This study aimed to reveal the impacts of different extraction technologies on the physicochemical properties and in vitro biological functions of dandelion leaf polysaccharides (DLP). The results revealed that the yields (8.69–11.25%), contents of uronic acids (10.29–16.64%), contents of conjugated polyphenolics (26.56–57.67 mg GAE/g), and molecular weights (fraction 1, 4.36–7.68 × 10 4 Da; fraction 2, 3.22–4.56 × 10 4 Da) of DLP were notably affected by different extraction procedures, whereas the primary structures (rhamnogalacturonan I, homogalacturonan, and arabinogalactan segments) of DLP were overall stable according to the FT-IR and NMR analysis. Additionally, the in vitro biological functions of DLP were also obviously affected by different extraction procedures. More specifically, the strongest biological functions, including in vitro antioxidant capacities (ABTS, IC 50 = 0.54 ± 0.01 mg/mL; DPPH, IC 50 = 1.03 ± 0.02 mg/mL; Nitric oxide, IC 50 = 0.21 ± 0.01 mg/mL), inhibitory effects on the formation of advanced glycation end products (IC 50 = 1.46 ± 0.04 mg/mL), and inhibitory effects against α-glucosidase (IC 50 = 14.28 ± 0.28 μg/mL), were found in DLP-P extracted by the pressurized hot water extraction among all selected technologies, which might be owing to its high contents of uronic acids and conjugated polyphenolics according to the heat map analysis. The findings can provide fundamental knowledge to select desirable extraction technologies for preparation of DLP. Indeed, the results are beneficial to well understanding the potential structure-function relationships of DLP. Graphical abstract
Lactic acid bacteria (LAB) have already been used as fermentation strains to enhance the antioxidant capacity of polyphenols. Antioxidant capacity is one of the most important factors to inhibit advanced glycation end product (AGE) formation and could LAB increase the inhibitory capacity of procyanidins on AGEs formation? It was surprising that opposite results were obtained both in simulated food processing and gastrointestinal digestion systems. After incubation with Lactobacillus plantarum (L. plantarum), litchi pericarp oligomeric procyanidins (LPOPCs) were bioconverted to several phenolic acids, which increased the antioxidant activity as expected. However, antiglycation ability and trapping carbonyl compounds capacity both weakened and it might be the primary reason for decreasing the inhibitory effect on AGE formation. Furthermore, it was found that LPOPCs incubated with L. plantarum inhibited the activity of digestive enzymes and thus decreased the digestibility of glycated protein. Our study systematically proposed for the first time that procyanidins bioconversion is an effective means to improve the antioxidant activity but has no remarkable promoting effect on AGEs inhibition.
An amyloid fiber-ferulic acid/chitosan-ferulic acid (AF-FA/CS-FA) double network hydrogel (DN) was synthesized in two steps after prefabricating micronetworks. Ferulic acid (FA) and laccase were used to form protein and polysaccharide micronetworks, respectively. Then, AF-FA and CS-FA were induced to form covalent cross-links using genipin (GP). The phase penetration behavior of the two biopolymers in different proportions could form a homogeneous microstructure. The higher structural complexity and mechanical integrity brought by this structure may be the main reason that it improved the controlled release ability of the gels. The results from a loading capacity experiment and infrared spectra showed that the DN had acquired the AF-FA network to provide a higher load rate (9.50%), possibly because adding the polysaccharide network had increased the proportion of β-sheet structures beneficial to loading FA. The DN hydrogel containing 0.7 wt% CS-FA (DN70) showed the most tightly ordered combination of protein and polysaccharide, which had the highest storage modulus (2552.82 Pa) and the lowest solubility (91.00%). The thermal and photodegradation constants of DN70 were reduced by 75.00% and 58.29%, respectively, compared to the FA monomer . The formation of advanced glycation end products (AGEs) was reduced by 44.75% in the cake with the addition of 0.5% (w/w) DN70. These results suggest that the AF-FA/CS-FA DN can improve the range of FA applications in food products and provide an attractive strategy for polyphenols as AGEs inhibitors in baked goods.
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