Influence of Sargassum pallidum and the synergistic interaction mechanism of 6-gingerol and poricoic acid A on inhibiting ovalbumin glycation.

This study aimed to investigate the antiglycation capacity of Sargassum pallidum extract on ovalbumin (OVA) glycation, and the interaction mechanism of its active compounds, including 6-gingerol (6G) and poricoic acid A (PA). The results showed that Sargassum pallidum extract, PA and 6G had excellent suppression on the formation of fructosamine, 5-hydroxymethylfurfural (5-HMF), acrylamide and advanced glycation end products (AGEs), which was higher than aminoguanidine (AG). The combination of PA and 6G showed good synergistic effect on inhibiting the formation of AGEs. PA exhibited the strongest inhibition activity for protein glycation products, and the content of 5-HMF and acrylamide decreased from 277.44 and 10.60 µg mL-1 to 208.37 and 5.46 µg mL-1, respectively, at 30.08 × 10-5 M compared with the control group. 6G and PA quenched the fluorescence of OVA with a static mechanism, and enhanced the hydrophilic microenvironment of the tyrosine (Tyr) and tryptophan (Trp) residues. The binding of 6G and PA with OVA was spontaneous and driven by hydrogen bonds and van der Waals interactions. Molecular docking indicated that 6G and PA entered the hydrophobic cavity of OVA, and formed hydrogen bonds with Ser103, Leu101 and Thr 91. These findings suggested that Sargassum pallidum extract, PA and 6G have great potential as antiglycation inhibitors to treat diabetes complications in healthy food.

Study on the pharmacokinetics of mulberry fruit polysaccharides through fluorescence labeling.

A sensitive and efficient fluorescence labeling method was developed and validated for the microanalysis and detection of polysaccharides. Fluorescein isothiocyanate (FITC) was successfully labeled on mulberry fruit polysaccharides (MFP) through a reductive amination reaction with the assistant of tyramine. The fluorescent labeled polysaccharides (FMFP) was identified by fluorescence, UV-visible, flourier transform infrared (FT-IR) and 1H NMR spectrum. Results demonstrated that the labeling efficiency of FMFP was 0.32%, and the FMFP was stable in simulated digestion fluid without cytotoxicity. The pharmacokinetics and biodistribution after administration were analyzed in rats, which indicated that the FMFP obtained could be absorbed in a short time (tmax 0.50 h) but eliminated slowly (t1/2 8.77 ± 1.38 h). At 24 h after administration, the polysaccharide could be tested mainly in intestine, stomach, liver and kidney. The FITC labeling method lays a foundation for investigating the absorption and metabolism of MFP, and provides references for the microanalysis research of bioactive polysaccharides.

Investigation into the mechanisms of quercetin-3-O-glucuronide inhibiting α-glucosidase activity and non-enzymatic glycation by spectroscopy and molecular docking.

The inhibition of α-glucosidase and glycation is closely related to the treatment of type 2 diabetes mellitus (DM) and its complications. In this study, quercetin-3-O-glucuronide (Q3GA) showed reversible and mixed-mode inhibition of α-glucosidase activity, with an IC50 value of 108.11 ± 4.61 µM. This was mainly due to the spontaneous formation of Q3GA-α-glucosidase driven by hydrogen bonding and van der Waals forces, which could change the microenvironments and conformation of α-glucosidase. In addition, Q3GA showed strong suppression of the formation of glycation products, including fructosamine, advanced glycation end products (AGEs), and 5-hydroxymethylfurfural (5-HMF). Molecular docking analysis demonstrated that Q3GA entered the hydrophobic pocket of ovalbumin to form six hydrogen bonds with amino acid residues, which affected the glycation process. These findings indicate that Q3GA is an excellent inhibitor of α-glucosidase and glycation, and promote its development as a drug or dietary supplement for DM.

Effect of Fructus Mori. bioactive polysaccharide conjugation on improving functional and antioxidant activity of whey protein.

Whey protein with high biological and technological values is an excellent source of nutrition. However, the limited functional properties prevent its widespread applications in food industry. In this study, the whey protein functionality was improved via glycation with mulberry fruit polysaccharide by Maillard reaction. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile and free amino groups determination confirmed the glycation occurred between whey protein and mulberry fruit polysaccharide. The emulsion capacity and stability of the conjugates were 1.40-fold and 1.52-fold higher than that of whey protein. The conjugates also exhibited remarkably improved antioxidant activity. The fish oil emulsion coated by conjugates demonstrated smaller droplet size, better storage and oxidative stability than that stabilized by whey protein. The findings would be of vital importance for updated understanding of the modification in emulsifying properties of proteins by glycation with natural bioactive polysaccharides as well as for the development of healthy foods.