Structural study of a pectic polysaccharide fraction isolated from “mountain tea” (Sideritis scardica Griseb.)

• Published in: Carbohydrate polymers 2021-05, Vol.260, p.117798-117798, Article 117798
• Main Authors: Ognyanov, Manol, Remoroza, Connie A., Schols, Henk A., Petkova, Nadezhda Tr, Georgiev, Yordan N.
• Format: Article
• Language: English
• Subjects: Chromatography, High Pressure Liquid; Enzymatic fingerprinting; HILIC-MS; Homogalacturonan; Hydrophobic and Hydrophilic Interactions; Mass Spectrometry; Molecular Weight; Mountain tea; Pectin; Pectins - chemistry; Polygalacturonase - metabolism; Polysaccharide-Lyases - metabolism; Polysaccharides - analysis; Polysaccharides - isolation & purification; Polysaccharides - metabolism; Sideritis - metabolism; Sideritis sp
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2021.117798

•Cellulose and pectin were the major constituents of mountain tea.•Mountain tea pectin was composed mostly of HG segments.•Acid-extracted pectin consisted of high Mw populations (60−100 kDa).•The presence of pectin blocks with a different Me-esterification pattern was demonstrated. The present study was conducted to investigate the structural characteristics of an acid-extracted polysaccharide fraction from mountain tea. The monosaccharide composition revealed that uronic acids (72.4 mol%) considerably predominated in the fraction, followed by smaller amounts of galactose (14.5 mol%) and glucose (6.2 mol%). The fraction contained mostly a highly methyl-esterified homogalacturonan (HG) – 71 mol%. The pectin had a high molecular weight population (∼60−100 kDa). Enzymatic fingerprinting was employed with a combination of HG degrading enzymes and LC-HILIC-MS, HPAEC, HPSEC to examine the structure in greater detail. Unsaturated oligomers released indicated the presence of large blocks of highly methyl-esterified GalA residues. Furthermore, the presence of blocks of non-esterified GalA residues and partly methyl-esterified and acetylated GalA residues in HG domain was demonstrated. The research findings provide a basis for further investigations regarding biological activity and commercial exploitation of mountain tea.