Gastrointestinal digestion and absorption characterization in vitro of zinc-chelating hydrolysate from scallop adductor (Patinopecten yessoensis)

Recent progress in the preparation of bioactive peptides using simulated gastrointestinal digestion processes

Bioactive peptides (BAPs) represent a unique class of peptides known for their extensive physiological functions and their role in enhancing human health. In recent decades, owing to their notable biological attributes such as antioxidant, antihypertensive, antidiabetic, and anti-inflammatory activities, BAPs have received considerable attention. Simulated gastrointestinal digestion (SGD) is a technique designed to mimic physiological conditions by adjusting factors such as digestive enzymes and their concentrations, pH levels, digestion duration, and salt content. Initially established for analyzing the gastrointestinal processing of foods or their constituents, SGD has recently become a preferred method for generating BAPs. The BAPs produced via SGD often exhibit superior biological activity and stability compared with those of BAPs prepared via other methods. This review offers a comprehensive examination of the recent advancements in BAP production from foods via SGD, addressing the challenges of the method and outlining prospective directions for further investigation.

Preparation, characterization and microencapsulation of walnut (Juglans regia L.) peptides-zinc chelate

In this research, a novel kind of walnut (Juglans regia L.) peptides-zinc (Zn-WPs) chelate was obtained using the mass ratio of the walnut peptides (WPs) to ZnSO4.7H2O of 3.5:1 at pH 8.5 and 50°C for 84 min, with the chelation rate of 84.5%. In comparison to walnut peptides (WPs), the contents of aspartic acid and glutamic acid in Zn-WPs chelate are approximately 27%, indicating that hydrophilic amino acids predominantly bind with walnut peptides. Following chelation with zinc ions, the ultraviolet-visible (UV) characteristic absorption peak shifted from 213 nm to 210 nm, while the average particle size of the chelate increased to 8.0 ± 0.14 µm, presenting a loose spherical structure under scanning electron microscopy. These findings suggest the formation of new substances. Fourier-transform infrared spectroscopy (FTIR) revealed carboxyl, amino, and peptide bonds as the chelation sites of WPs and zinc. The IC50 of walnut peptides-zinc (Zn-WPs) chelate is 2.91 mg/mL, indicative of a favorable DPPH radical scavenging rate. Furthermore, Zn-WPs chelate microcapsules were produced via the spray drying method, achieving an encapsulation rate of 75.67 ± 0.83% under optimal conditions. These microcapsules demonstrate robust stability across diverse environmental conditions. This study underscores the potential of Zn-WPs and its chelate microcapsules to enhance stability and bioactivity under varying circumstances. PRACTICAL APPLICATION: In this study, a new walnut peptide-zinc (Zn-WPs) chelate was prepared. The presence of zinc ions changes the structure and properties of walnut peptides and improves its stability. The production of Zn-WPs chelate microcapsules enables Zn-WPs to have strong in vitro stability under different pH and simulated gastrointestinal digestion conditions. These results provide novel insights for developing the walnut peptides as bioactive ingredients in functional foods.

The zinc absorption of the novel peptide-Zn complex in Caco-2 cells: effects of soybean peptides charge and hydrophobicity

BACKGROUND

The supplemental effect of zinc depends not only on adequate intake, but also on how efficiently it is absorbed in the small intestine. In the present study, weak hydrophobic peptides (WHP), strong hydrophobic peptides (SHP), positively charged peptides (PCP) and negatively charged peptides (NCP) were isolated from soybean peptides (SP). The peptide-Zn complexes (PCP-Zn, NCP-Zn, WHP-Zn, SHP-Zn and SP-Zn) were prepared to compare their promotion zinc absorption capacity in the Caco-2 cells monolayers model.

RESULTS

We found that the carboxyl, carbonyl and amino groups in peptide were the primary binding sites of Zn. Compared with zinc sulfate, the peptide-Zn complexes with different charge and hydrophobic peptides could improve zinc solubility at different pH. NCP-Zn had a lower Zn-binding capacity but a higher zinc absorption capacity compared to that of PCP-Zn in Caco-2 cells. In addition, the capacity of PCP-Zn to promote zinc absorption was lower than the control group (SP-Zn). There were no significant differences in transport rates, retention rates and uptake rates of WHP-Zn, SHP-Zn and SP-Zn. NCP-Zn could improve the activity of Zn-related enzymes, and the expression levels of PepT1 and ZnT1 were higher than other peptide-Zn complexes.

CONCLUSION

The promotion zinc absorption capacity of peptide-Zn complexes was not completely dependent on the Zn-binding capacity, but also depended on the charge and hydrophobicity of peptides. © 2024 Society of Chemical Industry.

Preliminary study on toxicological mechanism of golden cuttlefish (Sepia esculenta) larvae exposed to cd

BACKGROUND

Cadmium (Cd) flows into the ocean with industrial and agricultural pollution and significantly affects the growth and development of economic cephalopods such as Sepia esculenta, Amphioctopus fangsiao, and Loligo japonica. As of now, the reasons why Cd affects the growth and development of S. esculenta are not yet clear.

RESULTS

In this study, transcriptome and four oxidation and toxicity indicators are used to analyze the toxicological mechanism of Cd-exposed S. esculenta larvae. Indicator results indicate that Cd induces oxidative stress and metal toxicity. Functional enrichment analysis results suggest that larval ion transport, cell adhesion, and some digestion and absorption processes are inhibited, and the cell function is damaged. Comprehensive analysis of protein-protein interaction network and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was used to explore S. esculenta larval toxicological mechanisms, and we find that among the 20 identified key genes, 14 genes are associated with neurotoxicity. Most of them are down-regulated and enriched to the neuroactive ligand-receptor interaction signaling pathway, suggesting that larval nervous system might be destroyed, and the growth, development, and movement process are significantly affected after Cd exposure.

CONCLUSIONS

S. esculenta larvae suffered severe oxidative damage after Cd exposure, which may inhibit digestion and absorption functions, and disrupt the stability of the nervous system. Our results lay a function for understanding larval toxicological mechanisms exposed to heavy metals, promoting the development of invertebrate environmental toxicology, and providing theoretical support for S. esculenta artificial culture.

Improving Dietary Zinc Bioavailability Using New Food Fortification Approaches: A Promising Tool to Boost Immunity in the Light of COVID-19

Zinc is a powerful immunomodulatory trace element, and its deficiency in the body is closely associated with changes in immune functions and viral infections, including SARS-CoV-2, the virus responsible for COVID-19. The creation of new forms of zinc delivery to target cells can make it possible to obtain smart chains of food ingredients. Recent evidence supports the idea that the optimal intake of zinc or bioactive compounds in appropriate supplements should be considered as part of a strategy to generate an immune response in the human body. Therefore, controlling the amount of this element in the diet is especially important for populations at risk of zinc deficiency, who are more susceptible to the severe progression of viral infection and disease, such as COVID-19. Convergent approaches such as micro- and nano-encapsulation develop new ways to treat zinc deficiency and make zinc more bioavailable.