Extraction and physicochemical characterization of pectin polysaccharides from amaranth leaves
Автор: Minzanova S.T., Mironov V.F., Mindubaev A.Z., Tsepaeva O.V., Mironova L.G., Milyukov V.A., Gins V.K., Gins M.S., Kononkov P.F., Babayev V.M., Pivovarov V.F.
Журнал: Сельскохозяйственная биология @agrobiology
Рубрика: Биоактивные соединения
Статья в выпуске: 3 т.56, 2021 года.
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Polysaccharides are one of the most important classes of natural compounds that have practical application in various fields of science and technology. Pectin remains one of the most essential polysaccharides, being a primary constituent of the structural elements of the cell wall in higher plants, performs the functions of binding and strengthening components of the cell wall, and also regulates water metabolism. Pectic substances are widely used in medicine as detoxicants of heavy metals and regulators of metabolic processes in the human body. In addition, they are also a universal food additive (E440). Despite significant amounts of traditional raw material resources (apple and citrus pomace, beet pulp), new alternative sources of raw materials are being searched for, including vegetable plants introduced in Russia for the production of pectins and their use in the production of functional foods. Among non-traditional plant resources, amaranth ( Amaranthaceae ) holds a significant rank. Due to its high yield and high content of biologically active substances and antioxidants, this crop acts as a potential source of obtaining valuable plant-derived substances for medicine, agriculture and the food industry. The Amaranthus tricolor L. cv. Valentina plants were used to isolate pectic substances by the classical method and ultrasonic treatment at a frequency of 22 kHz. Sugars were quantified using a Shimadzu 20-AD Prominence liquid chromatograph (Shimadzu Corporation, Japan) with a Shimadzu RID-10A refractometric detector. Infrared spectra were recorded on an IRS-113 instrument (Bruker, Germany) with a resolution of 1 cm-1 in the range 400-4000 cm-1. The elemental composition was determined (a CHNSO-high-temperature analyzer Euro EA 3028-HT-OM, EuroVector Instruments & Software, Italy). All measurements by atomic force microscopy (AFM) were carried out on a Multi Mode V scanning probe microscope (Veeco Instruments, Inc., USA) in an intermittent contact mode. Structural study of the isolated polysaccharides by the IR spectroscopy method showed their possible affiliation to pectin substances. To study the monosaccharide composition, the samples of pectins were hydrolyzed with sulfuric acid (2 N) and partially hydrolyzed with trifluoroacetic acid (TFA). The high-performance liquid chromatography (HPLC) identified glucose, galactose, rhamnose, arabinose and galacturonic acid in the pectin fractions. Low galacturonic acid contents of 0.63 % and 1.68 % were determined in H2SO4 and TFA hydrolyzates, respectively. The conditions for hydrolysis-extraction which ensure the maximum yield of pectin substances were 0.5 % oxalic acid with complexone (0.5 % HDTA), 50-55 °С, 4 h, feed to extractant volume (hydromodule) ratio of 1:15. The physicochemical properties of pectin obtained under these conditions were studied using atomic force microscopy (AFM) and thermogravimetric/differential scanning calorimetry (TG/DSC) methods. After ethanol re-precipitation, this pectin sample showed an intense absorption band of stretching vibrations of carbonyls of carboxyl groups and ester groups at 1742 cm-1. The TG/DSC indicated a two-step weight loss. The Fourier-transform infrared (FTIR) spectrum of the gaseous products derived from thermal decomposition of pectin sample showed that water was the main component of the gas phase at the first stage of weight loss and at the second stage, pectin was decarboxylated. According to atomic force microscopy, the size of the aggregates was 2.4-2.5 μm maximum and ~ 330 nm minimum.
Amaranthus tricolor l
Короткий адрес: https://sciup.org/142230923
IDR: 142230923 | DOI: 10.15389/agrobiology.2021.3.591rus