Walnut-derived peptide PPKNW alleviate polystyrene microparticles-induced growth inhibition of Lactobacillus rhamnosus GG

Prediction and evaluation of purine-binding peptides using integrated molecular descriptors and docking analysis

Peptides and purines frequently coexist in food systems and can form specific molecular interactions, which may influence the physicochemical properties and bioavailability of purines. However, the structural basis and binding mechanisms of these peptide-purine interactions remain poorly understood. This study established a comprehensive screening approach combining molecular docking and descriptor analysis to evaluate peptide-purine binding interaction. The analysis revealed that strong-binding peptides were likely characterized by reduced cyclic structures and aromatic rings, with elevated electron-donor groups primarily composed of N and O atoms (p < 0.0001). These electron-rich functional groups appeared to enhance the formation of hydrogen bonds, which could play a crucial role in stabilizing peptide-purine complexes. Among various dietary purines, hypoxanthine emerged as the predominant species in processed meat products, warranting particular attention. Fluorescence spectroscopy experiments validated the computational predictions, confirming that the tetrapeptide WDQW (Peptide Purine Binding Score: -3.32) formed stable complexes with hypoxanthine exhibiting static quenching characteristics, primarily driven by hydrophobic interactions and hydrogen bonding. This investigation provides fundamental insights into peptide-purine binding mechanisms and establishes a screening platform for identifying peptide sequences with enhanced purine-binding properties, which might be valuable for modulating purine bioavailability in food systems.

The role of gut microbiota in MP/NP-induced toxicity

Microplastics (MPs) and nanoplastics (NPs) are globally recognized as emerging environmental pollutants in various environmental media, posing potential threats to ecosystems and human health. MPs/NPs are unavoidably ingested by humans, mainly through contaminated food and drinks, impairing the gastrointestinal ecology and seriously impacting the human body. The specific role of gut microbiota in the gastrointestinal tract upon MP/NP exposure remains unknown. Given the importance of gut microbiota in metabolism, immunity, and homeostasis, this review aims to enhance our current understanding of the role of gut microbiota in MP/NP-induced toxicity. First, it discusses human exposure to MPs/NPs through the diet and MP/NP-induced adverse effects on the respiratory, digestive, neural, urinary, reproductive, and immune systems. Second, it elucidates the complex interactions between the gut microbiota and MPs/NPs. MPs/NPs can disrupt gut microbiota homeostasis, while the gut microbiota can degrade MPs/NPs. Third, it reveals the role of the gut microbiota in MP/NP-mediated systematic toxicity. MPs/NPs cause direct intestinal toxicity and indirect toxicity in other organs via regulating the gut-brain, gut-liver, and gut-lung axes. Finally, novel approaches such as dietary interventions, prebiotics, probiotics, polyphenols, engineered bacteria, microalgae, and micro/nanorobots are recommended to reduce MP/NP toxicity in humans. Overall, this review provides a theoretical basis for targeting the gut microbiota to study MP/NP toxicity and develop novel strategies for its mitigation.

Effects of partial reduction of polystyrene micro-nanoplastics on the immunity, gut microbiota and metabolome of mice

Microplastic (MP) and nanoplastic (NP) could cause gut microbiota alterations. Although micro/nanoplastic (MNP) degradation is attracting increasing scientific interest, the evaluation of MNP reduction in gut needs to be further investigated. This study aimed to determine whether partial reduction of polystyrene MNP in gut could affect the immunity, gut microbiota and metabolome of mice. Serum eotaxin/CCL11 was at a lower level in the mice exposed to 200 μg and 500 μg NP (i.e., 2NP and 5NP groups, respectively) compared to those exposed to 500 μg MP (i.e., 5 MP group), while serum IL-2 and IL-4 were both greater in the 5NP group compared to the 5 MP group. The gut bacterial alpha diversity, fungal diversity and evenness were all similar among the MNP and control groups. However, the gut fungal richness was greater in both the 5NP and 5 MP groups compared to the control group. The gut bacterial and fungal compositions were both different between the MNP and control groups. Multiple gut bacteria and fungi showed different levels between the 2NP and 5NP groups, as well as between the 2NP and 5 MP groups. Increased Staphylococcus and decreased Glomus were determined in the 2NP group compared to both the 5NP and 5 MP groups. A Lactobacillus phylotype was found as the sole gatekeeper in the bacterial network of the 2NP group, while a Bifidobacterium phylotype contributed most to the stability of the bacterial networks of both the 5NP and 5 MP groups. Multiple differential gut metabolic pathways were found between the 2NP and 5NP/5 MP groups, and mTOR signaling pathway was largely upregulated in the 2NP group compared to both the 5NP and 5 MP groups. The relevant results could help with the evaluation of partial reduction of MNP in gut.

Peptides with Charged Amino Acids Mitigate nZnO-Induced Growth Inhibition of Lactobacillus rhamnosus LRa05

Growing concern is about the potential side effects of nanomaterials from food packaging, notably zinc oxide nanoparticles (nZnO). Previous research revealed that walnut-derived peptides could mitigate this inhibitory effect, but the mechanism involved is unclear. Here, we found that not all peptides have such an effect. Based on the growth inhibition model of Lactobacillus rhamnosus LRa05 induced by nZnO, we assessed the protective effects of various peptides. Notably, four peptides containing charged amino acids (PPKNW, WPPKN, ADIYTE, and WEREEQE) were found to effectively alleviate the growth inhibition phenomenon. We hypothesize that the peptide-nZnO interaction modifies this effect, as confirmed through infrared, Raman, and fluorescence spectroscopy. Our results highlight amide bonds, amino groups, carboxyl groups, and benzene rings as key peptide binding sites on nZnO, with static quenching primarily due to hydrogen bonds and van der Waals forces. This study elucidates peptide characteristics in nZnO interactions, facilitating a deeper exploration of food matrix-nanocomposite interactions.

Effect of walnut peptide‐ZnO nanocomposites on the colon adhesion behavior of Lactobacillus rhamnosus LRa05

When the nanoparticles (NPs) in food contact materials are exposed, they may be ingested with the food matrix, resulting in unknown impacts. Here, the biological response of the nanocomposites of nano zinc oxide (nZnO) and walnut protein‐derived peptides (i.e., PW5, WN5, AE6, and WE7) on the Lactobacillus rhamnosus LRa05 growth and adhesion was studied. In an in vitro mouse intestinal adhesion model, we first spotted that the probiotics LRa05 primarily adhered to and colonized the colonic segment. nZnO effectively inhibited the growth and adhesion properties of LRa05 at high concentrations (≥ 1000 μg/mL). Fortunately, when compared to the individual nZnO, the nZnO‐walnut‐derived peptides nanocomposites significantly increased the growth of LRa05. It was found that the alterations in the adhesion ability of LRa05 after treatment with various substances (nZnO and nanocomposites of nZnO‐walnut peptides) were related to the auto‐aggregating property on the LRa05 surface. These results shed light on the effect of food matrices on the safety of nanomaterials in food, and they may have far‐reaching implications for the use of nanomaterials in the food industry.