obtained and characterized by infra-red and NMR （nuclear magnetic resonance） spectroscopy, thermal analysis, X-ray diffraction and antioxidant capacity. Acetylation was confirmed by FT-IR, and βC NMR spectroscopy. Thermal analysis indicated that unmodified lasiodiplodan and the O-acetylated β-glucan derivative of degree of substitution 0.48 presented three stages of mass-loss, whereas acetylated derivatives of DS （degree of substitution） of 0.66, 1.03 and 1.26 presented four stages of mass-loss. X-ray diffractograms demonstrated that both native and acetylated lasiodiplodan presented crystalline regions in an amorphous polymeric matrix. Scanning electron microscopy revealed that O-acetylation promoted morphologic changes in the biopolymer according to the DS. Acetylation also contributed to improve antioxidant capacity.展开更多
文摘The objective of this study was to investigate the sulfonation of （1→6）-β-D-glucan （lasiodiplodan） as a potentiating mechanism for biological functionalities. Lasiodiplodan was sulfonated by the chlorosulfonic acid-pyridine method. The modified exopolysaccharide was characterized by FT-IR and 13C NMR spectroscopy, X-ray diffraction and SEM. Antioxidant activity was assessed by the methods of H2O2 and OH radical removal and reducing power. Antimicrobial potential was evaluated by the broth-microdilution method. Sulfonation resulted in a derivative with DS of 0.24. FT-IR analysis indicated the introduction of sulfonyl groups in the macromolecule structure through specific bands in the regions of 1,240 cm-1 and 810 cm-1. 13C NMR analysis suggested that sulfonation occurred at carbon 2 of the glucose residue. Sulfonation led to morphological changes in the structure of the biopolymer resulting in a heterogeneous structure with the presence of fibrils. Derivatization promoted an increase in the antioxidant ability of the macromolecule, with a high OH removal potential （74.32%）. Bacteriostatic activity against E. coli （Escherichia coli） and S. enterica （Salmonella enterica） typhimurium and fungicidal activity against C. albicans （Candida albicans） and C. tropicalis （Candida tropicalis） were found in the sulfonated sample. Sulfonation potentiated the antioxidant and antimicrobial activities of the biomacromolecule, suggesting that it is a potentiating mechanism of biological functions.
文摘β-Glucans are biomacromolecules that present biological properties of medical and pharmacological interest, The chemical modification of the primary structure of these carbohydrate biopolymers is a way to enhance or achieve new biological properties. Acetylated derivatives of （1→6）-β-D-glucan （lasiodiplodan） with different degrees of substitution （0.48, 0.66, 1.03 and 1.26） were obtained and characterized by infra-red and NMR （nuclear magnetic resonance） spectroscopy, thermal analysis, X-ray diffraction and antioxidant capacity. Acetylation was confirmed by FT-IR, and βC NMR spectroscopy. Thermal analysis indicated that unmodified lasiodiplodan and the O-acetylated β-glucan derivative of degree of substitution 0.48 presented three stages of mass-loss, whereas acetylated derivatives of DS （degree of substitution） of 0.66, 1.03 and 1.26 presented four stages of mass-loss. X-ray diffractograms demonstrated that both native and acetylated lasiodiplodan presented crystalline regions in an amorphous polymeric matrix. Scanning electron microscopy revealed that O-acetylation promoted morphologic changes in the biopolymer according to the DS. Acetylation also contributed to improve antioxidant capacity.
