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In this study, an enzyme‐assisted extraction method was used to extract Orchis chusua D. Don (Salep) polysaccharide (SP), which was then modified by sulfation, acetylation, phosphorylation, and carboxymethylation to obtain modified polysaccharides. Furthermore, their degree of substitution, chemical composition, and molecular weight were evaluated. The primary structural features were characterized by UV spectra, FT‐IR spectra, Congo‐red test, and scanning electron microscope. The phosphorylated polysaccharide (SP‐P) was demonstrated the highest scavenging ability on hydroxyl radical and growth‐promoting activity on Lactobacillus Bulgaricus. The carboxymethylated polysaccharide (SP‐C) was exhibited the strongest DPPH and ABTS radical scavenging effects. The acetylated polysaccharide (SP‐A) displayed the best proliferation effects on Bifidobacterium adolescentis, whereas the sulfated polysaccharide (SP‐S) maintained moderately stable antioxidant and probiotic ability. These findings indicate that the modified polysaccharides had their potential significance as new antioxidants and probiotics for the food industry. Practical Application: This article provides a new source for the development of polysaccharide derivatives as new antioxidants and probiotics for the food industry. [ABSTRACT FROM AUTHOR]

In this study, the effects of different solvents on the viscosity of the seeds of Plantago ovata Forssk (POF) were compared to select the extraction solvent; then, a three-level and four-variable Box–Behnken design (BBD) was applied to determine the optimum extraction conditions for the maximum yields of polysaccharides from POF. Two novel protein-bound heteropolysaccharides (POFG-1a and POFG-2a) with molecular weights of 118 kDa and 113 kDa were isolated and purified by ethanol fractionation precipitation, DEAE-650 M anion exchange column chromatography, and Sephadex G-100 column chromatography. POFG-1a and POFG-2a contain 49.6% and 17.2% of polysaccharide, 26.9% and 56.4% of protein, 9.1% and 5.0% of uronic acid, respectively; they are rich in monosaccharides, Ara, Gal, and Rha, and amino acids, Ser, Pro, Ile, and Phe. Based on FT-IR, β-elimination, methylation analysis, NMR spectroscopy, and some literature data, it was found that POFG-1a is a homogeneous acidic protein-bound heteropolysaccharide with O-glycosidic linkage. The main chain of POFG-1a is connected by 1→4 Ara f and 1→5 Ara f with a high degree of branching, connected to the branch at the O-2 and O-3 positions of 1→5 Ara f. The POFGs exhibited strong scavenging activity on DPPH, ABTS, and NO free radicals, which is rarely observed in other plant polysaccharides. These results indicate that POFGs might have potential applications in the medical and food industries as novel natural antioxidants. [Display omitted] • The polysaccharide was extracted from Plantago ovata Forssk using alkali extraction. • The maximum extraction yield was 38.9 ± 0.5% optimized by Box-Behnken design. • Two novel o-linked protein-bound heteropolysaccharide were obtained. • The main chain of POFG-1a is connected by 1→4 Ara f and 1→5 Ara f. • The polysaccharides exhibited strong antioxidant effects. [ABSTRACT FROM AUTHOR]

A water-soluble polysaccharide, named GPN, with molecular mass 38.7 kDa was isolated from Glycyrrhiza glabra with hot water extraction, ethanol precipitation, and purified by column chromatography. Monosaccharide composition analysis confirmed the presence of predominant glucose (98.03%) and trace amount of mannose, arabinose, and galactose. Methylation and GC–MS analysis revealed that the main glycosidic bonds in GPN comprised 1,4-linked Glc p , T-linked Glc p , 1,4,6-linked Glc p , and 1,6-linked Glc p. Based on these results and 1D/2D NMR spectroscopy, GPN has a linear backbone of 1,4-linked α-D-Glc p and 1,6-linked α-D-Glc p which substituted at C-4 of glucose. The side chain probably composed from 1,4-linked to main side α-D-Glc p and terminal 1-linked β-D-Glc p to the C-3 of D residue. Congo red assay confirmed the existence of triple helix structure. Moreover, SEM and XRD analysis revealed that the GPN had irregular fibrous, filaments like surface; and both crystalline and amorphous structure. GPN also displayed favorable thermal stability. Moreover, G. g labra polysaccharide showed good antioxidant activity. • A water soluble polysaccharide (GPN) was isolated and purified from Glycyrrhiza glabra. • GPN was a glucose predominant glucan like polysaccharide. • GPN was a repeating unit of 1,4- α -D-Glc p and 1,6- α -D-Glc p which substituted at C-4 of glucose. • Morphological features of GPN were determined by SEM, XRD. • The IC50 of crude polysaccharide on DPPH radical scavenging activity was 0.186 mg/mL. [ABSTRACT FROM AUTHOR]