Preparation, characterization and bioactivities of selenized polysaccharides from Lonicera caerulea L. fruits.

Native polysaccharide was obtained from Lonicera caerulea L. fruits (PLP). Two selenized polysaccharides (PSLP-1 and PSLP-2) were synthesized by the microwave-assisted HNO3-Na2SeO3 method, where the selenium (Se) contents were 228 ± 24 and 353 ± 36 µg/g, respectively. The molecular weights of PLP, PSLP-1, and PSLP-2 were 5.9 × 104, 5.6 × 104, and 5.1 × 104 kDa, respectively. PSLP-1 and PSLP-2 contained the same type of monosaccharides as PLP but with different molar ratios. The main chain structure of the native polysaccharide was not changed after selenization. PLP, PSLP-1, and PSLP-2 contained the same six types of glycosidic bonds. Bioactivity assays revealed that the two selenized polysaccharides possessed better antioxidant activities than PLP, but their bile acid-binding abilities and inhibitory activities on acetylcholinesterase (AChE) had weakened. In summary, PLP, PSLP-1, and PSLP-2 may be promising Se supplements in functional foods and inhibitors for the treatment of AChE.

Optimization of ultrasound-assisted aqueous two-phase extraction of polysaccharides from seabuckthorn fruits using response methodology, physicochemical characterization and bioactivities.

BACKGROUND: Seabuckthorn fruits contains many active subtances, among them, the seabuckthorn polysaccharide is one of the main active ingredients, and exhibits diverse bioactivities. The extraction of polysaccharides from seabuckthorn fruits is the most important step for their wide applications. Ultrasound-assisted aqueous two-phase extraction (UA-ATPE) is a promising green method for extracting polysaccharides. Additionally, physicochemical characterization and antioxidant activities can evaluate the potential functions and applications in the food and medicine industries. RESULTS: Based on the single-factor experiments, 20.70% (w/w) ammonium sulfate ((NH4 )2 SO4 ) and 27.56% (w/w) ethanol were determined as the suitable composition for aqueous two-phase. The optimum conditions of UA-ATPE obtained by response surface methodology were as follows: ultrasonic power (390 W), extraction time (41 min), liquid-to-material ratio (72: 1 mL/g), and the total yield of the polysaccharides reached 34.14 ± 0.10%, The molecular weights of the purified upper-phase seabuckthorn polysaccharide (PUSP) and the purified lower-phase seabuckthorn polysaccharide (PLSP) were 65 525 and 26 776 Da, respectively. PUSP and PLSP contained the same six monosaccharides (galacturonic acid, rhamnose, xylose, mannose, glucose and galactose), but with different molar ratios. Furthermore, PUSP and PLSP displayed certain viscoelastic property, had no triple helical structure, possessed different thermal stability, surface morphology and conformation in aqueous solution. PUSP and PLSP displayed strong antioxidant properties by the assays of scavenging ability of ABTS+ ·, the protection of DNA damage and erythrocyte hemolysis. CONCLUSION: UA-ATPE significantly increased the yield of seabuckthorn polysaccharides. PUSP and PLSP were different in many aspects, such as molar ratio, surface shape and antioxidant activities. Seabuckthornpolysaccharides possess great potential in medicine and functional foods. © 2022 Society of Chemical Industry.

Degradation of blue honeysuckle polysaccharides, structural characteristics and antiglycation and hypoglycemic activities of degraded products.

In this study, H2O2-Vc (hydrogen peroxide-ascorbic acid) oxidation system under 50 and 70 °C was developed to degrade blue honeysuckle polysaccharides. The results suggested that viscosity-average molecular weight was decreased and reducing sugar content was raised with the rise of time or temperature. The degradation was fitted to the second-order reaction kinetics. The gas chromatography revealed two degraded polysaccharides were consisted of six monosaccharides (Gal A, Rha, Ala, Gal, Glu, Man) with different ratios, and eight types of sugar residues were confirmed using nuclear magnetic resonance. Based on the linearity (R1), branching (R2), branch size (R3) calculation, PD70 (purified degraded polysaccharide at 70 °C) had a more linear structure and longer side chains comparing to PD50 (purified degraded polysaccharide at 50 °C). The absence of triple helical structure and sheet-like aggregation with rough surface were confirmed by the Congo red test and scanning electron. Rheological characterization proved the two degraded polysaccharides exhibited shear-thinning behavior and viscoelastic property. Besides, the two degraded polysaccharides displayed strong antiglycation activities, inhibitory effects against α-amylase and α-glucosidase, and exhibited competitive inhibitory kinetics. These findings support the potential application of blue honeysuckle polysaccharides as the treatment of diabetes.