Polysaccharides from Semen Astragali complanati (SACP) were obtained by hot water extraction followed by ethanol precipitation and separated by fractional precipitation with 20% and 25% ethanol into two fractions: SACP-20 and SACP-25, which was the major one with higher purity. Their physicochemical properties were determined by colorimetric methods, and their molecular mass distribution, conformation in solution and monosaccharide composition were analyzed by size exclusion chromatography coupled with muti-angle laser light scattering (SEC-MALLS) and high-performance anion exchange chromatography coupled with pulsed amperometric detection (HPLC-PAD). Results indicated that SACP-25 was a homogenous polysaccharide with total sugar content of 87.40% and was composed of galactose (42.92%) and mannose (57.08%). Meanwhile, it showed a random coil conformation in 0.1 mol/L NaNO₃. Analysis by methylation combined with gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy revealed that the main chain of SACP-25 was composed of β-1,4-linked-mannopyranose (Manp) with galactopyranose (Galp) side chains attached to C-6 of the Manp residues. This study indicated that Semen A. complanati is good natural source of galactomannans as a water-soluble dietary fiber. The results of this study may provide theoretical support for the ordered structure of polysaccharides and also provide a theoretical foundation for the development and application of SACP in the functional food and pharmaceutical industries.

In this study, a purified polysaccharide from Euodiae Fructus (EFP-40) was obtained by sequential water extraction, decolorization, and gradient ethanol precipitation. Chemical methods such as colorimetry and methylation, as well as instrumental techniques such as high performance gel permeation chromatography (HPGPC), gas chromatographymass spectrometry (GC-MS), and high performance anion exchange chromatography coupled with an amperometric detector (HPAEC-PAD) were used to characterize its physicochemical properties and structural characteristics. An in vitro fecal fermentation model was established to determine the effect of EFP-40 on the gut microbiota and short-chain fatty acids (SCFAs) production. Results indicated that the molecular mass of EFP-40 was 9.7 × 10⁴ Da, mainly consisting of rhamnose (4.36%), glucose (10.24%), arabinose (22.24%), galactose (24.79%) and galacturonic acid (33.36%). The degrees of methyl esterification (DM) and acetylation (DA) were 17.06% and 8.12%, respectively, and the polysaccharide was possibly a complex pectin containing structural domains such as RG-I (rhamnogalacturonan I) and homogalacturonan (HG). In addition, EFP-40 promoted the production of SCFAs, and regulated the gut microbiota by increasing the relative abundance of beneficial bacteria such as Bacteroidetes and Phascolarctobacterium, reducing the relative abundance of harmful bacteria such as Fusobacteriota and Proteobacteria, as well as the ratio of Firmicutes to Bacteroidetes. In conclusion, EFP-40 is a highly branched complex pectic polysaccharide, which can significantly regulate the gut microbiota, indicating its prebiotic potential.

In this study, the effects of binary matrices (amino-4-hydroxybenzoic acid (AHB)/2,5-dihydroxybenzoic acid (DHB), 3-hydroxycoumarin (3-HC)/DHB), ionic liquid matrices (N,N-dimethylaniline (DMA)/DHB, 2-(p-hydroxybenzene-azo) benzoic acid (HABA)/1,1,3,3-tetramethylguanidine (TMG), 4-hydroxycoumaric acid (CA)/TMG, 2,4,6-trihydroxyacetophenone (THAP)/TMG, N-methylaniline (NMA)/DHB) and reactive matrices (3-hydrazylbenzoic acid (3-HBA)/DHB, 6-hydrazine niacin (HYNIC)/DHB, 2-hydrazopyridine (2-HPM)) on the analysis of maltooctaose, trigalacturonic acid and Dextran T6 by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) were studied and compared with those of three solid matrices (DHB, THAP, α-cyano-4-hydroxycinnamic acid). The effects of various matrix solvents on the detection of maltoocatose as an oligosaccharide were studied. Meanwhile, the effects of solvent, reaction time and reaction temperature on the derivatization rate were addressed using reactive matrices. Results showed that all three matrices exhibited good detection performance for maltooctalose with good spectral reproducibility and increased peak intensity. Using the reactive substrates, the derivatization temperature was at least 65 ℃. 2-HPM had high derivatization efficiency, up to (96.28 ± 0.28)%, under all conditions, and using this reactive substrate, the derivatization reaction could be completed within a short period of time (15 min), but the derivatization rate was not high. While the signal-to-noise ratios of 3-HBA/DHB and HYNIC/DHB derived oligosaccharides were high, their derivatization rates were relatively low with a reaction time of at least 60 min. In addition, the concentration of oligosaccharides had a significant effect on the derivatization efficiency; when the concentration was less than 10⁸ fmol/L, the derivatization signal was very low or undetected. The m/z signal of tri-galacturonic acid was significantly higher when using THAP and 3-HBA/DHB compared to other matrices. For Dextran T6, both binary and ionic liquid matrices exhibited better detection performance, and AHB/DHB, 3-HC/DHB, THAP/TMG, and NMA/DHB could be used to detect a wider range of molecular mass, including polysaccharides with a polymerization degree of up to 36. The results of this study provide a reference for the analysis and identification of carbohydrates.