Molecular Characteristics and Antioxidant Activity of Spruce ( Picea abies ) Hemicelluloses Isolated by Catalytic Oxidative Delignification

• Published in: Molecules (Basel, Switzerland) Vol. 27; no. 1; p. 266
• Main Authors: Borovkova, Valentina S, Malyar, Yuriy N, Sudakova, Irina G, Chudina, Anna I, Skripnikov, Andrey M, Fetisova, Olga Yu, Kazachenko, Alexander S, Miroshnikova, Angelina V, Zimonin, Dmitriy V, Ionin, Vladislav A, Seliverstova, Anastasia A, Samoylova, Ekaterina D, Issaoui, Noureddine
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02.01.2022; MDPI
• Subjects: Acetic acid; Acids; Ammonium molybdate; antioxidant activity; Antioxidants; Antioxidants - chemistry; Antioxidants - isolation & purification; Arabinose; Catalysis; Catalysts; Cellulose; Chromatography; delignification; Free radicals; Galactose; Gas chromatography; gel permeation chromatography; Heating; Hemicellulose; Hot Temperature; Hydrogen peroxide; Infrared analysis; Infrared spectroscopy; Lignin; Lignin - chemistry; Lignocellulose; Liquid chromatography; Mannose; Molecular weight; molecular weight distribution; Picea - chemistry; Picea abies; Polymers; Polysaccharides; Polysaccharides - chemistry; Polysaccharides - isolation & purification; Solvents; Sulfuric acid; Thermogravimetric analysis; Titanium dioxide; Wood; wood polysaccharides; Xylose - chemistry; gel permeation chromatography; delignification; molecular weight distribution; hemicellulose; antioxidant activity; wood polysaccharides
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules27010266

Spruce ( ) wood hemicelluloses have been obtained by the noncatalytic and catalytic oxidative delignification in the acetic acid-water-hydrogen peroxide medium in a processing time of 3-4 h and temperatures of 90-100 °C. In the catalytic process, the H SO , MnSO , TiO , and (NH ) Mo O catalysts have been used. A polysaccharide yield of up to 11.7 wt% has been found. The hemicellulose composition and structure have been studied by a complex of physicochemical methods, including gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The galactose:mannose:glucose:arabinose:xylose monomeric units in a ratio of 5:3:2:1:1 have been identified in the hemicelluloses by gas chromatography. Using gel permeation chromatography, the weight average molar mass M of hemicelluloses has been found to attain 47,654 g/mol in noncatalytic delignification and up to 42,793 g/mol in catalytic delignification. Based on the same technique, a method for determining the α and parameters of the Mark-Kuhn-Houwink equation for hemicelluloses has been developed; it has been established that these parameters change between 0.33-1.01 and 1.57-472.17, respectively, depending on the catalyst concentration and process temperature and time. Moreover, the FTIR spectra of the hemicellulose samples contain all the bands characteristic of heteropolysaccharides, specifically, 1069 cm (C-O-C and C-O-H), 1738 cm (ester C=O), 1375 cm (-C-CH ), 1243 cm (-C-O-), etc. It has been determined by the thermogravimetric analysis that the hemicelluloses isolated from spruce wood are resistant to heating to temperatures of up to ~100 °C and, upon further heating, start destructing at an increasing rate. The antioxidant activity of the hemicelluloses has been examined using the compounds simulating the 2,2-diphenyl-2-picrylhydrazyl free radicals.